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Project Specific Discussions => Filters/Equalizers => Topic started by: jsteiger on November 25, 2016, 11:10:15 AM

Title: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on November 25, 2016, 11:10:15 AM
Hey folks

Tonight at midnight central time I am releasing the BT50, which is based on the original legendary 550.

Details and automated checkout can be had here:
http://capi-gear.com/catalog/index.php?cPath=22_117_119_213

I have changed the way the support docs and build pics are presented. Instead of cluttering up this thread with a zillion pics, I have them posted at my site along with detailed instructions.

The build pictorial can be found here:
http://capi-gear.com/catalog/Build_BT50_Rev_B.php

Since this is the official support thread, please post all questions, components and/or build problems here. I will do my best to help you get things sorted.

Full frontal:
(http://www.capi-gear.com/catalog/images/gallery/BT50/BT50-front-v.jpg)

Cheers, Jeff
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jasonallenh on November 25, 2016, 12:18:45 PM
Wowwwwww. I really like the way the new knobs interlock  :D
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on November 26, 2016, 10:29:20 AM
Wowwwwww. I really like the way the new knobs interlock  :D
Thanks! Making sure they work well in a concentric configuration was one of the up front priorities! I am pretty thrilled with how they turned out.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: Majestic12 on November 27, 2016, 01:10:55 PM
Just bought a pair of those. The 550 is by far my favourite EQ for tracking almost everything.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: brewbacca on December 09, 2016, 09:30:06 PM
Got  my pair working today, but I had a little confusion about the shunt jumpers for the input/output. If I'm running this with a typical modern  prosumer console (Toft) as an unbalanced insert, do I want the input jumper on the pins toward bottom and the output jumper on the pins toward the top?
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: maq3396 on December 16, 2016, 04:10:03 AM
New addition to the family...

Thanks for the great design and instructions Jeff. Haven't tried it yet but was a wonderful build. Cheers!
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: drummingninja on December 23, 2016, 03:18:18 AM
Just wrapped one of these up, sounds fantastic. Is it normal for there to be light to moderate clicking/popping when switching through frequencies and gain settings, as well as switching from shelf to peak? Or are setting changes intended to be silent?

Thanks,
Joseph
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on December 23, 2016, 06:37:45 PM
The Grayhills are make before break but still produce a small click at some settings. This is an inherent thing with the circuit. It is a little noticeable but should never be at the dangerous level.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: Potato Cakes on December 25, 2016, 12:08:17 AM
Jeff,

Just finished the first of 3 of these I have to build for a client. It worked right out of the gate and holy bologna these things are fantastic sounding! I'm putting Red Dots in these and they seem to be creating all those subjective terms that made not-to-be-mentioned company famous in the first place. Things like punch (especially in the low frequencies) and aggressive but not harsh mids and highs. And these indeed are easier to put together than the LC53A and dare I say, I think I prefer the sound of the BT50s? I know they are two different designs, but still...

I wish I was building these for myself. Maybe next time.

Keep up the phenomenal work and Merry Christmas!

Thanks!

Paul
Title: VERY nice EQ! (may have messed up my grayhills)
Post by: achase4u on January 08, 2017, 01:39:07 AM
Man.  I am on headphones right now as I just finished by build at around midnight.  It sounds so good!

Question - is it overheating that would cause a Grayhill to bind up?  Ive got good space between the knobs so thats not it.  It feels sticky between 4-12 db + on the low band.  Sort of like a strat pickup selector switch when it's been heated or soldered too much...

I think I'd rather have root canal than try to remove a Grayhill, so I will just leave it as a reminder for my next build not to screw up *smacking forhead*


EDIT*  Is it possible that pressure could cause the switch to not to work smoothly?  When I put them in, I noticed the front right side wasn't quite seated, maybe .010" gap.  So I held it in and soldered some pins to hold it there.  I wonder if that pressure it's under could have an effect.  Just thinking out loud.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: Undos on February 06, 2017, 05:40:10 PM
Hi GroupDIY
I'm new to the forum.
First I want to say thank you to all the helpful posts especially in the VP28  Support thread. :)

I just built two BT50 EQ's and tested  them on some material. Very nice on drums and guitars. Great design. First I had some trouble with the second built but after desoldering some components and put them back in, the thing worked. Measurement are fine on both kits now.
Love the CAPI Gear.

tim

Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on February 06, 2017, 08:37:30 PM
.....I just built two BT50 EQ's and tested  them on some material. Very nice on drums and guitars. Great design. First I had some trouble with the second built but after desoldering some components and put them back in, the thing worked. Measurement are fine on both kits now.
Love the CAPI Gear.
Thanks Tim! Glad you got them going OK and are loving them!  8)
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: geardude on March 27, 2017, 12:01:50 AM
Mentioned this in the 28 forum. But troubleshooting one of these as the line level return is the same. Trying out this test on a bt50 with the proper RME fx settings that I use to test the 28's in line mode & my line level return is -16.5 dbfs instead of -18 as it should be.  all knobs are in their correct orientation and using red dots as doa's.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on March 27, 2017, 12:39:54 AM
The normal startup position for the shunt jumper near the output transformer is 600Ω load. That is how all of the old 550's were. In the console they directly drove a 600Ω fader so they had a small 1.25 to 1.5dB bump in gain to compensate. You can change that jumper and it will be unity when driving a higher Z load.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: mudseason on April 22, 2017, 07:14:43 AM
Hi All,
I've completed the build of a pair of BT50.
I've asked Jeff about expected values to be read on the check points and he told me to use the VP26 assembly guide as a reference.

I've performed checks as reported in chapter 12.1.
All was as expected but for:

12.1.d Probe between the “C” and “O”(Output) sockets for the DOA. Your reading should be a high resistance, over 200K Ω.

On the output opamp socket I read around 50-55 Ω between C and O, this on both builds.

Apparently the two BT50 work fine:
1) If in bypass mode I just have a little drop of around 5dB which is expected if I'm not wrong.
2) If in bypass mode program material goes through unaffected (as when it passes thought my RND 551 or Kush Electras).
3) When active I get the curves that I would expect from it.
4) There are also a couple of peaks of harmonic distortion (2 and 3 kHz) around -100dBfs and a little rumbling below 100Hz (under -105dBfs), well these are identical to my original API 550A. So I would consider them OK.

Unfortunately Jeff told me that values of 50-55 Ω between C and O of the output DOA are just wrong.
He also suggested me to discuss the topic here.

What could be wrong?
Could it be just my DMM? It is a very low quality one, I have a fluke in the office I use when I need to calibrate stuff, but just for quick checks I rely on a $10 DMM.
I have an error in the build? Which could be the potentially involved components?

Thanks a lot.

Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on April 22, 2017, 11:19:24 AM
Hi All,
I've completed the build of a pair of BT50.

All was as expected but for:

On the output opamp socket I read around 50-55 Ω between C and O, this on both builds.

Unfortunately Jeff told me that values of 50-55 Ω between C and O of the output DOA are just wrong.
He also suggested me to discuss the topic here.

What could be wrong?
Could it be just my DMM? It is a very low quality one, I have a fluke in the office I use when I need to calibrate stuff, but just for quick checks I rely on a $10 DMM.
I have an error in the build? Which could be the potentially involved components?

Thanks a lot.
I believe I answered an email to a guy that was similar but was regarding a VP28 not BT50. I would have never told you to follow the VP26 results for a BT50.

**I must clarify, I found our email thread and the date span was over a month. Its hard to keep all of the emails straight sometimes. I do not have a built BT50 here at the moment but estimate that 50Ω from C to O on the output amp is likely pretty accurate. Theres a 47Ω R in series with the 8.5Ω 2503 primary so that sounds correct.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: mudseason on April 22, 2017, 11:26:43 AM
well,
that guy was me and yes it was about BT50.
however no problem.
it could even be a good news: chances are that my measurements were correct.
Were they?
Thanks!
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on April 22, 2017, 11:32:03 AM
well,
that guy was me and yes it was about BT50.
however no problem.
it could even be a good news: chances are that my measurements were correct.
Were they?
Thanks!
I just amended my post above.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: mysticmerlin on May 08, 2017, 06:54:48 AM
Hi , just finished 2 BT50's . One is working fine and sounds wonderful. However my second one has a roughly 30db gain increase whether in bypass or not and the mid section doesn't work but the LF and HF and filters work fine . On the opamp sockets I have high resistance between -v and +v/ 0 and +v/ 0and -v /c and +V / c and -v.   50Ohm between C and O on both units . I have 15.7 volts between +v and c and also between -v and c. Any ideas welcome.
Thanks
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on May 08, 2017, 09:33:30 AM
I would check to make sure all joints of the 6-pin header and socket that connect the mid band board to the main are clean and have no shorts. I recently had a guy forget to solder the header pins. Also closely inspect the mid band PCB and make sure there are no shorts on any of the Grayhill pins. This sounds like something is shorted to ground.

Since you have one good working unit, you could simply plug the good mid band PCB into the bad main PCB and see if it works. That will help narrow down the problem to the mid band PCB or not. Just make sure you mark the good and bad everything before you start so you don't get things mixed up.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: mysticmerlin on May 10, 2017, 10:01:28 AM
Well it is indeed the mid band PCB that is faulty. When swapped the unit works fine. However I am unable to find where the fault is.  I relflowed the joints twice. Any ideas where to look for now?

Thanks
Bruce
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on May 10, 2017, 10:42:51 AM
Well it is indeed the mid band PCB that is faulty. When swapped the unit works fine. However I am unable to find where the fault is.  I relflowed the joints twice. Any ideas where to look for now?

Thanks
Bruce
It is a short to ground somewhere. Its hard to tell in the pic but I see a handful of solder joints with excess solder that could be shorting to the ground plane. Look for the little blobs on the side of the solder pads that touch the ground plane. Looks like one on a switch wiper and a few on resisters near the back of the board.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: mysticmerlin on May 10, 2017, 01:15:05 PM
As usual you are right.  there is a short between the ground and the 3 rd resistor from the bottom. Fixed. Thanks a lot for your help. These units sound great and I've been longing for this particular eq for a long while.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on May 10, 2017, 01:16:35 PM
As usual you are right.  there is a short between the ground and the 3 rd resistor from the bottom. Fixed. Thanks a lot for your help. These units sound great and I've been longing for this particular eq for a long while.
Glad you found it!!
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: mysticmerlin on May 10, 2017, 03:16:11 PM
And this project brings me to the end of my DIY eq adventure. The idea was to have 16 eqs for my little 16 channel desk. I've also  built 14 compressors just need to finish 2 pyes. the patch bay is noramlled Converter->EQ -> Comp -> Line In plus a mult from the comp outs to the converter ins so I can track the 16 channels at the same time as the Mix out. Still working on the fairchild 670 for the Buss out but it's 90% done.
I just wanted to give a warm thank you to all the Group DIY community for making the whole thing possible. You're an amazing bunch.
Cheers
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: Blahpstick on June 13, 2017, 11:11:19 AM
Jeff! I just finished my sixth or eighth BT50 now and i went to test it. Everything works except the high band stays flat when switched to shelving mode. peaking works just fine.  :( :-[ :'(

Can you give me a lil help please
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on June 13, 2017, 12:02:04 PM
Jeff! I just finished my sixth or eighth BT50 now and i went to test it. Everything works except the high band stays flat when switched to shelving mode. peaking works just fine.  :( :-[ :'(

Can you give me a lil help please
OK, to begin with, the mini toggle SW4 either connects the signal to the peak or shelving network. When in shelving mode, the wiper (rear middle pin) of SW4 is connected to the top rear SW4 pin. From there it goes to the nearest front wiper pin of Grayhill SW2. You can see in the attached screen shot. That said, you should have continuity from the mini toggle wiper to the respective Grayhill pin (inside the green box) depending on the freq setting. If not, check the toggle itself or related solder joints. If you have continuity from the toggle wiper to all respective output pins of the GH front lower deck, we will take it to the next step.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: Blahpstick on June 13, 2017, 10:58:22 PM
...the mini toggle SW4 either connects the signal to the peak or shelving network. When in shelving mode, the wiper (rear middle pin) of SW4 is connected to the top rear SW4 pin. From there it goes to the nearest front wiper pin of Grayhill SW2. You can see in the attached screen shot. That said, you should have continuity from the mini toggle wiper to the respective Grayhill pin (inside the green box) depending on the freq setting. If not, check the toggle itself or related solder joints. If you have continuity from the toggle wiper to all respective output pins of the GH front lower deck, we will take it to the next step.

Thanks for the quick reply, Jeff!  Your customer service has been second to none.

I measured continutity between the wiper of SW4 to all 5 output pins and we have connection to each frequency selection.  What would the next step be?

