GroupDIY

Project Specific Discussions => Filters/Equalizers => Topic started by: jsteiger on April 18, 2012, 07:49:21 PM

Title: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on April 18, 2012, 07:49:21 PM
Since the kits have started shipping, it's time for the support thread!  :)

**This is a semi complicated build. It is very important to read completely thru the Assembly Aid before starting on anything. There are some points made in the doc that can save you much time and prevent crucial errors during the build.

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September 21st, 2015 Update:
All support docs for this project can be found on the recently added Support Docs (http://capi-gear.com/catalog/support_docs.php) page at www.capi-gear.com
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March 5th, 2016 Update:
Rev B boards are now shipping for the LC53A. To easily identify, the Rev B boards are green and they have the CAPI® label affixed. The receiver circuit has been changed so that a CMRR adjustment is no longer needed. Besides that, most of the circuit is the same. To find out what else has been changed, please read the Rev B Addendum (http://www.capi-gear.com/catalog/images/gallery/LC53A/Build-docs/Rev_B/0_CAPI-LC53A-Rev-B-Addendum.pdf). Like with all projects, it is crucially imperative that you follow the BOM that matches the revision of the PCB that you are building.
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Some details can be found here http://capi-gear.com/catalog/product_info.php?cPath=22_117_119_171&products_id=327

(http://www.capi-gear.com/catalog/images/gallery/capi_temp/temp-LC53A.jpg)

Cheers, Jeff
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on April 18, 2012, 07:50:02 PM
Here are a few pics to help point out some important things. They are not the best quality but will hopefully make their point until 'Chung can work his magic.

Click them to enlarge!!

This is the recommended LED bending.
(http://www.capi-gear.com/catalog/images/gallery/LC53A/Build-docs/pics/LED.gif) (http://www.capi-gear.com/catalog/images/gallery/LC53A/Build-docs/pics/LED.jpg)

This shows the standoffs and how the 2 boards fit together.
(http://www.capi-gear.com/catalog/images/gallery/LC53A/Build-docs/pics/standoffs.gif) (http://www.capi-gear.com/catalog/images/gallery/LC53A/Build-docs/pics/standoffs.jpg)

This shows the proper orientation of the Main-PCB to the steel bracket tabs.
(http://www.capi-gear.com/catalog/images/gallery/LC53A/Build-docs/pics/rear-pcb-mounting.gif) (http://www.capi-gear.com/catalog/images/gallery/LC53A/Build-docs/pics/rear-pcb-mounting.jpg)

In this pic you can see that none of the leads or solder joints protrude above the steel bracket.
(http://www.capi-gear.com/catalog/images/gallery/LC53A/Build-docs/pics/trimmed-leads.gif) (http://www.capi-gear.com/catalog/images/gallery/LC53A/Build-docs/pics/trimmed-leads.jpg)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: chunger on April 18, 2012, 07:51:11 PM
Don't mind me.  I'm just getting situated here.

What's in the box?

(http://studio939.zenfolio.com/img/s10/v18/p392300202-4.jpg)

A little inventory to get the lay of the land.

(http://studio939.zenfolio.com/img/s1/v21/p275290866-4.jpg)

I think Jeff has really raised the bar a few more notches on this kit.

(http://studio939.zenfolio.com/img/s3/v38/p507648283-4.jpg)

OK. . . from the top.  Jeff suggests building the Main PCB first.  The parts needed are pictured below:

(http://studio939.zenfolio.com/img/s3/v44/p176024056-4.jpg)

Referencing the BOM, I identify and sort all of the electronic components.

(http://studio939.zenfolio.com/img/s3/v44/p39156324-5.jpg)

Make sure you are able to read the small markings on the ceramic capacitors.

(http://studio939.zenfolio.com/img/s2/v52/p372732915-6.jpg)

First, I place my resistors.

(http://studio939.zenfolio.com/img/s3/v43/p348697146-4.jpg)

Then, bend the leads and solder from the back side.

(http://studio939.zenfolio.com/img/s3/v42/p46356129-4.jpg)

And, we're populating. . . CR1 and CR2 were next.  Generally, I just place the components in order of shortest to tallest.

(http://studio939.zenfolio.com/img/s2/v53/p454036862-4.jpg)

(http://studio939.zenfolio.com/img/s3/v45/p463974787-4.jpg)

Polarity matters on the Electrolytic capacitors.  Make sure you align the stripe side with the "-" marked holes.  Also, the longer of the legs on the radial caps are "+".  It does not hurt to triple check these before soldering.

(http://studio939.zenfolio.com/img/s2/v52/p232676890-4.jpg)

(http://studio939.zenfolio.com/img/s3/v44/p8294120-4.jpg)

Next, locate the opamp sockets for A1 and A2.

(http://studio939.zenfolio.com/img/s3/v42/p150054991-4.jpg)

Insert these from the back side of the PCB.

(http://studio939.zenfolio.com/img/s3/v43/p288635638-4.jpg)

I had to set my soldering temp up significantly to get these to flow in smoothly.  I solder from the back side and attempt to just flow the solder down into the front side of the PCB securing the sockets. 

(http://studio939.zenfolio.com/img/s3/v45/p436883158-4.jpg)

When new, the sockets are REALLY stiff. . . so, if you are building your own opamps, now is a good time to run one of the loose pins into and out of each socket a couple of times.  This will make initial insertion of opamps much easier and you run a smaller risk of bending pins.

(http://studio939.zenfolio.com/img/s2/v53/p101428619-4.jpg)

This PCB is now ready for CMRR calibration. . . but, I happen not to have op-amps on hand for the build.  According to Gary's post in this thread, it seems the GAR1731 is a VERY tasty choice for this build and it makes a lot of logical sense in an EQ especially when cranking on those frequencies to have the smooth 1731 in line.  So, for me. . . for this build, I'll start out with some GAR1731's.  NOTE: Please test opamps thoroughly prior to using them in a fresh build.

Since I'm actually building a pair, I will need 4 GAR1731's.  Each EQ requires 2 opamps.  There are a lot of flavors and excellent options available from Classic Audio Products.  I usually default to the GAR2520 complete kits because they have performed really well for me as a nice baseline that is true to the vintage API sound. . . and I'm cheap, but Jeff also carries Scott Leiber's nice red dot and blue dot assembled op amps and for that matter assembled and tested GAR2520 and GAR1731 op amps as options on these LC53A kits.

It's slow but therapeutic to build op-amps, so I decided to build a few up myself.

(http://studio939.zenfolio.com/img/s3/v44/p278235240-5.jpg)

and, we're populating.

(http://studio939.zenfolio.com/img/s2/v53/p137109370-4.jpg)

(http://studio939.zenfolio.com/img/s3/v45/p94524505-4.jpg)

(http://studio939.zenfolio.com/img/s2/v52/p215127405-4.jpg)

(http://studio939.zenfolio.com/img/s3/v43/p28048649-4.jpg)

(http://studio939.zenfolio.com/img/s3/v45/p177247580-4.jpg)

(http://studio939.zenfolio.com/img/s3/v44/p298172507-4.jpg)

(http://studio939.zenfolio.com/img/s3/v43/p245736386-4.jpg)

(http://studio939.zenfolio.com/img/s2/v53/p199154614-4.jpg)

And there we are. . . 4 freshly hatched GAR1731 op-amps.

(http://studio939.zenfolio.com/img/s2/v50/p534656703-4.jpg)

With opamps built, I set up for CMR calibration per the VC528 instructions and jeff's assembly aid document posted above.  This is the way I have configured my JLM powerstation for 51X use, and it is handy for testing and calibration on the bench.

(http://studio939.zenfolio.com/img/s2/v51/p769505055-4.jpg)

In this thread, a very slick calibration adapter is pictured that I think is absolute genius.  Not so much genius but equally functional is my calibration cable that I made per the VC528 CMR calibration instructions with 2 closely matched resistors.  These were the photos taken when I made my cable re-posted here as they are pertinent to this build.

(http://studio939.zenfolio.com/img/s11/v34/p76511216-4.jpg)

(http://studio939.zenfolio.com/img/s11/v30/p86133225-4.jpg)

Here I mark the cable so I know it's a calibration cable.

(http://studio939.zenfolio.com/img/s11/v30/p402289108-4.jpg)

(http://studio939.zenfolio.com/img/s11/v29/p215602644-4.jpg)

Setting aside the "-" cable on one end to feed identical signal to pins 2 and 3.

(http://studio939.zenfolio.com/img/s11/v34/p487932866-4.jpg)

(http://studio939.zenfolio.com/img/s11/v32/p179785986-4.jpg)

and the other end of the cable wired as normal

(http://studio939.zenfolio.com/img/s11/v30/p529547005-4.jpg)

My test cable complete.

(http://studio939.zenfolio.com/img/s11/v34/p239449084-4.jpg)

Here, I set up my 400Hz signal on a function generator and send through my special test cable into the main board.  I also connect my scope to the negative side of C2. 

(http://studio939.zenfolio.com/img/s1/v46/p924575928-4.jpg)

(http://studio939.zenfolio.com/img/s3/v44/p715567189-4.jpg)

notice, per the instructions, I am using a tested/proven GAR2520 instead of my freshly hatched 1731 for this calibration.  I did confirm on my new opamp though to verify that the setting was the same on the opamp designated for this build.

I also connected the ground of my scope to the common terminal on the other opamp.  It's here that I accidentally shorted the common to the -16V rail and created black smoke on my power supply which required a full stop and a trip to the electronics store :P

(http://studio939.zenfolio.com/img/s1/v49/p705744795-4.jpg)

Please use caution if you decide to use this terminal in your testing.  I used it because it gave me a slightly cleaner visual from my scope to observe because I was at the limit of my instrument's ability to read with such a small signal.

With a few twists on the trim pot, I was able to reduce the signal to the lowest measurable level on my scope.

(http://studio939.zenfolio.com/img/s2/v52/p985281497-4.jpg)

I increased the output of my signal generator a bit so I could see a slight sine wave change continuously all the way through the lowest point of adjustment and set my trim pot there.  Hopefully this methodology is sound.

(http://studio939.zenfolio.com/img/s1/v46/p788110310-4.jpg)

Previously, I used the DAW method in studio to calibrate my VC528's, but I do not have a functioning DAW currently at my house, so I decided to try the scope this time around.  If I recall correctly, the DAW method was just as accurate if not a bit easier.  Certainly it did not involve frying my test power supply.




Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: chunger on April 18, 2012, 07:51:26 PM
OK. . . next we start in on the cut/boost PCB.

(http://studio939.zenfolio.com/img/s1/v22/p635628880-4.jpg)

First step is to locate and install the sockets for the CT05 and DF.2 opamps and discrete voltage followers.

(http://studio939.zenfolio.com/img/s1/v46/p660213436-4.jpg)

(http://studio939.zenfolio.com/img/s3/v40/p784878447-4.jpg)

These are installed and soldered from the TOP SIDE of the PCB.

(http://studio939.zenfolio.com/img/s11/v34/p1008525867-4.jpg)

It cannot be emphasized enough on this step.  Use sufficient heat to smoothly solder these sockets and most importantly. . . USE ONLY THE ABSOLUTE MINIMUM AMOUNT OF SOLDER TO SET THE PART!!! Remove heat and solder IMMEDIATELY when when the solder liquifies and the socket settles into the PCB.

(http://studio939.zenfolio.com/img/s3/v40/p941819436-4.jpg)

After soldering in these sockets, insert one of the cut-off leads from a large capacitor to break it in as it can be quite difficult the first time a pin is inserted into the socket. 

(http://studio939.zenfolio.com/img/s1/v48/p1042197866-4.jpg)

You may discover as I did on this step that solder can migrate very quickly under this socket and seize up the contact fingers making it impossible to seat a pin.  I fancy myself a rather smooth soldering iron pilot and seldom muck things up, but I managed to mangle 3 of these sockets (3 extras are luckily provided in the kit) by keeping heat on the joint too long and/or using too much solder.  The "C" or common terminals that are connected to the ground plane can be EXTREMELY difficult to remove if they are mucked up.  I found the only way I could remove them was to go from the back side of the PCB and fill the socket with hot solder and push it out the front side w/ the soldering iron.  I almost destroyed one of the pads, but eventually cleared the solder from the pad by using Hakko 808 de-soldering tool on the front side while simultaneously sticking my soldering iron into the pad from the back side.

(http://studio939.zenfolio.com/img/s1/v22/p665679930-4.jpg)

Rather exciting. . . the 2nd LC53A kit went together without any issues because I remembered to use the absolute minimum necessary amount of solder and keep the heat on only long enough to set the part.

(http://studio939.zenfolio.com/img/s11/v29/p702701244-4.jpg)

Next, I sort the resistors for the CB board.  There are a few :)

(http://studio939.zenfolio.com/img/s2/v52/p248309516-5.jpg)

And, place them on the PCB.

(http://studio939.zenfolio.com/img/s2/v51/p204859590-4.jpg)

Bend leads to hold the components in place, and solder from the back side.

(http://studio939.zenfolio.com/img/s3/v43/p185512630-4.jpg)

As recommended by jsteiger in the build manual, I purchased a CHP-170 cutter on Ebay for ~$6.00  It really does allow you to cut close to the PCB as required on this board to provide clearance for the metal frame.

(http://studio939.zenfolio.com/img/s3/v42/p172541979-4.jpg)

(http://studio939.zenfolio.com/img/s3/v41/p282563083-4.jpg)

resistors are populated.

(http://studio939.zenfolio.com/img/s2/v50/p241357292-4.jpg)

(http://studio939.zenfolio.com/img/s2/v52/p315388504-4.jpg)

One more view of closely-cut leads on the back side of the PCB using the CHP-170 cutters.

(http://studio939.zenfolio.com/img/s3/v42/p363549862-4.jpg)

Ok . . . resistors are done.  Now for capacitors.

(http://studio939.zenfolio.com/img/s1/v46/p751037809-5.jpg)

Note the marking conventions on the yellow polyester film caps.

(http://studio939.zenfolio.com/img/s3/v43/p775250541-5.jpg)

and, we're populating.  Ceramic caps first.

(http://studio939.zenfolio.com/img/s3/v45/p987887904-4.jpg)

Mind the polarity on the electrolytic caps.  Solid line indicates negative side.

(http://studio939.zenfolio.com/img/s1/v46/p778650302-4.jpg)

(http://studio939.zenfolio.com/img/s2/v52/p721298170-4.jpg)

(http://studio939.zenfolio.com/img/s2/v52/p665494373-4.jpg)

Next, locate the baggie with headers.

(http://studio939.zenfolio.com/img/s2/v52/p616646718-4.jpg)

And locate these parts.

(http://studio939.zenfolio.com/img/s3/v38/p1001365093-4.jpg)

And install J3 and J4

(http://studio939.zenfolio.com/img/s1/v48/p916992307-4.jpg)

(http://studio939.zenfolio.com/img/s1/v47/p797683466-4.jpg)

Use the 3M jumpers to set output load to "HiZ"

(http://studio939.zenfolio.com/img/s1/v47/p1043244701-4.jpg)

Next, locate the baggie with switches.

(http://studio939.zenfolio.com/img/s2/v52/p905839254-4.jpg)

And pull out SW1 which looks like this.

(http://studio939.zenfolio.com/img/s2/v51/p720356956-4.jpg)

and install. . .

(http://studio939.zenfolio.com/img/s3/v38/p584746227-4.jpg)

and trim leads tight to the PCB.

(http://studio939.zenfolio.com/img/s3/v43/p997216596-4.jpg)

Next, pull out 2 of the grayhill switches.  Make sure to pull the ones with single front pin (some have 2).

(http://studio939.zenfolio.com/img/s1/v46/p764694457-4.jpg)

And install SW4 and SW6

(http://studio939.zenfolio.com/img/s1/v46/p910880397-4.jpg)

I solder 1 pin only on each.

(http://studio939.zenfolio.com/img/s1/v49/p977542702-4.jpg)

(http://studio939.zenfolio.com/img/s1/v49/p811501114-4.jpg)

and verify that the grayhill is sitting flush to the PCB and the front face is perpendicular.

(http://studio939.zenfolio.com/img/s1/v46/p1015471894-4.jpg)

(http://studio939.zenfolio.com/img/s2/v53/p956763559-4.jpg)

Once everything is lined up, solder the remaining leads in and trim the leads tight to the PCB.

(http://studio939.zenfolio.com/img/s3/v44/p721764093-4.jpg)

Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: chunger on April 18, 2012, 07:51:41 PM
Next, locate the baggie with stand-offs and mounting hardware.

(http://studio939.zenfolio.com/img/s3/v43/p1019533399-4.jpg)

and pull  3/8" screws and 1/8" standoffs.

(http://studio939.zenfolio.com/img/s3/v44/p980823007-4.jpg)

Intall screws on the back side of the CB PCB.

(http://studio939.zenfolio.com/img/s2/v52/p1009879810-4.jpg)

And standoffs on the front side.

(http://studio939.zenfolio.com/img/s2/v53/p1055681260-4.jpg)

Center these screws to the best of your ability in the solder pad on the PCB and tighten fully.

(http://studio939.zenfolio.com/img/s3/v42/p742586320-5.jpg)

Next, dig out the 7 pin header.

(http://studio939.zenfolio.com/img/s2/v50/p1008479615-4.jpg)

And place on the CB PCB.  important: DO NOT SOLDER THIS HEADER AT THIS TIME.

(http://studio939.zenfolio.com/img/s2/v52/p883294867-4.jpg)

Locate these bits:

(http://studio939.zenfolio.com/img/s3/v42/p942494689-4.jpg)

And assemble the main PCB to the CB PCB.

(http://studio939.zenfolio.com/img/s3/v44/p750455333-4.jpg)

Loosely install the long standoffs on the outside locations.

(http://studio939.zenfolio.com/img/s2/v50/p772248990-4.jpg)

(http://studio939.zenfolio.com/img/s1/v48/p813947663-4.jpg)

And the crush washer and nut in the middle location.

(http://studio939.zenfolio.com/img/s3/v45/p977291409-4.jpg)

Place the assembly on a flat, straight surface and set the length from the front of the PCB to the end of the connector pins at 5.87 inches.  I use my trusty dial calipers to make the measurement.

(http://studio939.zenfolio.com/img/s1/v47/p696161996-4.jpg)

 It may take a few tries to get everything square and correct on the length, but when you have everything lined up, tighten down all of the nuts and standoffs to final torque which is as tight as you can go without breaking anything.

(http://studio939.zenfolio.com/img/s3/v44/p322041775-4.jpg)

Flip the assembly over, press the 7 pin header towards the main PCB and solder.  Pushing the header this direction makes it so you do not have to cut the pins after soldering as they will sit low enough to clear the metal chassis.

(http://studio939.zenfolio.com/img/s2/v51/p324760576-4.jpg)

And solder the 7 pin header on the main PCB side as well.

(http://studio939.zenfolio.com/img/s2/v51/p342942352-4.jpg)

Next find the baggie with pushbuttons and stickers.

(http://studio939.zenfolio.com/img/s2/v50/p513328611-4.jpg)

and pull the cap for SW1

(http://studio939.zenfolio.com/img/s3/v43/p71003211-4.jpg)

(http://studio939.zenfolio.com/img/s2/v53/p186474999-4.jpg)

Next we insert our assembled unit into the metal chassis.

(http://studio939.zenfolio.com/img/s1/v49/p75025956-4.jpg)

locate these 2 1/4" screws.

(http://studio939.zenfolio.com/img/s2/v53/p396662626-4.jpg)

and fasten the back side of the main PCB to the chassis after aligning and possibly tweaking the chassis to fit.

(http://studio939.zenfolio.com/img/s2/v51/p530414049-5.jpg)

temporarily place the faceplate.

(http://studio939.zenfolio.com/img/s3/v43/p86937391-5.jpg)

Align the faceplate with SW1

(http://studio939.zenfolio.com/img/s2/v52/p534391347-4.jpg)

and loosely secure the grayhill switches to the faceplate.  Here I am using some console tape over my socket to protect the faceplate from scratches.

(http://studio939.zenfolio.com/img/s1/v47/p270083930-4.jpg)

Align the faceplate center and dead parallel to the metal chassis so the gaps are even on both sides.

(http://studio939.zenfolio.com/img/s3/v42/p501942741-4.jpg)

(http://studio939.zenfolio.com/img/s3/v44/p476320034-4.jpg)

and tighten down the grayhill switches just firmly enough to temporarily hold.

Next, install the LED.  Note:  The short lead on the LED goes into the PCB hole that the arrow is pointing towards.

(http://studio939.zenfolio.com/img/s2/v51/p527714405-4.jpg)

The leads must be bent to align with the holes.  I also had to sand the ends of the LED with some 220 grit sandpaper because they were slightly too wide to fit into the PCB's holes.

(http://studio939.zenfolio.com/img/s2/v52/p357643991-4.jpg)

The LED will look something like this with a few 45 degree bends.

(http://studio939.zenfolio.com/img/s3/v45/p63004196-4.jpg)

Position the 1/2" clear pieces of shrink tubing on the LED's leads.

(http://studio939.zenfolio.com/img/s2/v51/p220016770-4.jpg)


And position the LED.

(http://studio939.zenfolio.com/img/s1/v47/p512855102-4.jpg)

Before soldering, grab an available Grayhill switch and insert.

(http://studio939.zenfolio.com/img/s2/v53/p151618179-4.jpg)

check to make sure the LED leads clear the grayhill switch and will not short to the switch's chassis.

(http://studio939.zenfolio.com/img/s3/v45/p48054763-5.jpg)

Once confirmed, solder the LED and cut the leads tight to the PCB.

(http://studio939.zenfolio.com/img/s2/v51/p124250710-4.jpg)

Next, I install the 2 toggle switches.  build manual says to solder only 1 leg of the switch at this time, but since the switch remains in position quite well from friction, I decided not to solder and wait until everything is installed in the chassis.

(http://studio939.zenfolio.com/img/s1/v47/p497734691-4.jpg)

(http://studio939.zenfolio.com/img/s3/v42/p91652005-4.jpg)

Next up is SW3 (grayhill switch).  Now that the LED has been installed and positioned, we can place this switch.

(http://studio939.zenfolio.com/img/s2/v51/p343337051-4.jpg)

Solder 1 pin to hold in place but still allow room for re-positioning.

(http://studio939.zenfolio.com/img/s2/v51/p675669038-4.jpg)

and make sure everything is tight to the PCB and straight.

(http://studio939.zenfolio.com/img/s2/v52/p595644340-4.jpg)

Solder the remaining pins and trim tight to the PCB.

(http://studio939.zenfolio.com/img/s2/v53/p860530756-4.jpg)

Next, locate these header sockets.   It's important to install these on the CB PCB and not the other way around.  If installed on the wrong PCB, they will not fit into the chassis.

(http://studio939.zenfolio.com/img/s3/v45/p788602099-4.jpg)

(http://studio939.zenfolio.com/img/s1/v46/p1015818686-4.jpg)

(http://studio939.zenfolio.com/img/s3/v43/p895918286-4.jpg)

Make sure these sockets are vertical and tight to the PCB.

(http://studio939.zenfolio.com/img/s1/v47/p904826392-4.jpg)

Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: chunger on April 18, 2012, 07:51:58 PM
Next, install the output transformer.  Locate the baggie with the transformer mounting hardware.

(http://studio939.zenfolio.com/img/s3/v44/p605518516-4.jpg)

and locate these parts.

(http://studio939.zenfolio.com/img/s1/v47/p898828763-4.jpg)

(http://studio939.zenfolio.com/img/s2/v50/p710320315-4.jpg)

Install flat washers to the 2 long screws.

(http://studio939.zenfolio.com/img/s2/v53/p719587901-4.jpg)

And insert into the transformer from the top side.

(http://studio939.zenfolio.com/img/s1/v46/p678657628-4.jpg)

While holding the 2 screws in place with your fingers, install 2 additional flat washers on the bottom side of the transformer.

(http://studio939.zenfolio.com/img/s1/v48/p1053170150-4.jpg)

And place the assembly onto the PCB maintaining the flat washer between the transformer and the PCB.

(http://studio939.zenfolio.com/img/s3/v42/p817819571-4.jpg)

Add lock washers on the bottom of the PCB.

(http://studio939.zenfolio.com/img/s3/v42/p708875560-4.jpg)

Install nuts.

(http://studio939.zenfolio.com/img/s3/v44/p785305817-4.jpg)

Tighten with a screwdriver on the front side after verifying the transformer is aligned with the marked box on the PCB.

(http://studio939.zenfolio.com/img/s1/v46/p590505272-5.jpg)

Cut, strip and tin the leads 1 or two at a time making sure not to cut too short.

(http://studio939.zenfolio.com/img/s3/v42/p888160678-4.jpg)

I use small pieces of head shrink tubing to organize the wires as I install them into the PCB according to the marked colors.

(http://studio939.zenfolio.com/img/s1/v46/p554358973-4.jpg)

(http://studio939.zenfolio.com/img/s1/v49/p742447526-4.jpg)

And, transformer is installed.

(http://studio939.zenfolio.com/img/s1/v47/p599164857-4.jpg)

Next, refer to the provided document for CB PCB Grayhill switch stop pin positions and insert the appropriate pins into the 3 grayhill switches.

(http://studio939.zenfolio.com/img/s1/v48/p226664026-4.jpg)

They should look something like this.  Careful with these.  Drop one on the floor and it may just dissipate into the ether and never be found again.

(http://studio939.zenfolio.com/img/s1/v48/p467403515-4.jpg)

And install the silver stickers to retain the pins.

(http://studio939.zenfolio.com/img/s1/v47/p299382269-4.jpg)

Next, I move to the DF.2 discrete follower boards.

(http://studio939.zenfolio.com/img/s2/v53/p268443878-4.jpg)

(http://studio939.zenfolio.com/img/s1/v49/p516473304-4.jpg)

Sort the electronic components.

(http://studio939.zenfolio.com/img/s3/v44/p285374901-5.jpg)

This is my chosen method for installing the pins into the PCB.  (NOTE: This procedure deviates from the recommended build order in the assembly manual)  This is just he way I've grown accustomed to installing opamp pins and I did not feel comfortable risking a solder leak onto the side of the pin that would contact the socket on the PCB for fear of sticking everything together inadvertently.  Jsteiger may very well have much steadier hands and perhaps a finer soldering tip than I am using.

At any rate, I insert pins into the PCB first.

(http://studio939.zenfolio.com/img/s3/v42/p500766973-4.jpg)

Then, place the discrete follower PCB onto the pins and solder.

(http://studio939.zenfolio.com/img/s2/v52/p143201968-4.jpg)

(http://studio939.zenfolio.com/img/s3/v44/p155458277-4.jpg)

(http://studio939.zenfolio.com/img/s2/v50/p246694981-4.jpg)

I am using the recommended component bending method in the build manual using my smallest screwdriver as a bending tool.

(http://studio939.zenfolio.com/img/s1/v49/p431619405-4.jpg)

Populating. . . (Note: I deviated from the instructions again in the following sequence because I usually don't like shoving the resistors all the way into the PCB because I like to have a little solder flow onto the top side of the PCB if possible.  Due to clearance issues, I recommend putting theses resistors as low as possible into the PCB as described in the assembly aid document.  The clearances are VERY tight and the final height of the large, yellow capacitors on the LC-EP PCB are unpredictable.  Every thousandth of an inch here helps, so please push the resistors all the way into the PCB.  The build was successful, but I believe I had contact between a capacitor and one of my opamp resistors and had to go back in and jam the capacitor in further to clear.)

(http://studio939.zenfolio.com/img/s1/v46/p454537242-4.jpg)

(http://studio939.zenfolio.com/img/s2/v52/p346241468-4.jpg)

(http://studio939.zenfolio.com/img/s3/v42/p230228276-4.jpg)

Discrete followers complete.

