GroupDIY

Project Specific Discussions => Dynamic Processors => Topic started by: Igor on February 27, 2011, 08:09:57 PM

Title: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on February 27, 2011, 08:09:57 PM
Hi guys, we carefully checked all kits and almost ready to send them.....

(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050756.jpg)

BTW, maybe, there will be some kits available again ;)

Meanwhile, please take a look at the documentation here:
http://twin-x.com/groupdiy/thumbnails.php?album=417

Update: last version docs, everything is here:
http://ij-audio.com/downloads/51XF76.zip

Download the files, take 10 min to meditate on all this, than,
after you catch the logic, take some time to read schems.

As an educational reading, schematic redrawn in the way it is easy to understand how 1176 works.

I tried to make this unit 1176'is much as possible, however, if I have a choice, will never use "original" 1176 amplifiers of any version.
Yes, OK, this kind of compression did many great music, and this sound wrote history.
Anyway, kill me, the 1176 amps are out of my taste after building of some clones, comparing with "original", etc....
I had to make it more versatile, and to have more options with sound color.

You have some really nice surprises here. This unit can run at +/-16V, as well as on both +/-16 and +/-24 rails of 51X,
try my cascode topology input stage amp, with API output amp and Ed Anderson's 11148 replica for 500 format,
and tell about sound; yep, lot of color, all you freaks will like it  :) ;) :D ;D ;D ;D ;D ;D ;D ;D ;D
My taste is my input amp, LL1524 and my own out amplifiers (with all DOA's are running on +/-24V), it is less colored,
but the color itself is way more "pedigree", well, leave my fubaru English, back to stuff!
;)

The next 2 posts will be reserved for assembly guide, FAQ, some howtos, and test procedure.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on February 27, 2011, 08:10:18 PM
/reserved for assembly guide/

Full assembly procedure will be posted, but please take a look, here are some very important bits.

Grayhill switches stoppers:

(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/V2_GRAYHILL_STOPERS.jpg)

Put them as shown than attach stickers over it.

Meter LED's:

To have a very neat look, we using flat top LED's. There is a little trick.

(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050776.jpg)

First, see where + and - goes,  (check twice, put LED on PCB and put a dot on led's pins with a marker), than cut.

(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050774.jpg)

Than, solder first and last LED's. They should be very close to PCB.

(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050777.jpg)

(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050779.jpg)

Than, put the rest of LED's at their holes at front panel:

(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050781.jpg)

Line them up and solder...

(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050789.jpg)

(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050795.jpg)

(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050791.jpg)

(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050796.jpg)


Another freaky but same easy moment is RATIO and SLAM.

First, put RATIO switch and catch it with 2 pins:

(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050769.jpg)

Than, CUT the pins which at the side of SLAM pushbutton at the level of PCB and solder:

(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050771.jpg)

Well, more coming soon. Prepare to see really neat and easy assembly pictures !

 :)  ;D :D ;) :) 8) 8) 8)

Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on February 27, 2011, 08:10:49 PM
51X-F76 test procedure.

Important.
1). When running on +/-16V, in 500 format, install jumpers JP1, JP2
and cut pins 17/18 of card edge connector.

2). When running at +/-16 and +/-24V, !DO NOT! install these jumpers,
they can cause damage to power supply.

3). After running many audio tests, the best sounding FET's here, IMHO, are 2n5457,
BUT the PCB was designed for BF245.
Stereo kits were supplied with matched within 0.5dB in gain reduction range 2N5457 FET's.
IF using 2n5457, they have pinout GSD instead of DSG like BF245.
They won't be damaged if installed wrong way, but compressor will not work properly.
The right way to install 2N5457 in sockets:
(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050937.jpg)
(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050936.jpg)


After PCB's stuffed and everything checked, every component in place-

http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050847.jpg

Step 1. Audio (sound path).

Do not install audio and gain reduction FETS (2N5457 or BF245, Q1 and Q10).
Do not connect RATIO/ATTACK/RELEASE board.

Current draw.
Do not install input/output amps and chips in sockets; check if no smoke and current draw;
check -10V at LM337 out.

On FP (10 pin, dual raw) connector on motherboard,
short pins 9 and 10 to switch relays from BYPASS state to COMP IN.
(PC jumper will work fine).

(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050921.jpg)

Install input/output amps. Check if current draw is less than 70mA each +/-16 and +/-24V.
If don't have lab power supply, measure voltage on R91, 92, 93, 94 resistors (10R),
it should be maximum 0.7V at any resistor.


Now, we can check the amplifiers.

Input amp.
Close input and output pots, and, if my version of input opamp is used,
put DC voltmeter between amp's out and ground adjust amplifier's output
for +0.3...1V with trimpot located on amplifier's PCB.

(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050927.jpg)

Note 1: let amp heat up 5-10 min.
Note 2: to get VERY tasty sound from this amp, connect 1...2k, 1/4W resistor between its out and gnd.

(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050928.jpg)

Scope shows here transformer's, FET's and amp's residue on hot signal, COMP=OFF.
(For those who knows what is real cool harmonic signature)))

http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050930.jpg

If "original" amp used at 24V power supply, check its output is in range +12V +/-10% ref. to gnd.

Output amp.
Check DC offset is in range few millivolts ref. gnd for DOA or is +12V +/-10% for "original" amp.
Same way as with input amp.

Let's check input/output pots, maximum gain +37db and distortion.
Feed -20dBV (0.1V RMS) to input of 51XF76, input pot=max, output pot=max,
with 2:1 input transformer or balanced line receiver, and 1:2 output transformer,
maximum gain should be 36...37dB (output shows +16...17dB).

Feed 1V RMS to input, put input/out pots somewhere in the middle, check the distortion is less than 0.02%.
Check max. undistorted output is +24db at least.

Let's adjust 0=+4dB on meter.
Put GR/OUT switch in OUT position;
Connect AC voltmeter to output, adjust input/output pots for 1.23VRMS output and turn MTR_OUT pot untill yellow led
(0db) lits on; than, turn it back a bit to let LED go OFF, again, slightly turn to lit the yellow led ON.
This way, we can have more precision in multiple channels (the led meter is not linear thing, but we want
to catch the same threshold to light on the leds).


Step 2. Compression (sidechain, GR metering, BIAS, etc).

Connect RATIO/ATTACK/RELEASE board (and remove jumper between pins 9 - 10).
SLAM is OFF, LINK=OFF, RATIO at pos. COMP OFF, ATTACK=MIN, RELEASE=MAX.
Feed -20db to input, INPUT=MAX, adjust output for 0db.
Put FET's in sockets (Q1, Q10; mind, silkscreen is for BF245, 2N5457 are reversed).

Adjust BIAS for -1db.
If building stereo pair, adjust second chan. for -1dB BIAS as well.

Than, LINK=ON. Both should remain in same level. If no, adjust a little bit BIAS of one of channels.
+/-0.2db is fine.

BTW, don't forget to connect wire at back side of PCB if use LINK.

(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050938.jpg)
(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050942.jpg)
(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050939.jpg)

Back to Channel 1.
Distortion cancellation circuit.
Adjust DIST (R16) to get minimum of distortion on sinus wave.
Or, misadjust a bit for color, but mind, too much will not sound good.
0.01....0.04% THD is fine.
This step requires audio analyzer or PC soundcard.

GR meter.
!AA
Remove input signal, put METER to GR, and adjust 0 with 0GR trimpot.
Yellow LED should light ON. Light ON the +1 RED LED, than, turn the pot back, just to leave yellow LED.
Repeat this step 1-2 times.

Apply input signal 0db, and put INPUT approx. at 14.00 pos.

Set RATIO to 4:1 and check the output.
Find input potentiometer's position which has output change
between COMP.OFF and 4 ratio setting of 10dB gain reduction.
Adjust GR_SCALE trimpot just to turn ON -10 db LED, turn it back,
and find the threshold of -10 LED.
!BB
Repeat from !AA to !BB till you get nice meter reading
with and without 10db of gain reduction.

Apply audio and listen.

Have a fun!

Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: culteousness1 on March 06, 2011, 11:11:04 AM
Hey all.

I am almost done with the control board. Now I found that R76 seems to be mislabeled on the board.
Printing says 470R but BOM says 470K. I guess the BOM is right. Igor? Help!

Cheers,
Carsten
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on March 06, 2011, 03:27:22 PM
R76, according to schematic, is resistor at attack switch assembly, in parallel with 22nf; it is 470 Ohm.
Am I missed something:
Quote
1   470R        1/4W METAL FILM 1%   R76
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: culteousness1 on March 07, 2011, 05:39:15 AM
Ok. Thanks for clearing that up.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: zmgwg on March 15, 2011, 07:30:32 AM
Igor, will a EA-2623 work on output with this?
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: edanderson on March 15, 2011, 02:07:25 PM
electrically, it "should" work, but the 2623-1 is a smaller transformer than the b11148 or 2503, so mechanically it might be a little flimsy -- only one of the screw holes will line up with the PCB.  you could make a little riser for it to sit on, out of PCB stock or plexi, that fits the cutout on igor's PCB.

ed
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: reanimatorstudio on April 25, 2011, 08:05:36 PM
Quote
The next 2 posts will be reserved for assembly guide, FAQ, some howtos, and test procedure.
good idea!!
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: culteousness1 on May 04, 2011, 12:29:11 PM
Hi team,

I am almost done with this thingy. I only need to figure out what pot values are suitable for the I/O amps.
I am planning to use the provided IC amps and gar2520s.

Could someone please give me a hint?

Cheers,
Carsten
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: briomusic on May 08, 2011, 07:50:35 AM
Hi all,
I bought Igor's pcbs for this project, but not the kit.
I would like to start with a 'poor man's' version, so thats the lorlin/pot front and the IC amps I guess?
I am a bit confused - do I need to buy additional DOA's or do the little extra PCBs for the various in and out amps already constitute those DOA's?
The front panel in all the photos is for the grayhill version, and i need to make my own front for the lorlin/pot version, correct?
thanks
briomusic

P.S. I am also confused about what blocks go together and which are alternatives. Using the picture of a 4 course menu (with coffee and cognac  ;)) is the following correct:
INPUT TRANSFORMER
or
BALANCED LINE RECEIVER
--------------------------------------------
ORIGINAL INPUT AMP
or
IJ INPUT AMP
or
GENERIC DOA
--------------------------------------------
MAIN BOARD inc. METER
--------------------------------------------
1RU FRONT (LORLIN&POTS)
or
3 GRAYHILL FRONT
or
1 GRAYHILL AND 2 POTS FRONT
--------------------------------------------
ORIGINAL OUT AMP
or
IC OUTPUT AMP
or
GENERIC DOA
--------------------------------------------
OPTIONAL OUTPUT TRANSFORMER
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: AudioGimmer on May 08, 2011, 04:44:03 PM
I don't know if I can answer all your questions re lorlins and pots, but if you want the lowest cost options then you are right:

Thats balanced line receiver [ no input tranny ] with pot

IC input amp JFET
IC output amp

The choices are then determined by power supply:

ONLY +/- 16 [ 500 series rack] use AD711 etc for input amp and 5534 for output
511 rack with additional +/- 24 use OPA 604

You can only use the orig amps if you have the +/- 24 as well as +/- 16

Hope that helps a little

The Gimmer
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: briomusic on May 08, 2011, 05:53:36 PM
Thanks, this does clear things up a bit for me.
I do have a 51X rack and plan to check out the original amps at some later point.
So the line receiver replaces the input tranny, but I will need the output tranny in any case?

as for the controls, I think the cheapest 5xx style option is 1 grayhill (ratio) and two pots. the lorlin options is for rackmounting, it seems.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: culteousness1 on May 16, 2011, 12:13:00 PM
Hi all,

my question remains. So, please, give me a hint!

Cheers,
Carsten
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: AudioGimmer on May 27, 2011, 07:30:21 AM
Hi Igor, the F76s are coming together. Couple of questions:

1.) The output pot, what value is good here? I've used the grayhill switches so I have two pots over as part of the kit. Either of those any good? Otherwise a quality Bournes maybe, but suggested value?
2.) The link wire for stereo on the bottom of the board, is that needed for the stereo link to work, or just for calibration purposes?

I've gone with hairball's input tranny and  T-pad attenuator [not cheap, but I wanted the tranny input ] and Lundhal 1524 on the output.

I'll have to drill the bracket and faceplate for the attenuator, but you can't make an omelette without cracking eggs!!!

The Gimmer
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: AudioGimmer on June 07, 2011, 06:46:47 AM
Ok progress reports, how are people getting on with their F76s?

I'm about done with soldering number 1, got number 2 to start, then testing, adjustments and final assembly.
(http://farm3.static.flickr.com/2604/5803907628_19efe8c155.jpg)

These things are crammed! how Igor fitted it all together is impressive:
(http://farm6.static.flickr.com/5301/5803909172_e848eb6f71.jpg)

Some observations.
If you are using T pad input w tranny, you need to drill out the aluminium bracket to accommodate the attenuator [ approx 10mm in my case] Need to find a way to pack out the rear of the bushing so only the nut is on top of the bracket, otherwise the faceplate won't sit flush.