(http://img.photobucket.com/albums/v295/bgpratt/IMG_2001%20Edited_zpsr230xptr.jpg)
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on June 14, 2017, 12:23:11 PM
From
I measured continutity between the wiper of SW4 to all 5 output pins and we have connection to each frequency selection.  What would the next step be?
From those contacts of the Grayhill, each tap goes to its respective cap array. The 5 sets of caps (one or more for each freq point) all end up connecting together and go to the wiper of the E deck which is the 5th deck from the front. In the attached screenshot you will see all of those pads and tracks in highlight mode. This is the shelving Q deck and sets the bandwidth per step of boost/cut. This E deck wiper goes thru one or more R's to ground depending on the amount of boost or cut selected. I would make sure you have continuity from one of the highlighted cap pads thru the respective pin on the E deck of the switch. No contact is made when in 0. That said, you should have resistance to ground from the E wiper when in any boost/cut other than 0. HR4 is the last R in the string so the E deck connects the E wiper to HR4 which goes to ground when set to +/-12.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: Blahpstick on June 14, 2017, 07:36:45 PM
... I would make sure you have continuity from one of the highlighted cap pads thru the respective pin on the E deck of the switch. No contact is made when in 0. That said, you should have resistance to ground from the E wiper when in any boost/cut other than 0. HR4 is the last R in the string so the E deck connects the E wiper to HR4 which goes to ground when set to +/-12.

Alright, Jeff.  I made sure and all of the highlighted cap pads have continuity through each respective pin on the E deck.  I also measured and found that E wiper has resistance to ground in each position except for 0.  To be expected as per your quote.  Please let me know where else the trouble might lie, sir!
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on June 14, 2017, 08:15:28 PM
Alright, Jeff.  I made sure and all of the highlighted cap pads have continuity through each respective pin on the E deck.  I also measured and found that E wiper has resistance to ground in each position except for 0.  To be expected as per your quote.  Please let me know where else the trouble might lie, sir!
Well man, that is pretty much it for the high freq shelving part of the circuit. Its essentially nothing more than a series cap and a series resistor hanging off of the mini toggle. Its just a very complicated way to get the right frequency and right bandwidth.

If the above all checks out, it seems very strange to me that peaking works OK and shelving does not.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: Blahpstick on June 14, 2017, 10:38:29 PM
Whatever it was that happened it's working now!  I'm guessing I had a less than perfect joint somewhere in that chain and maybe the probes re-engaged contact.  I reflowed the solder joints that I had to probe during this troubleshooting session juuust in case!  Whatever the case it's working and she's ready to aggravate some audio :D Thanks so much for the attention, Jeff.  You're the best and I will continue to pimp out your gear as much as I can 8)

Hugs n kisses,
Billy
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on June 15, 2017, 12:42:48 AM
Thanks so much for the attention, Jeff.  You're the best and I will continue to pimp out your gear as much as I can 8)

Hugs n kisses,
Billy
Glad you got it sorted Billy!  \m/
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: DrywOwens on June 16, 2017, 11:47:25 AM
Hi Jeff!
I was hoping for a little help here... I have 2 BT50s here and one is working great. The other one is almost there - the only problem is that 200hz on the low band seems to do absolutely nothing in shelving mode. However, it is fine in peak mode! Where should I troubleshoot?
Thanks!
-Dryw
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on June 16, 2017, 07:59:42 PM
Hi Jeff!
I was hoping for a little help here... I have 2 BT50s here and one is working great. The other one is almost there - the only problem is that 200hz on the low band seems to do absolutely nothing in shelving mode. However, it is fine in peak mode! Where should I troubleshoot?
Thanks!
-Dryw
Hey Dryw, 200Hz shelving is only 1 cap and the 3rd pin up on the front deck of the LF Grayhill. See the highlighted track and pads in the attached screenshot. I would reflow those 2 pads.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: DrywOwens on June 17, 2017, 04:04:29 PM
Hey Dryw, 200Hz shelving is only 1 cap and the 3rd pin up on the front deck of the LF Grayhill. See the highlighted track and pads in the attached screenshot. I would reflow those 2 pads.

Thanks so much, Jeff.
I reflowed the pads in question to no avail. As I continue to test with a simple DAW analyzer, I'm noticing that the 200hz shelf (while not affecting 200) IS affecting something around 50hz or lower, but only in shelf mode. Peak works great.
This is making me think a cap mix-up may have occurred... Is this a possibility for the behavior I am describing? If so, can you advise me on which caps to desolder and check? I'd check 'em all, but I don't want to risk damage to the components or PCB with that much desoldering.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on June 17, 2017, 05:10:18 PM
Thanks so much, Jeff.
I reflowed the pads in question to no avail. As I continue to test with a simple DAW analyzer, I'm noticing that the 200hz shelf (while not affecting 200) IS affecting something around 50hz or lower, but only in shelf mode. Peak works great.
This is making me think a cap mix-up may have occurred... Is this a possibility for the behavior I am describing? If so, can you advise me on which caps to desolder and check? I'd check 'em all, but I don't want to risk damage to the components or PCB with that much desoldering.
Well, I would start by removing LC5 and seeing what value it is. It should be .022µF.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: DrywOwens on June 17, 2017, 06:32:52 PM
Well, I would start by removing LC5 and seeing what value it is. It should be .022µF.

I just pulled LC5 and it reads µ22k63... Is this the right one, or off by a zero?
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on June 17, 2017, 07:13:24 PM
I just pulled LC5 and it reads µ22k63... Is this the right one, or off by a zero?
That is super strange. I just sifted thru the parts bin and all say 22nJ100 just like pic 2.B.14 shows here http://capi-gear.com/catalog/Build_BT50_Rev_B.php#Sec2B

Odd thing is I don't even have a µ22k63 cap here. The closest thing is µ33J63. Can you post a pic?
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: DrywOwens on June 18, 2017, 04:52:32 PM
That is super strange. I just sifted thru the parts bin and all say 22nJ100 just like pic 2.B.14 shows here http://capi-gear.com/catalog/Build_BT50_Rev_B.php#Sec2B

Odd thing is I don't even have a µ22k63 cap here. The closest thing is µ33J63. Can you post a pic?
Just DM'd you photos.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: fdel on August 01, 2017, 04:38:20 AM
Hey Guys.  First post here total noob.  So please be gentle hahah.  This is only my second Build.  Previous build was a VP28, an amazing Pre Jeff well done I'll be buying more of these I love the sound of that thing!

Loving the DIY So I thought I'd try a couple of BT-50's.  I completed the first one and when I put it in my 500 series rack  I can't get any signal/power through it.  It doesn't seem to be getting any power.   Its not the rack I've checked that already. 

I"ll swap the transformer out for the other one on the second unit (not yet built) and see if that's the issue and I'll run the microscope over the all the resistors and caps again to see if there are any shorts etc.  Are there any other things I should check?

Any advice would be greatly appreciated.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: fdel on August 01, 2017, 09:37:03 AM
Update on my build. I managed to swap out the transformer and get power to it.  Yay!    And then there was the dreaded burning smell and it appears I still have a build error as I have melted  some resistors see photo.   Please help.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on August 01, 2017, 10:56:36 AM
Update on my build. I managed to swap out the transformer and get power to it.  Yay!    And then there was the dreaded burning smell and it appears I still have a build error as I have melted  some resistors see photo.   Please help.
The output transformer will have nothing to do with getting "power" to the module. From the results its something else.