(http://studio939.zenfolio.com/img/s1/v47/p508539272-4.jpg)

(http://studio939.zenfolio.com/img/s3/v42/p469805017-4.jpg)

Next, I buid the 2 DTO5 discrete opamps.

(http://studio939.zenfolio.com/img/s1/v46/p303950084-4.jpg)

Components sorted:

(http://studio939.zenfolio.com/img/s1/v46/p67985451-5.jpg)

I use the same method to install the opamp pins.

(http://studio939.zenfolio.com/img/s1/v48/p336915836-4.jpg)

(http://studio939.zenfolio.com/img/s3/v45/p98665565-4.jpg)

And populate. . .

(http://studio939.zenfolio.com/img/s3/v38/p417730190-4.jpg)

careful with the diodes.  Make sure the end with the line corresponds to the direction of the printed arrow on the PCB.

(http://studio939.zenfolio.com/img/s2/v52/p288653219-4.jpg)

(http://studio939.zenfolio.com/img/s3/v41/p108099149-4.jpg)

(http://studio939.zenfolio.com/img/s1/v48/p110733393-4.jpg)

Again, watch out for the orientation of the diodes.

(http://studio939.zenfolio.com/img/s1/v49/p519633034-4.jpg)

And the opamp is complete.

(http://studio939.zenfolio.com/img/s2/v50/p72396267-4.jpg)

(http://studio939.zenfolio.com/img/s1/v49/p14408886-4.jpg)

Next, build one more DTO5 discrete opamp.  I did them one at a time because they have a pair of matched transistors that I did not want to get mixed up between the baggies.  If building together, just remember to keep these HFE matched transistors paired together.

Both DTO5's complete.

(http://studio939.zenfolio.com/img/s2/v51/p117358598-4.jpg)

All CB PCB amps ready to install.

(http://studio939.zenfolio.com/img/s2/v51/p386985698-4.jpg)

(http://studio939.zenfolio.com/img/s3/v42/p241061330-4.jpg)

Main PCB and CB PCB complete. . . except for soldering a couple of switches to be complete with faceplate installed.

(http://studio939.zenfolio.com/img/s2/v53/p139742049-4.jpg)



Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: chunger on April 18, 2012, 07:52:12 PM
Next, we do what will hopefully be the final installation of the PCB assembly into the metal chassis.

(http://studio939.zenfolio.com/img/s3/v38/p539606970-4.jpg)

We will use lock washers now to secure the back of the PCB.  Make sure to push the PCB assemble all the way against the front of the metal bracket.

(http://studio939.zenfolio.com/img/s2/v53/p908143714-4.jpg)

(http://studio939.zenfolio.com/img/s1/v46/p897884735-4.jpg)

Next, re-install the faceplate.

(http://studio939.zenfolio.com/img/s1/v48/p642522021-4.jpg)

and install the supplied nuts.  Do not use the lock washers that came with the Grayhill switches.

(http://studio939.zenfolio.com/img/s2/v50/p1053418044-4.jpg)

This is a temporary placement, so we do not need to crank these down, but we want to align the faceplate so that the gaps on the top and bottom are dead even again.

(http://studio939.zenfolio.com/img/s3/v7/p780811807-4.jpg)

At this point, solder in the remaining switches on the CB PCB.

(http://studio939.zenfolio.com/img/s3/v44/p601737322-4.jpg)

And trim the leads tight to the PCB.

(http://studio939.zenfolio.com/img/s3/v7/p818393130-4.jpg)

Voila!

(http://studio939.zenfolio.com/img/s2/v51/p710724197-4.jpg)

(http://studio939.zenfolio.com/img/s3/v42/p844457996-4.jpg)

At this point, we are ready to test and see if the unit passes signal.  Here's I'm setting up to input 1K sine at 4dBu.

(http://studio939.zenfolio.com/img/s3/v44/p640821063-4.jpg)

(http://studio939.zenfolio.com/img/s1/v46/p615750798-4.jpg)

And, the output waveform looks good and the level matches at least as far as my meter can tell, so everything appears to be working on this build!

(http://studio939.zenfolio.com/img/s2/v53/p569456308-4.jpg)

Onward to the LC-EP PCB.

(http://studio939.zenfolio.com/img/s3/v42/p636907073-4.jpg)

First sort resistors and transistors.

(http://studio939.zenfolio.com/img/s2/v50/p1039145167-5.jpg)

And populate the flat-lying resistors first.

(http://studio939.zenfolio.com/img/s2/v52/p560377144-5.jpg)

Then move to the free-standing resistors around the grayhill switch.  This is how I set up to solder these in.

(http://studio939.zenfolio.com/img/s2/v52/p1057562536-4.jpg)

(http://studio939.zenfolio.com/img/s3/v7/p676609890-4.jpg)

And resistors are populated.

(http://studio939.zenfolio.com/img/s2/v50/p976594192-4.jpg)

Next, install the 5 transistors.

(http://studio939.zenfolio.com/img/s1/v48/p77939573-4.jpg)

And, we're sorting capacitors.

(http://studio939.zenfolio.com/img/s3/v42/p442494690-4.jpg)

And, populating capacitors. . .metalized polymer ones here.

(http://studio939.zenfolio.com/img/s3/v43/p533568081-4.jpg)

(http://studio939.zenfolio.com/img/s2/v51/p16383471-4.jpg)

Polystyrene caps go in.

(http://studio939.zenfolio.com/img/s2/v51/p231226253-4.jpg)

And polyester film caps next.  Some of these may need to be jammed pretty hard into the PCB as here is very little clearance available in the sandwich.  Check and adjust as needed.

(http://studio939.zenfolio.com/img/s1/v47/p190772144-4.jpg)

(http://studio939.zenfolio.com/img/s1/v49/p508522394-4.jpg)

One lonely electrolytic cap.  Watch the polarity on this one.

(http://studio939.zenfolio.com/img/s3/v8/p296412119-4.jpg)

Next, install the inductors.

(http://studio939.zenfolio.com/img/s1/v48/p210910143-4.jpg)

Note the dot on the sticker as well as the diagonal corner at the base indicating the "COM" pin which is labeled and has a square-shaped pad on the PCB.

(http://studio939.zenfolio.com/img/s3/v42/p27454991-5.jpg)

(http://studio939.zenfolio.com/img/s3/v42/p226813349-4.jpg)

Solder in the inductors and cut the leads tight to the PCB.

(http://studio939.zenfolio.com/img/s1/v47/p533587719-4.jpg)

Inductors populated.

(http://studio939.zenfolio.com/img/s1/v49/p177341368-4.jpg)

Next we install grayhill switches.

(http://studio939.zenfolio.com/img/s3/v44/p272753006-4.jpg)

(http://studio939.zenfolio.com/img/s1/v49/p96304078-4.jpg)

Solder one pin and check alignment.

(http://studio939.zenfolio.com/img/s2/v52/p473850002-4.jpg)

(http://studio939.zenfolio.com/img/s1/v46/p446751552-4.jpg)

(http://studio939.zenfolio.com/img/s1/v47/p245940127-4.jpg)

After confirming perpendicular to the PCB as well as sitting tight to the PCB, solder and trim the leads tight.

(http://studio939.zenfolio.com/img/s1/v46/p127038420-4.jpg)

Next, install toggle switches.

(http://studio939.zenfolio.com/img/s1/v49/p468645766-4.jpg)

(http://studio939.zenfolio.com/img/s3/v43/p105276487-4.jpg)

Only solder the middle rear pin on these at this time.  We need a little wiggle room to place the faceplate later.

(http://studio939.zenfolio.com/img/s2/v52/p410662106-4.jpg)

Next, locate these long jumpers and install.

(http://studio939.zenfolio.com/img/s3/v43/p9924404-4.jpg)

(http://studio939.zenfolio.com/img/s1/v47/p415742291-4.jpg)

(http://studio939.zenfolio.com/img/s1/v46/p62321377-4.jpg)

I solder one pin and then adjust to get them as straight as possible.

(http://studio939.zenfolio.com/img/s3/v44/p28364168-4.jpg)

Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: chunger on April 18, 2012, 07:52:38 PM
Install stop pins on the Grayhill switches next (refer to the proper document and confirm 12:00 and 5:00 placement.

(http://studio939.zenfolio.com/img/s3/v44/p156900234-4.jpg)

They should look something like this when installed.

(http://studio939.zenfolio.com/img/s3/v8/p291913271-4.jpg)

And, apply stickers to retain the stop pins.

(http://studio939.zenfolio.com/img/s1/v49/p344256643-4.jpg)

LC-EP PCB complete.

(http://studio939.zenfolio.com/img/s3/v44/p501446411-4.jpg)

(http://studio939.zenfolio.com/img/s2/v50/p365509062-5.jpg)

Next, remove the faceplate from the chassis and insert the LC-EP PCB straight down into the chassis while aligning the 2 long jumpers.  Verify proper seating from the strategically placed vent holes in the chassis.

(http://studio939.zenfolio.com/img/s2/v52/p359774232-4.jpg)

And install the faceplate.

(http://studio939.zenfolio.com/img/s3/v44/p19614295-4.jpg)

Carefully align the faceplate so the gaps are equal on the top and bottom sides of the chassis and parallel to the chassis.  Then,  install and tighten down the all of the grayhill switch nuts.

(http://studio939.zenfolio.com/img/s1/v46/p323103368-4.jpg)

(http://studio939.zenfolio.com/img/s2/v52/p439003302-4.jpg)

(http://studio939.zenfolio.com/img/s1/v48/p152217202-4.jpg)

With the faceplate aligned, solder in the 2 remaining toggle switches.

(http://studio939.zenfolio.com/img/s3/v42/p35584278-4.jpg)

And trim the leads tight to the PCB.

(http://studio939.zenfolio.com/img/s1/v47/p58955183-4.jpg)

Locate these 2 flat head screws.

(http://studio939.zenfolio.com/img/s2/v50/p514131147-4.jpg)

And secure the EP-LP PCB to the chassis.

(http://studio939.zenfolio.com/img/s3/v42/p310319174-5.jpg)

The EQ is now electronically complete.

(http://studio939.zenfolio.com/img/s3/v8/p2038010-5.jpg)

(http://studio939.zenfolio.com/img/s3/v7/p438880886-4.jpg)

Verify with a straight edge that there are no component leads or solder blobs protruding above the chassis on both sides of the unit.

(http://studio939.zenfolio.com/img/s3/v45/p274472368-4.jpg)

Locate the remaining small screws.

(http://studio939.zenfolio.com/img/s2/v52/p446175346-4.jpg)

And install the metal covers.

(http://studio939.zenfolio.com/img/s3/v42/p7075175-5.jpg)

(http://studio939.zenfolio.com/img/s3/v8/p98351416-5.jpg)

(http://studio939.zenfolio.com/img/s2/v53/p123455887-4.jpg)

using pliers, rotate all of the grayhill switches to the 3:00 position.

(http://studio939.zenfolio.com/img/s1/v47/p345877561-5.jpg)

And locate the knobs.

(http://studio939.zenfolio.com/img/s1/v47/p312262468-4.jpg)

frequency selection knobs should be installed first because of this clearance issue.

(http://studio939.zenfolio.com/img/s2/v50/p151553607-5.jpg)

(http://studio939.zenfolio.com/img/s3/v8/p247554430-5.jpg)

Install the cut/boost knobs and locate color coded stickers.

(http://studio939.zenfolio.com/img/s1/v48/p73469162-4.jpg)

Install blue stickers on the frequency select knobs and grey stickers on the cut/boost knobs.

(http://studio939.zenfolio.com/img/s1/v46/p72668499-4.jpg)

and the build is complete!

(http://studio939.zenfolio.com/img/s1/v48/p442542238-5.jpg)

Humans win!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: submergent on April 19, 2012, 06:20:00 PM
anyone having trouble soldering the milmax recepticals into the main board? specifically the "C" one? in both DOA positions i had one hell of a time trying to get solder in there... almost like a giant heatsink on there. Tips?

-pete

(adding)...
same deal with the super little ones for the DVF and the other DTO5s .. the "c" is impossible to solder... is this because these pads are part of the ground plane which takes up a lot of metal on the pcb, sinking most of the iron's heat? should i jack up the heat for these pads? something > 600deg F?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on April 19, 2012, 08:15:33 PM
Yes indeed that is why. A special note for these is in my nearly finished Assembly Aid document. The C is the hardest to solder and it is because they connect to the ground plane. What temp are you running? I am usually around 740F or so. I have done numerous builds and while not easy, they are always doable. Maybe try tinning the top of the pad without the socket in place. After it cools, drop the socket in and reheat while applying a little bit of solder. One thing to also watch for is the socket sticking to your iron tip when you remove the iron. I try to pull away horizontally, never vertically.

While we are on the subject, one can only solder from the top with these little sockets, never the bottom.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: submergent on April 19, 2012, 11:37:00 PM
ahh... yes- i'm doing EVERYTHING at 550ish... too low? are you saying you solder everything in this build up in the 700 range? or just the "c" pads?

another question...

in my other builds (vp25s) i inserted the DOA mil max sockets on the top of the PCB and soldered them from the top (the same way you do these little sockets...) this worked fine and the units are all good (and sounding wonderful)... i did the same for the main board of the lc53a here.. and a DOA fits fine, but i'm realizing that there's a lot less room in the enclosure and these may "stand" too high off the pcb... so  jeff... do you think this will be a problem ??

thanks!!

-pete
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on April 20, 2012, 12:19:02 AM
I am always at that temp and never change it.

You should be fine with the sockets for the 2520's the way you have them. The opamps should still sit far below the 2503 right? I would guess yes so no worries.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: submergent on April 20, 2012, 09:30:51 AM
quick update: bumping up to 700-ish deg. makes the ground plane related soldering much much easier. thanks jeff!

-pete
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on April 20, 2012, 01:51:46 PM
I have added the just completed LC53A Assembly Aid link to the first post of this thread. Please check it out and let me know if anyone finds any silly errors.

BOM's for the larger PCB's are coming in a few minutes.

Thanks for being patient guys!  ;)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on April 20, 2012, 02:23:57 PM
Links for all of the BOM's and build docs have been added to the first post of this thread. Currently, the only thing I am missing are the docs for the DF.2 and DTO5 PCB's. Will try to get those completed ASAP. I think the above will buy me 16-20 working hours though! :D
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: a zombie on April 20, 2012, 04:13:24 PM
For the Milmax DOA sockets I first use a flux pen on the pads, top and bottom.  Then I pre-cut six pieces of solder to the same length, then I solder each pin with one piece of solder each, at 750º.  Be sure to heat the pad and socket and not pull out the socket when you remove your iron.  The length of your solder pieces will vary, I use a piece long enough to give me a nice concave volcano, by using the same amount of solder on each one you get a nice consistent look from the top.

I solder the sockets first and use non-noclean solder, clean the board thoroughly, then stuff the rest.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on April 21, 2012, 02:57:20 PM
Alrighty folks, the DF.2 and DTO5 build guides and BOM's have been added to the first post. That should cover it for build docs. Everything is now complete.

Happy soldering!  8)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on April 21, 2012, 03:22:17 PM
Alrighty folks, the DF.2 and DTO5 build guides and BOM's have been added to the first post. That should cover it for build docs. Everything is now complete.

Happy soldering!  8)
Awesome support,a great work you´re doing,I owe you one in advance.
Looking forward to receive my ordered (and paid ;D) pair,I´m sure I´ll love them.

Best regards from munich,germany,

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on April 21, 2012, 09:42:06 PM
Hey guys

I added a few pics to the 2nd post of this thread. They point out a few important things.

I forgot to do the board overlays so guess I am not finished after all!

Cheers, Jeff
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: rob61 on April 22, 2012, 10:20:52 AM
Can't find my precision resistors, so can I complete the build and then do the CMRR alignment once its all assembled?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on April 22, 2012, 10:24:01 AM
Can't find my precision resistors, so can I complete the build and then do the CMRR alignment once its all assembled?
Yes, no problem.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on April 22, 2012, 12:21:36 PM
Overlay PDF's for the 3 large boards have been added to the first post of this thread.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: rob61 on April 23, 2012, 03:18:46 AM
Note : the leads of the LED are too large in diameter to fit through the LED holes on the CB motherboard.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on April 23, 2012, 08:43:20 AM
Note : the leads of the LED are too large in diameter to fit through the LED holes on the CB motherboard.
They may be a little snug but the fit OK. I like them snug. Maybe it's the approach angle or something? It's a tricky bend too.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: submergent on April 23, 2012, 04:09:01 PM
nah - they fit.. keep workin it in there.

-pete
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: rob61 on April 23, 2012, 06:17:02 PM
I guess I need to eat my Wheaties...
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: rob61 on April 24, 2012, 12:26:45 PM
Finished the main board and CB board and ran test for unity gain. Both pass signal fine but there is -11 db loss. I have NOT yet been able to adjust CMRR as I'm waiting for some precision resistors to arrive. Would that account for the drop until those are adjusted or should I be looking for something else? Both units exhibit the same level drop.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on April 24, 2012, 01:21:03 PM
There may be a minimal difference after the CMR adjustment but not 11dB. Usually .25dB or less. I would be 100% sure it is not cabling or a setting on a converter or something. This happens all the time. Next, be 100% sure it is not opamp related. I recommend to never test a module with unconfirmed opamps.

Keep us posted.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: rob61 on April 24, 2012, 09:53:20 PM
Finished the pair, popped in some DOAs and viola, they work. No signal loss, and everything tested fine.
(http://www.fasttrax.us/gallery/lc53pair.jpg)

Next, wanted to experiement with different DOAs I have. Using combo of gar2520 and gar1731. One order (A1-A2) works fine, reverse order and I get lower signal and hiss.???

I tried using a pair of 2050E and it blew the 48v fuse on my 51X. Not sure, maybe I seated a module wrong... hopefully nothing is toasted other than the fuse. Any reason the 2050E should not work? Also, why do I get the issue of noise and signal loss depending on order of the DOAs?

Will obtain more fuses tomorrow and see what all happened.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on April 24, 2012, 10:26:37 PM
I would assume the fuse issue on the 48V rail was related to seating the module. There is not even a gold finger on the LC card for 48V so it was probably the #14 finger shorting to the #15 pin in the connector. Are you sure the -16V rail is OK? That is what's on pin 14. Might explain the DOA hissing issue.

The 2050E should work no problem. Same with swapping the DOA's around. Maybe that was a module seating issue as well? Otherwise, I can't think of an explanation right now.

I didn't want to add the extra spacer on these cards for the 18 pin connector since the majority of my customers are just VPR guys. That I cannot explain but you may want to insert a little spacer of some sort so there can be no alignment problems. When I seat a 15 pin card into an 18 pin connector, I make sure I feel the card hitting against the top of the card edge connector before I insert it. Also, the steel cover may help as it is just barely oversized to drop over the 18 pin connector. I am pretty certain this would not happen with the cover on.

Otherwise, I will look forward to your thoughts sonically!  :)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: submergent on April 25, 2012, 10:47:06 AM
rob beat me!
anyway.... i finished my first one... took a while since i've been super busy with sessions and life in general..
on a whim i figured i'd plug it in and try it right off the bat without doing any interstage testing other than using two known good DOAs (tested first in preamps)... i haven't done the CMRR setting, but why not try it right?  lo and behold it works! sounded great too. kudos on wonderful build guides jeff!

-pete

Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on April 25, 2012, 12:11:49 PM
Awesomeness! Well done Pete!  8)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: rob61 on April 25, 2012, 12:22:49 PM
A new fuse in the 51X, and I'm ready to go again. Sounds great... lovin' it. Big ballsy low end, really nice and fat, mids have a nice presence and dimension about them, and highs are more sizzling than smooth, but definately usable on lots. Overall a real treat and will be a great addition to the arsenal.

Have tried the 2050Es, gar2520s, and again tried the 1731s. With the 1731s I blew another fuse! I tried to be very careful seating them. I've used these 1731s in other modules and they worked, but I wonder if one is bad. (recently built these so not a lot of testing). I also have some red dots but haven't experimented with those yet. Because of what they do to the highs, they might not be my first choise with these EQs. I'd rather pair them with something with a smoother high end. But I will try them out sometime.

The 48v blew (.125amp, others are 1.6A, so maybe that's why this goes out first)???  I'll test again from the build guide on any shorting, but my test when building was fine unless something got bent putting them in/out (tolerances are extremely close on the 1731, much closer than 2520).

Could a faulty 1731 blow the 48v???
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on April 25, 2012, 12:30:05 PM
...Could a faulty 1731 blow the 48v???
No it can't. I can only imagine that it was a seating issue.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on April 25, 2012, 01:00:29 PM
...Could a faulty 1731 blow the 48v???
No it can't. I can only imagine that it was a seating issue.
Hello Rob,
pardon me for chiming in.
Don't have these modules handy yet,but a simple question is:
Have you tried this on any other slots on your rack too?
If the fault follows you can shoot out the connectors on the backplane.
If not do a very good inspection on the inside of the connector with a magnifying glass under good light.Look for even the smallest parts that don't belong there!Maybe something went off and is moving;maybe it's a miniature piece of a parts leg while cutting it to length.These little beasts can "fly" pretty far.
I absolutely agree with Jeff-this fault must be something logical and mechanical.
Btw:Pin 15 is even not existing on the back pcb (it carries the +48vdc for mic pres) from what I've seen from Jeff's pics.
The DOA will not be the cause since it doesn't "reach" Pin 15 on the card edge connector.
Just what came to my mind when thinking about it.

Good luck and best regards,

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: dandeurloo on April 27, 2012, 11:05:07 AM
Lovely!

(http://sphotos.xx.fbcdn.net/hphotos-snc7/s320x320/576833_3783775318534_1401530323_3307860_2124085579_n.jpg)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on April 27, 2012, 12:23:45 PM
Congrats Dan,

I'm jealous at the moment,but today have received a message that my kits have hit the german border.They're at the customs now (where else?).
Have fun,

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: submergent on April 27, 2012, 03:43:49 PM
just finished my 2nd.
again... works perfect!

one very annoying gotchya on this one though... i was putting the stop pins in one of the grayhills and spaced out for a sec... when i came to my senses i had put it in the wrong hole. those things are a BUGGER to get out if you need to. i ended up grinding some of the aluminum housing away with a dremel, then had to loosen it with a pair of needle point tweeters... just when i thought i was going to have to order a new switch, i tuned it the board assembly over, tapped on the back of the switch, and it popped out! whew. also - i had a few pins in the first module go flying out of my pliers as i was trying to put them in... gone forever on the shop floor. so in their stead on this module i had to use lead clippings. those fit nicely.

good luck everyone!

-pete


Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: dandeurloo on April 27, 2012, 04:26:21 PM
I've done that before with the grayhills.  Super strong magnets pull them out as well!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: gar381 on April 28, 2012, 11:44:18 PM
Mine went together SOOOOOTH as silk !! :)
Great engineering and design work Jeff !!

I've tried pairs of 990s, gar2520s and gar1731s so far in both
positions.   The 990s are way to clean, sterile and lifeless
for my taste.  The gar2520s are not bad but at this point
loving the gar1731s muchly (SMOOOOOOTH)!!.  I haven't tried mixing them
up (1 and 1) yet nor have I had a chance to try Scott's red dots.  I would be interested
in knowing what DOA combos you guys are using and loving in these really
nice EQs.

GARY
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on May 02, 2012, 07:11:23 AM
Hi Jeff,

2 lovechildren arrived in germany.Everything is looking very beautiful,especially the pcbs.
Will check in depth for all parts at the weekend.

Thank you very much indeed,

Udo.

Addendum: Have done the main boards today.The milmax sockets are super-easy to solder in.
I use a Weller Magnastat from 1987,it's my companion since then and never failed.
Tearing the iron away horizontally does the trick,thanks for the hint Jeff.

Best regards,

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on May 09, 2012, 01:03:52 PM
Hello Jeff,

excuse me disturbing,but my package has been opened at the customs,so far everything seems o.k. except of small parts like 1 36k resistor(I have tons of them) and a rectifier diode 1n419 missing.
I have 1n4148 here,specs seem very similar.Can I take them as replacement (just wanted to get sure because it´s on the DT05 opamp and I don´t want start swapping parts on such a build,hahahaha....).

Thank you in advance,

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on May 09, 2012, 02:04:10 PM
Udo, the 1N914's are "cut-tape" and typically cut off in 4pc groups for the DTO5. You mean there were only 3pc? Very strange. From what I know, the 1N914 and 1N4148 are interchangeable and essentially the same part.

The DTO5 does not have a 36k on it. Do you mean the Discrete Follower Kit?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on May 09, 2012, 03:37:02 PM
Udo, the 1N914's are "cut-tape" and typically cut off in 4pc groups for the DTO5. You mean there were only 3pc? Very strange. From what I know, the 1N914 and 1N4148 are interchangeable and essentially the same part.
Yes,only 3 of them on tape,but no biggie,was just curious if a 1n4148 will do the job.

The DTO5 does not have a 36k on it. Do you mean the Discrete Follower Kit?
Yes,the 36k didn´t mean missing from the DTO5 but from one of the DF.2 bags.It had a hole on one edge,parts have dropped out.As said the package was opened at our customs and looked a little messed up.
Excuse my bad english.

Thank you for the fast reply,

best regards,

Udo ;)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on May 09, 2012, 06:52:39 PM
No worries. Your English is just fine. I understand and must say.......customs = nimrods in any language.

Let me know if you need me to send anything.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on May 10, 2012, 02:00:32 AM
No worries. Your English is just fine. I understand and must say.......customs = nimrods in any language.
Nimrod,didn't know this word,but yes,after doing a search I must say it fits pretty good!

Let me know if you need me to send anything.
Yes,two VP28,but that's a different story :D
Thank you for taking care!

Best regards from germany,

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on May 14, 2012, 01:20:09 PM
Success!

Have built 2 of these now.
Had to wait for allen wrench(?) keys,but they were in my post today-HOOOOORRRRRAAAAYYYYY!
After some testing and giving them some listening I simply must say:
No,these are no good EQs-these are absolutely stunning!

Everything worked from first fire-up,no issues at all.Except of having left-over parts,exactly 18 pieces (guess..... ;D).
The sound is unbelievable,these guys can be anything from subtle and warm up to big and "having big co****s".
Pardon me,can´t find the words of what I feel in the english language.

Jeff-this was a great experience for me,and you did an outstanding work creating them!Thank you so much indeed!

I wonder what will happen when I start swapping DOAs-I have put in gar2520s,can these guys really be improved???

Oh,before I forget to ask:Jeff,can you please tell us roughly what the lpf and hpf frequencies are and at which slope?
Also,the bypass switch,does it connect the in and out stages (A1 and A2)?Just for my/our info.

You made me be a lucky guy sir,can´t wait to order 2 of the VP28 full kits now.

Attached a pic for those who are interested.

Best regards from germany,

Udo ;).
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on May 14, 2012, 01:45:13 PM
Excellent news and congrats Udo!   8)

The filters are essentially the same as the bandpass on a 550A only they can be used independently. Both have a 12dB per octave slope. HPF is stated as 50Hz and the LPF is stated as 15kHz.

The In/Out switch simply lifts all of the LCR networks from their respective connections to ground. The signal still flows thru all of the opamps, followers and the 2503. So, it is not a hardware bypass but neither was the 553 or any of the other API style EQ's.  :D

Thanks again for the outstanding review. I may need to add it to my new Customer Testimonials page.  :)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on May 14, 2012, 02:25:44 PM
Excellent news and congrats Udo!   8)

The filters are essentially the same as the bandpass on a 550A only they can be used independently. Both have a 12dB per octave slope. HPF is stated as 50Hz and the LPF is stated as 15kHz.
Thank you!