I also needed to very gently open up the holes in the faceplate for the Grayhills and output pot. [I did it with a 6.5mm drill bit just held in my fingers]

Igor's input amp is TINY My optician won't be pleased next time I go see her.

Igor's tip for lining up the LEDs worked a treat, very neat

I bought some extra op amp pins so I can try some different options, like 2520 for output

I just have one question: I haven't put a zobel network in for my output tranny, do I need one for the LL1524?

Anyone else?

The Gimmer
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on July 25, 2011, 03:22:00 PM
Quote
Hi Igor, the F76s are coming together. Couple of questions:

1.) The output pot, what value is good here? I've used the grayhill switches so I have two pots over as part of the kit. Either of those any good? Otherwise a quality Bournes maybe, but suggested value?

The pots supplied with the kit are 10k log. Citec is high quality, I use them for years.

They can be used as input with balanced line receiver (THAT1246/INA137) and as output.

To get more smooth curve, take into account I don't need more than -40 db at neither in or out pot,
I connect the bottom (by schematic) pin of these potentiometers to ground via 100R resistor.

Quote
2.) The link wire for stereo on the bottom of the board, is that needed for the
 stereo link to work, or just for calibration purposes?

Rev.1.3 has this connection (trace) at PCB; at rev.1.4 I fixed some mech. issues, and this link has gone somehow.

To make a pair working in stereo link, you NEED this wire.
Quote
I've gone with hairball's input tranny and  T-pad attenuator [not cheap, but I wanted the tranny input ] and Lundhal 1524 on the output.

More distortion (iron); sounds nice as well.
Possible to use Elma 14mm, with line, grey, 6mm edit: 6.3mm shaft knob for Hairball T-PAD.

Quote
I'll have to drill the bracket and faceplate for the attenuator, but you can't make an omelette without cracking eggs!!!

The drill in bracket is for Citec pots, diam. 6.3mm. For 600 Ohm attenuator, you need to make hole bigger (9.5 or 10mm).

(http://i251.photobucket.com/albums/gg291/diy33609/drill.jpg)

Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on July 25, 2011, 03:31:14 PM
Quote
Some observations.
If you are using T pad input w tranny, you need to drill out the aluminium bracket to accommodate the attenuator [ approx 10mm in my case] Need to find a way to pack out the rear of the bushing so only the nut is on top of the bracket, otherwise the faceplate won't sit flush.

Yep)

Quote
I also needed to very gently open up the holes in the faceplate for the Grayhills and output pot. [I did it with a 6.5mm drill bit just held in my fingers]

Yep)
Quote
Igor's input amp is TINY My optician won't be pleased next time I go see her.

I have -7.5 on both eyes) But hey, this amp DOES sounds, aye?

Quote
Igor's tip for lining up the LEDs worked a treat, very neat

Thanx)

Quote
I bought some extra op amp pins so I can try some different options, like 2520 for output

That's funny. I tried about 15 different amp options, all have bit different sound.

Quote
I just have one question: I haven't put a zobel network in for my output tranny, do I need one for the LL1524?

O! That's important. Zobel network for LL1524.

Datasheet says nothing. However, I had some of these trannies used on SEEM AUDIO equipment;
they used 150R in series with 10nF (Wima, 100V, MKS-3) capacitor, without load (probably, the trafo was loaded at another stage).

For me, it is bit over-cut;
I used 1k...2k 1/2W resistor as load; 150R (1/4W) and (4n7...8n2) poly, 50...100V capacitor as Zobel.

Who finished the build? Have some time, at least this week, post questions now.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on July 25, 2011, 03:35:18 PM
Quote
I am almost done with this thingy. I only need to figure out what pot values are suitable for the I/O amps.
I am planning to use the provided IC amps and gar2520s.

10k, log

IMPORTANT

For use with input line receiver, DO NOT INSTALL R5' = 270R!!!!

For use with input IC amp, INSTALL R11' = 560k.

This resistor IS installed on "my" or "original" input amp PCB.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on July 25, 2011, 03:38:07 PM
Quote
So the line receiver replaces the input tranny, but I will need the output tranny in any case?

100% right.

Quote
as for the controls, I think the cheapest 5xx style option is 1 grayhill (ratio) and two pots.

Right. But, getting 5meg lin pot is not easy, so...
the difference in price between attack/release pots/Grayhill switches is approx. USD12-15.
Quote
the lorlin options is for rackmounting, it seems.

Yep)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on July 25, 2011, 03:42:58 PM
Quote
The choices are then determined by power supply:

ONLY +/- 16 [ 500 series rack] use AD711 etc for input amp and 5534 for output
511 rack with additional +/- 24 use OPA 604

That's right. IC options for both input/output amps will work with OPA604 on +/-24V ONLY.
AD711: can be replaced with low offset, low distortion, fast JFET opamp.
Again, OPA604 can be used on both +/-16 and +/-24V.
IMHO, it is really good sounding IC opamp.

Quote
You can only use the orig amps if you have the +/- 24 as well as +/- 16

Mmmmmm.... I never tried them at +/-16V and vote for using "original" amps on +/-24V ONLY.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Peterson Goodwyn on August 05, 2011, 10:58:23 PM
It looks as though there are not enough holes for the diodes on the input amp board (D2&D3). I see only 3 holes for 4 leads. What am I missing?

This kit is spectacular, btw
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on August 06, 2011, 02:29:21 PM
Quote
It looks as though there are not enough holes for the diodes on the input amp board (D2&D3).
I see only 3 holes for 4 leads. What am I missing?

Please, check the picture.
These diodes should be placed close to output transistor (thermal compensation).
Avoid shorting between diodes and transistor.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Peterson Goodwyn on August 07, 2011, 10:54:22 AM
Got it! Thanks
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: nielsk on October 13, 2011, 06:29:53 PM
Are these available?
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: bruce0 on October 26, 2011, 12:51:11 AM
Well I am finally getting around to building these, and I have a couple of questions.

The schematic in the FEELER (the only schematic I could find) says there is an attenuator option, I can't find it.

The circuit board specifies a Cinemag option, what is the cinemag transformer recommended or specified. (I would prefer transformer balanced input, So I want to choose that option).

What attenuator is appropriate, does it fit?

There are a lot of little op-amp boards hear, but it does not appear that there is a lot of op amp sockets to put them in.  Which should I build.

Is there any sort of guide beyond the photographs....

Is there an official schematic?

I need to order the input trafo and attenuator, and then I am off to the races.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on October 26, 2011, 02:03:41 AM
Bruce, i'd probably build it just like the VP2x's, meaning shortest component(usually diodes) to tallest (transformers/switches).
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: gzpz on October 26, 2011, 08:10:59 PM
Hi
Are these 51x-f76 kits available?
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: bruce0 on October 27, 2011, 02:08:25 PM
Thanks mulletchuck, I will build it short to tall.... But I want to put the attenuator and input transformer option in and I don't have information on the type of input trafo needed.

Not sure if you are familiar with this kit but it comes with a variety (4 or 5) op amp cards, and I am sure that I am not supposed to populate them all... I found a note in the materials that says that the kit includes enough to build 2 of them for the two amps, but which two should I use is not clear... it could be a preference thing if so I will just pick two at random?

There is no room to mount an attenuator that I can see.  I assume it is a 600 ohm T attenuator, but does it replace the make up gain control, or do I fit it somewhere else?

Anyone build one of these?



Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on October 27, 2011, 03:34:16 PM
Bruce0, i have my two kits that I haven't started building yet.   Igor does say that you can skype with him if you need help.   I've also chatted with him over Facebook chat.   But i haven't started my build yet either.   I know chunger also has a pair he is either building, or waiting to build, or they came pre-assembled. 
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: edanderson on October 27, 2011, 04:39:14 PM

Update: last version docs, everything is here:
http://ij-audio.com/downloads/51XF76.zip

Download the files, take 10 min to meditate on all this, than,
after you catch the logic, take some time to read schems.


Quote from: mb_bom.txt

INPUT TRANSFORMER OPTION:
1   CINEMAG,  0-12 CLONE,  OR OEP_A262

----OR

INPUT BALANCED LINE RECEIVER OPTION
1   THAT1246   OR INA137 OR SSM2143, DIP-8      IC2
------------------------

OUTPUT TRANSFORMER:

1   LL1524(1517), API OUTPUT, ETC               T1 

C100, R101, R84: OUTPUT TRANSFORMER'S LOAD AND ZOBEL NETWORK;
DEPENDS ON TRANSFORMER TYPE



seems like you can use the original O-12 input and B11148 output from hairball.  line inputs from cinemag and jensen have the same pinout but are cleaner / different character.  same thing with output -- plenty of choices, all up to how you want it to sound.

ed
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: bruce0 on October 27, 2011, 06:17:37 PM
Edit:

Ed, do you mean that the pinouts on ALL of the Cinemag's are compatible?  My problem is I can't figure out which one might do the trick.  The "CMLI-4x150D" appears to be able to do the stepdown, but I can't find a PC mount version, the "CMLI-600/600C" (doesn't appear to do the step down) maybe a "CMMI-2CPC" wired backwards?  Any ideas here?  I am going to contact cinemag and see if they can enlighten me.

bb

Ed, Thanks so much.  I actually was just perusing that material (but for my addled brain it wasn't 10 minutes, it was all day, and included a lot of research on the OEP, Cinemag, HAIRBALL and MNATS sites)

I understand that you created the C-3837-1 on hairball? The  C-3837-1 on hairball seems to have a 500:200 impedance ratio, but it says it is a reproduction of the 0-12.  Is it usable both ways? Do you know what input level it can handle at 30HZ (or any frequency for that matter) within some THD range?

The original 0-12 UTC was 200:500, but I don't know how it was used in the 1176.  I did find a schematic on the MNATS site that shows the C-3837-1 wired with the step down RATIO. and shows how to wire the attenuator, but I cannot find the same information in the schematic for the F76, which omits any attenuator. 

Assuming that I have this right the the possible part numbers are:

Transformer part numbers APPARENTLY usable with the F76 (I have not tried these, but since it took all day to figure it out, this might help someone trying to do this project).

A262A2E or A262A2C (C is with Mu metal can) from OEP
C-3837-1 or CM-3837-1 from Anderson Altran Hairball
Cinemag transformer (says it is usable, but I have not found a part number (they don't appear to have a low impedance PCB mount 1:2 ratio transformer)

I did find a note in the build thread that says if I do use an attenuator I need to drill out the backplate, but I don't yet see where it goes.  The space is so tight in this module that I cannot imagine where I would add one of those nice big hairball T attenuators, but gosh it's an option, and i want to do it.

The specs for all of these transformers sometimes give pin numbers but not the pin orientation on the can.

I can't find specs on anything but the UTC.  The OEP looks REALLY easy to overload (I found a reference to 1mw at 30HZ with less than 1% THD and 100mw at 300HZ), so maybe I will just do the C-3837-1 and hope the specs are up the O-12, which was easy to overload too it seems but not as bad as the OEP.

In the materials is possible to look at the PCB in my hand, and compare it with the PCB layout in each subdirectory, and there are some text comments in those directories.

It appears that Igor has 2 IC amps - On PCB's included

One for input, which is just a chip on a 2520 board.
One for output and the output has a current boost stage of BC140 BC139.  Sort of like the JLM one but biased differently.

There is an "Input Amp" of his own design.

There is a clone of the original AMP circuits for input and output, and there are comments elsewhere in the board suggesting that he thinks the other choices are better than the original from a sound point of view.

I did not find an Attenuator card, there is a directory to change from grayhill to potentiometer on the attack and release controls.

I think I will do more research on the Cinemag site, maybe I can find a transformer there, they spec the max input levels, and I want this to be "forgiving" when I chain it in.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: spase on October 27, 2011, 11:27:09 PM
did you still have that full kits for this one?
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: gzpz on October 28, 2011, 07:48:24 PM
Like he said...

I just looked at the schematic and it looks like a great and versatile design.  The drawing makes it easier to understand the 1176 circuit.  If these AREN'T available, they SHOULD be!
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on October 31, 2011, 10:43:02 PM
bruce0, how are you making out with your build?   i just started mine (2 units) and i'm not understanding how i would connect the In/Out attenuators from hairball.  are they just wired, like in Jeff's kits, assuming you purchase the little PCB that goes with it?  If that's the case, then it looks like 2 are required for the in/out positions.

What's the extra ratio board for which doesn't get populated with all the resistors?   the switches at the bottom of it don't even line up with the faceplate, so is that extra board for if you wanted to build your own faceplate and not use Switches for attack/release?  This project could definitely benefit from some "during" build photos.   

The cable needs to be built with the male and female sides pointing in opposite directions.   Female side faces down, towards the motherboard, and the male side points up, as it sits on the underside of the ratio board.