I assume the opamps are built by you? These smoked 6 R's are power damping resistors. 2 supply the 1st discrete opamp, 2 supply the 2nd discrete opamp and 2 supply all of the discrete followers. Burning all 6 means that you have a major error on each of the above locations.

The first rule of thumb is....you should never try to test a fresh module build with fresh opamp builds. In this situation you immediately thought it was the module but the smoking of the 10Ω power damping R's tells me it's the opamps. Here we also have the 10Ω's for the discrete followers smoked so I would look for incorrectly placed transistors there which is Q1-Q6. I'm not saying there can't be trouble on the module itself though.

PR1 and PR4 are for A1
PR3 and PR5 are for A2
PR2 and PR6 are for the discrete followers Q1-Q6

As for the gar2520 issues, you should visit that support thread.

Once you replace the 10Ω R's and get the Q1-Q6 parts sorted, you can power the module with no opamps to make sure the followers don't smoke their R's. Then use good known to be working opamps from another module to test this build.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: brianmatteson on August 07, 2017, 04:46:42 AM
Hello,

I'm looking for some help troubleshooting a BT50 I just built.

Hi and Mid eq's work great, but the low band doesn't eq. Any boost I try to add on the low band just distorts the signal. Also, the high and low pass filters seem to not do anything at all. I've checked my work and am totally stumped, any help would be greatly appreciated!

****UPDATE*****

I had one transistor facing the wrong direction I fixed that and now the low band works-but only in shelf mode. In peak mode it doesn't seem to add any bass. Again, any help is greatly appreciated!
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: brianmatteson on August 14, 2017, 08:12:34 PM
Hello Again,

Jeff are you able to help me out? I've done builds and am fairly experienced that way, but there are gaps in my knowledge, especially with troubleshooting-is there a way I can test areas of the circuit to see what's failing? The low frequency peaking mode isn't working and it doesn't seem like the filters are either. Everything else works very well and I've checked all the other components over-specifically LC1-LC18 to make sure they are in the correct spots. Any help at all is greatly appreciated!
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on August 14, 2017, 08:51:51 PM
Hello Again,

Jeff are you able to help me out? I've done builds and am fairly experienced that way, but there are gaps in my knowledge, especially with troubleshooting-is there a way I can test areas of the circuit to see what's failing? The low frequency peaking mode isn't working and it doesn't seem like the filters are either. Everything else works very well and I've checked all the other components over-specifically LC1-LC18 to make sure they are in the correct spots. Any help at all is greatly appreciated!
If none of the freq's are boosting on the LF, I would look for (or just touch up all) a bad solder joint on the mini toggle SW3 or the Grayhill SW1.

As far as the filters, it may be hard to detect with ears only depending on the source. Running some tones and analyzing the output may be a better way of "testing".
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: brianmatteson on August 14, 2017, 09:30:27 PM
Quote
If none of the freq's are boosting on the LF, I would look for (or just touch up all) a bad solder joint on the mini toggle SW3 or the Grayhill SW1.

As far as the filters, it may be hard to detect with ears only depending on the source. Running some tones and analyzing the output may be a better way of "testing".

Thank you for your reply! I will look at those specifically and report back.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: brianmatteson on August 14, 2017, 10:13:56 PM
Hey Jeff-I think it must have been a bad solder joint or something...everything seems to be working now. Thanks for the help!
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: CJBrain on January 14, 2018, 02:08:44 PM
Hi Guys

Just finished building a pair of these and while one of them is working perfectly,  i'm having some strange issues with the other one.

 It only passes signal through when the LF cut/boost pot is turned two clicks anti clockwise and onwards. As soon as I turn it anywhere else, the signal cuts out...

Not the easiest thing to explain in words so I can record a short video and send it to anyone who is willing to help me try and fix this issue.

Cheers

Colin.

Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on January 14, 2018, 02:29:13 PM
I would first look for shoddy cold solder joints or bridges on the Grayhill switch pins.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: CJBrain on January 15, 2018, 06:54:27 AM
Hi Jeff,

Thanks for your reply.

Had a look this morning and re-soldered any suspect points. Still the same problem though....

Cheers

Colin.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on January 18, 2018, 05:24:34 PM
Had a look this morning and re-soldered any suspect points. Still the same problem though....
Since you have a good working unit, I would inject a sine wave on the good one and write down all ACV at the test points and compare. Go in order on the bad unit. Once you see a major discrepancy tell us the TP # and that'll help me narrow down what to look for.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: Mario_checchia on February 04, 2018, 07:50:57 PM
Hi all. Just completed one of my two BT50s. It works at first but then crackling and popping begins to pick up until after about 20 seconds the output drops significantly while the crackling gets so loud it drownds it out.

I thought maybe a component was cooking; however, upon inspection nothing appears to have overheated, nor is there smoke or a smell. I plugged it back in and it worked for another 20 seconds until it suffered the same result.

Any ideas what this may be? Aside from touching up solder points I am unsure how to troubleshoot.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on February 04, 2018, 07:54:27 PM
What op
Any ideas what this may be? Aside from touching up solder points I am unsure how to troubleshoot.
What opamps are installed and who built them? Are they fully seated?
http://capi-gear.com/catalog/DOA_Install.php
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: Mario_checchia on February 04, 2018, 07:59:46 PM
What opWhat opamps are installed and who built them? Are they fully seated?
http://capi-gear.com/catalog/DOA_Install.php

I have built and installed the GAR1731 opamps. I ensured the millmax pins are fully seated. A bit of resistance at first but eventually they dropped in nicely.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on February 04, 2018, 08:22:31 PM
I have built and installed the GAR1731 opamps. I ensured the millmax pins are fully seated. A bit of resistance at first but eventually they dropped in nicely.
Maybe its the opamps that are built wrong? Maybe the problem is on the BT50? No real way of knowing. These EQ's should ONLY be tested with known to be good working opamps.

It is likely an active part of the circuit so I would first suspect the opamps.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: Mario_checchia on February 05, 2018, 02:37:37 PM
Maybe its the opamps that are built wrong? Maybe the problem is on the BT50? No real way of knowing. These EQ's should ONLY be tested with known to be good working opamps.

It is likely an active part of the circuit so I would first suspect the opamps.

Jeff,

Thanks for the quick reply! I will swap in a pair of known working opamps and determine if I can deduce that it is in fact the opamps that are the issue. Can’t rule out my soldering of the opamps as the source of the problem! I will report back when I have the chance. Thanks again.