The In/Out switch simply lifts all of the LCR networks from their respective connections to ground. The signal still flows thru all of the opamps, followers and the 2503. So, it is not a hardware bypass but neither was the 553 or any of the other API style EQ's.  :D
So that´s why,I simply put some music thru them without dialing anything in and it nearly blew me away!

Thanks again for the outstanding review. I may need to add it to my new Customer Testimonials page.  :)
Do it ;D

Cheers,

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on May 17, 2012, 01:28:32 PM
Hello,

for those who are interested:The current drawn of a LC53A with gar2520s is approx. 75mAs per rail (so you can run lots of them in your racks) :)).
--------------------------------------------------------------------------------------------------------------------------------------------

And a little helper for CMRR adjustment,built in a couple of minutes-look:

(http://img842.imageshack.us/img842/6903/offens.jpg)

I used some Neutrik XLR parts and cut them to my needs:

(http://img26.imageshack.us/img26/4198/partst.jpg)

Only the contact inserts,2 resistors (I used 1Ks,closely matched),a piece of solid core wire,the female metall housing and a part of the cable cap is needed.

Inserting it:

(http://img215.imageshack.us/img215/9321/insertt.jpg)

Assembled:

(http://img20.imageshack.us/img20/4124/assembledn.jpg)

Sticker put on for reference,done!

(http://img824.imageshack.us/img824/7133/stickerattached.jpg)

Cheers,have fun with your builds-I did ;)

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: chunger on May 17, 2012, 01:39:23 PM

(http://img824.imageshack.us/img824/7133/stickerattached.jpg)


Genius!  :o
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on May 18, 2012, 10:57:44 PM
Clever  8)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on May 20, 2012, 03:56:28 PM
Hello,

thank you for the nice comments :)

@chunger:

Sorry,I didn't notice you started your very nice photo documentary.
Perfect as always I must say!

Go chunger go!

Have fun,

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: EmRR on June 10, 2012, 10:18:27 AM
Worth noting that the color coding of the EA2503 is the same as found in the VP2x guide (and on the main pcb), but they likely come out of the bobbin in a different order than pictured in the VP2x guide. 

Chunger, do you work for LEGO in the manual dept?  Great work. 
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: EmRR on June 12, 2012, 06:22:41 PM
2 on the bench with CB/main assembled, and all amps loaded.  One is passing unity, the other is +5-6db up.  This is on the same test jig channel, one at a time, and also in comparison with each other when alternating positions. 

Swapped all amps from one unit to the other, one at a time, no change noted. 

Double checked transformer wiring, both colored the same and ohm out the same.

Compared in circuit resistance readings for MAIN pcb and all R (but not CBR) on CB pcb; all match from amp to amp. 

Difficult to know where to look next, guessing at schematic and flow.  Pointers?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on June 12, 2012, 07:37:22 PM
I would first verify the location of the shunt jumpers for both units.

If the main board is all good with R values, I would check the CB PCB for R values. You can ignore the CBR R's for the 3 switches.

Did you also swap the DF's around?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: EmRR on June 12, 2012, 07:47:44 PM
Shunts the same, also moved all 6 actives, one at a time, and checked the CB R's. 
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on June 12, 2012, 08:06:31 PM
OK.

I would start by taking some measurements from the properly working module. After injecting a signal, take a measurement of your choice at the output of each amplifier stage then see where the gain increases in the hot module.

1st reading: negative side of C2 on the Main PCB.
2nd reading: output pin of A1, DF on CB PCB
3rd reading: output pin of A2, DF on CB PCB
4th reading: output pin of A4, DTO5 on CB PCB
5th reading: output pin of A3, DTO5 on CB PCB
6th reading: neg side of C12 on the Main PCB

Those are in signal flow order.

We'll figure out the problem stage and go from there.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: area8 on June 17, 2012, 11:07:38 AM
Jeff - you're killing me here... just after I discover I haven't caught up with a "new" 2 stage preamp, you come up with a killer EQ. I'm gonna be broke. My wife is gonna be mad again.

This EQ is maybe the antithesis of the simplicity of a 312, but after looking at the way this fits together,
I think you might be the Massimo Tamburini of the audio world!

Frank
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: EmRR on June 17, 2012, 08:46:05 PM
Unity unit fully assembled, tested in bypass.  Hot unit lacking LC-EP board.  Feeding them 1k at +4dBu:

1st reading: negative side of C2 on the Main PCB.  - both 0.592 VAC
2nd reading: output pin of A1, DF on CB PCB  - both 0.591 VAC
3rd reading: output pin of A2, DF on CB PCB  - both 0.586 VAC
4th reading: output pin of A4, DTO5 on CB PCB  - both 0.4 VAC
5th reading: output pin of A3, DTO5 on CB PCB  - both 0.402 VAC
6th reading: neg side of C12 on the Main PCB - unity unit 0.402 VAC, hot unit 0.74 VAC

So we have a winner around the output amp. 
Compared resistances on main board again, all seem to match.

Tried and tested the following with no change:
Retouched all joints on main and J1-1 points
Swapped A1 and A2 positions

Wish I'd held off on fully assembling the good unit for comparative purposes.

Next idea?

Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: chunger on June 18, 2012, 03:51:23 AM
Quick question. . . I'm at the point where I have the main PCB and CB PCB built and passing signal.  I'm feeding it 1K sine @ 1.23V (4dBu) and the unit outputs 1.62V (6.4dBu).  Is this normal or should I be concerned?  Swapping op-amps results in the same behavior.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on June 18, 2012, 04:25:16 AM
Quick question. . . I'm at the point where I have the main PCB and CB PCB built and passing signal.  I'm feeding it 1K sine @ 1.23V (4dBu) and the unit outputs 1.62V (6.4dBu).  Is this normal or should I be concerned?  Swapping op-amps results in the same behavior.
Hi,
When I built mine I had just a small difference,about 0,1 dB or so,I used gar2520s.
Jumpers in correct position?
Did you have a a load on the output?
Maybe you can strap a 10 or 20k resistor over the output temporarily for giving it a load,your measuring equipment normally has an input impedance that is too high.

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: chunger on June 18, 2012, 02:58:21 PM
thanks Udo, I was just probing with my scope so I guess there was no load.  I connected to my cheap spectrum analyzer's balanced input and everything looks good.  0.0dBu in --> 0.0dBu out.  All is well.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on June 18, 2012, 03:11:02 PM
thanks Udo, I was just probing with my scope so I guess there was no load.  I connected to my cheap spectrum analyzer's balanced input and everything looks good.  0.0dBu in --> 0.0dBu out.  All is well.
Good to hear,go chunger!

Have fun,

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: chunger on June 19, 2012, 06:56:08 PM
Wheh!  Build photo-documentation complete.   :o

Please look through and let me know if there are any glaring errors in the build or the text.  The assembly aid as well as other documents were very thorough, and this project was a real treat to put together.  All aspects of the kit were really well thought out and executed.  I am very happy to be able to do my little part to showcase this build in detail.  Hopefully some fence-sitters will decide to take the plunge on a truly top-tier kit.

Now, let's see if this thing works when I fire it up!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: gar381 on June 20, 2012, 02:57:30 AM
Hey chunger

HOLY CRAP... Just checked out your  new photo-doc!!!

This is by far your VERY BEST WORK !!!!

congrats .. you are a very advanced DIY guy !!

NICE !!!

GARY
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: wolfgang on June 20, 2012, 03:13:22 AM
Quote
HOLY CRAP... Just checked out your  new photo-doc!!!

This is by far your VERY BEST WORK !!!!

congrats .. you are a very advanced DIY guy !!

NICE !!!

GARY

+1  :) :) :)
regards,
wolfgang
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on June 20, 2012, 03:23:55 AM
Quote
HOLY CRAP... Just checked out your  new photo-doc!!!

This is by far your VERY BEST WORK !!!!

congrats .. you are a very advanced DIY guy !!

NICE !!!

GARY

+1  :) :) :)
regards,
wolfgang
Same here!

Very well done  chunger,

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: chunger on June 20, 2012, 04:00:20 AM
Hey guys,

Hold the congratulations for a bit.  Jsteiger discovered L2 inductor labelled "L:7.0 H" is installed backwards on the photo thread.  I was able to fix it without issue w/ a Hakko 808 de-soldering tool, but I need to backtrack the photos and re-shoot a few of the LC-EP PCB sections.  . . all of the ones that show the L2 inductor that is  >:(  Luckily I have 2 kits on hand and can re-trace my steps.

These are the sort of errors you expect when you employ the services of a Chinese Labor Camp!  ;D
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: chunger on June 20, 2012, 07:12:59 AM
Effected photos have all been re-shot.  All photos showing L2 are now in proper orientation.  To my knowledge, the photo thread is now all correct again.  If you happen to be browsing through the thread for entertainment and find another error.  Please let me know ASAP.  I really don't want to mess anyone up.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: john12ax7 on June 20, 2012, 07:34:11 PM
Wow, what a nice photo build documentary, really well done.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on June 20, 2012, 07:59:36 PM
Unity unit fully assembled, tested in bypass.  Hot unit lacking LC-EP board.  Feeding them 1k at +4dBu:

1st reading: negative side of C2 on the Main PCB.  - both 0.592 VAC
2nd reading: output pin of A1, DF on CB PCB  - both 0.591 VAC
3rd reading: output pin of A2, DF on CB PCB  - both 0.586 VAC
4th reading: output pin of A4, DTO5 on CB PCB  - both 0.4 VAC
5th reading: output pin of A3, DTO5 on CB PCB  - both 0.402 VAC
6th reading: neg side of C12 on the Main PCB - unity unit 0.402 VAC, hot unit 0.74 VAC

So we have a winner around the output amp. 
Compared resistances on main board again, all seem to match.

Tried and tested the following with no change:
Retouched all joints on main and J1-1 points
Swapped A1 and A2 positions

Wish I'd held off on fully assembling the good unit for comparative purposes.

Next idea?
Sorry Doug. I did not see your post before now. I have not been getting my notifications for this thread...for some reason.

Well, good as you have narrowed some stuff down. I will have to get a schematic done for this guy I think. It will make life easier in the future.

For now, besides the obvious components on the the main PCB, check the following as I assume the problem lies here. These are on the CB-PCB. R11, R12, R17, R18 and R19.

R17 is a series R to the non-inverting input of the Main PCB's A2.
R18 is in parallel with R17 when the J4 shunt is in "Lo-Z". (Check for possible short on the header?)

R11 is a shunt to gnd on the inverting input of the Main PCB's A2.
R12 is in parallel with R11 when the J3 shunt is in "Lo-Z". (Check for possible short on the header?)

R19 is just across the inverting and non-inverting inputs of the Main PCB's A2.

If everything around A2 on the Main-PCB is clean, the issue must be in the above.

Keep us posted.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: EmRR on June 29, 2012, 06:48:49 PM
OK, I apparently can't see decimal places on my meter.  R17 was 1K rather than 10K.  I checked it 3 times previously!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on June 29, 2012, 08:01:18 PM
Well, sh*te happens. At least you got it sorted.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: EmRR on June 30, 2012, 01:21:36 PM
They sound cool, and different from Brian's TB550A.  They focus in different ways, for lack of a better descriptive.  Seems like more phasey whistle at extremes while sweeping, as inductors seem to bring out.  You can only really compare them apples to apples at +6 since they deviate in the extreme steps. 
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on June 30, 2012, 02:22:03 PM
Hello Doug,

Glad you got that issue sorted.
May I ask which DOAs you used,I have gar2520 s in mine and wonder if I should do some experiments with swapping them to different ones in different combinations.

Thank you in advance,

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: EmRR on June 30, 2012, 02:40:10 PM
Gar2520.  I don't have anything else to try.  I have some early API and Melcor op amps, but they are a shorter solder pin that won't work here. 
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on June 30, 2012, 02:57:59 PM
Thank you Doug,

Next time I order from Jeff I should take some of the orther types too.

Have a nice weekend,

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on June 30, 2012, 03:07:46 PM
FWIW, I have many old 2520's that I have desoldered from my desk and what not. While the pins are short, they seem to work just fine in the sockets I use. Give them a try and see what ya think.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: chunger on June 30, 2012, 03:16:17 PM
After testing these in the studio, we ended up settling in on the GAR2520's.  I our particular setup and use, the 2520 gave a bit more bite and definition in the treble that we were looking for.  One of our primary uses for this is drums, so we are actually looking for a little bit of punch out of the analog EQ's.

On vocals, the 2520 allowed for a tremendous amount of boost in the high end as while remaining smooth and not getting "spitty" and sibilant Amazing actually to be able to grab 10K and crank it up 8dB and have the vocal come forward in the mix without any nastiness.  With the 2520 behaving so well, I felt it gave more range than the 1731.  BTW, our console and D/A converters are a bit on the darker side so in another studio, the mellower 1731 is probably very sweet.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: HMPS on July 05, 2012, 02:58:31 PM
Jeff is awesome with support in case you were wondering.

Ok I have two units one is loud and one is soft.

I checked the R's in the amp section like you suggested and they all check out.

How can I check the OP amps & discrete voltage followers?  Where else should I look?

Thanks
David
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: dandeurloo on July 05, 2012, 03:30:12 PM
try swapping the op amp and followers from the loud one to the quite one and see if you can track down what might be causing the volume difference.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: HMPS on July 05, 2012, 03:41:55 PM
swip swapped all op amps, they all give out same reading, so the difference must be somewhere else. . .. but where?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: HMPS on July 05, 2012, 04:50:56 PM
"louder" eq
Negative C2 = .017 ACV
O of A1 = .017 ACV
O of A2 = .018 ACV
O of A3 = .018 ACV
O of A4 = .018 ACV
neg C12 = .018 ACV

Softer

Neg C2 = 0.017
A1=  .017
A2= .018
A3= .018
A4= .017
Neg C12 = .018

So they match pretty closely...

OK.

I would start by taking some measurements from the properly working module. After injecting a signal, take a measurement of your choice at the output of each amplifier stage then see where the gain increases in the hot module.

1st reading: negative side of C2 on the Main PCB.
2nd reading: output pin of A1, DF on CB PCB
3rd reading: output pin of A2, DF on CB PCB
4th reading: output pin of A4, DTO5 on CB PCB
5th reading: output pin of A3, DTO5 on CB PCB
6th reading: neg side of C12 on the Main PCB

Those are in signal flow order.

We'll figure out the problem stage and go from there.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: EmRR on July 05, 2012, 05:31:39 PM
Check output transformer secondary connections
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: HMPS on July 05, 2012, 06:25:45 PM
The soft at C12 measures .018 pins 2 &4 measures .019 on the loud
they measure the same on the soft.

Perhaps swap output transformers and see if that does the trick?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: EmRR on July 05, 2012, 06:36:41 PM
perhaps see if they are connected correctly and ohm out the same before anything else.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: HMPS on July 05, 2012, 09:47:09 PM
Ok swapped transformers and the loud is now soft and soft is now loud, which leads me to believe the output transformer is the culprit.

Where should I test for unity gain?  black ground, red to in pin 2 and then black ground, red to out pin 2?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: EmRR on July 05, 2012, 10:46:04 PM
Ohm out the transformers IN CIRCUIT and report.  It sounds like everything else is ok. 
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: HMPS on July 06, 2012, 01:20:56 AM
Ohm out the transformers IN CIRCUIT and report.  It sounds like everything else is ok.

Thanks for the suggestion.

I'm a newbie and haven't found any instructions on how to ohm out the transformer.

I assume set DMM to Ohm to measure.

How do I ohm out the transformer?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: EmRR on July 06, 2012, 09:10:46 AM
compare the resistance of the windings with your meter.  Transformer does not have to be disconnected.   
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: HMPS on July 06, 2012, 01:06:27 PM
I used mono out from my daw into the LC53A.  I was using trs out from the headphones to it, which I believe was giving the wonky readings.

Adjusted to 1.223 ACV

Used a different slot and clamped black down to a ground jumper on the 51x.

Checked +16v it read out.

These are the readings

unity gain unit

Input mono out from Daw at 1.223v

c2   .598
a1   .597
a2   .593
a3   .406
a4   .404
c12   .406

output

black 2 red 4   1.2 V


Signal Loss unity

c2   .598
a1   .597
a2   .592
a3   .408
a4   .405
c12   .398

output black 2 red 4   .129V
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on July 06, 2012, 03:39:42 PM
I don't know why I am not getting notifications to this thread. I have been receiving other ones?  :o  :'(

Anyhow, I have been helping via email which HMPS has been posting here as well. Turns out that he does have a short between two of the secondary leads on one of his 2503's. The constant 180mV readings at the test points were throwing me off but once he got thru that, it was easy to verify where the actual problem was. These trafo problems happen but are thankfully very few and far between.  :)  I am posting a replacement to you today David.  ;)

BTW guys, if you are using a DMM for these ACV measurements, make sure you know the frequency response of your particular model. Most have very poor response at 1k which can throw you for a loop. 400Hz is usually a better choice but sometimes that is too high. You can also easily verify by measuring the output of your generator at different levels to make sure your DMM is reading properly.

For example, to test your DMM you can use this calculator here http://www.sengpielaudio.com/calculator-volt.htm (http://www.sengpielaudio.com/calculator-volt.htm) This will also give you an idea of the internal operating levels of the amplifier stages. The receiver stage does drop the input level by appx 6dB.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on July 06, 2012, 03:44:11 PM
Hi,

Doug meant you should ohm out the windings in circuit.
The transformer has one primary and three secondary windings,look here,took it from the parts list on Jeff´s site:

http://www.classicapi.com/catalog/images/gallery/2503/2503-specs.pdf

Set your DMM to "ohms" and measure the pairs like this:

Primary:       Brown---Red=?
Secondary:   Orange---Yellow=?
                   Green---Blue=?
                   Violet---Gray=?

Cheers,

Udo.

Edit:OOOOPPPSSSS,double posted,excuse me Jeff ;)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on July 06, 2012, 04:00:35 PM
Hi,

Doug meant you should ohm out the windings in circuit.
The transformer has one primary and three secondary windings,look here,took it from the parts list on Jeff´s site:

http://www.classicapi.com/catalog/images/gallery/2503/2503-specs.pdf

Set your DMM to "ohms" and measure the pairs like this:

Primary:       Brown---Red=?
Secondary:   Orange---Yellow=?
                   Green---Blue=?
                   Violet---Gray=?

Cheers,

Udo.

Edit:OOOOPPPSSSS,double posted,excuse me Jeff ;)
Haha no worries Udo. Thanks for chiming in. Good info to have up here anyhow.

All of his windings were around 8.5 ohms as expected. He did have an internal direct short from Violet to Orange which is not good.... :-[
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: number2 on July 17, 2012, 09:35:17 AM
how nice to have all the baggies separated for each PCB.

how nice to have all these pictures, detailed instructions and warnings!

quick shipping, quick email responses....so far my experience has been GREAT with classic api ! I give an A+ at the moment
 
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: mulletchuck on August 26, 2012, 03:35:29 AM
ok, currently doing a build of 4 of these guys.   I finished up until the Unity Gain test.  all 4 units have 0.4db of gain.   I'm feeding from my DAW a -6dbFS 1Khz Sine, and my audio interface input is showing a -5.6dbFS signal.    Is that worth worrying about?  Seems negligible.    Also, this was using a 1731 in A2, and a 2520 in A1

Also, jeff, in your build guide, you say to install 1 op-amp in A2 before the unity gain test.   It wasn't until i installed both op amps that the units would pass unity gain(sort of).   When i had only A2 populated, the unit lost about 16db of signal.    And to support this, chunger's pics show him using 2 opamps when he tests for Unity Gain. 

(http://torrentpic.com/dm-M9KT.jpg) (http://torrentpic.com/pm-M9KT.html)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on August 26, 2012, 04:25:08 AM
Hello Chuck,

A nice job you're doing there!
I would say 0,4 dB is negligible low for unity gain difference,I wouldn't care for that.
My readings have been very close to yours.
Same at chungs builds after loading them correctly,hahaha......
And for unity gain test,yes,all DOAs,followers etc. must be installed.
I asked Jeff on how the bypass works,he replied as follows ( see reply #47 in this thread):

The In/Out switch simply lifts all of the LCR networks from their respective connections to ground. The signal still flows thru all of the opamps, followers and the 2503.

So all good I think,rock on,I swear you'll love them (that's what their name stands for!) ;)

Cheers,

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on August 26, 2012, 01:52:03 PM
...Also, jeff, in your build guide, you say to install 1 op-amp in A2 before the unity gain test...
Yes indeed Chuck. I said that assuming that the opamp in A1 was still in place from the CMR calibration. If I said to install both opamps for this unity test, you would have said " but Jeff, I already have an opamp in A1"!!  ;D

Like I said on FB, the .4dB is nothing to worry about and some small variations are to be expected. All 4 of your units are the same so I would say you are golden! Carry on.  ;)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: mulletchuck on August 28, 2012, 07:11:56 PM
just finished mine!
Fully tested, and fully functional.   The two on the left use 1731s, and the two on the right use 2520s!
(http://torrentpic.com/di-ZP9X.jpg)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on August 28, 2012, 07:45:07 PM
Wow,congrats Chuck!

I´ve only done 2,wish I had the money to fill up to a full rack with them ;D
Please post what you think about the different DOAs (mine have gar2520s).

Cheers,

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: qmp audio on September 17, 2012, 02:40:37 PM
Please post what you think about the different DOAs (mine have gar2520s).

I'm curious to hear your thoughts about the DOA differences too.  About to start a build soon  ;D
I have enough DOAs on the way to test a few different configs but curious to hear your report on the results between the two.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: mulletchuck on September 17, 2012, 03:27:00 PM
sadly i'm deaf, and can't hear the difference as of yet.   Also, my room has too much outside noise for me to hear anything clearly, to be honest.   but soon i'll pull the AC out of the window, and be able to close the window and listen without all of that outside noise pollution comin' thru.   
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: cowrange on October 27, 2012, 10:52:41 PM
Any more feedback on how these sound?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: mulletchuck on October 28, 2012, 12:48:44 AM
I made a little video showing them on some strings.   They're amazing:

http://www.youtube.com/watch?v=J-QmgczEb48&feature=g-upl
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on October 28, 2012, 04:05:41 AM
Very nice,

thanks for sharing Chuck!

Udo ;)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: olafrec on November 02, 2012, 02:45:13 AM
Hello,

I'm super excited to have this eq completed soon! I have my power supply pcb build to the point of needing to calibrate the cmrr and was hoping someone might be kind enough to verify my method before I dive in. I've garnered information from the assembly aid, the vc528 cmrr guide and from this thread to devise the following plan:

- Connect "special cable" to signal generator with +/- 500Hz sine wave. I'm assuming I can use a plug in my DAW as a signal generator.
- Adjust output for 1 volt AC as measured using a DMM with red probe to pin 2 and black pin to pin 1 of special cable.
- Connect special cable to card edge (input) of power supply pcb: I plan to use my API 500V as a power supply with the pcb inserted into the first slot and simply connect the cable to the xlr input. I'll empty it of all other modules and position it for the "easiest" access to the pcb. Please let me know if this is bad.
- Connect to input of DAW via XLR with other end of cable altered with aligator clips, etc... to connect pin 2 to negative side of C2 and pin 1 to the common terminal of A2, being sure to have installed a known-good op amp into A1. It's my understanding that I may have to also connect pin 3 to the common terminal of A2 if I don't see a signal.
- Power up and follow adjustment instructions.

I'd be grateful if anyone could give me the thumbs up on this approach or point out any flaws/suggestions.

Thanks!

Jason   
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on November 02, 2012, 09:48:33 AM
Sounds like a plan Jason.  ;)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: olafrec on November 02, 2012, 10:09:04 AM
Awesome. Thanks Jeff!

Jason
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: olafrec on November 08, 2012, 02:59:25 AM
Thought I'd share my completed build :)

Definitely my most intense build to date but it works perfect right out of the gate! Sounds superb! HF section, especially, is clean and musical. Even extreme boost levels maintain a usable/musical timbre. Can't wait to patch it into a mix!

Props to chunger for his excellent build guide in this thread; saved me a ton of time. Of course, thanks to Jeff for such a well engineered kit! (btw - when do we get a 525 or 527 clone?  :D)

Cheers!

Jason
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on November 08, 2012, 03:15:39 AM
Hi Jason,

congrats to your build!
Now that´s a great eq,isn´t it?Love mine!

Have fun,

Udo ;)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: mulletchuck on November 08, 2012, 05:22:39 AM
olafrec, Peter Purpose designed a 525/527 clone.  he hasn't issued PCBs in a few years, tho..
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: 11gerard on November 25, 2012, 10:41:27 AM
I had a VP25 on 10/2011 and I bought a LC53A EQ kit on 11/11/2012 and Jeff asks me to share my experience.
It took 10 days to have the EQ at home in the South of France with 127$ of custom fees.
It took me around 8 hours to have evrything built.
I do not have real difficulty. The documents Jeff sent to me are very precise, everything is explained.
I can just confirm the problems with CTO5 and DF.2 amps sockets. It may be easier with largerpads to warm first the pad. I have the feeling that the control of the soldering would be easier. For GND sockets, they may be easier to solder if the pad is connected to GND with a 5mm conductor instead of several very short conductor around the pad. The heat may not go into the GND as fast. Those are just ideas, not fully sure that they would work. Let me know your advice.
I confirm also that a CHP-170 cutter is mandatory. I bought an equivalent here in France and I added also pieces of protective paper on both sides to avoid any contact between the PCBs and the metal cover.
2 last minor points:
- I know it is a lot of work to do but I'd like to have schematics. I like to understand what I am doing and it helps also in case of problems.
- My old eyes hardly read the blue on dark writings on the face plate. Please, don't suggest a 500++ format just like those big phones with big numbers for very old people...

Now the best: the sound!!!!!..... It is simply perfect to me. I do not know the right words in english. Anyway, even in French, I have difficulties to explain... Let say clear and punchy.

I have to say thank you to Jeff for that very good job you do.
 

 
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: submergent on November 27, 2012, 12:22:45 AM
alrighty... here's an example of these EQs in action... they were used on the drum bus in this mix. (if i remember correctly). probably a push at 3k and 50hz. love 'em!!

http://www.youtube.com/watch?v=HqybvZdLUZY


-pete
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: mulletchuck on December 03, 2012, 06:11:20 PM
I think it would be great to see some frequency plots of this EQ using different OpAmps so we can see the sonic differences, since I pretty much can't hear the differences between the 2520 and 1731 in this.   I have 2 configured with 2 2520s, and 2 configured with a 2520 and 1731.  :-/ 
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on December 03, 2012, 06:35:19 PM
Chuck, I would guess that freq. sweeps would essentially look identical. I can currently only print out one B&W sweep result at a time with my AP Portable One. As soon as the System One arrives I will create some nice color pdf's for ya. I have been wanting to do this for some time now. Maybe not hearing a dif is a product of your monitors? Just wondering....dunno what you use.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: mulletchuck on December 04, 2012, 03:24:25 AM
i use Focal Solo6Be's and a symphony I/O.  it's pretty top notch!   however, i live in NYC with drafty windows and noisy streets and above a chinese restaurant, where the ventilation fan for their kitchen sits above my apartment, shaking the place at roughly 70hz from 11am til 11pm, 7 days a week, except for friday and saturday, when they're open from 11am - midnight lol
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: tonycamp on December 04, 2012, 11:02:15 AM
Hey Chuck, do you like chinese food? Hey, why don't you swap the1731 and 2520 from the pertinent 2 units and make a fully loaded 1731 eq? see what she sounds like, and report back at 0-800 hrs soldier! ;)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: mulletchuck on December 17, 2012, 11:12:00 AM
Just wanted to say that currently, my favorite uses for these guys are on the mix bus in a Mid/Side config feeding a pair of VC528s.   