I just wanted to point out to anyone who recently bought this kit.   DO NOT throw out the unlabeled parts of the PCB that are in this picture:   

(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/OP_TTRAF.jpg)

They're spacers for when you mount your transformer.    I didn't know this, and they are somewhere in a New York State garbage dump or recycling facility because they weren't labeled or explained.   Now they are explained lolol
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: gemini86 on October 31, 2011, 11:45:49 PM
uh oh...somebody must have thrown away the instructions... :D
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: bruce0 on November 01, 2011, 12:31:22 AM
Mulletchuck:

Thank you for the tip on the spacers, I would have thought they were junk too.

I have not started the build, because I have not collected all the parts yet.  I still need the input transformer, I have been mailing back and forth with the fellow at Cinemag, to see what they have that would work.  I will post the part number they give me when I find out.

If anyone knows what cinemag fits, please post the part number, rather than having me torture the folks over at Cinemag as we reverse engineer the pinouts.

I am glad someone else is building this too, because maybe we can help each other and leave some breadcrumbs.  I will take pictures as I assemble mine, and try to post some sort of information on it.

Regarding Attenuators

I am also confused on this, there is no data at all in the materials that I could find.  There is one comment earlier in this thread that refers to needing to modify a bracket, I think this might be because maybe the attenuator replaces the input pot and the hole is the wrong size, or the nut is too thick.  If you look at the schematic it appears that this pot is the output of the THAT 1246.  But I haven't got a clue as to what the little x's signify on the schematic (I did decode a guess that FRATT means from attenuator, and TOATT means to attenuator and att_61 and att_62 must be the attenuator, but what the attenuator circuit is is sort of greek because I don't know what kind of attenuator would have 2 connections to ground (dual T's)... and I wouldn't think that a balanced attenuator would be grounded at all.... maybe this is some sort of code that I (very new to this) have never seen on a schematic.  I am GUESSING that somehow the notion is to put an attenuator before the transformer, install it with wires, in the same hole that the input pot goes in (when I say Pot I mean whatever came with the kit for that input hole on the front panel, I don't know if it is a pot or a grayhill) although the line is balanced so I would think the attenuator circuit would be an H or a U, neither of which are grounded.

That's a guess.... Yep)

Regarding Ratio Card

Not lining up with holes on front panels, apparently there is some notion that this kit can be built not as a 500 module but in a rack.  At least that is what is apparent from Igor's concise reply to this post http://www.groupdiy.com/index.php?topic=43338.msg565065#msg565065 (http://www.groupdiy.com/index.php?topic=43338.msg565065#msg565065)

This is further confirmed by the fact that the card comes with a 1U_top card that sort of duplicates the function of the other card.  It also comes with a little card that has 2 xlr connectors and a 15pin card edge connector (like a 1 unit API rack.  I assume this is so you can wire up the card in a 1 U rack.  I will post a list of pictures of what comes in the kit, and update the info as I get through the build.

Thanks for your post, it motivated me to begin doing an inventory of the kit.

My next post is a picture of  picture of the segmented card as it arrives in the kit, labeled as I currently understand it.

Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: gemini86 on November 01, 2011, 01:49:29 AM
Sorry, no. I was mostly being a smart-ass. My apologies. Generally, I try not to throw away "extra" parts until I have a finished product in front of me.

Sorry again for my non-constructive post.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: bruce0 on November 01, 2011, 02:31:23 AM
Here is what is in the kit, it comes well organized into separate named bags.
Not included are optional input transformers and input attenuator, and output transformer



(http://i1221.photobucket.com/albums/dd463/Bruce0/F76%20Build%20Photos/labeledPCBSegmentsTop.jpg)
(http://i1221.photobucket.com/albums/dd463/Bruce0/F76%20Build%20Photos/PCBSegmentsBottom.jpg)



(http://i1221.photobucket.com/albums/dd463/Bruce0/F76%20Build%20Photos/AmpsBag1.jpg)
(http://i1221.photobucket.com/albums/dd463/Bruce0/F76%20Build%20Photos/AmpsBag2.jpg)
(http://i1221.photobucket.com/albums/dd463/Bruce0/F76%20Build%20Photos/AmpsBag3.jpg)
(http://i1221.photobucket.com/albums/dd463/Bruce0/F76%20Build%20Photos/AmpsBag4.jpg)


(http://i1221.photobucket.com/albums/dd463/Bruce0/F76%20Build%20Photos/AttackReleaseBag1.jpg)
(http://i1221.photobucket.com/albums/dd463/Bruce0/F76%20Build%20Photos/AttackReleaseBag2.jpg)
(http://i1221.photobucket.com/albums/dd463/Bruce0/F76%20Build%20Photos/AttackReleaseBag3.jpg)


(http://i1221.photobucket.com/albums/dd463/Bruce0/F76%20Build%20Photos/MotherboardBag1.jpg)
(http://i1221.photobucket.com/albums/dd463/Bruce0/F76%20Build%20Photos/MotherboardBag2.jpg)
(http://i1221.photobucket.com/albums/dd463/Bruce0/F76%20Build%20Photos/MotherboardBag3.jpg)
(http://i1221.photobucket.com/albums/dd463/Bruce0/F76%20Build%20Photos/MotherboardBag4.jpg)

Front panel front and back

(http://i1221.photobucket.com/albums/dd463/Bruce0/F76%20Build%20Photos/FrontPanelTop.jpg)
(http://i1221.photobucket.com/albums/dd463/Bruce0/F76%20Build%20Photos/FrontPanelBottom.jpg)

Knobs

(http://i1221.photobucket.com/albums/dd463/Bruce0/F76%20Build%20Photos/Knobs.jpg)

Lbracket

(http://i1221.photobucket.com/albums/dd463/Bruce0/F76%20Build%20Photos/LBracket.jpg)

matched fets

(http://i1221.photobucket.com/albums/dd463/Bruce0/F76%20Build%20Photos/MatchedFETS.jpg)

Milmax (or equiv) amp pins
(http://i1221.photobucket.com/albums/dd463/Bruce0/F76%20Build%20Photos/MillMaxorequiv.jpg)

Rack mount card? 15/30 pin API to xlr (18volts?)

(http://i1221.photobucket.com/albums/dd463/Bruce0/F76%20Build%20Photos/RackMountCard.jpg)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on November 01, 2011, 03:48:49 AM
ok, for the trimmers for the Motherboard:

121 T / W101 = 100R
X103 / 0104G = 10K
127 T / X 202 = 2K
the 100K trimmer was a different color than the others and said "100K" on it.   the other 3 were blue and did not indicate their value.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: bruce0 on November 02, 2011, 12:24:05 AM
More on attenuator.

I have been looking for balanced attenuator information.  I don't really have the experience to be sure, but it seems that if one wired either side of the balanced line to ground through a resistor or worse a variable resistor, unless those were perfectly matched it would interfere with the CMRR of the transformer.  A variable pot would never be perfectly matched, and even resistors would not be.

in the attached file you can see the "attenuator option" schematic.  I don't understand it, and I am beginning to believe that it is incomplete, but it does show the attenuator as grounded.

(this would be a good time for someone to show up with a clear schematic of the trafo attenuator option.  If there is anyone in the Levant with such a thing <grin>)

Now here is the original URIE Schematic from Waltzing bear sitehttp://www.waltzingbear.com/Schematics/Urei/Urei_1176LN_series_F_page_1.htm (http://www.waltzingbear.com/Schematics/Urei/Urei_1176LN_series_F_page_1.htm), which shows some attenuator wiring, which is not grounded.  It seems to be implemented with a simple single pot (I dont understand what the RIA pot is), and would not interfere with CMRR as far as I can see, although it would not maintain impedance through the range of attenuation. 

It might be possible to wire a U attenuator, using one of those 600 ohm attenuators, although I don't know what the taper's are and whether they would work to make a U, usually they are wired as a T.  I found a balanced attenuator wiring diagram in the Audio Cyclopedia, I could put up if you want, but I am not sure it is the right thing.

This thread talks about using the T attenuator to make a balanced attenuator, by basically putting the wings of the T in one side (ex. Hot side) and putting the common ground on the other side (cold).  Neither is grounded so the result I think (please correct me if I am wrong) is that the impedance with respect to ground is not effected, and thus CMRR is maintained for the transformer.

http://www.groupdiy.com/index.php?topic=11964.0 (http://www.groupdiy.com/index.php?topic=11964.0)

Here is a thread that speaks to the CMRR issue, if I understand it correctly

http://www.groupdiy.com/index.php?topic=2192 (http://www.groupdiy.com/index.php?topic=2192)

And another one...

http://www.groupdiy.com/index.php?topic=14888.msg190942#msg190942 (http://www.groupdiy.com/index.php?topic=14888.msg190942#msg190942)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on November 07, 2011, 02:14:12 AM
Please stare into schematic, top right:

TOATT+, TOATT-, FRATT+, FRATT-, ATT_G1, ATT_G2.

These pads are marked same way at bottom of PCB.

CMRR talks: all revisions of 1176 used unbalanced T-pad 600 Ohm attenuator before input trafo as
tones of other oldygoody equipment. It works.

Input trafo:

http://hairballaudio.com/shop/product_info.php?cPath=24&products_id=35

Same source for attenuator. You'll need to find a knob for 6.35mm shaft.

R'5, top right on schemo: (already was mentioned, but in case of whatever):
Use R'5 270 Ohm with inp traf and don't use it with bal. line receiver.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on November 07, 2011, 02:17:33 AM
Well I am finally getting around to building these, and I have a couple of questions.

The schematic in the FEELER (the only schematic I could find) says there is an attenuator option, I can't find it.

The circuit board specifies a Cinemag option, what is the cinemag transformer recommended or specified. (I would prefer transformer balanced input, So I want to choose that option).

What attenuator is appropriate, does it fit?

There are a lot of little op-amp boards hear, but it does not appear that there is a lot of op amp sockets to put them in.  Which should I build.

Is there any sort of guide beyond the photographs....

Is there an official schematic?

I need to order the input trafo and attenuator, and then I am off to the races.

http://ij-audio.com/downloads/51XF76.zip

audio_SCHEM.PNG
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on November 07, 2011, 02:24:54 AM
ok, for the trimmers for the Motherboard:

121 T / W101 = 100R
X103 / 0104G = 10K
127 T / X 202 = 2K
the 100K trimmer was a different color than the others and said "100K" on it.   the other 3 were blue and did not indicate their value.

Ops) They do, but not in normal human language)
104 = 100k
202 = 2k etc

Thanx for this picture, Bruce.

http://i1221.photobucket.com/albums/dd463/Bruce0/F76%20Build%20Photos/labeledPCBSegmentsTop.jpg

1U_top (bottom left) is for dual, 1RU build. NOT USED for 500 (51X).
The card with 18 pin connector and xlr's is for testing the unit, we had lot of spares and thrown them in first batch of kits.
For testing, I recommend RACKIT!
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: bruce0 on November 07, 2011, 04:56:40 AM
Igor:

Thanks... This helps.

To clarify:

*ATTENUATOR*

The attenuator is installed in the same location as the input pot, and is hand wired to the back of the board, to pads for that purpose.

The attenuator is a 600 ohm T attenuator, installed ungrounded (and thus  with the transformer it forms a balanced line attenuator, like the original URIE was).  The ground ATT_G1 and ATT_G2 on the schematic are also marked on the bottom of the circuit board, and are for grounding shields.  This is because the wiring for the attenuator runs the full length of the board and needs shielding, the shields to be connected at the back of the board.  The shields should only be grounded on one end (the back).

And yes, the attenuator will be lovely like that, and will not interfere with CMR, because it is not grounded but just bridges and attenuates the transformer. The ATT_G1 and ATT_G2 are shield grounding pads (not marked as such on the sketch, but they ground the shields on the sketch below).

*TRANSFORMER*

The ONLY transformers that are known to fit are the two from OEP and Ed Anderson, there is no CINEMAG option, despite the "Cinemag" on the soldermask. 

Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on November 07, 2011, 06:03:38 AM
CINEMAG????
Ops)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: bruce0 on November 07, 2011, 06:23:37 AM
I have attached a picture of the Cinemag .... Same text appears when I stare into the Schematic ;)

Hah!  that's funny...

Maybe it is just a typo!

I have been bothering the guy over at Cinemag, because the board shows that his trafo fits... And I couldn't figure what to order... Now that you are asking "Cinemag?" I begin to see why he is confused!!!

bb
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: edanderson on November 07, 2011, 09:22:13 AM
there is a cinemag input transformer that fits in the same footprint as the c-3837-1 and has a similar ratio: the CMMI-2PCA.  it is not listed on their website, and i've never actually seen one, but i do remember that david geren mentioned it being a new design in 2007.  you can contact cinemag to see if they will make it and how exactly to hook it up.

ed
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: 3nity on November 07, 2011, 09:32:56 AM
Footprint of the CMMI-2 is different than the one on the pcb.
Thanks
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on November 07, 2011, 10:07:28 AM
Got it. The package was taken from Cinemag without updating. Sorry guys, my typo.
In any case, I tried Hairball trannies+atten's. It works.
I prefer the sound with balanced line receiver, but mind, I have very bad taste :)
Many of people I know will like more trannie's sound and they using relatively cheap monitors,
but in clean environment with good acoustics, the things works different (for me, again).
All is matter of taste.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: edanderson on November 07, 2011, 10:38:42 AM
Footprint of the CMMI-2 is different than the one on the pcb.

footprint of the CMMI-2C is different, it is a much larger, rectangular transformer.  but the PCA versions of all of cinemag's transformers are in the same small round can/footprint as igor used -- it is a standard EE2425 bobbin.  again, i've never seen the actual CMMI-2PCA or datasheet, but it should be possible to make it work.  contact cinemag for further details.

ed
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on November 07, 2011, 10:46:12 AM
Yep. The iron which was used in many trannies. My personal favorite type(grade) is:
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: bruce0 on November 07, 2011, 12:31:27 PM
Igor and Ed:

Thanks so much, that is exactly what I needed, you guys are awesome... and Ed, the big square line trafo's etc wrong pinout... and trying the CMMI-2 that is what I sort of figured was the case, but having very little experience with cinemag, I appreciate the insight. I thought it might fit, but I didn't see the datasheet either...