P.s. these things are sweet to look at. Can’t wait to say how sweet they are to listen to.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: CJBrain on February 07, 2018, 10:25:36 AM
Since you have a good working unit, I would inject a sine wave on the good one and write down all ACV at the test points and compare. Go in order on the bad unit. Once you see a major discrepancy tell us the TP # and that'll help me narrow down what to look for.

Hi Jeff

I've attached a table showing the ACV test point results for each unit.

Cheers

Colin.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: mattk on February 09, 2018, 08:47:15 PM
Hi! Just finished building my first BT50! (Litz+RedDots)  :)

All went super smoothly, pictorial build guide was really helpful and, in general, I managed a pretty "clean" build, no solder excess etc, except for some flux here and there...

All works fine, except there is a  very noticeable, constant buzz, whether the unit is on or off. Apart from that, the eq works perfectly.
Any idea what could be causing this?

Thanks!
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: mrmike186 on February 10, 2018, 05:03:02 PM
It appears I have installed the blue 470 electrolytic cap backwards. The unit has been working fine but could I have possibly damaged something?

I will switch it but is there any rule to what side is negative? Maybe the direction arrows or the indented side is the positive side? I did it this way because there was no black stripe but the end is black
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on February 11, 2018, 01:04:37 AM
It appears I have installed the blue 470 electrolytic cap backwards. The unit has been working fine but could I have possibly damaged something?

I will switch it but is there any rule to what side is negative? Maybe the direction arrows or the indented side is the positive side? I did it this way because there was no black stripe but the end is black
The small arrows on the side point to the negative end. If you look close there is a "-" sign inside each arrow. The positive end has a small groove around it. You won't have damaged anything but you should make it the right orientation.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: mattk on February 11, 2018, 01:31:06 PM
Hi! Just finished building my first BT50! (Litz+RedDots)  :)

All went super smoothly, pictorial build guide was really helpful and, in general, I managed a pretty "clean" build, no solder excess etc, except for some flux here and there...

All works fine, except there is a  very noticeable, constant buzz, whether the unit is on or off. Apart from that, the eq works perfectly.

Thanks!

Any ideas?
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on February 11, 2018, 01:43:11 PM
Any ideas?
Could be many things I suppose. I've never experienced this so don't have a definitive place to look. It's likely there is no silver bullet fix. Have you ruled out all outside potential causes like rack slot, patchbay, cables etc? The input of the BT50 in unbalanced so it's possible the device you have before it does not like being unbalanced? Maybe its the rack itself?
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: mattk on February 11, 2018, 02:22:42 PM
The input of the BT50 in unbalanced so it's possible the device you have before it does not like being unbalanced?

Yes!!!! That's it!!!!
I had checked cables, different slots, etc, I even disassembled the eq to triple-ckeck for errors but had only tried it as a hardware insert in PT (out of an Apollo 16 throgh the patchbay).
Thankfully I'm mostly going to use the bt50 for tracking (after a pre) so I'm good.
Thank you very much Jeff!
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: CJBrain on February 22, 2018, 07:20:25 AM
Hi Guys,

Was wondering if anyone had any feedback from my last post?

Cheers

Colin.

Hi Jeff

I've attached a table showing the ACV test point results for each unit.

Cheers

Colin.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on March 15, 2018, 09:22:16 PM
Hi Guys,

Was wondering if anyone had any feedback from my last post?

Cheers

Colin.
Colin, if you are good at TP3 and have lost signal by TP4 (with the low band gain switch set to 0 cut/boost) then you have a likely bad solder joint on one of the R's, LR5-LR9 or the lowest (F) deck of SW1 pins which would be FC1 and F1-F5. See the attached screenshot.

You could also pull R7 and if the signal comes back at TP4, then your issue is with the discrete follower network of Q1, Q2, R13, R14.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: myers1st on June 10, 2018, 03:18:12 PM
 Hi all,

 I’ve just finished building a pair of BT 50s and one is working perfectly but the other has a weak output, perhaps 12 dB lower than the other one. The EQ functions seem to be working correctly. I have swapped op amps and rack slots and that is not the problem. Any ideas?

Thanks!
Steve
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on June 10, 2018, 03:25:00 PM
I’ve just finished building a pair of BT 50s and one is working perfectly but the other has a weak output, perhaps 12 dB lower than the other one. The EQ functions seem to be working correctly. I have swapped op amps and rack slots and that is not the problem. Any ideas?
Since you have one working properly, inject a sine wave and notate the ACV at all of the Test Points going thru them in order. Then move to the troubled unit and see where things go sideways. That will help pinpoint where the problem is. Otherwise its a needle in a haystack.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: myers1st on June 10, 2018, 09:58:20 PM
Hey Jeff, thanks for the quick reply.

Rookie mistake, had pink and red swapped on the Litz.  Switched them and all good.  These sound superb by the way!
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on June 10, 2018, 11:14:28 PM
Rookie mistake, had pink and red swapped on the Litz.  Switched them and all good.  These sound superb by the way!
Oh good, that was an easy one  ;)
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: Thekahn on June 16, 2018, 01:42:34 PM
Hi guys!
Just built my first BT-50 and everything works amazing, except the shelving on the low frequencies doesn't do anything when engaged. (The peak mode works perfectly on all frequencies).

I'm assuming I should reflow the solder joints at the mini toggle switch. Anything else I should look at specifically?
Thanks,
Chris
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on June 16, 2018, 03:33:21 PM
Hi guys!
Just built my first BT-50 and everything works amazing, except the shelving on the low frequencies doesn't do anything when engaged. (The peak mode works perfectly on all frequencies).

I'm assuming I should reflow the solder joints at the mini toggle switch. Anything else I should look at specifically?
Chris, sounds like a cold solder joint on the mini toggle and/or the LF Grayhill, and/or one of the low filter caps.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: Thekahn on June 17, 2018, 12:34:05 PM
Chris, sounds like a cold solder joint on the mini toggle and/or the LF Grayhill, and/or one of the low filter caps.

Thanks for the response Jeff,
I reflowed the mini switch, all low frequency caps and any of the gray hill pads that looked at all suspect (honestly they looked pretty good to me), to no avail.  It's almost as if when in shelving mode the signal isn't passing through any of the LF components, but in peak mode everything sounds glorious. Any way I can inject a sine wave or do a continuity test to help? Thanks!
Chris
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on June 17, 2018, 01:45:10 PM
Thanks for the response Jeff,
I reflowed the mini switch, all low frequency caps and any of the gray hill pads that looked at all suspect (honestly they looked pretty good to me), to no avail.  It's almost as if when in shelving mode the signal isn't passing through any of the LF components, but in peak mode everything sounds glorious. Any way I can inject a sine wave or do a continuity test to help? Thanks!
Chris
Using the attached screenshot as a guide...