Also, once I figure out how to do overlays with SpectraFoo, i'll post some pics of how the OpAmps compare, frequency-wise
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: EmRR on December 17, 2012, 11:20:36 AM
Spectrafoo:   snapshot, that opens a window that lets you select which to display where.  Manually drag them around.  Clicking on one in the window again lets you change ID, etc.   

I charted these and the TB550A, the extreme low end is pretty different between those two types, both using GAR2520's.  Chart in next post!

I doubt you will see frequency difference in a response chart.  If any, likely small difference on the bottom end below 20-30.  I'd look at noise and harmonics, which is tougher to separate. 
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: mulletchuck on December 24, 2012, 04:04:17 AM
ok, so one of my units has a weird anomaly in the 7K Shelving band.   basically, if i switch it to Hi Shelf mode, and set the switch to 7k, any gain setting results in gain throughout the entire frequency range.    Switching from 7K to another frequency results in a low freq "thump" into my interface.  That same thump occurs if I toggle from Hi Shelf to Hi Peak, while on the 7K band.   this doesn't happen for ANY OTHER frequency band.   i tested everything else.  Jeff said that the specific components to check at C23, C25, R13 and the Hi Freq Switch.   I've desoldered and resoldered those parts a couple times and the issue remains.    Any ideas?   How could i test if the capacitors are good and not borked?  again it's **only** the 7K Shelf where this happens. 
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on December 24, 2012, 10:32:37 AM
Chuck, I just sent a reply to you on Facebook. I think we need to narrow down our ways of communication cuz I can't keep up with all of them. If you are having trouble with something, lets just use the build threads and not private messaging on Facebook. That way, others who may experience the same issues can benefit.

So, to reiterate my last private message, if it is not F4 (which is the ground for the hi shelving band) it is most likely C23 which is in parallel with C25 which then has R13 in series to F4. Since the "pop" only occurs when the GH is switched to or from the 7k position, this tells me it has nothing to do with the peak/shelving switch or the inter-board pins/headers. It could also be the GH switch. Check for continuity when the switch is at the 7k position, between the B pin and pin 4 of the attached pic.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: mulletchuck on December 24, 2012, 09:56:41 PM
ok, the continuity tests were sucessful:

from pin B to pin 4 has continuity.
from pin B to both pins on C25 had continuity
from Pin B to both Pins on C23 had Continuity
from Pin B to both pins on R13 had continuity, as well as resistance around 1.82K which should be 2.49K.  Would that cause the problem?


edit:  resoldered R13, now it's showing up as 2.49K

Also, the pop occurs when switching TO/FROM Peak/Shelf when the GH switch is on 7K.   

basically, switching to/from 7K Hi Shelf results in a LF "boomp". 

edit2:
I discovered another source of the "boomp".  this happens on all 4 modules.  regardless of band/gain selected, the HPF switch gives a bump around 5hz, which comes in around -36dbFS on my interface.   
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on December 25, 2012, 02:15:17 PM
....I discovered another source of the "boomp".  this happens on all 4 modules.  regardless of band/gain selected, the HPF switch gives a bump around 5hz, which comes in around -36dbFS on my interface.
This is normal and expected as the switch is interrupting the audio signal by bypassing the series C's used for the HPF.

I think at this point, I would try removing those 2 caps, but only one at a time. Desolder C23 from the PCB and see if the issue is resolved. Keep in mind, the knee of the 7k freq will be changed but we are only trying to see if there is an issue with one of the caps. Then, reinstall C23 and remove C25. Check again.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: mulletchuck on December 26, 2012, 01:52:24 AM
Removed C25.   No change.  Reinstalled C25.
removed C23.   ISSUE IS GONE!!!   woot woot!

So i need to replace C23.   awesome!!   Add that to the list of things that need fixing/replacing :-D   Convert gain pot on VP312 to GainSwitch, convert F76 Input/Output pots to Switches with VP GainSwitch kits, replace blown C10 on VP312DI, inspect slot #2 on Rack#2, cuz the big caps in the VP26 and VP312 have blown as a result of being in that slot. 
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on December 26, 2012, 10:06:20 AM
...removed C23.   ISSUE IS GONE!!!   woot woot!
Well, I can send you a replacement C now or when you order the other bits you need. Just don't let me forget. Once past the switch, I knew it should be easy to find. Glad it is sorted.  8)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: mulletchuck on January 03, 2013, 12:32:09 AM
installed the replacement cap, and did an A/B against my other units.   identical sweeps (+/-1%)!!  awesome!!!   Back in action!!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: 901 on January 08, 2013, 05:32:27 PM
Got mine on Jan 2nd. I had to pay 179€ to customs here in Germany for the 2 kits.

Started to build and must say these are a real pleasure to build! Everything fits fine, everything is there and all the parts are top quality. I have to confess that I spoiled a couple of the small Millmax sockets right away. I consider myself a decent solderer, but was a little too careless in the first place . The extra 3 sockets in the kit really saved me!

Since I'm not only building because it's fun and to have a nice new toy, but also to learn about circuit design I would very much appreciate a schematic.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: mulletchuck on January 09, 2013, 02:02:08 AM
ouch on the customs fees!   i'm pretty sure the only way you'll get a schematic is if you rev-eng it from the traces on the PCB  :-\
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: 901 on January 12, 2013, 11:37:57 AM
i'm pretty sure the only way you'll get a schematic is if you rev-eng it from the traces on the PCB  :-\

Hm, not so much fun with a multi layer pcb. It's too late now anyways. I have finished my pair. And they sound just magnificent!

http://db.tt/WdGFe2gf
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on January 12, 2013, 12:48:51 PM
A nice rack you have there,congrats!

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: 901 on January 13, 2013, 11:50:48 AM
Thanks, Udo!
Yours aint's so bad either. How do your Love Children compare to the EQP-1s? How do you decide to use the one or the other?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on January 13, 2013, 01:27:03 PM
Thanks, Udo!
Yours aint's so bad either. How do your Love Children compare to the EQP-1s? How do you decide to use the one or the other?
Hi,thanks for the kind words.
Personally they are both absolutely great and very musical eqs,but they aren´t directly comparable.Both have their points where they work best.I´d say I use the lovechildren more on single channels and instruments incl. vocals while the pultec is more in use for complex signals like a mix or so because of its´"bump".But that´s just an example,I´m sure both do fantastic jobs on a lot of things.
Conclusio:Best to have them both-and lots of them ;D

Cheers,

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Electrobumps on January 14, 2013, 12:36:26 PM
Hi

Just cut a pad when trimming the leads tight on the LC-EP board.  I need to work out how to join this back in the circuit?  Any chance of getting a schematic. 

Capacitor is C43 Pad next to F4, if schematic is not available.





Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on January 14, 2013, 01:01:55 PM
....Capacitor is C43 Pad next to F4, if schematic is not available.
That pad is a connection to the ground plane. If you have solder inside the thru hole, you should be OK as the ground plane is on the top side of the PCB. I would measure for continuity between that pin and the pin of C44 or C45 that is closest to the edge of the PCB. Those are also connected to the ground plane.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Electrobumps on January 14, 2013, 08:35:30 PM
That pad is a connection to the ground plane. If you have solder inside the thru hole, you should be OK as the ground plane is on the top side of the PCB. I would measure for continuity between that pin and the pin of C44 or C45 that is closest to the edge of the PCB. Those are also connected to the ground plane.

Thanks for getting back to me so quickly on that one.  It would seem that I got away with removing the pad and it is getting to ground.

Just finished the two units.  I have one glitch on one unit. When the HF shelving is selected.  One unit gives a lot of low end boost when 7K is the selected freq other freq's are fine, does not happen when notch/bell is selected and Eq seems to function normally. 

I have swapped the EP board with the unit that was working and the fault has moved with the EP board. 

I have made visual checks of all components on both boards and they seem to mirror each other.  For good measure I also re-flowed switches 4 and 5.

Any ideas on where to start tracking this down? 
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on January 14, 2013, 08:55:44 PM
Scroll up towards the top of this page and you will see some correspondence between myself and mulletchuck. He had a similar problem, oddly with the same exact setting. I would follow the steps I told him to try. Turned out to be a faulty cap. Keep me posted.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Electrobumps on January 15, 2013, 12:12:49 PM
Scroll up towards the top of this page and you will see some correspondence between myself and mulletchuck. He had a similar problem, oddly with the same exact setting. I would follow the steps I told him to try. Turned out to be a faulty cap. Keep me posted.

I searched this post late last night and the answer was right under my nose!!!

Anyhow, I've removed C23,  The cap is shorting against itself in and out of the circuit.  When removed I have no HF band, but I guess this is to be expected.

Lucky I managed to put the faulty cap in C23 like mulletchuck for quick diagnostics. The other 3 6800J caps across both units do not short. 

 
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: EmRR on February 04, 2013, 02:22:54 AM
LC53A and TB550A response, EQ flat and filters in.

Click this link for a full size pic (http://farm9.staticflickr.com/8509/8444163080_9f170db50d_o.png)

(http://farm9.staticflickr.com/8509/8444163080_78b161614b_z.jpg)

LC53A (green) and TB550A (red) 6dB boost and cut response,  50, 1K5, 15K.  You can see the effects of the differing amp response on the curves.  The TB550A boosts also drop off of marked boost as frequency increases. 

Click this link for a full size pic (http://farm9.staticflickr.com/8516/8444163314_16734495cb_o.png)

(http://farm9.staticflickr.com/8516/8444163314_6358fcf025_z.jpg)

LC53A 10dB (green) and TB550A 9dB/12dB (red) boost and cut response,  50, 1K5, 15K.  The apples versus oranges part of the show, gain steps that don't coincide.

Click this link for a full size pic (http://farm9.staticflickr.com/8079/8444163256_026aa6396f_o.png)

(http://farm9.staticflickr.com/8079/8444163256_0f1b1703f9_z.jpg)

TB550A curves for a broader overview of this general EQ type.  This is all the +12 and -12 settings, both peaking and shelf, and 50, 1K5, and 15K have every gain step shown. 

Click this link for a full size pic (http://farm9.staticflickr.com/8054/8444162906_2b4c1e37ff_o.png)

(http://farm9.staticflickr.com/8054/8444162906_f269812606_z.jpg)

Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 04, 2013, 09:05:35 AM
Very cool stuff. Thanks for posting Doug.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Indecline on February 04, 2013, 10:05:00 AM
Just wanted to add that another love child lives! 8)

My buddy built the boards and I did the dt05's and voltage followers. After finding a faulty 2520 (that I built :-X ) it fired up first errr.. Second shot!

Thanks jeff!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Electrobumps on February 14, 2013, 02:34:58 PM
Hi

Just been using these on various bits and really liking them, Smooth EQ.

Just strapped them across the mix buss and one unit is 1.4db hotter,  when the EQ is out.  Is this normal for two units to differ so much?  As it is enough to noticeably skew the image on the mix. 

Thanks
Iain
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 14, 2013, 04:52:06 PM
No this is not normal. It sounds like maybe the shunt jumpers for the lo-z/hi-z load do not match from unit to unit. The typical setting will be hi-z load. If it's not that, I would put the 2 side by side and compare each and every resistor. Any 2 proper units should be within .2dB or better.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: BricktopRecording on February 19, 2013, 08:50:57 PM
I just finished my build and have a couple issues-

Signal passes through but the output is loud and a bit distorted both with the EQ engaged and disengaged-  I'm thinking this may have to do with my CMRR adjustment but I'm not exactly sure,  I can hear the filters working when I cut/boost, engage HP/LP, etc.  Has anyone else run across this? 

Second,  the cut/boost switches seem to be a bit off,  its hard to explain- but they seem to function normally until I get to lets say -8db and it sounds like it jumps to +8db, but the whole way there it will be cutting until that point.  Is this fix as just moving the stop pins?

Thanks
Pete
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 20, 2013, 09:44:26 AM
Pete

The CMRR adjustment will not cause distortion. It must be something else. It could be opamp related. The first trhing I would do is swap out opamps especially if they were kits. Use known good working opamps that you have tested in another build like a preamp.

If you scan early in this thread, I give some probe points to "step" thru the circuit so you can measure ACV and see where things go wrong.

It doe sound like you have some GH pins in the wrong locations.

Cheers, Jeff
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: BricktopRecording on February 20, 2013, 04:26:26 PM
Thanks Jeff,  swapped the op amps with ones from working pre's and I'm still getting the super loud blown out sound.  I check earlier in the tread for the ACV points.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 20, 2013, 06:18:51 PM
I would check all of the R's around the opamps. Sounds like maybe something got swapped around.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: BricktopRecording on February 24, 2013, 04:13:11 PM
All the resistors on the main pcb near the opamps are correct,  though R6 & R7 measure about 3.6k in the circuit but are the correct 10k when out.  Could this be a potential issue?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 24, 2013, 04:22:27 PM
No since you can't accurately measure an R while it's in circuit. You would have to lift one end.

I think you will have to find the test points that were mentioned near the beginning of this thread. Measure those for ACV while injecting a balanced signal as was discussed back then. If you only have a DMM for this, I would suggest using a lower freq, something like 400Hz.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Unit7 on March 03, 2013, 02:02:49 PM
Hello,

I'm super excited to have this eq completed soon! I have my power supply pcb build to the point of needing to calibrate the cmrr and was hoping someone might be kind enough to verify my method before I dive in. I've garnered information from the assembly aid, the vc528 cmrr guide and from this thread to devise the following plan:

- Connect "special cable" to signal generator with +/- 500Hz sine wave. I'm assuming I can use a plug in my DAW as a signal generator.
- Adjust output for 1 volt AC as measured using a DMM with red probe to pin 2 and black pin to pin 1 of special cable.
- Connect special cable to card edge (input) of power supply pcb: I plan to use my API 500V as a power supply with the pcb inserted into the first slot and simply connect the cable to the xlr input. I'll empty it of all other modules and position it for the "easiest" access to the pcb. Please let me know if this is bad.
- Connect to input of DAW via XLR with other end of cable altered with aligator clips, etc... to connect pin 2 to negative side of C2 and pin 1 to the common terminal of A2, being sure to have installed a known-good op amp into A1. It's my understanding that I may have to also connect pin 3 to the common terminal of A2 if I don't see a signal.
- Power up and follow adjustment instructions.

I'd be grateful if anyone could give me the thumbs up on this approach or point out any flaws/suggestions.

Thanks!

Jason

Just wanted to check that I get this right... Using this method, does it mean that I could do the cmrr without a dedicated oscilloscope and use my Purple Sweet Ten as power supply when testing?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on March 03, 2013, 03:07:16 PM
Yes it should work. Just be careful.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Unit7 on March 03, 2013, 04:37:39 PM
Yes it should work. Just be careful.
Thanks Jeff!
I'll be careful

Except for making the special cable with the two resistors, for the cmrr test I thought about making a cable for connecting the board to the DAW input: Two millmax pins and an alligator clip on one side and a male XLR on the other. Millmax pins connected to pin 1 & 3, and alligator clip to pin 2.
Would that work?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on March 03, 2013, 04:40:01 PM
Sorry, not sure I follow you exactly....
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Unit7 on March 03, 2013, 05:14:49 PM
Sorry, not sure I follow you exactly....
Sorry,
Instead of saying 'Except for making…' perhaps  i should have said 'In addition to making'…
To be able to do the test with the board in my Purple rack, for convenience I thought it would be a good idea to also solder a cable for connecting the board to the input of my DAW.
Edit: Clarification: To be able to connect this cable to the PCB board in my Purple rack without the risk of the alligator clips slipping and causing damage I thought of soldering two millmax pins directly on the cable (to be connected to DOA C connectors - one of them optional as stated in your instructions) and one alligator clip (to be connected to negative side of C2). On the other end of the the cable - male XLR going in to my DAW for measuring.
Still unclear?..
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on March 03, 2013, 07:20:42 PM
Sorry, not sure I follow you exactly....
Sorry,
Instead of saying 'Except for making…' perhaps  i should have said 'In addition to making'…
To be able to do the test with the board in my Purple rack, for convenience I thought it would be a good idea to also solder a cable for connecting the board to the input of my DAW.
Edit: Clarification: To be able to connect this cable to the PCB board in my Purple rack without the risk of the alligator clips slipping and causing damage I thought of soldering two millmax pins directly on the cable (to be connected to DOA C connectors - one of them optional as stated in your instructions) and one alligator clip (to be connected to negative side of C2). On the other end of the the cable - male XLR going in to my DAW for measuring.
Still unclear?..
Hi,
if I get it right you want to do the cmrr calibration with the module mounted inside your rack?
If so it might be way better to use an extension-cable and have the module laying on the side in front of you.
Or connect it to an external +/-16 vdc psu.
But you must have the module parts accessable.
About extension cables,you can easily do it on your own (I made it this way using some edac connectors and prototype boards) or get cheap kits to build one pretty easy.They'll help you with troubleshooting/calibrating/matching for stereo tracking etc. on other modules too.
Just my 2ct.....

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: mulletchuck on March 03, 2013, 10:40:41 PM
just do what I did for testing the module.   Unscrew the backplane of your rack and pull it out from the side/top/bottom walls so it's all by itself. 

Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Unit7 on March 04, 2013, 04:47:31 AM
Udo and Chuck, thanks for the suggestions! Really appreciate it!

I'm new to DIY, and I'm not (yet) building anything but complete, 'ready to build' kits, so I'm not planning to buy bench PSU, oscilloscope etc, if I don't really have to. I've built Horvitz's chorus and 550A eqs, and now plan to build a pair of LC53As and a VP28. Then if I like them I'll add more units from time to time.

I've got my Purple rack mounted and hooked up in my rack in my studio and need it to be operational for my work. Demounting, unhooking and demounting the rack itself, and then all back again seems a bit inconvenient and time consuming for my situation.

Udo, yes, if possible I'd like to do the test with the pcb board in my Purple rack (placed in my studio rack, accessible via the patch bay), and your suggestion with the extension cable seems good. I'll look into that!

But if I could solder another cable for the CMRR test I believe it would be much more convenient and time saving for me.

By now, I've read Chunger's superb guide in this thread, Jeff's CMRR and LC53A aid doc five times and my brain boils!..

Please bear with me and help me starting from square one, with these couple of questions:
- For the CMRR test, it's possible to do by routing the signal from the PCB board to the input of a DAW for measuring, correct?

- If the above is correct, the connections should look like this:
PCB board A2 Common terminal -> DAW XLR input, pin 1
PCB board Capacitor 2, minus side -> DAW XLR input, pin 2
PCB board A2 Common terminal -> DAW XLR input, pin 3, OPTIONAL

Correct?

Thank You!
Paul
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on March 04, 2013, 05:23:03 AM
Hi Paul,

yes,looks correct for me.
Picking up the common at A2 is just because it is easy to reach.In general you can use any common point in the circuit for that.So attaching a piece of wire to a fresh doa pin and plugging in to the common point at A2 is o.k.
Connecting the common to pin 3 on the xlr too as an option depends on whether your interface input is floating or not.
Looking good so far,keep us posted,

Udo ;)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Unit7 on March 04, 2013, 11:13:28 AM
Hi Paul,

yes,looks correct for me.
Picking up the common at A2 is just because it is easy to reach.In general you can use any common point in the circuit for that.So attaching a piece of wire to a fresh doa pin and plugging in to the common point at A2 is o.k.
Connecting the common to pin 3 on the xlr too as an option depends on whether your interface input is floating or not.
Looking good so far,keep us posted,

Udo ;)
Great, thanks Udo!
I'm still waiting for the VP28 to be in stock at cAPI before I'll order it and a pair of LC53As, so I haven't started to build yet, except for eight GAR2520s made this weekend. But now I'll be able to prepare those test cables!

Follow up questions:
- Does Steiger's special CMRR cable require a shielded cable (for pin 1)?
- Is there any reason why Chunger uses a cable with so many leads? On Jeff's drawing it seems a simple shielded instrument cable would do the job
- Would 'my' test cable (desribed in my last post) require/benefit from the use of a shielded cable? In that case, on which pin?
- I've checked my plugin collection in ProTools (HD) and Logic and don't find a good measuring tool that displays dB continuously and in two decimals. Any recommendations on a really cheap plugin for Mac OS 10.6 that will do the job?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: sharpeleven on March 15, 2013, 01:40:02 AM
Two more Love Childs alive and well here.

Everything went well with the build except the calibration part left me scratching my head for a while until I figured it out. you basically have to build two cables for the cal procedures and the rest is easy.

The LC's sound good! I got blisters from turning those knobs...!

All red dot op amps. Lows feel a bit loose, mids/high are very smooth sounding.

thanks, Jeff, for creating yet another great tool!!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Trench Recordings on March 26, 2013, 06:59:26 PM
I built my first of two... gonna test and cmrr adjust tonight.

Questions. what resistor value is best for the cmrr calibration cable ? and how important is my steel case cover. I cant get all the screw holes to line up on the cover. Everything else is installed and the faceplate is on and looking good. Maybe the metalwork on the cover is a touch off ?

-Dave

Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on March 26, 2013, 07:35:08 PM
Some of the flanges need a tweak to get them to line up. I would adjust them if you can. The steel is soft and can be adjusted with pliers pretty easily. The value of the R's is not super critical as long as they are a very good match to each other. Anything between 500-ish to 3k should be fine.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Trench Recordings on March 26, 2013, 09:33:20 PM
Ok first one tested and seems like everything is working. I couldn't get the cover on and all screw holes lined up. I didn't feel like taking off the knobs, faceplate and boards out just to get the cover on so I left it off.

Silly question, How does the lpf and hpf work ?  Does the freq selector affect them ? I flipped them on and off but didn't really hear a difference. What should I be hearing ? Anyway to test them ?

Other than that it sounds great. Nice mojo !

Thanks,
-Dave
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on March 27, 2013, 01:09:19 AM
Hi Dave.

Ok first one tested and seems like everything is working. I couldn't get the cover on and all screw holes lined up. I didn't feel like taking off the knobs, faceplate and boards out just to get the cover on so I left it off.

Sad to hear.It's a tight fit,but it works fine.Maybe washers mounted wrong on the standoffs?

Silly question, How does the lpf and hpf work ?  Does the freq selector affect them ? I flipped them on and off but didn't really hear a difference. What should I be hearing ? Anyway to test them ?

Dave,you need to apply a signal that contains those frequencies to hear or measure anything.
And your speakers should be able to reproduce that too.Maybe your ears don't work good enough where the LPF sits at.
Jeff once answered my questions where those (fix) frequenciies are and at which slope in reply #47:

......Both have a 12 dB per octave slope.HPF is stated as 50Hz and the LPF is stated as 15kHz......

But you can test them pretty easy:Apply some (pink) noise to the eq while eq is active but the three main bands are set to zero (flat).
Monitor the eq output with an analyzer,maybe you have one in your daw or so.Analyzer should be set to no weighting filters!
Toggling the HPF as well as the LPF should show roll-offs at the very low and very high frequency-bands now.

Hope to have helped,

Best regards,

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: EmRR on March 27, 2013, 01:13:13 AM
I think I may have had to extend some holes in a cover to get it to fit on. 
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: mulletchuck on March 27, 2013, 11:38:44 AM
I built 4 and none of them have the cover on.    works/sounds fine without it.   
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on March 27, 2013, 11:49:07 AM
The frames sometimes need a little adjustment to get everything to line up. I have built many and get the covers to work every time no problem. You need to verify the fit of the cover before final assembly otherwise it's hard to do and no one wants to work backwards.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Trench Recordings on March 27, 2013, 06:17:59 PM
Thanks for the info Udo. I will pink noise it to check. Ouch with the "maybe my hearing isnt good enough comment". lol

I will play with the cover some other time. For now its installed and working :)

Thanks everyone,
-Dave
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on March 28, 2013, 03:17:51 AM
Ouch with the "maybe my hearing isnt good enough ").
Hi Dave,

I didn't want to tell things wrong,sometimes there's still the language barriere and it's a bit hard to find the right words,hahaha........
15kHz is quite high and can be pretty close to what people are able to hear,I'm not refering to the normal loss while getting older but especially the young people nowadays.
A lot of my students certainly do have problems in that frequency range!They are aged around 20 to 24 years,and the older guys here will know why this happens....and it is irreversible!
I'm 50+ but do hear them btw.
So always take care,our ears are the most valuable instruments we audiofreaks have!

But this is completely off-topic now,me culpa ;D

Have fun with these great equalizers (I do),

cheers,

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Trench Recordings on March 30, 2013, 02:24:25 PM
Just an update. I tried the cover from the other kit I haven't built yet and everything lined up perfectly. So the hole are off on that first cover. Not a big deal, I just need to drill the holes out a bit to make it work.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: tonycamp on April 02, 2013, 02:40:07 AM
Oh happy day!, i wont be able to put them through the paces for a while though :(
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Unit7 on May 09, 2013, 07:42:44 AM
Finally started the LC53A project and did the CMRR today, with PCB board in my Purple rack and an extra special cable in addition to the CMRR cable.

Used DAW for both signal generation and measuring (Logic Pro -> Fuzz Measure).

Managed to find the lowest point on the variable resistors with approx .25dB difference between my two units, so I hope I'm ok.
Only had one thing I would like to check:
When unit was off (no power) the signal was stable, but with power on the signal started to wobble approx ±0.5dB. Happened with both units and with two different GAR2520s. Is this normal?

(edit: tested same two GAR 2520s in one of my TB550s and signal was stable)
(edit 2: got word from jeff that he sometimes get a ±.25dB fluctuation, so hopefully I'm fine...)

Cheers!
Paul
Title: Sorting sheets
Post by: Unit7 on May 12, 2013, 03:09:05 AM
Soon ready and again, SO grateful for Chunger's guide! So here's my µ-contribution. I've got it in Word format too, so if you prefer that, or if you find an error please just pm.
Title: Re: Sorting sheets
Post by: kante1603 on May 12, 2013, 03:44:07 AM
Hi Paul,

great,thank you very much for sharing!

Best,

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Axelerator on May 12, 2013, 11:35:36 AM
Hi Jeff, my lc53a´s are sounding soo nice but building two more seems to time consumpting..so i want to ask about the lc553  :-) !?.any news on them ? 8)
greets,
axel
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on May 12, 2013, 06:49:21 PM
Hi Axel

I need to find the time to put together all the build docs, BOM's, pricing and list them at the store. I have had all the parts since Feb 2012! I just never seem to find enough extra time to get that all handled. One of these days I will get to it..... :-\
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Unit7 on May 13, 2013, 10:35:21 AM
Done! Interesting to compare to Brian's 550s. As I believe Doug mentioned somewhere, the 53As sounds a tad bit more natural/uncolored. First impression is that the TB550s smears transients a bit more, in a way I really like. Guess I'll be looking at two more of each to fulfill my dream of a full eq rack...

A note on Chungers photo guide, regarding joining the main PCB with the CB PCB. As I don't have the tools to measure accurately the way Chunger did, I checked that the screws and standoffs were centered more or less, then had boards laying on the side on my table (to get things straight) while semi fastening the screws and then simply put the joined boards in the chassi to check that holes matched. Worked fine obviously, but I'm interested to hear what other builders say about that.

Ciao!
Paul
Title: LC53A bypass switch makes loud pop when engaged/disengaged
Post by: fluxofpinkindians on May 31, 2013, 04:49:01 AM
I love this EQ and loved building it.

The bypass switch on my build makes a loud pop/click when engaged or disengaged.