I use everything on the road, it moves.  Iron is heavy, that's bad... but I have to say that I love transformers for making sure I don't have hum and noise when I set up.  It is always really clean that way.

I was however tempted to try the 1206 from THAT on something... But it is not completely plug compatible with the 1246, and bought a couple to try it out, but I think I will go with transformers for this build... so I can tell the artist... "just like old timey!"

Thanks again... I am ready to go... I will just chose and go.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on November 07, 2011, 01:39:52 PM
Igor, could you post some pics for how the pots for Input/Output get connected to the "TOATT+ TOATT- FRATT+ FRATT-" pads?    the motherboard also has INP_LVL and OP_LVL pads i'm curious about.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: bruce0 on November 07, 2011, 07:06:47 PM
Mulletchuck:

Attached is a picture, I think this is how it works.

Hairball has a little PCB for $1.75 that wires the attenuators you purchase there correctly (they have TOATT labeled Input), if it won't fit, it will at least help wire it.

http://hairballaudio.com/shop/product_info.php?cPath=29&products_id=54 (http://hairballaudio.com/shop/product_info.php?cPath=29&products_id=54)

So does Classic API

http://classicapi.com/catalog/product_info.php?cPath=48&products_id=255

Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on November 07, 2011, 08:18:04 PM
I was referring to the non-TPad version.   regular old Potentiometers.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on November 09, 2011, 03:34:48 AM
Non-T-Pad version: FORGET about T-Pad and all these to_att, from_att pads.

Connect 10k log potentiometers (they are supplied with kit) to INP_LVL and OP_LVL

1=CW
2=WIPER
3=CCW

No scanner here, sorry

To get more precision range of 40db on potentiometers, put 100R resistor between pad 3 (ground) and CCW.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on November 16, 2011, 12:31:44 AM
I discovered tonight that all of Jeff's 2520 DOA variants fit because they all use 1mm pins.   So, have fun!   be sure to check voltages first so you don't fry a DOA
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: gasmanian on November 16, 2011, 02:17:17 PM
Any full kits available? I searched the site but no news  :D
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: chunger on November 16, 2011, 04:26:54 PM
OK. . . a little late to the party, but Igor indicated that I could post in the official support thread, so hopefully this won't be a complete waste of bandwidth.

(http://studio939.zenfolio.com/img/s11/v27/p637583722-4.jpg)

Now, we will see if this monkey can figure out how to put together an IJ research kit.  I'm sure hilarity will ensue as much of the schematics look Greek to me, but doesn't stop me from squinting at them for a couple of days to try and get some orientation.

This is very different than the starter projects I tried before that were very defined and to be honest more geared towards production and sales as kits.  If I understand correctly, Igor's main focus is manufacturing small runs of completed units for his clients but carries a side benefit of DIY availability.  So, not as much hand-holding on the support side, and a different type of documentation to study.  Luckily, full kits were made available, so much of the component selection (which would be difficult and time-consuming for newbie) has been done.  Still, this seems to me like a big-boy project with lots of choices.

Build options:

I figure Igor has had the most experimentation with various possible configurations, so I will attempt to build to his preferred configuration and hear the unit that way . . . which I understand deviates from the classic 1176 sound but in his verbiage is more flexible and sounds "more pedigree".  Everyone has different tastes and this kit has options, but I figure I'll try it this way first.  But, I do have a couple of questions about his configuration.  Here is how I plan to build.  Please let me know if this is in line with Igor's preferred configuration.

1. Balanced Line Receiver

2.  IJ input amp

3.  3 Grayhill front (as supplied in kit)

4.  input/output pots (as supplied in kit)

5.  ???? output amp ????  Is this s +-24V amp?  Igor indicates he uses "his own" output amp, but I do not see an IJ one supplied in kit.  So, as indicated in docs, I can build one of the kit options. . . which one would Igor prefer from the kit?  I also have a pair of APP2520E amps that can run 24V.

6.  LL1524 output transformer (sourced through Igor's friend salvaged)

Ultimately, I would like to try all of the included amp options, but I assume I will have to buy a few more small components to build out all of the amps.

OK. . . a few general questions that I hope I will get some answers on, but for now, I'm going to saw apart the PCB's and clean them up.  I used a hacksaw blade, a wire cutter, and a file to get these separated.

(http://studio939.zenfolio.com/img/s11/v32/p587088541-4.jpg)

(http://studio939.zenfolio.com/img/s11/v34/p1027047205-4.jpg)

(http://studio939.zenfolio.com/img/s11/v31/p542883096-4.jpg)

and, pretty PCB's ready to go.

(http://studio939.zenfolio.com/img/s11/v34/p712163465-4.jpg)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on November 16, 2011, 04:51:07 PM
Just want to comment on the GR_SCALE trimmer's orientation vs the 0GR trimmer's orientation. 

this picture shows igor orienting them the same way.   but the silk screen on the PCB (v1.4) shows them facing opposite directions:

(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050937.jpg)

(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/MOM_V2.jpg)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: zayance on November 16, 2011, 04:53:24 PM
iirc i think reading that with the kits he provided some Transistors, that had pins reversed so that's what you see in his picture, check first page on the support thread or the files about the build.....

EDIT: Reply#2
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on November 16, 2011, 07:40:22 PM
I built up Igor's Input amp today for the kit.  My order for building was just like the Gar2520s

1.  place the pins in the sockets on the main PCB.  stick the DOA boards on top of the pins and solder.
2.  the little ceramic capacitors first (C1, C2, C3)
3.  R5 comes next
4.  the two BD139s are next.  Be careful about orientation.  for the BD139s supplied with my kit, they were not beveled so, i had to test them to find out which pin was the emitter.   For me, the silk screen on the BD139s ended up facing C1 and C3.
5.  D2 and D3 come next.   Note the way igor combined them in this post:  http://www.groupdiy.com/index.php?topic=43338.msg567412#msg567412
6.  T1, T2, T3 are next.
7.  R8, R1, R4, R2 and R3 in that order.
8.  The trimmer R7 is next. 
9.  R6 and R9 come next.
10.  D1, the Zener diode is last.

a fairly painless build, although small.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on November 17, 2011, 02:09:53 AM
Can anyone tell me what to order for the Q1/Q10 sockets on the main PCB?     the little 3-pin sockets for easily swapping out those transistors.   
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: zayance on November 17, 2011, 03:48:24 AM
Can anyone tell me what to order for the Q1/Q10 sockets on the main PCB?     the little 3-pin sockets for easily swapping out those transistors.   

You need this, or if you have nothing else to order, just gently dismantle a IC socket, be carefull because one or the other
option are tricky to break, because you can loose the pin while doing so, better always cut one pin more and take
the last one out after...


http://www2.mouser.com/ProductDetail/Mill-Max/800-10-064-10-002000/?qs=sGAEpiMZZMs%2fSh%2fkjph1trRw3Iqu89Lvlk1mjsAI7Bw%3d
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: chunger on November 17, 2011, 08:25:35 AM
A little more progress on my f76 build. . . I heard rumor from a few people that there were some mechanical assembly difficulties with the kit, so I decided next, I would try to assemble the major components to discover what those difficulties are and figure out a way to shift the tolerances so the build will be as polished-looking as I can manage.  I thought this might be important before I started populating the PCB's so I do not accidentally install a mis-aligned component that is difficult to remove and adjust.

First, I located the main PCB mounting hardware.

(http://studio939.zenfolio.com/img/s11/v35/p94685931-4.jpg)

And proceed to temporarily mount the main PCB.

(http://studio939.zenfolio.com/img/s11/v32/p355834183-4.jpg)

(http://studio939.zenfolio.com/img/s11/v35/p96677933-4.jpg)

(http://studio939.zenfolio.com/img/s11/v33/p301254899-4.jpg)

(http://studio939.zenfolio.com/img/s11/v36/p293793600-4.jpg)

Next, I located my input and output pots along with their nuts.

(http://studio939.zenfolio.com/img/s11/v28/p484473827-4.jpg)

And, discover that they will not mount flush to the L-bracket without slight modification.

(http://studio939.zenfolio.com/img/s11/v35/p8746091-4.jpg)

so, I modify.

(http://studio939.zenfolio.com/img/s11/v27/p31803881-4.jpg)

Next, I discover the pots will not fit into the faceplate. . .

(http://studio939.zenfolio.com/img/s11/v34/p4644233-4.jpg)

So, I use a 1/4" drill bit and open up the holes slightly.  I ran my drill backwards to get a smoother cut and try not to damage the nice faceplate.

(http://studio939.zenfolio.com/img/s11/v37/p452549159-4.jpg)

no problem now.

(http://studio939.zenfolio.com/img/s11/v35/p343427181-4.jpg)

(http://studio939.zenfolio.com/img/s11/v30/p442108971-4.jpg)

(http://studio939.zenfolio.com/img/s11/v35/p150033561-4.jpg)

Next, I locate my grayhill switches

(http://studio939.zenfolio.com/img/s11/v36/p135062774-4.jpg)

I worried for a moment that I would confuse the 2 types of switches and then realized that they have different mounting tabs. . . there is no way to install them in the incorrect locations  ;D

(http://studio939.zenfolio.com/img/s11/v34/p526042149-4.jpg)

But, unfortunately, they also do not fit on the faceplate. . .

(http://studio939.zenfolio.com/img/s11/v28/p203920152-4.jpg)

So, a bit more drilling for the grayhill switches.

(http://studio939.zenfolio.com/img/s11/v36/p421083503-4.jpg)

At this point, I take a step back and decide that I should align the main PCB components before moving up to the secondary PCB and the grayhill switches, so I put the grayhills aside and concentrate on the main PCB components.

Next, I install LED's as clearly described in this thread by Igor.

(http://studio939.zenfolio.com/img/s11/v31/p157719798-4.jpg)

(http://studio939.zenfolio.com/img/s11/v29/p499448393-4.jpg)

(http://studio939.zenfolio.com/img/s11/v29/p225500415-4.jpg)

(http://studio939.zenfolio.com/img/s11/v34/p114136824-4.jpg)

I used a clamp to help me position the end LED's for soldering.

(http://studio939.zenfolio.com/img/s11/v30/p499484166-4.jpg)

(http://studio939.zenfolio.com/img/s11/v32/p305810698-4.jpg)

(http://studio939.zenfolio.com/img/s11/v27/p16767645-4.jpg)

(http://studio939.zenfolio.com/img/s11/v34/p215525386-4.jpg)

and, LED's installed.

(http://studio939.zenfolio.com/img/s11/v28/p124391722-4.jpg)

Next, I install my metering GR/output switch making sure to ONLY solder 1 pin.

(http://studio939.zenfolio.com/img/s11/v36/p482826078-4.jpg)

Then, I re-assemble to see how things are lining up.

(http://studio939.zenfolio.com/img/s11/v33/p207708107-4.jpg)

And, they are lining up poorly.

(http://studio939.zenfolio.com/img/s11/v31/p36777157-4.jpg)

It seems the LED's are pushing the main PCB upwards a bit creating a bend, and causing the switch to move upward.  The LED's are all soldered in and I do not foresee them moving easily, so I decide to modify the switch to fit better.

(http://studio939.zenfolio.com/img/s11/v33/p79998626-4.jpg)

I figure I should try to compensate and make an adjustment so the switch is not installed under strain.  I remove the switch (luckily, I only soldered one lug) and file the front mounting tabs.

(http://studio939.zenfolio.com/img/s11/v27/p54048014-4.jpg)

now the switch will mount in a compensated position.

(http://studio939.zenfolio.com/img/s11/v31/p321123961-4.jpg)

I re-mount soldering again, only one lug to verify.

(http://studio939.zenfolio.com/img/s11/v33/p406719961-4.jpg)

And, my alignment is now reasonable.

(http://studio939.zenfolio.com/img/s11/v29/p256595250-4.jpg)

I install the external button to confirm

(http://studio939.zenfolio.com/img/s11/v34/p287103817-4.jpg)

And then, when I am satisfied that the switch position is good to go, I solder the 3 accessible lugs in place.