1. With DMM continuity, make sure you do not have a direct short from Grayhill SW1 wiper pad EC1 to ground.

2. When in shelf mode, the middle wiper pin #2 of mini toggle SW3 should be directly connected to Grayhill SW1 wiper pin EC1.

3. Grayhill wiper pin EC1 goes to ground thru the resistor string LR18->LR19->LR20->LR4->LR3->LC8->GND, depending on the cut/boost position. So, if +/-12dB you should have 6k34 DCR between the wiper of SW3 and the right end of LR3.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: Thekahn on June 18, 2018, 01:33:30 AM
Using the attached screenshot as a guide...

1. With DMM continuity, make sure you do not have a direct short from Grayhill SW1 wiper pad EC1 to ground.

2. When in shelf mode, the middle wiper pin #2 of mini toggle SW3 should be directly connected to Grayhill SW1 wiper pin EC1.

3. Grayhill wiper pin EC1 goes to ground thru the resistor string LR18->LR19->LR20->LR4->LR3->LC8->GND, depending on the cut/boost position. So, if +/-12dB you should have 6k34 DCR between the wiper of SW3 and the right end of LR3.

Jeff,

1. I have confirmed when I put one probe on ground and one probe on SW1 EC1, there is no continuity.

2. I have confirmed when on shelf mode, there is continuity between pin #2 on mini toggle SW3 and SW1 EC1.

3. When I try measuring resistance from EC1 to pin 2 of LR3, it keeps climbing up and up, upwards of 12 mega ohms and doesn't really stop. Do I need to desolder that leg of LR3 to measure it properly(IE to pull it out of the circuit) ? Or does the data above give you the info you were looking for? 
Thanks,
Chris
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on June 18, 2018, 10:07:50 PM
3. When I try measuring resistance from EC1 to pin 2 of LR3, it keeps climbing up and up, upwards of 12 mega ohms and doesn't really stop. Do I need to desolder that leg of LR3 to measure it properly(IE to pull it out of the circuit) ? Or does the data above give you the info you were looking for? 
No you should not have to desolder anything. I just checked on a good unit here with the mini toggle set to shelving and full boost of low band and I get appx 6k34 from the wiper (pin #2) of the mini toggle to the right end of LR3. It takes a second or 2 to settle but goes right there and stays. That is telling me you have a cold solder joint(s) on the string of R's I posted above or one or more of the switch pins of the E deck of the Grayhill.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: Thekahn on June 19, 2018, 02:00:32 AM
No you should not have to desolder anything. I just checked on a good unit here with the mini toggle set to shelving and full boost of low band and I get appx 6k34 from the wiper (pin #2) of the mini toggle to the right end of LR3. It takes a second or 2 to settle but goes right there and stays. That is telling me you have a cold solder joint(s) on the string of R's I posted above or one or more of the switch pins of the E deck of the Grayhill.

Hi Jeff,
There is definitely  no connection from EC1 to any of the E deck pins on the gray hill, nor the resistors mentioned above. I can track resistance values all down the E deck of the gray hill all the way down to the right side of LR3, but when I put it on EC1, it turns into mega ohms and keeps rising and rising. Is it possible my grayhill is broken internally? I get 25 ohms of resistance from the wiper of SW3 to EC1 on the gray hill, but like I said, it's as if EC1 stops there. Any ideas? Thanks again for the help.
Chris
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on June 19, 2018, 12:13:13 PM
Hi Jeff,
There is definitely  no connection from EC1 to any of the E deck pins on the gray hill, nor the resistors mentioned above. I can track resistance values all down the E deck of the gray hill all the way down to the right side of LR3, but when I put it on EC1, it turns into mega ohms and keeps rising and rising. Is it possible my grayhill is broken internally? I get 25 ohms of resistance from the wiper of SW3 to EC1 on the gray hill, but like I said, it's as if EC1 stops there. Any ideas? Thanks again for the help.
Chris
I would reflow the solder on the EC1 pad. Its possible the switch is bad but very unlikely. Try checking continuity from the EC1 metal wiper that that comes out of the Grayhill switch body to the associated E deck pins. They should beep out as you turn thru its rotation.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: Thekahn on June 19, 2018, 09:55:33 PM
I would reflow the solder on the EC1 pad. Its possible the switch is bad but very unlikely. Try checking continuity from the EC1 metal wiper that that comes out of the Grayhill switch body to the associated E deck pins. They should beep out as you turn thru its rotation.

Hi Jeff,
There is no continuity from any of the E deck pins from EC1, even when I turn the gain knob and freq knob to different positions. I have re-flowed EC1 many times, and I even checked for continuity from the top side of the wiper pin at the grayhill body when checking the E deck pins.  What's odd is that I get continuity from the SW3 wiper to EC1 but no continuity from EC1 to any of the  E deck pins or related resistors. I'm thinking its a bad switch but I can't tell for sure.  Not really sure what to do now.  Any help would be great.
Thanks,
Chris

Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on June 19, 2018, 10:01:14 PM
Hi Jeff,
There is no continuity from any of the E deck pins from EC1, even when I turn the gain knob and freq knob to different positions. I have re-flowed EC1 many times, and I even checked for continuity from the top side of the wiper pin at the grayhill body when checking the E deck pins.  What's odd is that I get continuity from the SW3 wiper to EC1 but no continuity from EC1 to any of the  E deck pins or related resistors. I'm thinking its a bad switch but I can't tell for sure.  Not really sure what to do now.  Any help would be great.
Thanks,
Chris
Chris, send me an email thru the store.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: Thekahn on June 20, 2018, 12:18:30 AM
Chris, send me an email thru the store.

Email sent. Thanks Jeff
Chris
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: Riff0601 on July 20, 2018, 12:57:34 PM
Hi All
I did very well with the 2 vp28 and the Bt50, only that the Bt50 does not work for me as a line signal, I read that something has to be done with the jumpers, but I really do not understand what. Could you explain please, thank you very much
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on July 30, 2018, 11:09:42 AM
Hi All
I did very well with the 2 vp28 and the Bt50, only that the Bt50 does not work for me as a line signal, I read that something has to be done with the jumpers, but I really do not understand what. Could you explain please, thank you very much
The BT50 is line only. The recommended starting position for the two 3-pin option jumpers is shown in the below pic.
http://capi-gear.com/catalog/images/build/BT50/1_main_PCB/23.jpg

J4 is to select for a typical higher impedance load or a 600Ω load. There is appx 1.3dB more gain when set to 600Z.