Just wondering if this is normal or if anyone had any suggestions as to why ?

thanks to all
Title: Re: LC53A bypass switch makes loud pop when engaged/disengaged
Post by: jsteiger on May 31, 2013, 09:55:22 AM
The bypass switch on my build makes a loud pop/click when engaged or disengaged
There is a small click but typically nothing loud or dangerous sounding.
Title: Re: LC53A bypass switch makes loud pop when engaged/disengaged
Post by: sharpeleven on May 31, 2013, 02:56:58 PM
I love this EQ and loved building it.

The bypass switch on my build makes a loud pop/click when engaged or disengaged.

Just wondering if this is normal or if anyone had any suggestions as to why ?

thanks to all
No audible artifacts when engaging/disengaging here, unless there's a signal present and a considerable low frequency boost/cut applied.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: sharpeleven on June 06, 2013, 12:33:47 PM
Two more Love Childs alive and well here.

Everything went well with the build except the calibration part left me scratching my head for a while until I figured it out. you basically have to build two cables for the cal procedures and the rest is easy.

The LC's sound good! I got blisters from turning those knobs...!

All red dot op amps. Lows feel a bit loose, mids/high are very smooth sounding.

thanks, Jeff, for creating yet another great tool!!

Just would like to refine my earlier statement about the low band. By "loose" I didn't mean to question the sound quality in any way. "Lush" might be a better way to describe what I'm hearing. It's definitely not the tight/controlled low end & focus you might get with eg. some of the pultec type EQs. The LC53a always sounds very big and lush in comparison. Highly useful imo. Sounds killer on close micd piano!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Unit7 on October 01, 2013, 02:48:52 PM
My 2nd pair ready! Hoping to see more in stock soon for my final 3rd pair and my DIY 500 rack filled with 53As and Horvitz's 550As. :)

Found that the sorting sheets I posted earlier are working fine, so Jeff please feel free to link or use them anyway you want.

Also, inspired by Horvitz's 550 build manual, on the four 53As I've built I've only soldered one pin on the Greyhills until the faceplate is on. Makes things a bit more flexible me thinks. Seems to be a good idea to handle tenderly before fully soldered, especially when installing the stop pins. But if there's another downside I should be aware of please educate me.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Unit7 on October 02, 2013, 09:46:48 AM
Problem with one of my new 53As. All is ok except that 7k shelving is boosting/cutting on/from a much lower frequency than 7k. It sounds like it's still shelving (not peak) but sounds more like 200hz or 400hz than 7k. I'll open up and look for obvious errors, but meanwhile it would be great to get directions on which Greyhill pins and components that are in the 7k shelving path.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on October 02, 2013, 09:58:45 AM
Problem with one of my new 53As. All is ok except that 7k shelving is boosting/cutting on/from a much lower frequency than 7k. It sounds like it's still shelving (not peak) but sounds more like 200hz or 400hz than 7k. I'll open up and look for obvious errors, but meanwhile it would be great to get directions on which Greyhill pins and components that are in the 7k shelving path.
Scroll back thru this thread. I think Chuck or someone had a similar problem. It was traced down to a bad cap. See if that is the case for you and let me know. I will send a replacement pronto.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Unit7 on October 03, 2013, 05:25:24 AM
Problem with one of my new 53As. All is ok except that 7k shelving is boosting/cutting on/from a much lower frequency than 7k. It sounds like it's still shelving (not peak) but sounds more like 200hz or 400hz than 7k. I'll open up and look for obvious errors, but meanwhile it would be great to get directions on which Greyhill pins and components that are in the 7k shelving path.
Scroll back thru this thread. I think Chuck or someone had a similar problem. It was traced down to a bad cap. See if that is the case for you and let me know. I will send a replacement pronto.
Thx! Found the posts at pg 7 from both Chuck and Electrobumps. And I seem to have the exact same issue. I removed C23 and issue is gone. I presume this points at C23 and that I don't have to put it back to test w/o C25?

I'm waiting for 53As to be in stock again for another pair, so if you don't need to get this out of the way I'll remind you to put the new cap with that order. No sweat.

Follow up question: I guess this indicate a high percentage of bad 0.0068µF polystyrene caps? In that case, what would we be hearing if the other 0.0068µF cap (C28) was bad?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on October 03, 2013, 10:00:05 AM
Yeah for some reason I have had a bad few. Only a few though. If they are bad, they are shorted internally. There should be no "in between".
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: yosh on October 17, 2013, 03:40:22 PM
Hi,
I'd like to double check my CMRR calibration results. I used a DMM to measure ACV at negative side of C2 and ground. The lowest value I can get is about 60mV. This is with the 1K pot turned fully clockwise. At fully counter-clockwise the value is about 162mV. As I turn the pot clockwise from 162mV the voltage slowly drops until it reaches 59-60mV. At no point in the travel of the pot does it dip below 59-60mV. It seems like from what I read about CMRR calibration that 60mV is high. I should be able to get it within 0.1-0.2mV, right? I tested with a known good opamp. I double checked all resistor placements. I double-checked my results with another DMM and an oscilloscope. I'm an experienced builder and understand troubleshooting so I don't think I missed anything obvious, but you never know, if I did, this wouldn't be the first time. By the way, I'm building two units and have the same results with both. Anyone have any ideas? Or am I misunderstanding something and this result is acceptable?

Thanks in advance!
Josh

edit: I am using 478.8 ohm resistors out of the signal generator.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on October 17, 2013, 03:51:04 PM
What frequency are you using? What DMM is it?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: yosh on October 17, 2013, 05:31:27 PM
400 Hz as recommended. It's a Fluke DMM. Just discovered I had a bad test lead. Now I'm reading 50mV at full counter-clockwise with a slow and steady drop to 22.5mV at full clockwise.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on October 17, 2013, 05:45:41 PM
Something does not seem right with those results. The low spot is usually about 5-7 turns CW from the center which is the starting point when the trimmer is untouched. Do you have another way to test? DAW maybe?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: yosh on October 17, 2013, 06:04:17 PM
Yeah, I'll probably finish the build then take these to my studio and test them there with the DAW. Thanks!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Drumbreak on November 01, 2013, 03:58:20 PM
Hey all!  I was wondering if anyone has tried, or if it's possible to put the EA 1166-500 output xfrmr in one of these babies.  The primary side of the 1166 is a 200ohm load, compared to a 75ohm load on the 2503.  I'm not sure if loading the circuit that much is possible or good.
I have been borrowing a friends BAE 1073d, which sounds extra smooth in the upper mid-range compared to the more up front mids of the LC53a.  I really like both flavors with their similar inductor sound, but thought a Neve style output would change the flavor for another veriety.
Thanks, and cheers!
Brendan
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Tiotever on December 11, 2013, 07:03:44 AM
Hi, I'm new to the community. I've built 4 preamps, and I'm totally hooked!  I've started 2 LC53A's and didn't realize in advance that I would need to calibrate them.  I'm reading all of the information, and without really understanding any of it, I think I will eventually be able to pull it off.  But with my current limited understanding of Ohms law and electronics in general I'm wondering if I might be better off finding someone in the LA area that can help me through these first 2 babies?  Hope I'm not breaking a DIY code here,...but I'm glad to pay an hourly rate to get these calibrated so I can finish them off before a session early next week.  Seems like a really good way to learn too!! If anyone's got any suggestions in my area please let me know.  In the meantime I'm gonna keep building these suckers..  Cheers!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on December 11, 2013, 11:56:33 AM
It's pretty easy to do if you use my test jig. There are even instructions on the board's silk screen. http://classicapi.com/catalog/index.php?cPath=22_117_185 (http://classicapi.com/catalog/index.php?cPath=22_117_185)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Tiotever on December 11, 2013, 03:53:02 PM
Hey Jeff,  Thanks for the response.  I ordered the extension jig bundle last night before posting.  Hopefully its going in the mail soon.  I'm gonna give it a shot.  Cheers! 
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on December 11, 2013, 03:55:38 PM
Yup. Already packed and leaving here in about an hour.  ;)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Tiotever on December 13, 2013, 08:40:31 PM
Question about the cable build required to do the calibration.  The outputs on my DAW that i plan to generate the test tone with only have 1/4" TRS outputs.  Can I make my cable with one side 1/4" TRS and the other the side XLR male (with the matched resistors)?  Or perhaps another option would be to make both sides XLR and use an XLR to TRS adaptor for the DAW output side.  Will both of these options work?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on December 13, 2013, 08:43:08 PM
If you use my test jig there is no need for a special cable. Just follow the steps on the test jig.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Tiotever on December 13, 2013, 09:18:08 PM
Well that just goes to show how well I understand what I'm about to do.  Going to my workspace now to build my jig, and go fully calibrate.   Will I need 4  or 2 alligator clips attached to my DMM?  As of now I only have the 2 probes that came with it.  Btw thanks for the prompt shipping!!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on December 13, 2013, 09:30:11 PM
Well, with the test jig built and inserted into your 500 rack, LC53A module connected to the test jig, you will need to send a sine wave signal to the input of that 500 slot (XLR or whatever, depending on your rack). If you can monitor an unbalanced signal with your DAW, (set a channel up to record enable) I would just use the DAW instead of the DMM. If you use a DMM, you can just clip your probes on. If you need to make a cable for your DAW, you will need only 2 alligator clips. I think 'Chung has pics of that part in his build pics.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Tiotever on December 13, 2013, 09:52:52 PM
Jeff thank you for the quick responses and awesome patience. I can get in and out of the the DAW and monitor that way easily. I think perhaps most of my confusion stems from the different possibilities displayed on getting this calibration done. So far my usage of the DMM has been limited to testing resistors. I can check ohms on a resistors like nobodies business but have no idea what it all means.  Ha!  That being said I will gladly stay away from that method of calibration.

Ok so once I send the sine wave out of protools into my op amps and then back into protools, what am I looking for as I tweek the trim component? In other words how will I know I have calibrated it?  Once again thank you for your patience!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on December 13, 2013, 10:36:26 PM
That is all in the CMRR doc in the support docs zip.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Unit7 on December 26, 2013, 11:00:48 AM
Humans win! :)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on December 26, 2013, 12:40:57 PM
Humans win! :)
Wow!! Humans win big-time!!! Nice  8)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: brent on February 04, 2014, 09:42:36 PM
Yeah for some reason I have had a bad few. Only a few though. If they are bad, they are shorted internally. There should be no "in between".

I just finished building 1 of 2 kits I ordered.  It looks like I have at least one bad C23 as well.  I read through the thread and noticed a few others have this problem, so I removed it first after doing the continuity tests, and sure enough the boomy high shelf at 7k went away.  I temporarily swapped in one of the 68nf from the other kit, and the 7k shelf seems to be fine now.

What's odd is the "bad" C23 measures fine on my fluke 287, but perhaps this isn't a sure fire way to make sure a cap is good?

Also, what are the symptoms if  the 68nf in C28 would also be faulty?  It looks like there are a few bad 68nf floating around out there, I just want to make sure I can verify these caps are good somehow.

I guess I need to get at least 1 replacement from you at this point.

Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 04, 2014, 11:15:29 PM
Yeah there are a few out there. A bad one will measure very low DCR almost a short from lead to lead.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: brent on February 05, 2014, 12:42:03 AM
Yeah there are a few out there. A bad one will measure very low DCR almost a short from lead to lead.

OK that makes sense.  There's definitely continuity from lead to lead on the bad capacitor.  I'll shoot you an email.

Cheers,

- B
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on February 05, 2014, 12:54:29 AM
Humans win! :)
Now that's a great rack you have,congrats Paul!

Udo ;)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: brent on February 09, 2014, 09:30:52 PM
Yeah there are a few out there. A bad one will measure very low DCR almost a short from lead to lead.

Hey Jeff,

Does C23 have any effect on the 10k shelf?  I've been testing the 2nd unit ( without C23 for now) and the 10k shelf doesn't seem to boost much.. it's almost like it's at +2db when the level is at +10db.  The peak 10k mode seems to be fine.

-B
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 09, 2014, 09:38:51 PM
No it shouldn't. The 10k shelf is C28||C29 with R14 after them in series to gnd.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: brent on February 09, 2014, 10:10:18 PM
No it shouldn't. The 10k shelf is C28||C29 with R14 after them in series to gnd.

Ah, I just took apart the unit and realized what I did.  I left C28 out  instead of C23... I'll check it again when the replacement 68nf arrives.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: brent on February 13, 2014, 11:30:55 PM
Replacement 68nf cap arrived today.  Popped it in and everything is back to normal.  Thanks Jeff!

-B
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jswagler55 on April 14, 2014, 01:53:57 AM
So just got done with two of these beauties. One of them worked 100% the other sounded fine just the output was about -15db weaker. Looked through everything and switched all the amps between the two and still nothing changed.

I switched the output transformer and seems to be the issue. The weaker output is around 4.2ohms on the Gray-Violet and the green-blue secondary windings, but on the louder eq all windings are 8.5 like they should be.

Just looking for some confirmation on if this seems like it is the problem.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on April 14, 2014, 10:16:21 AM
So you swapped outputs and the problem followed the transformer?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jswagler55 on April 14, 2014, 11:34:23 AM
yes
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on April 14, 2014, 12:21:15 PM
Please send me an email with the order # and I will get you a replacement shipped today. jsteiger1965 at yahoo
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: maq3396 on June 10, 2014, 08:38:02 PM
Hi Everyone,

Quick question...

Currently using one of Jeff's VP28 preamps and a Great River MP-500NV for a small home system.
Would the LC53A be a good eq for male and female vocals?
Interest is blues, crooner, and rock from 60-80's.

Thanks in advance

Cheers
Mac
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on June 11, 2014, 12:25:10 AM
Yes,and much more..... ;)

Best,

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: gar381 on June 17, 2014, 05:19:40 PM
Yes,and much more..... ;)

Best,

Udo.

Got 8 of these guys..  They are GREAT for everything!!

GARY
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Kan Kaban on August 09, 2014, 06:39:53 PM
At the beginning...
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Kan Kaban on August 09, 2014, 06:43:07 PM
Mundorf Supreme...
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Kan Kaban on August 09, 2014, 06:44:53 PM
Hot?...
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Kan Kaban on August 09, 2014, 06:45:33 PM
Hot!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Kan Kaban on August 09, 2014, 06:47:00 PM
Gold children!.  ;)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on August 10, 2014, 03:10:12 AM
Hello and welcome,

congrats to your builds.
I really like the way how you got everything prepared in the first pic!
That's the way to go people!
Also a cool idea with a nose pliers and a rubber band creating a vise-excellent and very creative I must say.

Enjoy your lovechildren,

Udo.

Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Kan Kaban on August 10, 2014, 04:37:16 AM
Thanks a lot Udo.

I started handcrafting circuits late 80´s when I was 13. Last year I recovered this passion forever, with a pair of CAPI VP28. As a multimedia artist, being able to build your own tools, has many, many advantages. Besides the money, more important ones. The "lab" was improvised for this studio located at the Andes, S.A. beautiful place. Those nights where just perfect.

Long live DIY!!!.

Next: Passive network on silver wire / teflon. I hope to find a local artisan / supplier.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: bdunard on September 12, 2014, 12:15:14 PM
Hello all I just finished my first LC53A eq.  After building a VP28 and it working right I was hoping to get the same result with this build.  I am close I would say 85% works.  Hopefully someone can help me track down the issues so I can fix it.

1.  When boosting the high shelf at 10k it seems to just boost the overall audio...all other bands in the HF section seem to work.  10k DOES seem to work correctly if I switch to peak instead of shelf.  I read through the forum build and the closest I could find was capacitor 23 was an issue for some other HF issues but they were not exactly like mine.  Thoughts

2.  The LPF and HPF don't seem to be working.

I'm assuming that with the first problem the audio is just passing through somewhere without hitting the circuit that boosts and cuts 10K.   However, I figured this would make more sense if it happened on both peak and shelf.  So again I'm guessing that the problem has to be somewhere after the shelf switch that doesn't effect other frequencies so maybe this would be a specific cap or resistor.

I'm attaching a dropbox link to some images of my build. 

Thanks!

https://www.dropbox.com/sh/49j9sp3g70cnptc/AABGRTakGSDlg2sT5qw73tcAa?dl=0
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on September 12, 2014, 04:07:48 PM
The 10kHz shelf is C28 and C29 in parallel, then R14 in series to ground. I would remove C28 and measure it for DCR. It should be open with no measurable resistance. IIRC, that was the problem cap in the other 7kHz situations. I have been checking all of these before we kit them up but maybe this was a straggler from before.

Are you running a sweep to verify that the HP and LP filters are not working? That is the best way to test. Testing by ear can be misleading. The LP is @ 15kHz and the HP is at 50Hz. They are separated by voltage followers so have no interaction with each other. The fact that neither is working seems odd to me.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: bdunard on September 12, 2014, 07:44:44 PM
I pulled both C28 and C29 out and check both for any resistance and there wasn't.

What is IIRC cap for 10K...as I'm not sure what that is and how do I test it?

Just wanted to remind you that I don't have a common pin on one of the voltage followers...you didn't seem to think it would be a big deal to get up an running without but just wanted to throw that out there.  I will have that fixed when my shipment comes in.

I will run a few test tones (low and hight) through the unit and into my DAWs spectral display which should tell me if anything is happening.

Any other items I should check or test before putting it back together and running some more tests?

Thanks!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: bdunard on September 12, 2014, 08:27:24 PM
Ok so I put it all back together and now no eq function works...

It passes audio fine but no eq function.

I tried directly into the chassis and also with the JLM extension jig.

If pushed a bit from side to side on the JLM extension rig it would work very quickly but it was too short to tell.  I just left one of the mid bands boosted and twisted around the card connection and I could get it to jump in level like it was boosting but it was very short lived.

So any thoughts...I didn't think it was going to get worse but...it did.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on September 12, 2014, 08:44:11 PM
Ok so I put it all back together and now no eq function works...

It passes audio fine but no eq function.

I tried directly into the chassis and also with the JLM extension jig.

If pushed a bit from side to side on the JLM extension rig it would work very quickly but it was too short to tell.  I just left one of the mid bands boosted and twisted around the card connection and I could get it to jump in level like it was boosting but it was very short lived.

So any thoughts...I didn't think it was going to get worse but...it did.
Hello,

I have a feeling now that the issue is just loosing the ground connection on the filters side.About two years ago I asked Jeff how the bypass switch works or better if it is a true bypass or not.Here's the reply:

http://groupdiy.com/index.php?topic=48426.msg615008#msg615008

Leads me to think  that your bypass switch might be broken or at least the ground connection gets lost in this area.

Just an idea......

Good luck,

Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: bdunard on September 12, 2014, 09:16:47 PM
That makes sense why things aren't working now...possibly the bypass switch but not sure that explains the earlier problem with the 10K shelf.

Who knows maybe I have fixed the problem on the 10K shelf, but created another problem before I could test it.   One thing I should mention is that when I was taking it apart I forgot to take the faceplate off so I did slightly bend a jumper between boards...totally my fault but maybe that made the jumper solder joint loose. 

I don't think I have any solder joints that are touching the chassis but I can see one of the screws that holds the two boards together is close but it looks like that shouldn't matter anyway.

So outside of replacing the "in/out" switch...do you have any recommendations for chasing this down?

Thanks for your reply Kante1603.

Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: bdunard on September 15, 2014, 08:16:29 PM
I touched up a few solder joints and took my straight edge to make sure no solder pads or legs are higher than the casing threshold. 

If I use my JLM extension cable and apply pressure to one side of the connection on the LC53A the eq does come on and it seems to be working.  I don't know if it causes something to make contact or it is causing something to not ground out.  I checked the solder pad heights to hopefully help rule out the 2nd one.

Does anyone know what this may point to as far as the problem?

Any other tests I could do?

Thanks!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on September 16, 2014, 01:25:29 AM
Does it behave the same way directly seated in the rack?
Could it be it's just a broken extension cable,e.g.  ribbon cable not seated well in the idc headers,cold solder joint etc.?
I'd sort that out first and measure the contacts for continuity from both sides.
Best done with aligator clips instead of probe tips and moving the cable/wires while measuring.


Best,


Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: bdunard on September 16, 2014, 09:49:34 AM
I did put it in the rack.  It passes audio fine but I can't push or contort it to get the eq'd sound to intermittently come on like I can with the cable. 

I also now notice when I push the in/out button there is a bit of a  "thump" sound. 

Could you explain your continuity test a bit more?  I do know that particular slot on the rack works because I double checked it with another module. 

I'm assuming that if the engage switch just lifts the ground to bypass the eq circuit then the problem must be something related to that.  I'm just not sure what I did to have this thing basically working then take it apart, reassemble and it doesn't work?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on September 16, 2014, 10:20:13 AM
Are you 100% sure the long headers are in their sockets properly? Sounds like the issues lies there. You can beep them out with your DMM to make sure you have continuity from board to board.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: bdunard on September 16, 2014, 07:25:10 PM
Jeff,

Good news and bad news.

One of the long header sockets was indeed out and putting it in does make the eq almost function.

I can tell that both LPF and HPF are both working too.

However, there is a new problem...

At every frequency band I try to boost  more than a couple of notches to the clockwise it starts to oscillate and distort and jumps greatly in level...I can't tell how much because it clips everything and sends the dogs a runnin'

If I were going to guess with my limited knowledge...I would say it is much like the circuit is feeding back into itself much like a microphone and a speaker. 

Any thoughts as to why this might be occurring?

EDIT:  I should also note that no audio has to be passed through the eq for these loud distorted oscillations to happen.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on September 17, 2014, 12:45:49 AM
This sounds like an opamp or discrete follower problem. Early in the thread there are test points. I would check all of those and see where the issues start.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: bdunard on September 17, 2014, 12:02:49 PM
Jeff is this the test that I should perform to figure out my issue?  Just wanted to check and make sure since I don't have a properly functioning unit to compare it with.

Also, I don't think it's the opamps because I used my red dots from my functioning VP28 and it has the same issue.

It doesn't seem like anything has changed since it first worked (minus the 10K and LPF,HPF issue)

Since the HPF and LPF now work do you think it could be somehow related to that part of the circuit now effecting all of the boost points on the peaking bands?



OK.

I would start by taking some measurements from the properly working module. After injecting a signal, take a measurement of your choice at the output of each amplifier stage then see where the gain increases in the hot module.

1st reading: negative side of C2 on the Main PCB.
2nd reading: output pin of A1, DF on CB PCB
3rd reading: output pin of A2, DF on CB PCB
4th reading: output pin of A4, DTO5 on CB PCB
5th reading: output pin of A3, DTO5 on CB PCB
6th reading: neg side of C12 on the Main PCB

Those are in signal flow order.

We'll figure out the problem stage and go from there.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on September 17, 2014, 02:29:31 PM
It could also  be one of the DTO5's.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: bdunard on September 17, 2014, 03:20:48 PM
Can I attach my common ground anywhere on the chassis for ground...or does it need to me on a common from one of the removed opamps?

And I'm assuming I should leave the DTO5 inplace?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: bdunard on September 17, 2014, 03:51:18 PM
Ok with everything in place except the Boost/Cut PCB I attached a ground to the chassis and ran a 500Hz signal in to the unit at 1.23 V.

My readings are:

1.14 V   --  1st reading: negative side of C2 on the Main PCB.
1.14 V   --  2nd reading: output pin of A1, DF on CB PCB
1.135 V   --   3rd reading: output pin of A2, DF on CB PCB
.777 V    --  4th reading: output pin of A4, DTO5 on CB PCB
.781 V    --  5th reading: output pin of A3, DTO5 on CB PCB
.782 V   --   6th reading: neg side of C12 on the Main PCB

Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on September 17, 2014, 06:07:58 PM
You should be looking for the THD that you said was present. Check for it at the mentioned test points to see where it begins.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: bdunard on October 02, 2014, 11:22:27 AM
Just wanted to post an update to my LC53A issue.

Turns out the Eq was fine the whole time.  I was testing it in a rack that has both xlr and db25 connections.  I was using xlr to tt cables just to quickly patch into the channel  on the rack  and test.  Meanwhile the db25 connectors were patched into a normalled patch on the patch bay which allowed it to feedback into itself while using the xlr connections at the same time.   
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: fancytimestudio on November 23, 2014, 02:18:23 AM
Hey everyone!
New to post here but I've been reading this forum a lot. I assembled a Love Child and I'm having an issue with it. I was hearing some sort of distortion so I re-did the CMR calibration and that didn't seem to fix the issue. Anyway, I have a couple of screen shots here. The top audio file is the "clean" 400Hz sine wave. The middle audio file is the sine wave returned from the EQ. Lastly, I lined up the two audio files and flipped the phase so I could see the difference. That's what the bottom audio file is, the difference. I looked for bridged solder points and didn't find any. I also checked to make sure my diodes were all attached with the correct polarity. I would love some help with this. Pretty sure this isn't how this EQ is supposed to sound. Any ideas?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: fancytimestudio on November 23, 2014, 02:20:02 AM
Here is a zoomed screen shot.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on November 23, 2014, 11:23:34 AM
Is this audible THD? A % of THD+N would be a more helpful measurement IMO. I don't have a completed unit here in front of me but don't recall it being much over .05% on avg. Maybe in the .1% @ 20Hz with a +4dBu input sine.

Distortion will most likely be coming from an active stage like an opamp or discrete follower. I would suggest measuring THD at all of the test points and see where it starts. Make sure all of the amps are fully seated. http://classicapi.com/catalog/DOA_Install.php

Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Studio Mollan on November 23, 2014, 05:13:54 PM
Hi,
I've built 18 of these and use them every day in my api console. Super nice eq that was well worth the effort of putting them together. (Took quite a while..)
I recently modified a diy neve 1073 eq for a wider Q midrange filter and now Id like to try out a mod on the lc53. How about getting rid of the hi-pass and instead use that switch as a wide Q (wider would be more appropriate). Could you point me in the right direction here Jeff? I need to find the resistor in series with the mid band inductor and increase the value right?
Since I have hi-pass filters in the console I could live without it on the eq.

/
Emil
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on November 23, 2014, 05:53:48 PM
This would take some doing. All of the inductance values would need to be changed as well as caps and then resistors. With this EQ, I don't think you could easily toggle between wide and narrow Q's. It would almost need to be one or the other.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Studio Mollan on November 24, 2014, 06:01:17 PM
This would take some doing. All of the inductance values would need to be changed as well as caps and then resistors. With this EQ, I don't think you could easily toggle between wide and narrow Q's. It would almost need to be one or the other.