(http://studio939.zenfolio.com/img/s11/v35/p39146212-4.jpg)

Then, I disassemble and solder the remaining lugs.

(http://studio939.zenfolio.com/img/s11/v27/p50582962-4.jpg)

Here I am for now. . . slow, but steady gets the job done right I hope. . . next, I will align the grayhills on the upper PCB.

(http://studio939.zenfolio.com/img/s11/v36/p438920479-4.jpg)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: AudioGimmer on November 17, 2011, 10:14:18 AM
Hey Chunger

I'm just checking, but you do know the nuts on the pots go on the aluminium bracket and so are hidden by the nice face plate right?  ;)
That's why there is a recess on the back of the faceplate...

look:(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/51xf76_assembly/P1050913.jpg)


Good luck with it

The Gimmer
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: chunger on November 17, 2011, 12:51:55 PM
Awesome. . . .no, I did not.  That's why there are "redundant" alignment/securing screws for the faceplate :)  Cool stuff.  I do not think the build has been adversely effected yet with the exception of a few scratches that will be covered by the knobs.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on November 17, 2011, 11:56:29 PM
finished one of mine!   Not sure if I got the meter calibrated correctly but who gives a sh*t, check out this audio clip!!!

this is just an Apple drum loop.   Wait for the SLAM mode at the end!

http://www.zshare.net/download/96271568919bf8bd/
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: AudioGimmer on November 18, 2011, 03:14:21 AM
Igor.

Almost done [finally] with my 2 F76s

Question about R11'

Is this used with all input amps? I am planing to use your cascode amp. Is it also required with simple IC input amp [ AD7111 or OPA 604] and also 'original' version

Thanks

The Gimmer
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: chunger on November 21, 2011, 05:07:08 AM
some more progress tonight, and a bit of frustrations with this project. . . at this point in physical build, I wanted to move upward onto the chassis and place the control components of the attack/release/ratio board.  When I examined the board, one resistor would prove difficult to solder after the grayhill switches were installed, so I needed to go to this baggie and find R79 (270K).

(http://studio939.zenfolio.com/img/s11/v27/p640351932-4.jpg)

(http://studio939.zenfolio.com/img/s11/v35/p682484593-4.jpg)

After installing R79, I went ahead and installed the release and attack switches soldering only 1 lug for easy shifting or removal so I could verify physical alignment prior to soldering more.

(http://studio939.zenfolio.com/img/s11/v30/p663912341-4.jpg)

(http://studio939.zenfolio.com/img/s11/v33/p554061871-4.jpg)

per the instructions, the ratio grayhill switch needs to be trimmed on the 2 outer legs to allow the slam button to be installed.

(http://studio939.zenfolio.com/img/s11/v28/p575007090-4.jpg)

(http://studio939.zenfolio.com/img/s11/v34/p636704127-4.jpg)

(http://studio939.zenfolio.com/img/s11/v33/p932036121-4.jpg)

(http://studio939.zenfolio.com/img/s11/v28/p556819182-4.jpg)

And those 2 legs can now be soldered in pretty much flush to the PCB.

(http://studio939.zenfolio.com/img/s11/v33/p1071458226-4.jpg)

Verifying alignment of grahill switches attack, release, and ratio.  Looks good. so far.

(http://studio939.zenfolio.com/img/s11/v36/p1000010916-4.jpg)

The release switch along with the input/output pots will have to have their shafts cut at some point.

(http://studio939.zenfolio.com/img/s11/v33/p1057581437-4.jpg)

Verify the grayhill switches are flush to the PCB. . .

(http://studio939.zenfolio.com/img/s11/v37/p710031447-4.jpg)

. . . and I solder in 1 more lug on each switch to secure the back side flush to the PCB.

(http://studio939.zenfolio.com/img/s11/v35/p575743270-4.jpg)

Alignment is good still.

(http://studio939.zenfolio.com/img/s11/v35/p984132183-4.jpg)

Next I pull the switches for this board.

(http://studio939.zenfolio.com/img/s11/v30/p1067803951-4.jpg)

And position them on the chassis to see where I am in terms of alignment.

(http://studio939.zenfolio.com/img/s11/v30/p610744174-4.jpg)

Pretty good on the bypass, link, and HPF switches, but the slam switch is off a bit.

(http://studio939.zenfolio.com/img/s11/v36/p636770013-4.jpg)

So, i file a bit on the front standoffs. . .

(http://studio939.zenfolio.com/img/s11/v37/p544937511-4.jpg)

And, it looks much better here.

(http://studio939.zenfolio.com/img/s11/v28/p806755546-4.jpg)

. . . so I solder from the back side.

(http://studio939.zenfolio.com/img/s11/v29/p593258842-4.jpg)

Then, flip and solder the remaining lugs.

(http://studio939.zenfolio.com/img/s11/v29/p392645684-4.jpg)

Next I solder all of the accessible lugs (including grayhills) with the switches, faceplate, and chassis assembled.

(http://studio939.zenfolio.com/img/s11/v29/p448269757-4.jpg)

disassemble, flip and solder the remaining lugs.

(http://studio939.zenfolio.com/img/s11/v35/p240812275-4.jpg)

switches are all aligned and installed.

(http://studio939.zenfolio.com/img/s11/v27/p469104561-4.jpg)

(http://studio939.zenfolio.com/img/s11/v31/p21527118-4.jpg)

(http://studio939.zenfolio.com/img/s11/v29/p523066949-4.jpg)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: chunger on November 21, 2011, 04:54:00 PM
OK. . . a few questions in this post.  I hope Igor can chime in and help a newbie out.

Next, I decided to stuff the attack/ratio/release board because I had it out, and was already digging through the resistors.  I discovered that there were several different brands/colors/types of resistors, and further, there were value substitutions in the kit.  For a seasoned electronics tech, this should not be a problem, but for a new builder like myself, this is problematic.

(http://studio939.zenfolio.com/img/s11/v34/p403529918-4.jpg)

After stuffing the board, I did not have confidence enough to solder the resistors in without verifying substitutions are correct and proper.  Also, I am attempting to build a stereo pair, so I wanted to confirm that my 2nd kit which due to packing mistake on the initial batch, arrived quite a few months later with different components and substitutions was not dramatically different.  I tried my best to shuffle resistors around between the 2 kits and match the values but have questions about some of the changes and differences.  To Igor's credit, a few of the substituted value resistors in the kit had enough spares included to cover another PCB.  I guess this problem was somewhat anticipated, but I still do not quite understand why so many substitutions.  I need to find out if I will have to order some more parts to get the values closer, or if this is all ok, and I can solder these parts in.

(http://studio939.zenfolio.com/img/s11/v31/p190395815-4.jpg)

R25 (68K) on the ratio switch . . . one kit has 67.8K and the other kit has 68.8K.  Will this offset the 2 units drastically?

R74 and R75 (47K) on the detector. . . the closest resistors I found were 2x 47.5K and 2x 46.5K . I put 47.5K into the first kit and 46.5K in the second kit because the schematic looked like these resistors may need to balance within the circuit.  Will these alterations in the detector portion make sonic differences between the 2 units?

RA9 (15K) one kit has 14.69K and the other 15.05K

R42 (470R) was substituted 464R in both kits.  . . any problems with this?

R76 (470R) was substituted 462R and  464R . . . any problems here?

R79 (270K) the kit supplied these as 274K, but I am missing one.  Kit cannot be completed without.
(http://studio939.zenfolio.com/img/s11/v37/p120121375-4.jpg)

Should I re-order any of these resistors to find closer matches?  or is it ok to solder?  I will wait until confirmation before sticking these components together :)

This is a bit frustrating for me chasing values around the documentation instead of moving forward with assembly.

(http://studio939.zenfolio.com/img/s11/v35/p216356921-4.jpg)

Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: earl on November 21, 2011, 09:23:38 PM
Igor will you be offering kits for the 1176 again?
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: AudioGimmer on November 22, 2011, 02:47:16 AM
Hey Chunger.

I had the same thing, but in my case I had a lot of resistors from previous projects so I was mostly covered where I wanted to have closer values between 2 kits.

I'm no expert but I would say remember this:
These are 1% resistors but the original 1176s would have been built with 5 or 10% tolerances, so don't sweat it too much. For example your RA9, one is 14.69K and the other 15.05K. The 14.69 is only just outside 1% the other well inside.
OTOH I agree that when building a stereo pair it's good to match channels as closely as possible, (but then e.g. for attack and release and side chain circuit  you'd also want to match caps values closely too.)
Resistors are cheap and you could always just buy the values that you think are too far off.

Hopefully Igor will chime in here. I still have a question regarding R11'


Question about R11'

Is this used with all input amps? I am planing to use your cascode amp. Is it also required with simple IC input amp [ AD7111 or OPA 604] and also 'original' version

Igor?


The Gimmer
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: chunger on November 22, 2011, 11:00:11 PM
Ok. . . waiting still on replies about resistor quiestions and waiting to see if I should put in an order to get the pair to match a bit better.

I thought an input amp build might cheer me up a bit. . . (correction from previous). . . please note, parts are only provided for 1 input amp and 1 output amp option.

I figure I'll start with the Igor's input amp.

To decided to start by putting the Mil Max sockets in.  Your methods may be different and better, but this way got the job done.

(http://studio939.zenfolio.com/img/s11/v30/p300419462-4.jpg)

I was hoping with the little ridges on the sides that there would be some sort of friction fit on these to hold them in place for soldering because I was afraid to get solder on the inside of the sockets and have them seize up, but these are very small and very loose, so my plan of attack changed to soldering these in from the bottom and hoping gravity would keep the solder from flowing up into the sockets.

(http://studio939.zenfolio.com/img/s11/v37/p92109700-4.jpg)

I had to re-heat and press down on the sockets to make them seat properly, but it seems everything worked out ok.

(http://studio939.zenfolio.com/img/s11/v32/p60636152-4.jpg)

(http://studio939.zenfolio.com/img/s11/v36/p8216326-4.jpg)

Then, I inserted the milmax pins so I could have them aligned nice and straight when I solder them to the amp PCB.

(http://studio939.zenfolio.com/img/s11/v32/p352081437-4.jpg)

AMPS-BAG3 contains the components for Igor's input amp. . . I hope.

(http://studio939.zenfolio.com/img/s11/v36/p532071389-4.jpg)

The holes for C1 and C3 were very close to the milmax pins, so I thought I should insert them prior to soldering the pins just in case I got solder overflow and ended up plugging up the holes and making a mess.

(http://studio939.zenfolio.com/img/s11/v28/p519549203-4.jpg)

And, this is how I solder on the pins.

(http://studio939.zenfolio.com/img/s11/v35/p243974049-4.jpg)

I did have to clean up the solder joints for the capacitors from the bottom, and I probably didn't have to install them at the same time with the pins, but better safe than sorry, eh?

(http://studio939.zenfolio.com/img/s11/v35/p295657644-4.jpg)

And, we're populating.

(http://studio939.zenfolio.com/img/s11/v36/p163509580-4.jpg)

(http://studio939.zenfolio.com/img/s11/v34/p469403630-4.jpg)

A little piece of heat shrink tubing over Q2 helps to keep D2 and D3 from shorting against the metal part.

(http://studio939.zenfolio.com/img/s11/v37/p183612587-4.jpg)

D2 and D3 are marked like this:
(http://studio939.zenfolio.com/img/s11/v37/p527446841-3.jpg)

(http://studio939.zenfolio.com/img/s11/v35/p154267866-4.jpg)

(http://studio939.zenfolio.com/img/s11/v34/p324208607-4.jpg)

(http://studio939.zenfolio.com/img/s11/v33/p30729045-4.jpg)

(http://studio939.zenfolio.com/img/s11/v35/p101842917-4.jpg)

(http://studio939.zenfolio.com/img/s11/v30/p158606340-4.jpg)

(http://studio939.zenfolio.com/img/s11/v33/p219543567-4.jpg)

(http://studio939.zenfolio.com/img/s11/v34/p45074195-4.jpg)

D1 has the following markings:
(http://studio939.zenfolio.com/img/s11/v30/p358896757-3.jpg)

(http://studio939.zenfolio.com/img/s11/v28/p230097320-3.jpg)

(http://studio939.zenfolio.com/img/s11/v28/p41651933-3.jpg)

(http://studio939.zenfolio.com/img/s11/v34/p225982379-4.jpg)

And that completes this input amp.  There is a modification that Igor suggests for "tasty sound" that I may try on this amp as well, so I should put that resistor on my shopping list, but for now. . .

(http://studio939.zenfolio.com/img/s11/v34/p178775160-4.jpg)

(http://studio939.zenfolio.com/img/s11/v36/p301078389-4.jpg)

Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: chunger on November 23, 2011, 03:57:50 AM
Found another missing part in my kits. . . in AMPS-BAG2:

 2N5087 937 found possible replacements at Mouser. . . 2N5087TA, 2N5087TF, and 2N5087BU. . . checking to see if any of these will work.