Since the input of the BT50 is unbalanced, J5 will increase the BT50's level by 6dB so you can run it from an electronically balanced piece of gear and not loose 6dB.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: scotthundley on July 31, 2018, 09:10:52 PM
Hey guys,

I built two BT50's  a few months ago and one works perfectly and the other has a few issues.  I've run tests tones through the BT50 have found that the  12.5k shelf doesn't boost or cut properly. It boosts/cuts starting from about 2k.  The 15k band in peak boost/cuts at 10k instead of 15k and then the 1.5k band actually boost/cuts at 10k.


Any ideas? Thanks!

-Scott
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: RyanCat on August 07, 2018, 12:13:04 PM
Hello guys,

i just finished a bt50. I think have a problem in the LF. In peak mod three of the five frequencies seemed to boost/cut not only the chosen frequency but the entire signal. In shelving mod i think everything works fine. I also think that the LPF does not work. In the other bands i have no problems.

Could you please give me some tips where i can look for troubleshooting?!

Thanks!

Jan 
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on August 09, 2018, 10:39:53 AM
Hello guys,

i just finished a bt50. I think have a problem in the LF. In peak mod three of the five frequencies seemed to boost/cut not only the chosen frequency but the entire signal. In shelving mod i think everything works fine. I also think that the LPF does not work. In the other bands i have no problems.

Could you please give me some tips where i can look for troubleshooting?!

Thanks!

Jan
Jan

Measure continuity between the LF Grayhill switch wipers and ground. Its possible that one of them is shorting. You will need to desolder that specific wiper and torque/push/slightly bend it a little to get some space above the PCB and resolder. It seems the width of the wiper pins are varying a little and some have rough edges on the bottom that are making contact to the top ground plane.

The HPF is at 50Hz so it might be hard to hear especially on smaller monitors. The only way to know for sure is to run a sweep or monitor level of a low frequency like 20Hz and compare with the pushbutton in/out.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on August 09, 2018, 10:45:33 AM
Hey guys,

I built two BT50's  a few months ago and one works perfectly and the other has a few issues.  I've run tests tones through the BT50 have found that the  12.5k shelf doesn't boost or cut properly. It boosts/cuts starting from about 2k.  The 15k band in peak boost/cuts at 10k instead of 15k and then the 1.5k band actually boost/cuts at 10k.


Any ideas? Thanks!

-Scott
Sounds like you have mixed up some of the caps in the HF area.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: RyanCat on August 09, 2018, 11:39:26 AM
Jan

Measure continuity between the LF Grayhill switch wipers and ground. Its possible that one of them is shorting. You will need to desolder that specific wiper and torque/push/slightly bend it a little to get some space above the PCB and resolder. It seems the width of the wiper pins are varying a little and some have rough edges on the bottom that are making contact to the top ground plane.

The HPF is at 50Hz so it might be hard to hear especially on smaller monitors. The only way to know for sure is to run a sweep or monitor level of a low frequency like 20Hz and compare with the pushbutton in/out.

Thank you very much for your advices. I try to fix it.

I meant LPF not the HPF. This one works as it should.

Jan
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on August 09, 2018, 12:00:29 PM
Thank you very much for your advices. I try to fix it.

I meant LPF not the HPF. This one works as it should.

Jan
Same situation applies. The LPF is @ 15kHz so it may be hard to hear. Its a 2 pole so down appx 12dB an octave which would mean -12dB @ 30kHz. so of course noticeably less than that in the audio band.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: scotthundley on August 21, 2018, 06:27:38 PM
I did indeed switch some caps! I mixed up two .015uf caps with two .0015uf. All good now. Thanks Jeff!
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: JeffTD on October 29, 2018, 12:34:01 PM
Hey Jeff! Finished this one up last night and it sounds AWESOME, but I'm having one issue with the "bypass" I haven't seen mentioned by other folks. My "In' switch doesn't seem to do anything other than turn the red light on/off - the signal remains affected by the eq curves I've defined regardless of the position of the switch.

Have you ever heard of this kind of problem? Do you have any ideas for places I can begin to troubleshoot? It's a funny kind of issue in that I'm still going to use the unit even if I can't bypass it, but it'd be great to have for quick A/B comparisons.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on October 29, 2018, 01:16:40 PM
Hey Jeff! Finished this one up last night and it sounds AWESOME, but I'm having one issue with the "bypass" I haven't seen mentioned by other folks. My "In' switch doesn't seem to do anything other than turn the red light on/off - the signal remains affected by the eq curves I've defined regardless of the position of the switch.

Have you ever heard of this kind of problem? Do you have any ideas for places I can begin to troubleshoot? It's a funny kind of issue in that I'm still going to use the unit even if I can't bypass it, but it'd be great to have for quick A/B comparisons.
I would look for a bad solder joint on the 90˚ header and/or the switch on the switch PCB. The FET circuit needs to be grounded to put the filters in their off state. Sounds like that is not happening.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: JeffTD on October 29, 2018, 02:13:47 PM
I would look for a bad solder joint on the 90˚ header and/or the switch on the switch PCB. The FET circuit needs to be grounded to put the filters in their off state. Sounds like that is not happening.

Thanks Jeff! One other question - I could be overthinking this... upon further testing with some pink noise, the "In" button bypasses/enables the filters themselves, but doesn't bypass the 3 EQ bands controlled by the concentric pots. Is the "in" only supposed to toggle both filters on/off?
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on October 29, 2018, 04:41:29 PM
Thanks Jeff! One other question - I could be overthinking this... upon further testing with some pink noise, the "In" button bypasses/enables the filters themselves, but doesn't bypass the 3 EQ bands controlled by the concentric pots. Is the "in" only supposed to toggle both filters on/off?
No, "IN" removes the filters and the 3 EQ bands from being active.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: JeffTD on October 29, 2018, 07:33:18 PM
No, "IN" removes the filters and the 3 EQ bands from being active.

Interesting, I've got some digging to do then. I've just re-flowed all the solder points on the board (switches, resistor, capacitor, 90º bracket), and am getting the same results; "in" only bypasses the HPF and LPF.  I can't see any extra bridging between other points on the main board that could be causing a connection that should be toggled by the switch instead. Both filters toggle on/off individually, and I can toggle both of them off via the "In" switch, but not the EQ bands.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on October 29, 2018, 08:42:49 PM
Interesting, I've got some digging to do then. I've just re-flowed all the solder points on the board (switches, resistor, capacitor, 90º bracket), and am getting the same results; "in" only bypasses the HPF and LPF.  I can't see any extra bridging between other points on the main board that could be causing a connection that should be toggled by the switch instead. Both filters toggle on/off individually, and I can toggle both of them off via the "In" switch, but not the EQ bands.
Check the orientation of the 3 small package 1N914's. There are 2 on the main PCB and one on the mid PCB. Also the orientation of the 3 FETs. J111's IIRC.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jona on November 12, 2018, 03:26:44 PM
Hi,

i just finished 2 bt50 and both are working and  but both add a  good amount of hum to the signal..and when i press  the in/ bypass switch it produces a loud click... the hum is still there in bypass... i have two capi 511 vpr racks full of capi modules 312/vp26/vp28/vc528/LC53 and all have no problem with hum... what could be the problem? can you help ?

thank you,

jona
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: Barklay on November 15, 2018, 02:08:37 PM
Hello, Jeff and everyone here!