Hi jeff and thanks for your reply.
On the neve 1084 the hi-q switch switches the resistor directly after the inductor. Higher value gives wider q. On the 1073 I managed to do this pretty easily but the lc53 is not designed the same way then?
/
Emil
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on November 24, 2014, 06:18:29 PM
No Emil, its a different topology. Only switch the R would mostly change the amount of cut or boost.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: fancytimestudio on November 24, 2014, 07:25:41 PM
Thanks for replying Jeff. Yes, this is an audible distortion more noticeable at lower levels. During CMMR calibration using the extension jigs, I was able to get the 400 Hz sine wave down close to -80dB (lowest I was able to meter).  I checked all of my solder points on the DOA sockets (they were fine) and tried two different sets of tested opamps with the same result. I forgot to mention that this distortion occurs whether or not the EQ is engaged ("in" button not pushed in). Here is a screen shot of what is returning from the EQ with the 400 Hz sine at -10dB generated from Pro Tool's signal generator.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on November 24, 2014, 08:57:10 PM
The in/out is not a hard bypass. All it does is lift or connect the LCR filters to ground. The common mode adjust is simply a null for the receiver amp. It has nothing to do with THD. I would suggest making up a cable or probe so you can "follow" the signal thru the circuit and see where the distortion starts. That will help us narrow down the cause. Use the test points PDF that was posted pretty close to after 'Chung's build pics.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: fancytimestudio on November 24, 2014, 10:37:41 PM
1st reading: negative side of C2 on the Main PCB. -clean
2nd reading: output pin of A1, DF on CB PCB -clean
3rd reading: output pin of A2, DF on CB PCB -clean
4th reading: output pin of A4, DTO5 on CB PCB -clean
5th reading: output pin of A3, DTO5 on CB PCB -real dirty
6th reading: neg side of C12 on the Main PCB -real dirty

I popped out the A3 and checked for cold solder joints and popped it back in and it's the same so there must be an issue with that DTO5
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on November 25, 2014, 12:38:12 AM
Yes indeed. Check all of the resistors and transistors for proper location. Something must be wrong.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: fancytimestudio on November 25, 2014, 09:23:46 AM
Thanks Jeff. Everything looks good on the layout. Transistors and resistors are in their proper places. I went back over all of the solder points one more time just to be sure there wasn't a cold joint and I'm still getting that same distortion. 
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on November 25, 2014, 11:06:13 AM
OK, swap the position of the DTO5's A3 and A4. Then see if the distortion follows the amp or stays after A3.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: fancytimestudio on November 25, 2014, 11:34:50 AM
Did that already and it follows the amp.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on November 25, 2014, 12:18:22 PM
Can you send a close pic of the amp? Top and bot please
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: fancytimestudio on November 25, 2014, 02:23:07 PM
Here's the Bottom.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: fancytimestudio on November 25, 2014, 02:23:37 PM
And the top.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on November 25, 2014, 02:33:02 PM
I would reflow the points on the bottom while heating and adding a touch more solder. Its hard to tell in the pic but a few of them look like they could use it.

On the top, I should have been more clear but I wanted to try and verify all of the components and their placement.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: fancytimestudio on November 25, 2014, 02:49:58 PM
My apologies. Were the quality of photo good enough? They look a little blurry on here... I'll do the soldering and if that doesn't fix the problem post some more helpful photos. Thanks again Jeff!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: fancytimestudio on November 25, 2014, 05:25:48 PM
Here is pic 1
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: fancytimestudio on November 25, 2014, 05:26:43 PM
Pic 2
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: fancytimestudio on November 25, 2014, 05:27:47 PM
pic 3
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: fancytimestudio on November 25, 2014, 05:28:38 PM
Pic 4
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on November 25, 2014, 08:03:55 PM
OK, is it possible that two of transistors got mixed up? You would have to gently pry the adjacent ones apart so you can read the part #'s on them. Besides a cold solder joint, there is not much left on the board. The R's and diodes look placed correctly.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: fancytimestudio on November 26, 2014, 09:18:47 PM
I checked the transistors and they are all in the correct places. I'm going to try one more time to dump a bunch of solder on this puppy and if that doesn't work I might just hit you up to get another one. I really appreciate you taking the time to help me solve this. Thanks a bunch Jeff!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: fancytimestudio on December 18, 2014, 01:59:25 PM
Hey y'all, after ordering a new DTO5 from Jeff I’m still having issues with this. The new DTO5 worked for about 10 seconds, then distortion. I pulled the transistors and found a bunch of the 2N5088 and 2N5087 transistors from both the old opamp and the new one were open or shorted. I ordered a bunch more from a parts distributor and replaced them today.  After replacing Q3, Q4 ad Q5 I plugged it back in and it sounded clean for about 10 seconds and then smoke and distortion from the opamp that’s been giving me trouble. I'm thinking that there is something surrounding the opamp it that isn't working properly. Do you have an indication of voltages from different test points on the module? This thing is starting to drive me nuts! :o Any help is much appreciated!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on December 18, 2014, 02:22:33 PM
I would start by measuring the +/- voltages at the opamp sockets.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: fancytimestudio on December 18, 2014, 02:51:25 PM
They all look the same at around 15v dc at all 4 points.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: fancytimestudio on December 18, 2014, 02:57:29 PM
Could be closer to 16v but I'm on an analog meter.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: fancytimestudio on December 18, 2014, 03:50:51 PM
Ok, depopulated the transistors. Q3 tested good but Q4 and Q5 are no good.  The smoke came from R5 and R6 which are totally fried now. Not sure if this helps.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: fancytimestudio on December 18, 2014, 03:53:56 PM
seeing some variation in the diodes... I'm going to suss this out and post my findings.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: fancytimestudio on December 18, 2014, 07:36:57 PM
So one of the diodes in the new (D1) DTO5 wasn't working properly (chicken and egg scenario, not sure which issue caused what, perhaps I was a little too beast-like when I bent the leads???). I replaced it with one I got from Mammoth Electronics, replaced the burned out resistors with the ones from the old DTO5 and the burned out transistors with some I got from Mammoth and now IT IS WORKING!!!!!!!!!!!! (knock on wood) The little pc board looks a little post-apocolyptic now from all of the parts getting swapped out  but oh man, I'm so excited! Going to try out some different opamps in it soon but I honestly don't want to look at the inside of that thing for at least a week. Thanks Jeff for all of your help. I learned a lot in this process and I can't wait to have a heap more questions for  you when I decide to build 9 more of these things!  ;)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: PeteJE on December 20, 2014, 06:58:37 PM
Looking for suggestion - This would be my first capi project (I do have diy audio experience) and my first product with gar op amps.  I ordered one each of the 2520 and 1731 to build first.  I understand the admonitions to use a known working op amp in the LC53A, but I will only have my built ones and nothing to test them in.  How would you proceed?  Do I have to buy a built up op amp, or could I test the gars I make thoroughly enough with qc'ing the boards closely and a dmm? 
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Chryst on December 24, 2014, 06:55:05 AM
Dear people,

I'm building a couple of LC53A's right now. I have a question: with calibrating the units, is it important to keep the main PCB separated? Or can I also do the calibration after the units are finished? I have the main PCB's connected to the CB PCB's, should I separate them again to calibrate properly? The reading should be in the tenths of microvolts AC right (0.1, 0.2, etc.)?

Thanks a lot for your help!!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on December 24, 2014, 10:08:12 AM
It doesn't matter if the PCB's are all assembled or not. The CMRR adjustment is only dealing with the first stage receiver amp.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Chryst on December 31, 2014, 08:27:15 AM
Thanks for the quick reply. One more question though and I hope I'm not overlooking something really obvious here.
The problem is that the trimmer does not seem to influence the measurement of either my DAW or a good DMM.

I have made and tested the cable with the resistors. I've tried both a signal from my DAW as well as a signal from a signal generator. Both come through and give a reading of -35 dBu to -45 dBu, but the trimmer doesn't seem to have any influence. I've also tried swapping out the opamps (red dots). I'm building three units and all the trimmers have the same problem.

As said I've connected the PCB's already, but this shouldn't have any influence according to the last post. Am I overlooking something?


Thanks for your help.
It's very much appreciated!!





Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Chryst on January 04, 2015, 04:04:32 AM
The only thing I can imagine now is that the connection of the pcb's does have some sort of influence. Should I desolder and try or is this really a waste of my time?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: stringmike on January 07, 2015, 05:45:12 PM
I just finished the build of 2 lc53's, but none of them are passing audio. Regardless of the bypass button is in or out. The calibration went well, so I guess the first place to start would be the second op amp? Any other places to look?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: stringmike on January 08, 2015, 05:20:54 AM
OK, started on the first and switched the DOA's to ones that I knew 100% were working, but still no luck. Before I went signal hunting, I trimmed the DTO5s and the voltage followers nicely on the back, since I didn't have a good trimming tool when I made those. I covered the back with insulating tape as well, and now, the unit passes audio, so there must have been a short somewhere here. But the audio distorts. When I engage the HPF, the audio gets even louder, and distorts even more. The other filters seem to be working properly (apart from the distortion). The amount of distortion depends on the input level of the material.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: stringmike on January 08, 2015, 05:23:56 AM
BTW, the audio level matches very well both in bypass and in, so no issues here.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: stringmike on January 08, 2015, 03:47:53 PM
Update: I worked on the second one, and after trimming the DTOs and the DFs, it worked! So I swapped first the DTOs from the working unit and then the DFs, and the last DF (A1) turned out to be bad. I checked the components, everything working here. But there was one soldering, that looked a little odd. So I resoldered, and voila! Both units alive and kicking!!

So as Jeff points out: It's imperative
to point out that each and every single lead at the bottom of this PCB must be trimmed as close as possible to the PCB!!!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: gar381 on January 08, 2015, 05:21:26 PM
since I didn't have a good trimming tool when I made those.

These guys are your best friend when building LC53s :)

http://www.all-spec.com/products/CHP-170.html

Take it from a guy that has built 8

GARY

Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Chryst on January 10, 2015, 10:07:27 AM
A small update. The power supply seemed to be at least part of the problem. I now have a consistent reading for 2 out of 3 units and I could do the CMM test with those units.

The third one still gives me trouble though. The trimmer doesn't seem to have any influence and I'm stuck between 40 and 240 mV at the negative side of C2.

I've swapped the opamp.
I've desoldered the big caps and tested them.
I've desoldered the diodes and tested them.
I've desoldered the big resistor and tested it.
I've desoldered the trimmer and tested it.

They all seem fine.
As said this is one out of three units that cosmetically look the same. The soldering looks fine and I see no physical damage anywhere.

Does somebody have an idea where else to look? I hope I'm not overlooking something stupid.

Any help is greatly appreciated! Thank you very much.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: PeteJE on January 30, 2015, 01:56:26 AM
Oooops question....
This is a picture of the main PCB underside of C7; you can see I got too aggressive (slipped) with my cutters and snipped the underside pad right off.  Dang.  I seemed to have flowed enough solder that the damaged pad leg does make continuity with several spots on the PCB that I assume it is supposed to (it seems to connect to many grounds - pin 13 ground on the rack mate pins, the bottom right corner ground on the PCB mount, + side of C8, - side of C9,etc) .  Should I just move on thanking my lucky stars that the connection seems good?

(http://i.imgur.com/s4zihEel.jpg)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on January 30, 2015, 10:40:27 AM
That is the ground connection for that cap. Since the ground plane is on the other side of the board and the holes are plated thru, it sounds like you have enough solder in the barrel of the hole. To be safe, you could solder a short jumper wire from that lead over to the ground pad of C8. That is the hole that has no visible trace running to it. You could also just heat up that nub of a lead and add a little more solder to what is showing. That is what I would do.  :)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: PeteJE on January 30, 2015, 12:52:01 PM
That is the ground connection for that cap. Since the ground plane is on the other side of the board and the holes are plated thru, it sounds like you have enough solder in the barrel of the hole. To be safe, you could solder a short jumper wire from that lead over to the ground pad of C8. That is the hole that has no visible trace running to it. You could also just heat up that nub of a lead and add a little more solder to what is showing. That is what I would do.  :)

Thank you Jeff!  About to do CMRR later today - voltages on pins and transformer wiring holes are good.
Title: LC53A - No midrange band
Post by: Musepro on February 05, 2015, 12:01:44 PM
Hi all! I built an LC53. While doing final testing, both the HPF and LPF work and both the HI and LO bands work at all frequencies in shelf/bell.

However, the midrange boost/cut gives me nothing. All components are in their correct places/polarities with known working GAR-2520s in place and I don't see any bridged or cold solder joints.

Anyone have any ideas as to what the issue is? Thanks!

jt burke
Title: Re: LC53A - No midrange band
Post by: Musepro on February 14, 2015, 10:30:37 AM
Hi all! I built an LC53. While doing final testing, both the HPF and LPF work and both the HI and LO bands work at all frequencies in shelf/bell.

However, the midrange boost/cut gives me nothing. All components are in their correct places/polarities with known working GAR-2520s in place and I don't see any bridged or cold solder joints.

Anyone have any ideas as to what the issue is? Thanks!

jt burke

I went ahead and reflowed the solder joints, swapped the DT05 and DF2 positions and tried another pair of 2520s from two of my VP28s, but I still have no midrange boost/cut, even though every other function works perfectly and the unit calibrated well and sounds good. Any thoughts?

jt  burke
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 14, 2015, 08:29:44 PM
JT, sorry for the delay. I was away in Nashville for a week and have been hammered with store orders since my return.

With the boards plugged in and assembled to each other, make sure you have continuity between the switch wiper of the CB-PCB's SW4 and the LC-EP PCB's SW3 wiper. If not, look at the center pin of J2's header/socket. Its J2 on each PCB.

If that is all good, I would look to make sure the common pin of L3 is getting to ground thru R11 when the EQ circuit is engaged.

If you have a good way to desolder, I would next remove L3 and measure DCR from the common pin to any and all of the other used pins of the inductor. I do check each and every inductor when I receive the batches to make sure none are open circuit.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Musepro on February 15, 2015, 11:18:36 PM
Jeff,

I have solid continuity between the wipers (C1) of SW3 and SW4. All 3 pins of J2 are solid between the boards as well. Common pin of L3 to ground is solid, before and after the 2.1K R11 resistor with EQ engaged. I removed L3 and, looking at L3’s bottom with the common at top left going down, I get DCRs of 24.5, 31.7 and 45.8; then NC, NC, 62.9 and 63 down the other side. I did not attempt to measure inductance.

What do you think? Thanks a lot!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 15, 2015, 11:24:04 PM
Hmm, well that all checks out. If you have DCR, the inductance will be fine and nothing looks open there.

My next thought is that the stop pins are in the wrong spot on the freq select Grayhill on the LC-EP PCB.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Musepro on February 16, 2015, 10:18:42 AM
Hmm, well that all checks out. If you have DCR, the inductance will be fine and nothing looks open there.

My next thought is that the stop pins are in the wrong spot on the freq select Grayhill on the LC-EP PCB.

Good grief! I removed the stop pins and spun the switch around, all 5 frequencies work perfectly! I obviously had the switch in the wrong position when I installed the pins at noon and 5. Thanks for helping Jeff! Happy it was only a minor, simple fix!

I do have a question about the stop pin placement; On the HI and LO bands, which have been working perfectly from the start, with the pins at noon and 5 on the 2-pole SW1/4, I get one click below and one click above the frequency range (7 positions). I assumed this was to facilitate single band bypass. However, with the pins in the same noon-5 holes of the 1-pole SW3 mid band switch, it lines up perfectly with only one click per frequency (5 positions). Is this correct? Thanks!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 16, 2015, 10:26:16 AM
All switches should only travel to what is designated on the faceplate, not one position further each way. I would imagine those were also moved before the pins went in? Hence 7 positions instead of 5. 12-7=5 so those wipers are also between the wrong sides of the stops pins.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Musepro on February 16, 2015, 12:46:39 PM
All switches should only travel to what is designated on the faceplate, not one position further each way. I would imagine those were also moved before the pins went in? Hence 7 positions instead of 5. 12-7=5 so those wipers are also between the wrong sides of the stops pins.

Got it. Not sure why I was confused about the FREQ  switch positions before I installed the pins, but it's clear to me now. Everything is perfect now. Thanks!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Tschem on February 20, 2015, 02:43:42 AM
hello all!
just finished with building 2 units. the first works, the second one too but has around 6 or 7dB less output. this is also the case when the unit is in bypass. i've already interchanged all DOA and DVF from both units but it's still the same. in the second unit there's no L1 4H inductor installed yet, but according to jeff this shouldn't be the problem.

can someone plz help me troubleshooting from here?
thx in advance,
Georg
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 20, 2015, 09:22:27 AM
hello all!
just finished with building 2 units. the first works, the second one too but has around 6 or 7dB less output. this is also the case when the unit is in bypass. i've already interchanged all DOA and DVF from both units but it's still the same. in the second unit there's no L1 4H inductor installed yet, but according to jeff this shouldn't be the problem.

can someone plz help me troubleshooting from here?
thx in advance,
Georg
Georg, the inductor won't be the cause since it not being installed is no different than what happens when the EQ is not "ON". The LCR series component strings are lifted from ground when not ON.

Since you have already swapped around all of your opamps and followers, it must be a couple of accidentally swapped resistors. Near the beginning of this thread, I posted a procedure to check audio levels at certain points throughout the audio path. Locate that post and follow those instructions. There is a PDF posted with test points to take ACV readings while injecting a sine wave. This will help narrow down the stage where the problem starts.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Tschem on February 21, 2015, 06:06:58 AM
thx for your replay jeff!
i exported a +4dBu sine into the working unit and got more or less the same values like already another use measured in post #59. in my case 2nd reading: output pin of A1, DF on CB PCB  about 0.591 VAC.

when connecting the not-working unit, i'm measuring about 1.59 VAC. again i swapped the A1 with the one of the first unit, but nothing changes.  i don't know that this means and why the unit is actually more quiet.
i've looked at the resistors and all the other parts on main pcb but can't find a difference between the units.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 21, 2015, 10:04:27 AM
OK so you are saying the unit with 1.59VAC at A1's output has a lower overall output?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Tschem on February 21, 2015, 12:45:00 PM
yes, thats right. when the  unit is switched on, i get an decrease in volume. what i've noticed is that if it is turned off, i get an increase!
 right now the difference is less tragic than before, its around +- 2db, depending on whether i've turned it on or off. all i've done is to play around with RV1 a little bit...is it possible, that i've messed up my CMRR measurement?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 21, 2015, 01:06:48 PM
OK. Lets concentrate on the unit that is fully built. Leave the other one alone for now.

The CMRR trimmer should never be touched except for the calibration procedure. Once that has been properly executed, I put a splotch of fingernail polish on the adjustment screw so it doesn't get moved.

With the load jumpers set to HiZ, the ON switched disengaged/out, the module should pass signal at or very near unity gain. The change should be within maybe +/- 0.25dB. Its been forever since I built one but anything much more than that and there is a problem somewhere.

With filters out, all cut/boost switches set to 0, engaging the ON switch should not really change the audio thru level at all. If there is any change in thru level, something is wrong.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Tschem on February 21, 2015, 01:43:19 PM
on the one which is fully build i experience exactly what you're saying, no change in volume whether it's off or on with 0 cut/boost, no matter which DOA i use.
i consider that one as finished.

but yes, on the second one (the one with the missing L1), there is a problem. ~3dB higher output with unit off, ~2 db lower output with unit on. so, not 7 dB less anymore like i said before. there's not much i changed except that i've swapped around the DOAs, but that hasn't changed anything. i also played around with RB1 trying to make a CMRR re-calibration, so i thought this could have contributed to the issue.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 21, 2015, 02:10:15 PM
OK good  :)

So, on the trouble child, it sounds like the gain is coming from the A1 area. Let's concentrate on signal throughput with EQ disengaged, ON switch out. The gain here is a little odd to me since there is not much more than the ON switch between the receiver opamp's output and the A1 followers input. Besides that switch, the signal goes thru R3 on the CB PCB which is a 1k R. Even with R3 jumpered, the gain would not increase that much. What is your ACV at the input of A1?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Tschem on February 21, 2015, 02:34:04 PM
with switch out and ~ 1V input, i get 0,32V at R3 and  0,27V at each (+/-) input of A1.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 21, 2015, 02:54:14 PM
I meant A1 of the CB PCB which is the discrete follower. I thought that was the amp that had gain at the output of it?

From a previous post, I gathered that A1 on the Main PCB was good since you had what was expected at the output of that amp.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Tschem on February 21, 2015, 03:07:36 PM
 :)
in and out of A1 of CB pcb is 0.313, also in and out of A2 is 0.313.
some more values: in of A3 + and - is 0,26V, A3 out is 0,53. same with A4.

Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 21, 2015, 03:42:51 PM
Hmm, so I am confused. Where is the 1.59VAC reading that you had before? I thought that was at the output of A1 on the CB PCB?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Tschem on February 21, 2015, 04:30:10 PM
i'm getting confused too, i'm sorry for wasting your time, i will try to make things clear:

- at first, i had this -7dB issue, at that time i was measuring this 1,5 V at - C2.
- then i did some swapping around of DOAs and DFs, which had no effect on the good unit.
- then i also played around with RV1. this was the time i didn't encounter the -7dB issue, but the -2 dB when on / + 3 db when off.
- the voltages in the last post are correct for ~ 1V input (so for +4dBU i'm measuring about 0.5 V as before)

and because i'm so desperate, i've again swapped the DOAs and installed some factory-new ones i bought recently, so no self-build ones. these new ones are working properly on my pair of api 550a.
same behaviour: unit on-2dB, off -3 dB. so: no chance that there's an issue with A1 and A2 on the main pcb.

that's why i was asking: is it possible that this problem lies in CMRR adjustment / RV1 setting?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Tschem on February 21, 2015, 04:49:31 PM
one more update:
again, i swapped A1, A2, A3, A4 of cb pcb on both units, same behaviour. no difference in output on the good one, -2/+3 on the other one. all resistors on main and cb pcbs are identical.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 21, 2015, 06:03:10 PM
With the known good working opamps in place, go back to the post around #59 and follow those steps. Inject a 1k sine wave at +4dBu and measure ACV at all the points specified.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Tschem on February 22, 2015, 03:58:35 AM
Input on both: on - : 1,67 ,  on + 1,79
c2 - : ~0,83 both
R2: 0,83 both
A1 in/out: 0,83 both
A2 in/out: 0,83both
now it gets interesting:
A3/4: in/out on BAD one 1,39
A3/4: in/out on GOOD ond 0,56
c12- : 0,693 on bad one
c12-: 0,56 on good one.

both measurements for units on and off.

units back in lunchbox: good one has same level on and off, bad one ~2-3 dB less when on, more when off.

Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 22, 2015, 10:58:14 AM
So it looks like they are consistent at the in/out of A1 and A2 on the CB PCB. The difference and increase in level begins at the output of A4?

BTW, the signal hits A4 before A3 on the CB PCB.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Tschem on February 22, 2015, 03:15:57 PM
exactly, thats what i'm measuring!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 22, 2015, 03:55:01 PM
Well, you did mention at "the in/out of A4" so I am trying to make sure. I did not see "In-" and/or "In+" when referring to A4.

If the increase is present at In+ of A4, I would check R10. It should be 14k3. With the exception of C6, R10 is the only series component between the output of A2 and the In+ of A4. R25 should be 10k, its the feedback R of A4. Also check R22, R23 and R24.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Tschem on February 22, 2015, 04:32:29 PM
i think you mean 14k7 for R10?
R10 on both units 14k7.
R25 on both units 10k.
R22, 23, 24 have the same correct colourcode on both units, but i can't measure the same values.

R22 on the good one: 7K
R22 on the bad one: 14,7

R23 on good and bad one: 6k4

R24 on good one: 3k
R24 on bad one: 3k3

that's just what i'm measuring, the colourcodes are correct with the values of the BOM!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 22, 2015, 04:40:00 PM
Yes sorry, 14k7. That was a change I made but was still showing as 14k3 in my PCB software.

You cannot measure a resistor's value with both ends soldered in circuit. Yes color band verification is prolly the best way to go, unless something is really incorrect.

BTW, I did not see a confirmation of the ACV at the input(s) of A4?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Tschem on February 23, 2015, 01:19:28 PM
last time, i just measured the +in on A4/A3 so, that was the value i was talking about.

but, jeff, you will think that i'm crazy now or something but let me tell you this:
without doing anything, no swapping around DOAs or DVFs or whatever, the -7 dB problem is back.
so, i'm not measuring +/- 3 dB when turned off and on, right now i have equal gain when turned off and ~ -7bB when turned on again, like i experienced in the initial posts. i'm completely confused now, cause i didn't even touch my measurement toolchain, just turned signalgenerator and lunchbox off for a day.

any idea what could cause such issues? a defect condensor, or just a bad contact??   ???
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 23, 2015, 01:36:08 PM
Bad solder joint somewhere is my guess.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Tschem on February 24, 2015, 04:40:06 PM
tripple-checked everything now, every resistor, diode, capacitor, the transformer, DVFs, DOAs, every solder joint...even put more solder on the DOA sockets...measured possible connections of solder joints, re-calibrated CMRR...can't find nothing.

any more ideas?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 24, 2015, 09:25:20 PM
If the level keeps changing, there must be some intermittent problem somewhere on the build.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: PeteJE on March 01, 2015, 05:50:33 PM
Grayhill stop pins - yes, I lost one, arg.  Can I use a very stout piece of wire lead from a component in place of the stop pin?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on March 01, 2015, 05:55:54 PM
Grayhill stop pins - yes, I lost one, arg.  Can I use a very stout piece of wire lead from a component it place of the stop pin?
Yes indeed. A short piece of resistor lead will work a treat.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: PeteJE on March 03, 2015, 04:26:32 PM
Silly newbie question....  I got to the first unity gain test before final assembly.  When first put up, the output was loaded down and the unit was humming.  I swapped out the A2 (output?)  gar 1731 op amp to a different one (ML2520) and all was fine - simple, bad op amp (both kit built).

Now, just for grins,  I put back that first op amp again (gar 1731) and the original issue cleared up and unity gain good with no hum.   

Why would this happen - it seemed seated fully first time - maybe components touching, seating exercised??  not sure.  Hoping not another coincidental issues or really just some A2 op amp issue on that first try?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on March 03, 2015, 06:24:34 PM
Are they fully seated? http://classicapi.com/catalog/DOA_Install.php
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: PeteJE on March 03, 2015, 10:29:28 PM
Are they fully seated? http://classicapi.com/catalog/DOA_Install.php
Thanks for the link, Jeff.  That is all I can imagine, maybe not fully seated at first, then swapping back and forth fixed this issue and brought it to working condition.   

I guess I ask because, if not fully seated A2 are possible symptoms a loaded down or reduced output and hum (not clean, more like harmonics - a humming buzz)?     

Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: PeteJE on March 04, 2015, 12:32:45 AM
Oh boy, oh boy, oh boy......  chunger, TY for the excellent build pictorial, getting to those two sweet words is awesome - humans win!
Final test tomorrow.....
(http://i.imgur.com/Th4Xgfxl.jpg?1)
(http://i.imgur.com/F9fcoKDl.jpg?1)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: PeteJE on March 05, 2015, 12:15:05 PM
It works!  Sounds incredible,  so smooth, musical, no odd nodes or resonances,  just perfect!  Thanks Jeff for your help along the way and Chunger for making this possible for me to do (I call it adult legos - because your guide is so good).   I currently have gar2520 in A1 and gar1731 in A2 - I would be curious to know any differences to be expected with both 2520 or both 1731 or any other op amp preferences/experiences.

I have one BIG problem.... I need a second one ASAP, and the store is out for now, ;) - I'll keep checking stock.  (also kind of excited for the FC526 too).


(http://i.imgur.com/SghKZEul.jpg)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on March 05, 2015, 03:46:25 PM
I have one BIG problem.... I need a second one ASAP, and the store is out for now, ;) - I'll keep checking stock.  (also kind of excited for the FC526 too).
Congrats,you can sell your 480 or 300 to gain a lot of money for several lovechildren (that's a LARC on the right side in the pic,no?) ;D .......but only if you have a spare one,hahaha!
Did you experience that the LC53 adds fantastic "sound" even when in bypass ;) ?
I have them inserted just for that in a lot of scenarios (on a stereobus to get rid of "digital sound" we have to deal with nowadays)!


Have fun,


Udo.


(Edited typo)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: PeteJE on March 05, 2015, 04:48:33 PM
I have one BIG problem.... I need a second one ASAP, and the store is out for now, ;) - I'll keep checking stock.  (also kind of excited for the FC526 too).
Congrats,you can sell your 480 or 300 to gain a lot of money for several lovechildren (that's a LARC on the right side in the pic,no?) ;D .......but only if you have a spare one,hahaha!
Did you experience that the LC53 adds fantastic "sound" even when in bypass ;) ?
I have them inserted just for that in a lot of scenarios (on a stereobus to grid rid of "digital sound" we have to deal with nowadays)!