Note to self:

Original output amp (AMPS-BAG2) "steals" the following components from (AMPS-BAG1. . . the IC output amp bag):

1x 10p ceramic capacitor (10J)
1x .1u ceramic capacitor (104)
1x BD140 transistor
1x BD139 transistor

if building all amp options, these components along with extra Mil-max pins will have to be purchased.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: chunger on November 23, 2011, 07:54:19 AM
On to output amp. . . I chose to build the "original" amp. . . largely because I do not own a vintage or clone 1176 and wanted to hear what the original was all about. . . distortion and all.  My gut feeling is the IC output amp may give better sonics, but I have a pair of APP2520E that can run on +-24V.  In the original application (VP312DI), preferred the GAR2520, so I can use these in the f76 builds if I like them.  My plan is to order parts to build all amps in this kit and hear them.  Contacted Igor about his Albatross op-amp that he prefers as well.  Options. . . no point having them if you can't hear them for yourself  ::)

For this step, I refer to the following files in the documentation:

orig_outamp.txt  (component list)
orig_outamp.png  (schematic)
orig_outamp.gif  (PCB top view graphic)

First, I use the main PCB to align the Milmax pins and solder in this position.

(http://studio939.zenfolio.com/img/s11/v35/p413287209-4.jpg)

(http://studio939.zenfolio.com/img/s11/v30/p289703671-4.jpg)

Most of the components for the "orginal" output amp are found in AMPS-BAG2.

(http://studio939.zenfolio.com/img/s11/v28/p479875032-4.jpg)

And, I begin populating the board:

(http://studio939.zenfolio.com/img/s11/v30/p201238773-4.jpg)

Note: in the next step, CBP23 (.1uf marked 104) is taken from AMPS-BAG1.

(http://studio939.zenfolio.com/img/s11/v36/p229779134-4.jpg)

Note: in the next step, Q8 (BD139) and Q9 (BD140) are taken from AMPS-BAG1.

(http://studio939.zenfolio.com/img/s11/v30/p243833586-4.jpg)

(http://studio939.zenfolio.com/img/s11/v35/p441607123-4.jpg)

(http://studio939.zenfolio.com/img/s11/v37/p428471118-4.jpg)

(http://studio939.zenfolio.com/img/s11/v37/p459634179-4.jpg)

Note: in the next step, C12 (10p marked "10J") is taken from AMPS-BAG1.

(http://studio939.zenfolio.com/img/s11/v28/p425525220-4.jpg)

(http://studio939.zenfolio.com/img/s11/v29/p413392673-4.jpg)

And, the "original" output amp option is complete.

(http://studio939.zenfolio.com/img/s11/v35/p202532284-4.jpg)

(http://studio939.zenfolio.com/img/s11/v33/p6964729-4.jpg)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: chunger on November 26, 2011, 07:16:28 AM
Tried to make some more progress on the build, but have a quick question before I move forward and post erroneous photos.  I can't seem to be getting fast replies from Igor. . .

2   200PF         5 OR 7.5MM <>      C3, C4

These are the silver/clear weird-looking capacitors.  The 2 that I have in one of the kits are marked "220J":

(http://studio939.zenfolio.com/img/s11/v34/p660435656-4.jpg)

this indicates to me 22pF which would be quite far off from 220pF which would have been a substitute value?  I believe this capacitor may be incorrect and do not want to proceed with posting step-wise build progression photos until I can confirm.

(http://studio939.zenfolio.com/img/s11/v34/p1003810999-4.jpg)



Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on November 26, 2011, 11:00:07 PM
yes, those are the 200pF.   Think of the designation as:   2, 2 zeroes.  and then J means PF, i guess.    Wima kinda uses the same format.    xy, where x is the Most Significant digit and then y is the number of zeroes.

If you look at igor's assembly pics, you'll see those same capacitors used in that location.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on November 30, 2011, 09:27:51 PM
does anyone have any ideas as to what would cause the meter to go backwards?    I finally got my 2nd unit fully assembled and the first unit's meter started behaving backwards after I started tweaking the bias dial.     I am confused...

edit:

Nevermind, got it figured out.   if you crank the GR_SCALE too much, the meter will run backwards for whatever reason.    Both units are dialed in now!!!

Could someone explain what the Link switch does?    Does it cause both units to run off of the average of the two channels?   
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on December 01, 2011, 04:38:55 AM
I found this little site which really helped for converting between Vrms and dbU and other units.   

http://www.sengpielaudio.com/calculator-db-volt.htm
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: zmgwg on December 10, 2011, 06:19:55 PM
what sockets did you use for opamps? the ones from CAPI are slightly too big [pins are ok]
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: AudioGimmer on December 10, 2011, 06:59:01 PM
Hi.

According to the BOM, from Farnell the P/N

PINS/SOCKETS FOR DOA:
149318, 149319, 1336236, 1336237

I finished mine up this weekend, just need to fire em up, calibrate and test 'em. FINALLY!

The Gimmer
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on December 10, 2011, 08:15:19 PM
@audioGlimmer, if you don't care about the visuals, aside from checking the voltage on Igor's Input Amp, the other calibration steps are for the meter display only.  So, if you don't care about that, you can go ahead and run audio thru it!!
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: AudioGimmer on December 11, 2011, 04:45:46 PM
Finished my 2 F76s. The results so far:

Unit 1 perfect.
Adjusted Igors input amp, and all other voltages checked out fine.
Calibration procedure is very clear and worked perfectly. Used external signal generator and hardware VUs for bias, GR and led 0VU calibration, v easy and used s/w scope for distortion adjust. [Actually you could do that almost by ear with 1KHz tone and good monitors, listen for 1st harmonics minimum level]

Unit 2 issues:
Hmm. Voltages all check out fine, adjusted input amp all good. However, the LED meters are not working. On GR the topmost LED is lit [as it was on first unit so probably fine but needs to be adjusted to display 0 gr correctly] but on level the LEDs are not working properly. Occasionally they flicker up and down, otherwise stuck on red LED  only. Its not the TL074 or the LM3916 I checked the chips in the working unit. Out of time today so I'll check the board over during the week. maybe a cold joint in the LED section. The unit was passing audio I think so I suspect its just the metering section.

The unit that is working sounds fantastic. Thanks Igor, excellent work. My lunch box is now sadly full  :-\
2x API 512C
2 F76s
Mixbuzz 500
Fantastic portable recording treats!

The Gimmer
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on December 11, 2011, 06:55:03 PM
I had the same issue on one of mine.   I just had to keep messing around with the GR_SCALE trimmer before it worked right.   On mine, if I had that trimmer cranked too far in one direction, the LED meter would literally display in reverse. 
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: chunger on December 12, 2011, 03:54:45 AM
I'm in a bit of a holding pattern for my build right now. . . for the zobel network in the LL1524 output transformer, I'm using 4n7 WIMA capacitor and 460R resistor.  As I understanding it, higher value resistor and lower value capacitor will induce less treble roll-off.  Igor concurred that these were the values he utilized on his builds.  I will have to wait for parts to arrive from Mouser, but for now. . .

back to the attack/release/ratio board.  Capacitors will be found in this baggie.

(http://studio939.zenfolio.com/img/s11/v35/p549835851-4.jpg)

(http://studio939.zenfolio.com/img/s11/v30/p144527575-4.jpg)

(http://studio939.zenfolio.com/img/s11/v37/p242860219-4.jpg)

Next, I assemble the interconnect cable for the attack/release/ratio board.

(http://studio939.zenfolio.com/img/s11/v30/p183358606-4.jpg)

The trick here is to always be aware of pin 1's position and to make sure the red-marked cable corresponds to pin 1.  The PCB is marked for pin 1.

(http://studio939.zenfolio.com/img/s11/v37/p404351310-4.jpg)

(http://studio939.zenfolio.com/img/s11/v27/p479711058-4.jpg)

I used a C-clamp to seat the press-fit cable ends.

(http://studio939.zenfolio.com/img/s11/v37/p262789196-4.jpg)

(http://studio939.zenfolio.com/img/s11/v35/p139278171-4.jpg)

(http://studio939.zenfolio.com/img/s11/v36/p354175874-4.jpg)

(http://studio939.zenfolio.com/img/s11/v36/p31127514-4.jpg)

After double checking the proper cable positioning and pins are in the correct locations via multimeter, solder the cable to the attack/release/ratio PCB.

(http://studio939.zenfolio.com/img/s11/v34/p483503279-4.jpg)

(http://studio939.zenfolio.com/img/s11/v33/p506224633-4.jpg)

Next, I locate the Grayhill switch stop pins and retaining stickers.  Watch out. .   . they're tiny.  Now is no time to let things roll off the table.

(http://studio939.zenfolio.com/img/s11/v29/p481479477-4.jpg)

Per the documentation on the front end of this thread, insert the pins into position.

(http://studio939.zenfolio.com/img/s11/v34/p390854465-4.jpg)

It should look something like this when all the pins are in.

(http://studio939.zenfolio.com/img/s11/v37/p67437617-4.jpg)

And, place the retainer stickers to set the pins.

(http://studio939.zenfolio.com/img/s11/v34/p323196800-4.jpg)

Attack/release/ratio board is now complete.

(http://studio939.zenfolio.com/img/s11/v35/p210931424-4.jpg)

Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: chunger on December 12, 2011, 04:10:14 AM
Next, I decided to do the main PCB resistors.  Note, because I'm building with the IC line receiver, I do not install R5' 270R.

(http://studio939.zenfolio.com/img/s11/v34/p499975478-4.jpg)

(http://studio939.zenfolio.com/img/s11/v33/p97190260-4.jpg)

And the the main PCB capacitors

(http://studio939.zenfolio.com/img/s11/v33/p367462855-4.jpg)

(http://studio939.zenfolio.com/img/s11/v34/p1003810999-4.jpg)

(http://studio939.zenfolio.com/img/s11/v36/p393211983-4.jpg)

Next up were the IC sockets, trimmer pots, and relays.

(http://studio939.zenfolio.com/img/s11/v35/p160270577-4.jpg)

(http://studio939.zenfolio.com/img/s11/v35/p397902333-4.jpg)

And, more capacitors. . . watch out for polarity on these guys.

(http://studio939.zenfolio.com/img/s11/v37/p515664787-4.jpg)

This cap did not have any polarity indication except for the long leg (+).

(http://studio939.zenfolio.com/img/s11/v36/p400687254-4.jpg)

The + side of these little guys are indicated by markings. . .

(http://studio939.zenfolio.com/img/s11/v34/p65218455-4.jpg)

Make sure they correspond to the markings on the PCB when installing.

(http://studio939.zenfolio.com/img/s11/v34/p13173392-4.jpg)

And, capacitors are in.

(http://studio939.zenfolio.com/img/s11/v37/p264845539-4.jpg)

(http://studio939.zenfolio.com/img/s11/v29/p546319267-4.jpg)

(http://studio939.zenfolio.com/img/s11/v35/p735957544-4.jpg)

I purchased a pair of salvaged LL1524 output transformers from Igor's friend, and they were shipped with my kits. . . they probably didn't know which ones were going in for photo shoot  ;D  There are a few dings on them, but hopefully they have been tested electronically and passed muster.

(http://studio939.zenfolio.com/img/s11/v34/p771826160-4.jpg)

I don't think it's completely necessary, but I put a couple strips of electrical tape here.

(http://studio939.zenfolio.com/img/s11/v35/p699393846-4.jpg)

And soldered the transformer in.

(http://studio939.zenfolio.com/img/s11/v29/p1058982323-4.jpg)

(http://studio939.zenfolio.com/img/s11/v30/p830025784-4.jpg)

And, that's where the project stands. . . just one resistor and one capacitor left for the zobel network, and I can do final assembly and calibration.  I borrowed a scope and a signal generator from a friend, so I'll have to learn how to use those funny tools in short order.

Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on December 12, 2011, 02:36:11 PM
lookin' good.   Be aware when you wire your Input/Output pots that they're reversed on the pcb compared to the faceplate. 
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: AudioGimmer on December 12, 2011, 06:18:04 PM

I just wanted to point out to anyone who recently bought this kit.   DO NOT throw out the unlabeled parts of the PCB that are in this picture:   

(http://i251.photobucket.com/albums/gg291/diy33609/51F_X76/OP_TTRAF.jpg)

They're spacers for when you mount your transformer.    I didn't know this, and they are somewhere in a New York State garbage dump or recycling facility because they weren't labeled or explained.

Thought I'd just quote this to remind others who might be following this thread. No need to insulate the trannys if you remember to space them off the board with these...