I'm building two of BT50's, one works fine, and second works on high and mid frequencies, but there is some troubles with LF.
For the frist time i’ve tried it - in 0db it's ok, signal flows, in all other gain boosts or cuts signal dissapears. i've tried to look at ground shrots, re-soldered. now in gain cuts signal still dissapears, and in gain boosts it is distorted and slightly boosted.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on November 16, 2018, 09:26:02 PM
Hi,

i just finished 2 bt50 and both are working and  but both add a  good amount of hum to the signal..and when i press  the in/ bypass switch it produces a loud click... the hum is still there in bypass... i have two capi 511 vpr racks full of capi modules 312/vp26/vp28/vc528/LC53 and all have no problem with hum... what could be the problem? can you help ?

thank you,

jona
Might be opamp related or cabling outside of the rack?
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on November 16, 2018, 09:28:14 PM
Hello, Jeff and everyone here!

I'm building two of BT50's, one works fine, and second works on high and mid frequencies, but there is some troubles with LF.
For the frist time i’ve tried it - in 0db it's ok, signal flows, in all other gain boosts or cuts signal dissapears. i've tried to look at ground shrots, re-soldered. now in gain cuts signal still dissapears, and in gain boosts it is distorted and slightly boosted.
Check continuity from each of the LF Grayhill wipers (the metal tabs that stick out of the switch body) to ground. You are looking for a short or very low Ω reading.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: Barklay on November 17, 2018, 12:15:56 PM
Check continuity from each of the LF Grayhill wipers (the metal tabs that stick out of the switch body) to ground. You are looking for a short or very low Ω reading.

Ok, i’ve checked. Three of 8 were about 30 ohms. As Jeff posted earlier to Jan, i’ve de-soldered them and slightly bended, then re-soldered. After all, it works correctly
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jona on November 18, 2018, 06:43:04 AM
Might be opamp related or cabling outside of the rack?
thanks  for the reply jeff..
i used red dots as for some of my other builds too.. i dont think it has to do with cabling.. i tried it in different slots and even in a different rack.. none of my other modules have this problem.do you have. any other  idea ? the strange thing is both bt50 have the exact same problem...
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: attisma on November 26, 2018, 11:34:50 PM
Hello Jeff,

I just built a pair of BT50's. I'm using known working gar2520's. My current issue is that when I run audio thru them, and with "IN" in either position, and all frequencies set to 0, I'm getting what sounds like a low cut filter.  If I boost/cut low LF, they seem to filter but I would expect the sound to be unchanged when positions are at 0.  Can you advise the best way to troubleshoot.

I've already spot checked and re-soldered my joints for good measure but to no avail.

Any help is appreciated.

Thanks
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: jsteiger on November 27, 2018, 07:34:27 PM
Hello Jeff,

I just built a pair of BT50's. I'm using known working gar2520's. My current issue is that when I run audio thru them, and with "IN" in either position, and all frequencies set to 0, I'm getting what sounds like a low cut filter.  If I boost/cut low LF, they seem to filter but I would expect the sound to be unchanged when positions are at 0.  Can you advise the best way to troubleshoot.

I've already spot checked and re-soldered my joints for good measure but to no avail.

Any help is appreciated.

Thanks
How are you testing them? What device is just before them? The BT50's input is unbalanced (like the vintage counterpart). Is it possible that whatever you are feeding them with does not like being unbalanced by shunting its XLR pin 3 signal to ground? Maybe try a quick test with a transformer output device before them.
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: attisma on November 28, 2018, 02:19:13 AM
How are you testing them? What device is just before them? The BT50's input is unbalanced (like the vintage counterpart). Is it possible that whatever you are feeding them with does not like being unbalanced by shunting its XLR pin 3 signal to ground? Maybe try a quick test with a transformer output device before them.

I was using a balanced cable. Problem solved!!

Thanks Jeff!!
Title: Bypass switch not working
Post by: Ngr on January 28, 2019, 10:03:20 AM
Hello Jeffrey,
I just built a BT-50. Everything is working fine except for the bypass switch. The eq is always on, no matter if the IN button is depressed or not. Where do I have to look at?
Thank you
Title: Re: Bypass switch not working
Post by: jsteiger on January 28, 2019, 10:13:02 AM
I just built a BT-50. Everything is working fine except for the bypass switch. The eq is always on, no matter if the IN button is depressed or not. Where do I have to look at?
I would look for a short/solder bridge on the bypass switch itself or the 6-pin header that connects the switch PCB to the main PCB.
Title: Re: Bypass switch not working
Post by: Ngr on January 28, 2019, 12:41:29 PM
I would look for a short/solder bridge on the bypass switch itself or the 6-pin header that connects the switch PCB to the main PCB.

No bridges, or shorts. I checked the switch pads and they appear to be all shorted within themselves when the IN button is pressed. When button is depressed only the first two pins ( looking at the board top side from left to right ) are shorted. On the 6 pin header there's a short between pin 1 and 3 when button is depressed, a short between 2 and 6 when it is pressed. Is that correct?
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: staylor200 on April 04, 2019, 05:31:58 PM
Hi, Jeff. Just completed a clean BT50 (with gar 1731's) and need some help. First power on and some of the 10ohm power dampening resistors started to smoke. I swapped in other 2520 opamps and no smoke. I checked the two gar 1731's and it looks like r14 & r15 on both 1731's slightly started to burn up.

thank you
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: Potato Cakes on April 04, 2019, 05:42:32 PM
Check to see if the 10R resistors are still reading 10 ohm. If not replace and then try again with the different op amps and see if there is still no smoke. If they are still measuring good and the unit is working fine with the different op amps then you have an issue with the gar1731's and that should be addressed on the that particular build thread.

Thanks!

Paul
Title: Re: [Build] CAPI BT50, 500 Series EQ (a la 550), Official Support Thread
Post by: staylor200 on April 04, 2019, 11:19:22 PM
Check to see if the 10R resistors are still reading 10 ohm. If not replace and then try again with the different op amps and see if there is still no smoke. If they are still measuring good and the unit is working fine with the different op amps then you have an issue with the gar1731's and that should be addressed on the that particular build thread.

Thanks!

Paul

Thank you, Paul. Forgot to mention BT50 works and sounds great with a gar2520 & rogue five in it.