Have fun,


Udo.

Ha!  It is a 480L.  On that note, although I like them very much, the JLMs may get "traded in" for the FC526.........  we'll see. 
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on March 05, 2015, 05:05:09 PM
Ha!  It is a 480L.  On that note, although I like them very much, the JLMs may get "traded in" for the FC526.........  we'll see.
Don't do that!
Use them in a chain,I do it all the time to get the mostt "bombastic" Rock-Vocals ever:1176(F76 in my case) to catch just the transients,then into optocomp (LA500s in my case too) to make it "powerfull".Maybe do the slow-attack-mod.


Very curious for Jeff's take on the FC576 btw.!


Best,


Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Tschem on March 07, 2015, 04:35:53 PM
just wanted to add that the issue with different I/O levels is solved. the problem was a solder joint of a resistor leg, which looked perfectly soldered from the backside of the pcb but apperently wasn't. so no chance to see it, it was solved more or less incidentally. nonetheless, thx for the support!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jaminem on March 08, 2015, 11:01:29 AM
Hi all, new to this forum - thanks for having me.

Big fan of Jeff's kits and have built several pre-amps now building this EQ.

The CMRR calibration has me stumped.
I got the test jig to make this easier, but to be fair I'm pretty clueless (I play bass)...

I'm out putting a 100hz sine wave from my DAW to my 500 rack.

have the card plugged in, to the rack and the main pcb, put a DMM on as chungers build suggested but got nothing from C to the negative of the large blue cap? I get something from V+?

Can I measure what ever it is i'm supposed to be measuring back at my DAW?

Totally no idea, and the CMRR doc and chungers build don't use the jig, so not even sure how this works?

help!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on March 08, 2015, 11:08:47 AM
You must engage the pushbutton switch on the Extension Jig's PCB to do the CMRR adjustment. You are trying to measure the output of the first amp stage. If you are using a DMM you must set the meter to ACV. Do you have an opamp in position A1?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jaminem on March 08, 2015, 11:33:39 AM
Hi Jeff, switch engaged, multimeter on ACV - mine has options for 750 or 200? im using 200? pre built 2520 on opamp A1.

red DMM lead on c, black on - leg of big blue cap?

Got nothing?

oddly I get a reading when the switch is off?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on March 08, 2015, 11:43:05 AM
I would imagine that its a DMM thing. It may be better for you to try an monitor this level thru your DAW. You will need to rig up and unbalanced cable with the signal coming from the same cap location that you had the red probe hooked to.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: PeteJE on March 09, 2015, 12:07:55 AM
Hi all, new to this forum - thanks for having me.

Big fan of Jeff's kits and have built several pre-amps now building this EQ.

The CMRR calibration has me stumped.
I got the test jig to make this easier, but to be fair I'm pretty clueless (I play bass)...

I'm out putting a 100hz sine wave from my DAW to my 500 rack.

have the card plugged in, to the rack and the main pcb, put a DMM on as chungers build suggested but got nothing from C to the negative of the large blue cap? I get something from V+?

Can I measure what ever it is i'm supposed to be measuring back at my DAW?

Totally no idea, and the CMRR doc and chungers build don't use the jig, so not even sure how this works?

help!

Not sure if helpful but I can share how I did mine.  I used a protools channel on input, sent the unbalanced signal back to this input with some alligator clips using a TT to XLR (XLR back into protools from my snake, and using a tt to xlr because the tt is easy to clip onto with the clips from the unit).  I have a plug in that reads pretty sensitive and instantaneous dbu (avid pro limiter) and this made it easy to see and verify the low point of the trim pot.  I did use 400hz as in the instructions, not sure if 1k would be better (since I wasn't really dealing with a DMM), but my unit ended up quiet and clean.  This was using Jeff's extension jig for connection to the rack and input to the unit (with the button in and led lit on the extension jig). 
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jaminem on March 09, 2015, 04:18:36 AM
Thanks guys, I'll knock up an unbalanced cable and see how it goes  :D
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jaminem on March 09, 2015, 05:32:13 AM
Just re-read your post so actually let me just confirm this then.

Connect DAW to 500 rack sending 400hz tone from DAW to xlr in
connect card to 500 rack on corresponding xlr input
connect Main pcb to other end of card via ribbon cable with op amp in A1
connect xlr to trs lead (got no tt) to input of daw with plugin to monitor dbu
connect crocodile clip from tip of trs to C on A2
connect crocodile clip from sleeve (or ring?)  to negative side of C2
Switch on
find low point of trim pot

Thanks
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on March 09, 2015, 09:33:34 AM
Close. The tip will go to the neg side of C2. Connect the sleeve (and possibly ring) to the C socket of A2. Be VERY careful not to short anything out as this can snap off in a split second and short your racks PSU.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: PeteJE on March 09, 2015, 12:21:06 PM
What Jeff said - I did C2 cap to tip and C of A2 to the ring (for me this was the way my unbalanced to balanced into the protools worked).  To avoid the leads slipping or shorting as Jeff warns, I used a spare millimax pin in the C socket of A2 and used a small retractable hook/pincer probe lead to connect to this pin and then clipped the alligator to the other end of this lead coming off the millimax pin (same type of lead with the C2 connection).
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jaminem on March 10, 2015, 02:29:42 PM
Just wanted to say thanks for your help.

As you rightly suggested Jeff, It was my DMM - the missus is always telling me not to buy cheap crap. Got a decent one, got some crocodile clips to go in it, switched the jig on , instantly got a reading where the previous DMM was blank, trimmed until the lowest pt before it started to go up again.

Sorted.

I hope.

Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Trench Recordings on March 22, 2015, 05:37:42 PM
I was calibrating another 500 series EQ that I just finished.

I measured the love child to compare and I noticed they are +6 dB gain to the signal even in bypass ?

1k tone balanced out of a Scarlett 2i2 @ 0.77 VAC comes back out of the love child at 1.58 VAC.

Is this normal ? anyway to adjust overall gain? or am I measuring wrong somehow?

Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on March 22, 2015, 05:49:42 PM
Hmm, there is something wrong somewhere. I forget the exact amount but they will pass to within 0.3dB or so.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Trench Recordings on March 22, 2015, 05:58:38 PM
Hmm... ok I will pull them out for service one day soon and take a closer look.

Thanks Jeff
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Trench Recordings on March 22, 2015, 06:21:23 PM
Nevermind... My measuring test rig had a unbalanced cable wired up. Cold to ground causing a 6dB level drop from my scarlet. Im gonna have to pull and recalibrate all my other units now    ::)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kante1603 on March 22, 2015, 06:30:13 PM
That's vaguely what I thought,6dB differences normally are caused by a balancing/debalancing issue.


Best,


Udo.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: DonnieDarko on March 24, 2015, 09:48:24 AM
Hey guys,

I have a problem with my unit.

On the Low Band, the 400 hz position doesn´t work. The problem only exists the shelf mode, when set to peak, it´s fine.

Does anybody have a suggestion?
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on March 24, 2015, 10:26:40 AM
On the Low Band, the 400 hz position doesn´t work. The problem only exists the shelf mode, when set to peak, it´s fine.
400Hz shelving is only R5 in series with the .575H pin of L1. I would resolder those connections. It can't be an open winding on L1 since it is the closest pin to the "end" or COM pin. All of the LB shelving freq's use the same cap C9 so if the rest of them work fine its not that.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: DonnieDarko on March 25, 2015, 03:22:19 AM
Thanks! I will try that!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: ryanakeith on April 20, 2015, 01:09:36 AM
Hello,

If the level does not change with the RV1 adjustment, where might the problem be? Is the RV1 bad? I'm using the DAW method with the cable going back to DAW input and the signal is returning and is visible on the meter.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: danielbrecher on May 10, 2015, 12:53:03 PM
Hey Jeff and Guys,

So I finished building two of these eq's and I noticed two things:

1. I don't hear anything happen when I engage the HPF and LPF on both units.
How is it supposed to respond?
2. On one unit, when the low frequency is set to "bell" the volume acts as a master
volume for the whole signal, disregarding the frequency.  This does not happen when
the band is set to shelf.

Where did I go wrong?
thanks
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on May 10, 2015, 01:05:39 PM
1. I don't hear anything happen when I engage the HPF and LPF on both units.
How is it supposed to respond?
The HP is @ 50Hz and the LP is @ 15kHz. Both are 12dB per octave so not super aggressive. Depending on your source and/or monitoring, it may be tough to "hear" these but can easily be measured.

Quote
2. On one unit, when the low frequency is set to "bell" the volume acts as a master
volume for the whole signal, disregarding the frequency.  This does not happen when
the band is set to shelf.
Try the unit without the steel cover in place. Sounds like maybe a lead somewhere is shorting out to the cover which is chassis ground.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: danielbrecher on May 10, 2015, 01:22:40 PM

Quote
Try the unit without the steel cover in place. Sounds like maybe a lead somewhere is shorting out to the cover which is chassis ground.

This was the problem. Thanks.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: bapa on May 17, 2015, 11:22:58 AM
Hello!

Just build an LC53A and i´m superhappy about how it came out and sounds! Anyway does anyone know how to modify the HPF, which is 50Hz stock build, to about 80Hz. Without the schematic, all i can see is that C4 is connected to the HFP-switch via the PCB. Maybe another value of that capacitor?

Thanks/bastian
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on May 17, 2015, 12:59:19 PM
Hello!

Just build an LC53A and i´m superhappy about how it came out and sounds! Anyway does anyone know how to modify the HPF, which is 50Hz stock build, to about 80Hz. Without the schematic, all i can see is that C4 is connected to the HFP-switch via the PCB. Maybe another value of that capacitor?

Thanks/bastian
I just had a quick look. It depends on how accurate you want to be. You will also have to measure with an analyzer and make a few tweaks. On the CB PCB, I would start by changing C9 from .039uF to .027uF and change C10 from .39uF to .27uF. Run some sweeps and see what you think. If you want the knee to be higher, you could either decrease R2 to 120k and R13 to 12k and/or use .022uF and .22uF for the caps. Either way, I would suggest some experimentation. These changes will be pretty slight IMHO.
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: bapa on May 17, 2015, 03:11:29 PM
Thanks a lot, ended up with .022 and .22uf. Sounds fine to me!!
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: G-Sun on June 02, 2015, 01:02:50 PM
Any pointers to how these units sounds without actually getting my hands on one?
I connect API with rock and a little aggressive flavour. Is that true for the LC53?
(Myself I'm more into acoustical, soul, classical, maybe vintage pop)

I don't have any DOAs on beforehand. Just ordering 2 unassembled is a bad idea, right?
So, I need assembled to be on the safe side?

gar1731 or gar2520? (no idea)
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Studio Mollan on July 13, 2015, 07:33:05 AM
Hi,
I'm using these eq:s in a console that already has HP filters and i would like to try and change the one ine the EQ to 300Hz. Also i would like to try and change the LP to 12k. I'm not sure which caps are setting the cutoff FREQ. Can you point me in the right direction Jeff? Also if might need to adjust my new cutoff to taste so a set of numbers to calculate that would be appreciated,
Thanks!
/
Emil
Title: Re: [BUILD] LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on July 13, 2015, 11:16:13 AM
Hi Emil

C9/R13 and C10/R2 are for the HPF

R7/C4 and R5/C5 are for the LPF.

You can use the calculators here to find your new values. http://sim.okawa-denshi.jp/en/CRhikeisan.htm

IIRC, I followed the bandpass filter from the 550A
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kokkobil3 on November 19, 2015, 07:19:39 PM
Dear Jeff and everybody,
built my first one of two, with red dots in.

Everything works right except for a couple of positions:
5k HF peaking seem centered on a 9k area with a sharper q than the other settings.
seems shelving works ok.

400 LF both peaking and shelving doesn't work at all.

any clue for me?

thanks

Raffa


Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on November 19, 2015, 08:12:11 PM
Everything works right except for a couple of positions:
5k HF peaking seem centered on a 9k area with a sharper q than the other settings.
seems shelving works ok.
Raffa, which 5k. Mid band or high band?

Quote
400 LF both peaking and shelving doesn't work at all.
This is a little odd because they are actually completely unrelated. I mean that they do not share any common circuitry. Could it be a bad solder joint(s) problem?
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kokkobil3 on November 19, 2015, 08:25:02 PM
Hello Jeff, thanks for the quick reply:
5K high frequency in peaking mode. In shelving seems to be working fine.

Regarding 400... It can be, even if my soldering skills are really improved in the last month.
The only thing shelving and peaking has in common is the frequency selector. I'll start double checking that. Any other clue?
Thanks!
Raffa
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on November 19, 2015, 09:34:58 PM
5K high frequency in peaking mode. In shelving seems to be working fine.
So it is the high band control? I asked since 5k peak is also available on the mid band control. After the switch, 5k peak on the high band is C31 in parallel with C32 and then to inductor L4. Since .075H and .0047µF give us 8.5k, my guess is there's a bad solder joint on C31 (.01µF) or its failed open which can be measured if you desolder it. Its prolly a bad solder joint though. I would reflow C31 first.

Quote
Regarding 400... It can be, even if my soldering skills are really improved in the last month.
The only thing shelving and peaking has in common is the frequency selector. I'll start double checking that. Any other clue?
Well, the switch is a 2 pole switch. One side for peak and one side for shelving so even though they share the same switch they are not electronically related inside of it. 400 peak on the low band is R10 to C10 to the L2 inductor. I'd reflow those points. 400 shelving is R5 to L1. C9 is the common cap that is between L1 and ground so if the other low shelving bands are fine, it won't be C9.

It probably won't be the inductor(s) for either 400 problem since that tap is closest to the common so if the rest of the pins are OK, chances are that one is too.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: kokkobil3 on November 20, 2015, 03:57:25 AM

Solved everything! :)
tried it on some real audio... wow.
Great!!

Raffaele
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Golgoth on January 05, 2016, 07:37:09 AM
What is the most popular opamp combo on this one?
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on January 05, 2016, 08:41:01 PM
What is the most popular opamp combo on this one?
Folks order then all different ways. I don't think there is really a bad choice. Not sure if that is helpful or not.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Golgoth on January 06, 2016, 04:02:36 AM
It doesn't really help but it confirms I'm going to go for 2520/1731 like in my 28  ;D
Thanks Jeff
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: rabe on January 12, 2016, 08:02:20 PM
Hi Jeff,

I botched the building of a DT05 for my LC53A kit.  Is there a way I can purchase just a DT05?

Thanks,
Rob
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on January 12, 2016, 08:40:55 PM
I botched the building of a DT05 for my LC53A kit.  Is there a way I can purchase just a DT05?
Yeah man. Just send me an email thru the store.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: rabe on January 13, 2016, 03:31:47 PM
I botched the building of a DT05 for my LC53A kit.  Is there a way I can purchase just a DT05?
Yeah man. Just send me an email thru the store.

Thanks!!!
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Golgoth on January 26, 2016, 01:02:48 PM
Hi,

I am currently gathering tools and informations for my future 53A build. I’d like to get some answers to the questions I have before starting, especially regarding calibration (I hate trimmers!!!).

- First of all my audio installation has -6db inputs. Is it ok to add a plugin to my DAW’s input track before monitoring anything to get unity? I assume it is.

- I will be using the extension test jig and not a special cable, where should I take the measurements to adjust the generator’s output to 1 volt AC?

- Do I really need to monitor the output with both my DAW and a MM? Finding the lowest possible dBu value on the computer screen should be enough, right?

Having two different methods available for calibration got me confused I think…

>>> To the people in Europe and especially France where the Hakko CHP-170 is impossible to find, the Plato 170 is the exact same cutters and is easily findable for 5€ from UE sellers on eBay!

I hope the kit is back in stock soon, I can't wait to get started!  ;D
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on January 26, 2016, 02:22:57 PM
I am actually in the midst of building/testing a new updated board layout for LC53A. I had to change some silkscreen things (remove the small arrow) so figured I would make a few layout improvements. One of those things was to change the receiver stage in a way that CMRR cal is no longer required. As soon as I get the build finished and tested, I will post the stock. Hopefully over the next few days. I also made the mounting of the follower's and DTO5's a bit easier.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Golgoth on January 26, 2016, 02:39:26 PM
That's amazing news Jeff! Will the building process differ a lot from the old version? Chunger's guides are always so helpful...
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on January 26, 2016, 03:51:57 PM
That's amazing news Jeff! Will the building process differ a lot from the old version? Chunger's guides are always so helpful...
A few details but mainly on the small end. His work is 2nd to none  :)
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Golgoth on January 26, 2016, 04:04:13 PM
His work is 2nd to none  :)

VITAL for beginners like me.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: okdaniel on January 30, 2016, 09:46:01 PM
Can't wait for the stock to come in. I need to build another to make it a stereo pair. I need to change the faceplate knobs on my old one too I guess. It's all about the front panel right? :) 

Will the new "version" sound at all different? Hoping to get the two as similar as possible. I suppose it might just be a noise floor difference.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on January 30, 2016, 10:03:24 PM
Can't wait for the stock to come in. I need to build another to make it a stereo pair. I need to change the faceplate knobs on my old one too I guess. It's all about the front panel right? :)
Yes, front panel and knobs. I have Nip-N-Tuck kits posted for all old modules now http://capi-gear.com/catalog/index.php?cPath=209

Quote
Will the new "version" sound at all different? Hoping to get the two as similar as possible. I suppose it might just be a noise floor difference.
No, there should be no noticeable difference in sound or function. The noise floor will be the same. Should be nothing to worry about really  ;) I am literally just about to test all of the frequency controls and filters.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Mr. Steve on January 31, 2016, 04:57:31 PM
Hey Jeff!

My first Love Child is already working and sounds nice, but now I have a problem with the second one.

When I tested only the Main PCB, the +16/-16V voltages on the sockets were ok.
Then I assembled the rest and wanted to do a signal test.
Before that i checked for solder bridges.

I turned on my Lunchbox and the +16V led was blinking, telling me there is a problem.
I checked all the components on the CB PCB, but everything seems to be in the right place.
Then I removed the op amps and checked the voltages on the sockets.
Now the voltages on the Main PCB sockets are at -16V but +0V.
I checked the CR1 and CR2 diodes with my DMM and they seem to be ok.

Do you have any ideas, what could have caused the problem and what i can check?
Without schematics I don't know what else to do, other than look if I maybe swapped some parts.

I would really appreciate any help or input!
The first built went really smooth, so it's kind of a bummer ;)

Oh and the Lunchbox is ok, other modules are working just fine!
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on January 31, 2016, 05:33:36 PM
.....Now the voltages on the Main PCB sockets are at -16V but +0V.
I checked the CR1 and CR2 diodes with my DMM and they seem to be ok.....
It sounds like something is shorted to the +16V rail somewhere on the EQ build. Was this last test done with the steel cover in place? My first guess would be that a component leg is shorting out to the frame or cover? It could be opamp or follower related as well. With the module not connected to the rack, measure DCR from a +16V socket to ground to see if the resistance is near a direct short. I would one by one pull the opamps and followers and keep checking. Since it was OK when you first checked, its most likely something you did after that step. Maybe a bad opamp build on the main PCB?
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: eqp1a on February 01, 2016, 03:34:37 PM
Just finished my first LC53A build. Everything seems to be working, except the signal is about 20dB quieter on the output than the input (also, inserting the EQ causes another approximately 2.5dB drop in signal). I followed Jeff's instructions of tracing the signal through the circuit, and found everything to be OK until the 4th reading, the output pin of A4. I then swapped the two DTO5s and the same problem persisted. Thoughts? Anything else I should be checking? I believe I've scoured this entire thread, but apologies if I've missed something and a similar problem has already been addressed.

Cheers

Ian
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Mr. Steve on February 01, 2016, 06:07:18 PM
.....Now the voltages on the Main PCB sockets are at -16V but +0V.
I checked the CR1 and CR2 diodes with my DMM and they seem to be ok.....
It sounds like something is shorted to the +16V rail somewhere on the EQ build. Was this last test done with the steel cover in place?

Well, I'll be double dog damned!

Long story short, C13's +/- was bridged resulting in 0V at all +16V sockets.

When it didn't work, I also figured, that there must be a short somewhere.
C13 looked suspicious, so I removed some of the solder, but apparently not enough….
When you also said it must be a short I rechecked everything with a mangnifying glass and removed all of the solder from C13 and redid the joints.

It's crazy how a little solder bridge can be responsible for the failing of the whole +16V circuit…  :D


To answer your other question and describe my steps,
I just tested the Main PCB with the CB PCB, without the steel cover.
So I knew it must be one of the op amps, followers or the CB PCB itself.
First step was to remove all of the op amps and followers.
The voltage was still at +0V, so I knew it must be something with the CB PCB!

I unplugged the unit and like you said, checked the DCR on all +16V sockets.
All of them showed 0 resistance, so I got my magnifying glass and checked all of the joints.

Now I found the tiniest of bridges on C13 and redid the joints.

Then I put all of the op amps and followers in and turned the unit on.
The +16V rack led wasn't blinking so it was time to do another signal test.
The waveform recorded in my DAW was a nice 1K sinus as it should be!

Thank you very much for your input Jeff!
You motivated me to check the joints again for bridges!


everything to be OK until the 4th reading, the output pin of A4. I then swapped the two DTO5s and the same problem persisted. Thoughts?  Anything else I should be checking?

Hey Ian!

Did you check the voltages on A4?
C to -V and +V.
That's the first thing I would check!
If you already did that, better wait for Jeffs input ;)
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: eqp1a on February 01, 2016, 06:43:40 PM
everything to be OK until the 4th reading, the output pin of A4. I then swapped the two DTO5s and the same problem persisted. Thoughts?  Anything else I should be checking?

Hey Ian!

Did you check the voltages on A4?
C to -V and +V.
That's the first thing I would check!
If you already did that, better wait for Jeffs input ;)

Hey Steve! Yes, I'm reading +15.45VDC and -15.33VDC respectively.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Mr. Steve on February 01, 2016, 07:25:40 PM
I'm reading +15.45VDC and -15.33VDC respectively.

That's good, but also bad, because there must be a problem somewhere else ;)
I would first check for solder bridges and then  if every component is in the right place.

My whole +16V circuit wasn't working because of a tiny solder bridge…
Also I had a problem on a 1176 built with one resistor too much and the whole compressor wasn't working.

Little things can cause big problems! :D

But I'm sure Jeff can tell you where to look exactly!


Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: NoahShain on February 09, 2016, 02:11:44 AM
Just finished my first LC53 build.
 :-\
Not passing signal at all...just a buzz. Like a nice loud 60 cycle hum.
Any tips where to start diagnosis? My instinct says the little op amps or followers...they're tough!

Thanks all
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Mr. Steve on February 12, 2016, 01:45:31 PM
Any tips where to start diagnosis?

Hey!

I would remove all the opamps and followers and check the resistance on the turned off module.
Every +V and -V to C on the DOA sockets.
Jeffs FC526 manual says, that the resistance should be greater than 500Ohm.
Also you can turn on the module and check the DCV on the sockets.
Again +V and -V to C … should be about +-16V.
If it's smaller than 500Ohm/not +-16V you have a short somewhere, which is what we are looking for!

Get a magnifying glass and check every solder joint for little bridges.
All of the 3 PCBs and especially the opamps and followers, cause they sure are tricky! ;)
Also check again, if the metal cover is not touching any of the joints!

If both of these steps are ok, you know it's one of the opamps and followers.
Put them in one by one and check the DCV again.

That's the easiest way to find something suspicious!
Also check the polarity of all the diodes and caps.

The next and very useful step would be, to check, if every component is in the right place!
That can be a lot of work, with all the resistors, but I'm sure, that your module will work, if there are no bridges/shorts and every component is in the right place!

You could post a picture of your module, maybe that helps to help you!

Good luck! :)




Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: okdaniel on February 19, 2016, 02:06:17 AM
Any word on when these will be available for order again on the site?
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 21, 2016, 06:32:51 PM
Any word on when these will be available for order again on the site?
The new PCB's are fully tested and ready. I need to make some small adjustments to the BOM's and get a round of parts sorted. I had a small surgery 1.5 weeks ago and have spent my recovery time laying out an exciting new module. I am almost fully done with that so getting these LC kits ready will be my next main goal. I know that doesn't exactly answer your question but it should be fairly soon now!  ;)
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: NoahShain on February 22, 2016, 09:00:26 PM
Thank you for the detailed reply!
All of the resistance and DCV measurements are correct. WELL over the suggested resistance and 15.8 (or so) vdc everywhere. I removed all 4 of the little opamps and followers, got 16vdc everywhere and replaced them 1 by 1.  Same measurements. I can see no solder bridges anywhere and all caps are placed in the correct spots and with proper polarity.
Any tips as to what to check next?
Output transformer is wired correctly.
Maybe I check for other test points?
This isn't my first build but I am an electronics newbie.
Any additional help will be GREATLY appreciated.

Thanks!!!

Any tips where to start diagnosis?

Hey!

I would remove all the opamps and followers and check the resistance on the turned off module.
Every +V and -V to C on the DOA sockets.
Jeffs FC526 manual says, that the resistance should be greater than 500Ohm.
Also you can turn on the module and check the DCV on the sockets.
Again +V and -V to C … should be about +-16V.
If it's smaller than 500Ohm/not +-16V you have a short somewhere, which is what we are looking for!

Get a magnifying glass and check every solder joint for little bridges.
All of the 3 PCBs and especially the opamps and followers, cause they sure are tricky! ;)
Also check again, if the metal cover is not touching any of the joints!

If both of these steps are ok, you know it's one of the opamps and followers.
Put them in one by one and check the DCV again.

That's the easiest way to find something suspicious!
Also check the polarity of all the diodes and caps.

The next and very useful step would be, to check, if every component is in the right place!
That can be a lot of work, with all the resistors, but I'm sure, that your module will work, if there are no bridges/shorts and every component is in the right place!

You could post a picture of your module, maybe that helps to help you!

Good luck! :)
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 22, 2016, 09:17:55 PM
@Noah, there are some test points listed in this post http://groupdiy.com/index.php?topic=48426.msg618790#msg618790

A few threads after that Doug (emrr) and I discuss the results.

The only way to figure out what your trouble is, is to isolate where things go south. Did you have a close look for trimmed off pads?
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: NoahShain on February 23, 2016, 02:13:43 AM
@Noah, there are some test points listed in this post http://groupdiy.com/index.php?topic=48426.msg618790#msg618790

A few threads after that Doug (emrr) and I discuss the results.

The only way to figure out what your trouble is, is to isolate where things go south. Did you have a close look for trimmed off pads?

Hahahahahaha!!!! I did not trim any pads off THIS TIME!!! I was EXTREMELY careful about it while trimming component leads.
Just to double check, is my DCV reading of 15.8 v acceptable or should I be getting precisely 16vdc?
Also, as I check resistance from C to V- and V+ (On all opamps and followers) I get well over 500ohms on V- but V+ sends my Klein digital meter to O.L. Which I understand to mean OverLoad. It's shows an M in the display to indicate it's into Megaohms but beyond the meters range. Is this acceptable?
And, since I'm such a newb, I have to ask...to do the readings of the test points you referenced me to, do I need to send a signal in to the module?
Sorry to ask 101 type questions here among you experienced, educated folks. Is there an easy reference for basic test procedure?
Or maybe I do it with the unit just powered up?

Also worth mentioning that I am doing all this testing with just the main and CB pcbs in place. I completed the build and installed the complete unit and got the hum so I took it back apart and started testing (like the build guide said to do :-[).
Also, the metal cover is NOT installed.