The Gimmer
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: chunger on December 12, 2011, 08:23:36 PM
One of my kits had the spacers (complete PCB), and one of them did not (pre-cut PCB).  I figured I'd build to the "worst case" scenario.  The tape solution is redundant as the metal casing does not come close to contacting anything. . . furthermore, the factory put a plastic film over the transformer covering critical areas.  This arrangement should be solid for the long haul.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on December 12, 2011, 08:41:40 PM
you don't need those spaces if you use the LL1524s.  cuz those spacers would prevent the pins from touching the PCB.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: AudioGimmer on December 14, 2011, 06:08:26 PM
UPDATE

Unit 2 fixed, calibrated and working perfectly.
The issue with the meters turned out to be a broken switch. I took the boards apart, had a real good look for any cold solder joints or other problems. [I knew the chips were good as I had swopped them in a good unit and they worked fine.] I worked through the meter section following the schematic. All components were correct, resistor values, caps etc and I checked the diodes were OK too. Hmm Surely couldnt be the switch could it?
Yup. Only intermittent connectivity in either position. Looked closely and switch looked slightly undone. Gave it a little prod and BAM:
(http://farm8.staticflickr.com/7009/6512933801_12f03d3f30.jpg)

So, need to fit a replacement switch.
I didn't have the correct size one to hand, and since I wanted to finish up calibrating the unit and actually USE it, I cludged an off board temp solution with some thin wires thru the front panel and an old DPDT switch I found lying about.

You can see the wiring and switch here:
(http://farm8.staticflickr.com/7031/6512932949_9196ecd0e0_z.jpg)

These units sound fantastic, I'm very very pleased with them.

The Gimmer
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: 901 on January 07, 2012, 10:53:07 AM
I am building the F76 from naked PCB and so I am hunting for parts right now.

I chose to go with the balanced line receiver, all three Grayhills, the IJ Input amp and the IC output amp. Unfortunately I can´t find the 2N4249 (T1 in IJ amp) and the 2N4250A (Q14 in IC out amp). I just guessed now that a BC560 would do. What do you guys think?

And what´s your favourite source for the Lundahl LL1524 in Europe?
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on January 23, 2012, 06:01:00 PM
@ chunger :

AWESOME pictures!!!
Really, amazed by your photo skills.

901: pn2484, pn4250 are the same transistors just in plastic. Or, pn4249.

LL1524: I bought them from andre tchmil


@ andre tchmil do you have 2 1524 output trannies available still? I'd take 'em


sure how many kilograms do you need ?  ;D

email me for ordering, thanks
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: 901 on January 24, 2012, 04:54:06 PM
Thanks for the info! I was already quite desperate on the transistors. But now I can even get it on Mouser. BTW if anyones interested I´d be happy to share my Mouser parts list once my unit is complete and working and I know I selected the right parts...

The Belgian cycling hero already sold me a chunk of Swedish metal and after desoldering it using American tools from the remainder of its previous home it fitted well with the PCB from Isreal. I´m in Germany fwiw. Globalization can be a good thing actually!  8)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: 901 on January 28, 2012, 06:27:29 PM
Just wanted to let you guys know: I have finished mine after all!

There are a few things I had hassles with and maybe this info is of good use for others as well.

- as stated earlier I had difficulties sourcing 2N4249 and 2N4250A. I managed to get my hands on two 2N4248 though. The BOM mentions these as the primary parts to get with the PNxxxx types as exchangle. The 2Nxxxx have metal housing, th PNxxxx are plastic. I would like to advise heavily AGAINST the 2N types since they all so easily touch other parts on the heavily stuffed DOAs and cause shorts! And they are larger, too.

- The LEDs don´t line up well with the cut-out in the metal bracket and front causing a little tension on the motherboard. If I had to do it again I would try to place them not so tight against the board so that the pins get gently bent rather than the board itself.

- The Attack and Ratio Grayhills didn´t expose enough shaft for the knobs that I chose. Fortunately I could mill away a millimeter from the metal knobs. If you can´t do that pay attention to the dimensions when choosing knobs.

- For some reason I had difficulties to get buttons for the push switches. I´m currently using an interim solution by abusing the heads of two M4 hex screws. I think it´s funny...  8)

After adjusting everything I just toyed around with it a little and this thing is really fun! Even if my points from above may sound like trouble, it was fun to build and absolutely worth the effort.

Unfortunately I have never used a real Urei 1176, so I cannot compare. But I don´t care for originality. I think Igor made an excellent job on this one!

Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on January 28, 2012, 09:43:58 PM
lookin' nice, dude!
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: zayance on January 29, 2012, 04:52:44 AM
Nice job.

Quote
- The Attack and Ratio Grayhills didn´t expose enough shaft for the knobs that I chose. Fortunately I could mill away a millimeter from the metal knobs. If you can´t do that pay attention to the dimensions when choosing knobs.

I'm using same Kilo knobs, bigger ones tough, yes you need to trim the bottom, but i was aware of that, but needed bigger knobs,
feels better when turning those grayhills...

Allright Done Deal, had some weird things on this one, and i was kind of slow at troubleshooting, had been a while since last DIY.
First error was one my side and nothing that you'll encounter, had done myself a double sided home etched board like the Rackit,
for feeding both rails with one Supply, and audio on board etc.. one of the connections was not made properly so...

Second error, i had one resistor on the ratio Control wrong, and i was lossing signal when inserting the control Board.

Anyway Thanks Mr kapelevich.

I went all original, attenuator, Tranny, Amp etc....

(http://img707.imageshack.us/img707/6927/20120130130757.jpg)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: AudioGimmer on January 30, 2012, 07:41:46 AM
Nice job Zayance, looks great with those knobs. Which Kilo ones are they?

I went T Pad & transformer input too. Did you use Igor's DOA [ the one that's like an eye test to build! ]

Incidentally Igor, nice touch with the metering, very nice ballistics. I also like the way in GR mode the very bottom LED is half lit to show you are in GR mode.


The Gimmer
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: zayance on January 30, 2012, 07:50:32 AM
It's those:

6.35mm
http://search.digikey.com/us/en/products/OEJL-63-2-5/226-1089-ND/710652

3.17mm
http://search.digikey.com/us/en/products/OEJL-63-2-6/226-1085-ND/710656

So as said, you need to trim the bottom, AND also trim the grahill shaft, because the screw is landing on the sharp side and not
on the back of the D, Plus trim a little the inner screw tip to make it seat flat on the trimmed shaft.
A little expensive considering all the extra you have to do to make them fit..
But those Elma's were too tiny for my fingers and those Grayhills.

I didn't bother trimming the Input and Output ones...

Quote
I went T Pad & transformer input too. Did you use Igor's DOA [ the one that's like an eye test to build! ]

No i went Original Amps, but i builded all of them, so i'll try it out...
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on January 30, 2012, 02:38:45 PM
Just wanted to let you guys know: I have finished mine after all!

There are a few things I had hassles with and maybe this info is of good use for others as well.

- as stated earlier I had difficulties sourcing 2N4249 and 2N4250A. I managed to get my hands on two 2N4248 though. The BOM mentions these as the primary parts to get with the PNxxxx types as exchangle. The 2Nxxxx have metal housing, th PNxxxx are plastic. I would like to advise heavily AGAINST the 2N types since they all so easily touch other parts on the heavily stuffed DOAs and cause shorts! And they are larger, too.

- The LEDs don´t line up well with the cut-out in the metal bracket and front causing a little tension on the motherboard. If I had to do it again I would try to place them not so tight against the board so that the pins get gently bent rather than the board itself.

- The Attack and Ratio Grayhills didn´t expose enough shaft for the knobs that I chose. Fortunately I could mill away a millimeter from the metal knobs. If you can´t do that pay attention to the dimensions when choosing knobs.

- For some reason I had difficulties to get buttons for the push switches. I´m currently using an interim solution by abusing the heads of two M4 hex screws. I think it´s funny...  8)

After adjusting everything I just toyed around with it a little and this thing is really fun! Even if my points from above may sound like trouble, it was fun to build and absolutely worth the effort.

Unfortunately I have never used a real Urei 1176, so I cannot compare. But I don´t care for originality. I think Igor made an excellent job on this one!



Congrats 901 and thanx for feedback!!!
The buttons for push switch are available on DigiKey, check the BOM for P/N's.
Soldering LED's is bit tricky, but I did it with about 20 compressors.... and it worked.
Knobs: my favorite is ELMA. They have virtually any shaft/size variations. I cut Grayhill shafts with Dremel tool and cut-off discs.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: chunger on March 10, 2012, 12:42:12 AM
Sorry about the extended delay. . . a few other projects came creeping in, but I'm starting to make some more headway on these f76 builds.

I had a misunderstanding about the nut locations on these, but I think I've got it now.  The nuts for the pots and grayhill switches seat underneath the faceplate in the machined recesses.  So, there are a couple of threaded inserts and hex screws that hold the faceplate on.  These did not readily fit into the holes completely.  Since the location would be very difficult to tighten, I figured I'd just try and press them in.

(http://studio939.zenfolio.com/img/s11/v36/p24762661-4.jpg)

(http://studio939.zenfolio.com/img/s11/v37/p285187313-4.jpg)

(http://studio939.zenfolio.com/img/s11/v37/p256016805-4.jpg)

Boom. . . works like a charm.

(http://studio939.zenfolio.com/img/s11/v36/p425177560-4.jpg)

Next my Zobel network resistor and cap.  R101 and C100.  As I understand it, the higher value resistor and lower value the cap, the less treble attenuation will happen, so I went with those ends of the recommended range.

R101 469R
C100 4.7nf

(http://studio939.zenfolio.com/img/s11/v37/p75873719-4.jpg)

The cap I ordered is wider than the PCB was designed for, so it did not fit very cleanly, but I think this should hold up ok.  I really don't feel like delaying this project anymore.

(http://studio939.zenfolio.com/img/s11/v35/p291844666-4.jpg)

(http://studio939.zenfolio.com/img/s3/v41/p504953775-4.jpg)

(http://studio939.zenfolio.com/img/s11/v35/p115044516-4.jpg)

Next, I soldered a few leads onto the input and output pots.

(http://studio939.zenfolio.com/img/s3/v39/p204196256-4.jpg)

and connect to the PCB. . . please let me know if the leads aren't properly connected.  This is how I decided to go after looking at the schematic a little, but unfortunately, I don't know how to read schematics, so there you have it.  That's how confident I am  :-\

(http://studio939.zenfolio.com/img/s3/v39/p72355395-4.jpg)

Next, per the build instructions in the 1st 2 posts, I connect my link lead just in case I use this as linked pair.. .

(http://studio939.zenfolio.com/img/s11/v35/p68850546-4.jpg)

And, it looks like I'm ready to apply power and do my 1st round of voltage checks.

(http://studio939.zenfolio.com/img/s11/v36/p522147486-4.jpg)

Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: chunger on March 10, 2012, 05:35:57 AM
Ran into some problems w/ my input amp upon initial testing . . . hopefully Igor can help me find the cause.

Ok. . . hooking the F76 up to my testing power supply which is JLM powerstation.

(http://studio939.zenfolio.com/img/s3/v41/p353874247-4.jpg)

No smoke!  Humans win!

Checking voltage at LM337.  I am looking for -10v here according to test procedure.  I guess -9.7 isn't too bad?

(http://studio939.zenfolio.com/img/s11/v37/p364082322-4.jpg)

While I'm here, I might as well poke around a few of the other power points and check to make sure amps will be happy.

(http://studio939.zenfolio.com/img/s11/v36/p416112168-4.jpg)

(http://studio939.zenfolio.com/img/s3/v39/p346664361-4.jpg)

Installing test jumper

(http://studio939.zenfolio.com/img/s11/v37/p153731691-4.jpg)

Installing main PCB IC's

(http://studio939.zenfolio.com/img/s3/v41/p270145074-4.jpg)

(http://studio939.zenfolio.com/img/s3/v38/p288229664-4.jpg)

(http://studio939.zenfolio.com/img/s3/v40/p510292872-4.jpg)

(http://studio939.zenfolio.com/img/s3/v39/p156733251-4.jpg)

Output amp goes in.

(http://studio939.zenfolio.com/img/s11/v35/p8924691-4.jpg)

Input amp goes in.

(http://studio939.zenfolio.com/img/s3/v39/p376260130-4.jpg)

(http://studio939.zenfolio.com/img/s3/v38/p65479305-4.jpg)

And, here's my problem.  Test procedures say with input and output pots closed,  I should adjust the input amp's trim pot to read .3V - 1V with a volt meter between the amps output and ground.  At the end of the trim pot's adjustment range, I can only get it down to 11.6V which is wildly out of range.  So, I'll stop here and see if anyone can take a look at my build progression photos on the input amp and spot a component error. . . or if i wired my input/output pots wrong.

(http://studio939.zenfolio.com/img/s11/v37/p227400165-4.jpg)

UPDATE:  Found the problem.  There was a faulty BD139 on Q1.  With faulty part replaced, input amp trims out within spec.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on March 10, 2012, 08:16:16 AM
for that last step, you don't have the GR/Audio transistors installed.  Does that make a difference?   I remember having a similar problem with mine, i just had to keep turning and turning the trimpot and eventually it worked.    i mean, turning it both directions the whole range.   it was not intuitive.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: chunger on March 10, 2012, 02:50:37 PM
test procedure is saying not to install audio and GR transistors yet. . . I messed with it again, and now the range is 23V-9V.  Still out of range.  I double checked my photos for the resistor values installed on the amp via photos, and those look to be ok.