Again...apologies for all the face palming that I must be causing and THANKS A MILLION for the help!!!

BTW Jeff, all 4 of the 553s are up and running and they SLAY on guitars. I love them! I didn't have any experience with them before and I can't believe how great they are.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Mr. Steve on February 23, 2016, 07:41:49 AM
hey,

check this post out http://groupdiy.com/index.php?topic=48426.msg619418#msg619418
he's sending a 1kHz sine signal at +4dBu (1,228V).
compare your values and you know where the problem is!

and 15.8V is totally fine!
for the resistance, as long as you are above 500ohm, it's ok!
i think i got some overloads myself :D
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: NoahShain on February 23, 2016, 05:59:35 PM
hey,

check this post out http://groupdiy.com/index.php?topic=48426.msg619418#msg619418
he's sending a 1kHz sine signal at +4dBu (1,228V).
compare your values and you know where the problem is!

and 15.8V is totally fine!
for the resistance, as long as you are above 500ohm, it's ok!
i think i got some overloads myself :D

Thanks for the help boys. I'm set up to do this testing.
500hz sine  @ 1.233v AC
Going in to the powered up module. All DO5 and followers installed. 2 known working opamps in A1 and A2...
Here's where I show my inexperience... I don't know where to clip my black test probe?
Ground?
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 23, 2016, 06:48:32 PM
Thanks for the help boys. I'm set up to do this testing.
500hz sine  @ 1.233v AC
Going in to the powered up module. All DO5 and followers installed. 2 known working opamps in A1 and A2...
Here's where I show my inexperience... I don't know where to clip my black test probe?
Ground?
This is one of the things I have added on the soon to be released latest version.

For your test, with the EP inductor board unplugged, the easiest spot to clip onto ground is pin #3 of J1 on the CB PCB. See the attached jpg
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: NoahShain on February 23, 2016, 07:19:25 PM
Thanks for the help boys. I'm set up to do this testing.
500hz sine  @ 1.233v AC
Going in to the powered up module. All DO5 and followers installed. 2 known working opamps in A1 and A2...
Here's where I show my inexperience... I don't know where to clip my black test probe?
Ground?
This is one of the things I have added on the soon to be released latest version.

For your test, with the EP inductor board unplugged, the easiest spot to clip onto ground is pin #3 of J1 on the CB PCB. See the attached jpg

Thanks Jeff and Mr Steve

I did some testing.
Results are:
1st reading: negative side of C2 on the Main PCB.  - 0.617VAC
2nd reading: output pin of A1, DF on CB PCB  - 0.615VAC
3rd reading: output pin of A2, DF on CB PCB  - 0.610VAC
4th reading: output pin of A4, DTO5 on CB PCB  - .417VAC
5th reading: output pin of A3, DTO5 on CB PCB  - wacky wildly fluctuating OL dmm reading
6th reading: neg side of C12 on the Main PCB - 0VAC

Then I swapped A4 and A3 and got the wacky reading 1 step earlier and 0s after that.

I pulled the DTO5s and made sure there are no solder bridges and all leads trimmed tight.
Indeed.
I have another kit.
I can build another set of DTO5s.
Is that a good next step?

Gracious thanks.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 23, 2016, 08:08:34 PM
Yes it sounds like you have a bad or faulty DTO5.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: NoahShain on February 23, 2016, 09:38:41 PM
Yes it sounds like you have a bad or faulty DTO5.

That's what it was.
I had 2 transistors in the wrong spots. Swapped them and we're good!!!
CMRR done!
1 problem, which I think, based on posts earlier in the thread, will be a Cap in the CB board...

12k shelf is boosting a LOT. +2 on the knob produces a 5db increase in level.

I'll read back through tonight later but if this is an easy fix I'll be building my 2nd tomorrow.

Thanks again for all the help Jeff!!
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: NoahShain on February 24, 2016, 12:21:26 PM
Yes it sounds like you have a bad or faulty DTO5.

Morning!
So I can't find anything in the thread about a volume jump happening with the 12k shelf.

Is there a schematic that might help me check the caps in that path? Not that I'd be able to read it!!! :P

Any tips here Jeff?

Thanks again
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 24, 2016, 01:03:46 PM
Hey Noah, the 12k5 shelf connections/components are shown in the attachment. I would check the value of R15.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: NoahShain on February 24, 2016, 01:11:52 PM
Hey Noah, the 12k5 shelf connections/components are shown in the attachment. I would check the value of R15.

Thanks Jeff. I'll do that today.

Should I follow the other steps described in the earlier post about the 7k shelf?

Checking continuity on the GH pins?
Removing and checking cap values and such?

And to clarify, I should remove R15 and check its resistance value?

Thanks again
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 24, 2016, 02:31:50 PM
Hey Noah, the 12k5 shelf connections/components are shown in the attachment. I would check the value of R15.

Thanks Jeff. I'll do that today.

Should I follow the other steps described in the earlier post about the 7k shelf?

Checking continuity on the GH pins?
Removing and checking cap values and such?

And to clarify, I should remove R15 and check its resistance value?

Thanks again
I would check R15 with color codes myself. You can post a close pic of that area if you want and I can tell you. I would also look for a short on one of the 2 caps shown above.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: NoahShain on February 24, 2016, 07:19:13 PM
Hey Noah, the 12k5 shelf connections/components are shown in the attachment. I would check the value of R15.

Thanks Jeff. I'll do that today.

Should I follow the other steps described in the earlier post about the 7k shelf?

Checking continuity on the GH pins?
Removing and checking cap values and such?

And to clarify, I should remove R15 and check its resistance value?

Thanks again
I would check R15 with color codes myself. You can post a close pic of that area if you want and I can tell you. I would also look for a short on one of the 2 caps shown above.

So R15 is indeed a 2.37k resistor.

I'm not sure how to check C26 and C27 for shorts. What is the procedure there?

Thanks Jeff
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: NoahShain on February 24, 2016, 07:44:40 PM
Hey Noah, the 12k5 shelf connections/components are shown in the attachment. I would check the value of R15.

Thanks Jeff. I'll do that today.

Should I follow the other steps described in the earlier post about the 7k shelf?

Checking continuity on the GH pins?
Removing and checking cap values and such?

And to clarify, I should remove R15 and check its resistance value?

Thanks again
I would check R15 with color codes myself. You can post a close pic of that area if you want and I can tell you. I would also look for a short on one of the 2 caps shown above.

Okay...
C26 and C27 were both shorted internally.
Soldering in replacements from my 2nd kit now.

Will report.

Thanks!
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: NoahShain on February 24, 2016, 08:14:02 PM
@jsteiger LC53A up and running.
Thanks for the guidance!

It was 2 shorted caps.
C26 and C27

gonna get back to work making music.

Thanks a million for all the help everyone.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 24, 2016, 08:30:41 PM
C26 and C27
So both of those 2 caps have their leads shorted internally? That is odd. I have had a few  .0068µF's that folks found shorted but never the .0047µF's. The sad thing is, I am not even sure that I can order these caps again. No one is carrying them in the radial package. I still have a pretty healthy stock of all values on hand though. Let me know what you need and I'll send them out.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: NoahShain on February 25, 2016, 01:07:14 AM
C26 and C27
So both of those 2 caps have their leads shorted internally? That is odd. I have had a few  .0068µF's that folks found shorted but never the .0047µF's. The sad thing is, I am not even sure that I can order these caps again. No one is carrying them in the radial package. I still have a pretty healthy stock of all values on hand though. Let me know what you need and I'll send them out.

Yep. Both of those .0047uf caps beep out on my DMM, leg to leg, out of the pcb.

Thanks Jeff
I better get the next 10 ordered before they're all gone.

Console is starting to look (and sound) real sexy !
CAPI through and through.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Mr. Steve on February 25, 2016, 08:01:08 PM
@jsteiger LC53A up and running.
Thanks for the guidance!

It was 2 shorted caps.
C26 and C27

gonna get back to work making music.

Thanks a million for all the help everyone.

Great to hear, that your module is working! :)

When I recapped my console preamps, a friend sent me some polystyrene caps and said, that I should be careful soldering them in.
They don't like too much heat!
"Be carful soldering these caps in, they can be easily dammaged from very hot soldering iron or prolonged contact with soldering iron. Once you have them in place heat the pcb pad first with the soldering iron and just touch a tiny bit of solder in there to make contact between the pad and the cap lead."
I'm sure you were careful after a few kits, but it's a good advice for someone soldering his first kit!

and @ Jeff,
mouser is still carrying some of the radial polystyrene caps!
they have 0.01uF, 1000pF, 4700pF and 5000pF!
and quite a few axial ones.
I bought them to recap my console EQs! ;)
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 25, 2016, 08:06:53 PM
and @ Jeff,
mouser is still carrying some of the radial polystyrene caps!
they have 0.01uF, 1000pF, 4700pF and 5000pF!
and quite a few axial ones.
I bought them to recap my console EQs! ;)
Yes I saw 4 values but they are going away which sucks  :'(
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Mr. Steve on February 28, 2016, 04:58:52 PM
Yes I saw 4 values but they are going away which sucks  :'(

yeah, my friend also thinks, that they stopped manifacturing polystyrene caps, but then i found the ones from xicon at mouser!
do you think it's just the rest of their stock?
that would be a bummer!

btw i don't know, if the thread already has a picture of your new design…
here are my two lovechilds, just to make sure ;)
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Golgoth on February 28, 2016, 05:35:36 PM
The new design is amazing... Can't wait for stock!
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on February 28, 2016, 07:55:22 PM
The new design is amazing... Can't wait for stock!
Thanks guys! I am very happy with the rebranding and new look.

We have a batch of LC parts kits nearly sorted. I am waiting on one last cap value to arrive which is due in Tuesday. That said I plan to post them to the store next Wednesday.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on March 01, 2016, 02:44:23 PM
I just added a round of the new Rev B LC53A kits to the store.

http://capi-gear.com/catalog/index.php?cPath=22_117_119_171
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Golgoth on March 01, 2016, 02:47:50 PM
 ;D !!!ORDERD!!!  ;D
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on March 01, 2016, 03:02:52 PM
;D !!!ORDERD!!!  ;D
Man that was fast!! Thanks! Will ship it out tomorrow.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: NoahShain on March 02, 2016, 11:54:12 AM
2nd LC works perfect at first power up.
6 channels of CAPI EQ in the 1608 now.
Looking, and sounding, amazing. All Litz.
I'll post some pics when I fill it ;)

Thanks Jeff
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on March 02, 2016, 12:56:54 PM
2nd LC works perfect at first power up.
6 channels of CAPI EQ in the 1608 now.
Looking, and sounding, amazing. All Litz.
I'll post some pics when I fill it ;)

Thanks Jeff
Awesome Noah! Can't wait to see it  ;)
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on March 05, 2016, 07:02:03 PM
Rev B build docs have been posted on the support docs page at the store. The first post of this thread has also been modified to reflect the updates.

Cheers! Jeff
 8)
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Golgoth on March 06, 2016, 05:13:20 AM
Hi Jeff,

I just revised the sorting sheets I had prepared before rev B for my build.

So R5 and R6 have been swapped on the CB board right?

What is it to test during the build on rev B?
Passing audio before installing the filter board I assume (Can I just plug it into my lunchbox with the extension jig for that?).
What else?

Thanks!  :)
Martin
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on March 06, 2016, 10:49:24 AM
Hi Jeff,

I just revised the sorting sheets I had prepared before rev B for my build.

So R5 and R6 have been swapped on the CB board right?

What is it to test during the build on rev B?
Passing audio before installing the filter board I assume (Can I just plug it into my lunchbox with the extension jig for that?).
What else?
Hi Martin, yes some R's were swapped around during the layout so please use the Rev B BOM as your guide to part placement.

The CMRR adjustment is no longer needed. I have 2 working units here at the present so I plan to get the Test Points guide completed and published today. You can just plug into your LB but it may be easier to have the jig so the module can be flat in front of you. Reaching all of the test points when inside the rack will be a challenge to say the least  ;) But if there are no problems and audio passes at unity, you would not need the test points.  :o
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Golgoth on March 06, 2016, 01:22:59 PM
Thanks a lot!  :)
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: ENS Audio on April 03, 2016, 04:34:01 PM
Just received the LC53A kit which I'm going to start working on within a few weeks but was wondering if I'll need an OP amp test jig to test my 1731's and voltage followers when I have them all soldered up?   


Thanks.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: n2712121 on April 07, 2016, 06:06:48 AM
Sorry if this has been asked before -
I have a Rev A LC53A.  The low frequency band gain knob doesn't change the output anymore (I can't tell if the low frequency selector's sonic operation has been affected).  The upper two bands work fine and the low one did last time I checked.  The unit passes signal properly otherwise.  Between checking it last and now it had been loaned out and (I'm guessing) opened by someone who shouldn't have opened it.   
Can someone please suggest a good place to start troubleshooting?  Unintentional grounding on either PCB? Blown cap? Voodoo?

Thanks in advance.  D
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: DrFrankencopter on April 07, 2016, 10:42:51 PM
Hi Jeff,

Just got my 2 rev B Love Children together last night, and had a chance to test today. All is great, except on one of them the 10k band produces what sounds like a full band pure boost (pretty sure I was just testing in shelf mode). I'm guessing this points at a cap problem. But where should I be looking (which cap)?

FWIW, one of the polystyrene caps came with three leads...but it was one of the bigger ones, and both my kits appeared to have an extra resistor (I forget which bag...either the main pcb, or the cb one).

In my build I managed to install the output transistors in one of my GAR2520's reversed (PNP where the NPN should be and vice versa), and this made the 15 ohm build out resistors release their magic smoke, but I replaced them with 10 ohm resistors that I had handy and that unit is otherwise fine.

Any help on the 10k band issue would be much appreciated.

Cheers

Kris
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on April 09, 2016, 10:50:00 AM
Hey Kris

10k shelf is C28 in parallel with C29 and then to R14.

The supply rail damping R's are all 10Ω.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: eqp1a on April 13, 2016, 11:56:36 AM
I posted previously about problems I was having with a build.

Quote
Just finished my first LC53A build. Everything seems to be working, except the signal is about 20dB quieter on the output than the input (also, inserting the EQ causes another approximately 2.5dB drop in signal). I followed Jeff's instructions of tracing the signal through the circuit, and found everything to be OK until the 4th reading, the output pin of A4. I then swapped the two DTO5s and the same problem persisted. Thoughts? Anything else I should be checking? I believe I've scoured this entire thread, but apologies if I've missed something and a similar problem has already been addressed.

I've since revisited, and while the same problem persists (minus the above described drop in signal when instantiating the EQ), the voltages readings I'm getting are different: previously when I swapped the DTO5s, the voltage dropped off at A4 regardless; now, no matter their position, once is consistently reading ~6V on the output while the other reads ~0.1V. I've double and triple checks for shorts, bad solder joints, and wrong components and I can't seem to find the source of the problem.

Anyone have any ideas?

Cheers

Ian
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: ENS Audio on April 17, 2016, 12:36:48 AM
Finally got my LC53A working after I changed out one of the 1731's I built with an already assembled Red Dot from my VP312 after I kept burning up the 10R resistors PR1 and 2  ???

Oh man does this thing sound amazing!  I ran my Dean 6 string fretless bass through it and through my Waves L2 Ultramaximizer and  what a difference does it make!   :D

Thanks to Jeff of CAPI for making this possible!!  :)
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: DrFrankencopter on May 01, 2016, 08:32:23 PM
I've pulled C28 and it is shorted internally...

I also noticed on the same board that I managed to get PR3 & PR4 rather warm, as well as the output resistors of the GAR2520 that's the input receiver. This was the one that I had the output transistors swapped on. Probably not a coincidence. Funny thing is, that it sounded ok. There's no other signs of trauma inside this 'problem child'.

Jeff, I figure I'll buy a pre-built GAR2520 from you. Can you toss a replacement C28 in along with it?

Cheers

Kris



Hey Kris

10k shelf is C28 in parallel with C29 and then to R14.

The supply rail damping R's are all 10Ω.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: bsconz on May 04, 2016, 04:11:36 AM
Not sure if this is the right place for this question...

I am building a pair of LC53A's and want to to the CMMR adjustment using a bench top power supply, DMM, and signal generator.

I can follow along nicely with the instructions provided by CAPI...BUT...how which card edge contacts would I connect DC power to the card and at what voltage?

I can't seem to find an answer to this question just by searching around.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Floti on May 04, 2016, 04:42:28 AM
(https://www.gearslutz.com/board/attachments/so-much-gear-so-little-time/16907d1142092019-api-lunch-box-15-pin-edge-connector-pin-out-12-13-14-15-picture-23.jpg)
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: bsconz on May 04, 2016, 02:56:33 PM
(https://www.gearslutz.com/board/attachments/so-much-gear-so-little-time/16907d1142092019-api-lunch-box-15-pin-edge-connector-pin-out-12-13-14-15-picture-23.jpg)

Big thanks to Floti!!!
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: bsconz on May 06, 2016, 08:30:13 PM
I'm trying to complete the CMRR adjustment on the pair of LC53A's I'm building and need a little help troubleshooting some funky stuff. I built 4 gar1731 op-amps for these guys but 2 of them were giving me some weird results during the CMRR adjustment.

The attached photo shows my CMRR adjustment setup and the 2 test points I was measuring while adjusting the trim pot. O-scope is currently out of service so used my Fluke 87. Function Generator was set to produce 100 Hz sine wave with ~1.0 VAC amplitude. Bi-polar power set to 16.9VDC (to match the chassis power supply it's going into).

Issue 1) One of the gar1731's heated up extremely fast when power was switched on. Specifically one of the large power transistors Q7. I checked over and over for bridged joints both under a magnifying glass and with my meter.

Issue 2) With another one of the gar1731's installed, I could adjust the trim pot all the way CW or CCW and almost no difference was measurable on the meter (set to AC voltage) between the 2 test points.

The other two gar1731's adjusted just fine. Both were able to be adjusted down to 8.5mVAC.

Are these common issues? Any ideas? I know the build guides say to start with known good op amps first so maybe I need to order a set of pre-built/tested op amps?
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Mr. Steve on May 26, 2016, 05:14:30 PM
hey bsconz,

it's been some time, have you solved the problem already?

it looks to me, that the CR1 diode on the left module is in the wrong direction.
but the pic is quite small, so i can't really see it ;)

maybe that helps, if you haven't solved it alread!
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: bsconz on May 26, 2016, 05:34:01 PM
When I built the gar1731's, I was drinking beer and it was late at night... 2 strikes already.

2 of the 4 op-amps happened to be built correctly and those were the ones I used to complete the CMRR adjustment.

The other 2 had various issues each including flipped power transistors, backwards FET's , and backwards diodes....what an idiot I thought to myself.

Moral of the story: don't drink and solder.

They're completed and installed in the studio...Sounding phenomenal too!!!
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: eqp1a on June 18, 2016, 09:43:24 AM
I posted previously with no luck about a problem I was having with a build. I believe I've narrowed the problem down to one of the DTO5 opamps. When measuring DC voltages  at both the inputs and output of one of the DTO5s I got approx -1.8VDC at both IN+ and IN-, and -3.6VDC at OUT. This behaviour is specific to the particular DTO5 (voltages follow the particular opamp when I swap the two), and is only observed when the opamp is in the circuit.

Am I correct in thinking this is where the (or a least a) problem lies? I've double and triple checked for shorts and dodgy solder joints, but to no avail. Not quite clever enough to pinpoint the source of the problem on the opamp itself, despite the existence of a published schematic. Any help/guidance/thoughts would be much appreciated.

Cheers

Ian
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on June 18, 2016, 04:15:31 PM
This sounds like an error on the DTO5 build. There should be very little DC offset present at the in/out of any of the active subassemblies. I would first check for swapped transistors on the particular opamp. Also make sure the 470R and 4k7 were not flipped. That has happened to folks before as well.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: eqp1a on June 18, 2016, 06:38:46 PM
Hey Jeff, thanks for the reply. Have double and triple checked all components are in the correct places and oriented correctly. R2 and R4 aren't swapped, diodes are all the correct way, transistors are all where they should  be, etc. Also double and triple checked for shorts and dodgy solder joints. At a bit of a loss.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Potato Cakes on August 06, 2016, 11:49:40 AM
Hello, everyone!

So I spent about 17 hours on my day off in a hotel room working on a pair of these. When I got to the gig, I was able to find time and start doing some testing. One of the them burned a 10 Ohm resistor by the op amp closest to the transformer. Classic! So I will have to wait till I get home since I don't have any more 10 Ohm guys out here with me.

The other one is working. Mostly. There are just three strange things happening that I was wondering if anyone else has had something similar happen.

The high band with the peak mode selected is just a gain knob, and set to -10dB it mutes the audio.

Same with the low band, plus it happens when 300 Hz is selected, but I may have an errant solder joint.

Lastly, the low band in shelf mode behaves like a high shelf EQ.

The thing that makes trouble shooting a little more difficult is that my test jig is at home. I'd love to try to figure this out on my next day off, but I'm not quite sure how the peak/shelf function switch works without a schematic. Any insight would be greatly appreciated.


Thanks!

Paul
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Potato Cakes on August 06, 2016, 03:22:35 PM
So....

I seemed to miss the part in the build documents about cutting everything as close to the PCBs as possible since there was very little clearance with the enclosure.

I cut the leads down on the one that was partially working and now it seems to work, at least testing with pink noise. Probably this is also the cause with the resistor burning out on the other one. Still have to wait till I get home to repair that one.

DIY is great!

Thanks!

Paul
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: woolie on September 06, 2016, 11:38:50 AM
I was wondering if you have any guidance for building your little test rig with the JLM Powerstation? Seems very prudent/handy to have a rig to test devices.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Potato Cakes on September 06, 2016, 11:44:40 AM
Hello,

I got home, swapped resistors, cut the leads down again. Both units working great. Love your work, Jeff.

Thanks!

Paul
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Potato Cakes on September 06, 2016, 11:49:23 AM
I was wondering if you have any guidance for building your little test rig with the JLM Powerstation? Seems very prudent/handy to have a rig to test devices.

Did you see the previous post with the edge connector pinout? Just connect the proper voltages to the correct pin then wire in a male and female XLR (in/out) also to the correct pins and then you should be great. Make sure you adjust your Powerstation to the correct voltages beforehand.

Thanks!

Paul
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: drummingninja on September 07, 2016, 11:58:19 PM
I have a pair of these working for the past year, but one has just started making a crackling sound. Unit still passes audio, EQ functions well, everything seems as normal but theres a crackling. Occasionally there will be a rather large peak, which looking at the waveform, they come in twos, one positive, one negative then just crackling for a minute then another pair of large peaks.

Ive taken the board apart, crackling is still present without the freq selection board, still present without op amps, I've reflowed most of the joints, still crackling no matter what. Any ideas?
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Potato Cakes on September 08, 2016, 12:46:18 AM
Does it still do it when unsoldered from the CB board (JP3-1)?

Thanks!

Paul
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: drummingninja on September 08, 2016, 04:47:51 PM
Does it still do it when unsoldered from the CB board (JP3-1)?

I just unsoldered the CB board from the trafo/doa board and recorded the output of just the trafo/doa board for a while, no crackling, no random spikes. Very interesting, must be something in the CB board. Thank you so much for the suggestion, nice to narrow it down to a single board at least.

Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: drummingninja on September 08, 2016, 10:40:15 PM
Connected the CB board only of the crackling unit to the doa/trafo board of my other fully functional unit and there is crackling. I can now completely confirm it is just the CB board causing the crackling.

Any ideas beyond solder joints that can cause crackling and random spikes? Still trying to learn the deep nature of troubleshooting audio circuits.

Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Potato Cakes on September 09, 2016, 07:20:23 PM
No worries. It's a little more of a pain to remove A1-4 on the CB PCB on the Rev A since they are not socketed, but my bets on one of those guys. If you could find out which order they are in from output to input and work that way you should be able to find it. Also, have you seen the voltage test points for that board?

http://www.capi-gear.com/catalog/images/gallery/LC53A/Build-docs/Rev_B/9_CAPI-LC53A-Rev-B-Test-Points.pdf

Thanks!

Paul
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: woolie on September 10, 2016, 12:07:07 PM
I was wondering if you have any guidance for building your little test rig with the JLM Powerstation? Seems very prudent/handy to have a rig to test devices.

Did you see the previous post with the edge connector pinout? Just connect the proper voltages to the correct pin then wire in a male and female XLR (in/out) also to the correct pins and then you should be great. Make sure you adjust your Powerstation to the correct voltages beforehand.

Thanks!

Paul

I found the pinouts you were referring to. TY. As to the 'correct voltage', any ideas where I could find those? Sorry for the n00b questions.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Potato Cakes on September 15, 2016, 01:55:47 AM
http://www.capi-gear.com/catalog/images/gallery/LC53A/Build-docs/Rev_B/9_CAPI-LC53A-Rev-B-Test-Points.pdf

All the information for all of Jeff's modules are listed at the bottom of the CAPI website under support docs.

Thanks!

Paul
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: choolder on March 10, 2017, 08:37:32 AM
Hi guys,

I just build 2 LC53a's. One works perfect, the other has a problem with 1 frequency: 1,5k. If a boost/cut at that frequency nothing happens. Any starting points were to start looking?

Thanks!

Peter

Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on March 10, 2017, 09:01:55 PM
I just build 2 LC53a's. One works perfect, the other has a problem with 1 frequency: 1,5k. If a boost/cut at that frequency nothing happens. Any starting points were to start looking?
Peter, the following points are involved for the 1.5k freq. All are on the LC-EP PCB.
1. Grayhill SW3, the 3rd pin in from the end where the wiper pin is located, this is connected to:
2. Caps C16 and C17 in parallel, which then go to:
3. The .25H pin on inductor L3.

I would first look for a bad solder joint on one of these.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: choolder on March 20, 2017, 05:00:10 AM
thanks!

Peter
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Blackdawg on May 16, 2017, 02:19:36 AM
Is this Kit gone? Not on the site anymore  :'(
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: jsteiger on May 16, 2017, 10:38:50 AM
Is this Kit gone? Not on the site anymore  :'(
I am out of the metalwork and have not reordered. Not sure I will since the release of the BT50. They overlap as far as responsibilities and I think the BT50 is an better overall designed module, cleaner/easier build and sonically a tad more aggressive than the LC53A.
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: Blackdawg on May 16, 2017, 11:13:19 AM
I am out of the metalwork and have not reordered. Not sure I will since the release of the BT50. They overlap as far as responsibilities and I think the BT50 is an better overall designed module, cleaner/easier build and sonically a tad more aggressive than the LC53A.

Gottcha! Sorta figured they were the same(ish) but wasn't 100% sure.

BT50 it is 8)
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: bleedingearaudio on July 20, 2018, 11:12:37 PM
Tap tap tap...Is anyone still here?

I have an LC53A RevA that is not working.  audio is very low and distorted.  measuring +6V on inverting input of A1 (no DOA installed) and +15V on output of A3 only when A3 is installed.  when A3 is not installed, there is no voltage.  voltages measured with module in test jig and bench supply at+/-16.5V

I tried replacing A3 (DT05) but no change.  I can not see any other problems.  All caps are visually ok.  voltages measure correctly at all power pins. 

Thanks
Eric
Title: Re: [BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
Post by: cryptokoan on August 09, 2019, 02:31:13 PM
Hi guys,

I just build 2 LC53a's. One works perfect, the other has a problem with 1 frequency: 1,5k. If a boost/cut at that frequency nothing happens. Any starting points were to start looking?

Thanks!

Peter

I have the exact same issue, were you able to fix yours Peter? Re-soldered all the points Jeff mentioned, still not able to change the 1.5k range