Chuck, do my input/output pots look wired correctly?
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on March 10, 2012, 11:28:50 PM
yes they do.   Also, I tested my amps between the GND pin on the amp, not the GND pin on the 51x connector.   Not sure if it makes a difference...   one would think that they are part of the same GND circuit....    But i know nothing lol.    You might want to hit up igor on FB, cuz he's posting a lot of pics recently.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: chunger on March 12, 2012, 05:18:14 AM
Igor says he'll be back from vacation tomorrow.  In the meantime I attempted to build from my 2nd kit Igor's input amp to test.  I have awesome pictures, but unfortunately, I reversed D2 and D3 1N4148 like an idiot, so I got white smoke. . . and I can't post the pictures because I don't want anyone repeating that adventure.  Since I was looking right at the amp when I flipped the power on and shut it down in ~2 seconds, I'm hoping the damage is isolated to those parts.

Oh well, a trip to the electronics store tomorrow is in order.  I also recorded all actual resistor values when building this one looking for discrepancies that could cause my voltage woes, and noticed that R6 and R9 (R6 6 being adjacent to the trimmer pot) have substitute values. . . 909K instead of 1M indicated on schematic.  I'll pick up a pair of 1M resistors as well when I'm at the store and see if that gets me closer to where I need to be.  Guess that's a 9.1% difference though.  Probably insignificant but that's the only quirk I found.

Once more the Hakko 808 is saving my butt.  Pulling out D2 and D3 on a built PCB would have been tough without it.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on March 12, 2012, 04:45:16 PM
I do believe someone once posted that these guys were originally designed for use with 20% parts.   So, that 909K resistor is within spec..   Maybe that was for the LA-2A tho.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: briomusic on March 12, 2012, 07:14:16 PM
I am finally getting around to building my F76. As this one will go into the portable rig in my API lunchbox, there won't be any +-24V which whittles down the options.
I am starting off with the most basic setup:
INPUT LINE RECEIVER -> IC INPUT AMP -> IC OUTPUT AMP - > B11148

Questions:
-Does the B11148 need termination and a zobel network? There are conflicting messages in the other 1176 threads (and nothing in this one).

-I have two pairs of very well-matched B245A's and the pairs match each other fairly closely. Should the very close matches go into the signal paths of the left and right channels respectively, or into the signal and meter paths of a single unit?

Thanks for all the tips so far and the mechanical gotchas.

Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: chunger on March 13, 2012, 09:20:26 AM
progress and problems today. . .

First, I needed to repair the 2nd Igor Cascode-type input amp that I smoked last night.  Luckily, I have an electronics store local that actually has parts in stock.  Hakko 808 to the rescue.

(http://studio939.zenfolio.com/img/s11/v37/p885747333-4.jpg)

Since I had my de-soldering tool handy, I decided to replace the 901K R6 and R9 resistors on the 1st (mis-behaving) amp to see if that resolves my problems with it.

(http://studio939.zenfolio.com/img/s11/v36/p891053713-4.jpg)

The bad news is the 1st input amp is still not showing the correct output voltage.  It is now ~16 volts with the trim pot bottomed out.  The good news is, the 2nd unit is working within spec.

(http://studio939.zenfolio.com/img/s3/v38/p948212295-4.jpg)

It's trim pot is also bottomed out, but it's reading within the .3-1 volt range.

Next, I took out a whole bunch of tools I have no idea how to use.

(http://studio939.zenfolio.com/img/s3/v38/p736896891-4.jpg)

My friend let me borrow a function generator and a scope that didn't have a probe. . . the electronics store luckily had a probe at a not-to-astronomical price, so I was in business.  So, these tools are now on semi-permanent loan since my friend seldom uses them anymore and they were in his storage unit.

(http://studio939.zenfolio.com/img/s11/v35/p1068334890-4.jpg)

(http://studio939.zenfolio.com/img/s11/v3/p718695195-4.jpg)

Since the F76 is balanced in and balanced out, I figured I should inject balanced signal, so I'm using my direct box which is of the IC opamp variety.

(http://studio939.zenfolio.com/img/s11/v3/p794098659-4.jpg)

the setup on my table for starting to test.

(http://studio939.zenfolio.com/img/s11/v3/p584061618-4.jpg)

ok. . . after pushing buttons like monkey on the scope, I think I finally figured out how to do some things with it.  Please keep in mind, I've never used a scope in my life, so all this is very new to me.

First test was to input a .01v RMS (-37.78 dBu) signal into the f76.  Here I'm using a 1K sine.

(http://studio939.zenfolio.com/img/s11/v35/p591257097-4.jpg)

And check output for ~37db undistorted gain.  Here, I have 3.32v RMS (12.64 dBu) output w/ input and output pots both at maximum.

(http://studio939.zenfolio.com/img/s3/v38/p643726568-4.jpg)

OK. . . please note here that I have another problem. . . My pin 3 and pin 2 outputs on the f76 are off by a large amount.  Pin 3 output is 8.78db lower than pin2.  I'm wondering if this indicates my output transformer is defective?  It is evident in the photos that there is significant physical damage to the casing, but I assumed Andre had tested these before they shipped.  The above reading is off of pin 3 (the low output one).

Taking into account the problems, I continue testing.  I insert 1v RMS signal.

(http://studio939.zenfolio.com/img/s11/v37/p796124400-4.jpg)

and max undistorted output on pin 3 is 10.2v (22.38 dBu)  minimum of 24dB is Igor's spec.

(http://studio939.zenfolio.com/img/s3/v41/p1025698932-4.jpg)

max undistorted output on pin 2 is 28v (31.16 dBu)

(http://studio939.zenfolio.com/img/s3/v41/p625780664-4.jpg)

and, another view of the pin 3 output which is low.

(http://studio939.zenfolio.com/img/s11/v36/p177344079-4.jpg)



ok. . . problems aside, I move forward.  I adjust input/output pots to output 1.23v RMS.

(http://studio939.zenfolio.com/img/s3/v38/p295115594-4.jpg)

and adjust trim pot until yellow light is solid on the meter.  The GR switch is in the "out" position.

(http://studio939.zenfolio.com/img/s3/v38/p35178407-4.jpg)


That's all for now. . . Questions for Igor:

1.  What is my next step to diagnose the malfunctioning input amp that is giving me ~16v at output?

2.  Do I have a defective output transformer that is giving me weak output on pin 3?

EDIT:

question #1 concerning the malfunctioning IJ Cascode input amp is still a mystery to me.  I went chasing around the schematic and PCB today with a patient and helpful friend on the phone trying to figure it out.  Pulled the 50K trim pot. . . tested ok. . . re-installed it.  Replaced Q2, T3. . . no change. . . Replaced C1, C3 mostly to make sure solders were all solid around the -24v area.  Still no luck.  This tiny amp is kicking my @ss.  Very frustrating.

question #2 Jeff from CAPI helped with.  It's more of a common knowledge answer that I simply was unaware of.  Many output transformers do not have a ground reference, so they are floating ground.  The + and - side of output will not necessarily reference to ground equally so the offset I am seeing on the scope is normal.  I decided to calibrate 0 dB with a sound meter w/ a balanced input, and when I connected a load, the + and - sides evened up significantly on the scope.  The output transformer is fine.  Verified by pulling the output transformer and replacing it w/ same behaviors.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: briomusic on March 14, 2012, 01:55:15 PM
Have run into a bit of trouble with my build....voltages are fine without the amps and chips,
but as soon as I drop in my IC OutAmp Resistors R93 and R94 start smoking, before I even get a chance to measure the voltage across them. I am using slightly different Transistors:
PN2484 instead of 2N2484, as Farnell don't carry the latter.
My version of the 2N4250A is a bit different as well, it comes in a metal container.
I checked PNP and NPN and pinouts on datasheets and with the hfe function of my meter - everything in order.
with the IC OutAmp inserted, I still have normal readings across the voltage rails (-16 to Gnd, Gnd to +16), around 1k Ohm and rising as the PSU caps charge.
Any ideas anyone?
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: chunger on March 16, 2012, 03:36:07 AM
ok. . . one more push to finish up this build.

Please note, this step is pre-mature, so I will have to take out the audio and GR fets for a calibration in the following steps, but this is when I put them in, so here are the pics.

Audio FET here:

(http://studio939.zenfolio.com/img/s3/v38/p346493286-4.jpg)

Gain Reduction FET here:

(http://studio939.zenfolio.com/img/s3/v40/p282120568-4.jpg)

Note these are matched pairs provided in the kits and they are different than original spec FETs so these insert reverse direction from the indicated markings on the PCB.

NExt, I address a mechanical fit issue I noticed when rough assembling the module.

(http://studio939.zenfolio.com/img/s3/v41/p160579574-4.jpg)

This nut is too thick to seat fully into the recess provided in the front panel, so we will have to thin it a bit.

(http://studio939.zenfolio.com/img/s3/v41/p162716615-4.jpg)

Some 220 grit sandpaper does the trick.

(http://studio939.zenfolio.com/img/s3/v41/p156401396-4.jpg)

(http://studio939.zenfolio.com/img/s3/v41/p492057572-4.jpg)

Fits now.

(http://studio939.zenfolio.com/img/s3/v39/p158671637-4.jpg)

Next, I take out my jumper, attach the attack/ratio board, and assemble the whole mess again.

(http://studio939.zenfolio.com/img/s3/v41/p152206792-4.jpg)

(http://studio939.zenfolio.com/img/s3/v39/p375371217-4.jpg)

(http://studio939.zenfolio.com/img/s10/v16/p181390021-4.jpg)

The front panel needed a bit more persuasion for everything to align, so I filed a bit on a few of the holes.

(http://studio939.zenfolio.com/img/s3/v39/p153823392-4.jpg)

Voila!

(http://studio939.zenfolio.com/img/s3/v40/p446419737-4.jpg)

Next, I need to take care of these long pots.

(http://studio939.zenfolio.com/img/s3/v39/p472118226-4.jpg)

So, I use a straight edge and mark my cut location.

(http://studio939.zenfolio.com/img/s3/v41/p438901041-4.jpg)

And cut with a cut-off wheel on a dremel.

(http://studio939.zenfolio.com/img/s3/v40/p958708901-4.jpg)

Voila!  Look at that precision. . . it's almost like they were cut with a laser beam.

(http://studio939.zenfolio.com/img/s3/v41/p677594239-4.jpg)

This hex screw secures the front panel to the L-bracket.  There are 2 of them.

(http://studio939.zenfolio.com/img/s3/v41/p1021383897-4.jpg)

(http://studio939.zenfolio.com/img/s3/v39/p991559272-4.jpg)

Next, I assemble knobs.

(http://studio939.zenfolio.com/img/s3/v38/p860269521-4.jpg)

And secure them to the pots and grayhill swithes.

(http://studio939.zenfolio.com/img/s3/v41/p823546819-4.jpg)

(http://studio939.zenfolio.com/img/s3/v39/p922256589-4.jpg)

Now, I need to remove my GR and Audio fets and inject -20dB signal.  Input pot set to max, adjust output pot to 0dB or  1.23v output.

(http://studio939.zenfolio.com/img/s3/v38/p728570821-4.jpg)

(http://studio939.zenfolio.com/img/s3/v38/p587507700-4.jpg)

Then, I re-install the audio and GR FETS and adjust bias for -1dB.

Next, I adjust the Dist trim pot. . . I read the instructions and didn't quite understand the adjustment so I just put the ouput on the scope, turned the output until I saw distortion on the sine wave, and twisted the adjustment pot.  So, it shifts the distortion more towards the top or bottom of the waveform.  I adjusted until it was even top and bottom upon distortion which would give me the greatest gain before distortion.  I twisted the output pot back and forth from clean to distortion and toyed with it until the top and the bottom of the waveform flatten out at the exact same time.  It was at a pretty close setting actually prior to starting.

Next, I unplug input signal, put in GR mode and adjust 0GR trim pot for yellow LED to just light.

Then, I feet 0dB into the input, set ratio to 4:1 . . . and flip back and forth between OFF and 4:1 ratio.  I adjust the input pot until I find the point where the difference between 4:1 ratio and OFF position is 10dB.

Here's my reading at 4:1 ratio.

(http://studio939.zenfolio.com/img/s3/v41/p846522103-4.jpg)

And my reading at OFF ratio.

(http://studio939.zenfolio.com/img/s3/v41/p910124615-4.jpg)

At this point, I return the ratio knob to 4:1 and adjust the GR scale trim pot until the meter reads -10

(http://studio939.zenfolio.com/img/s3/v39/p692764152-4.jpg)

At this point, the unit is calibrated and ready to run.  Humans Win!

The only remaining step is to put the caps on the knobs and take pretty pictures of the finished product.

(http://studio939.zenfolio.com/img/s3/v40/p846441576-5.jpg)

(http://studio939.zenfolio.com/img/s10/v16/p789414964-5.jpg)

(http://studio939.zenfolio.com/img/s3/v38/p817347398-4.jpg)

(http://studio939.zenfolio.com/img/s3/v38/p914200996-4.jpg)

(http://studio939.zenfolio.com/img/s3/v39/p912041504-4.jpg)

(http://studio939.zenfolio.com/img/s3/v38/p689904404-4.jpg)

(http://studio939.zenfolio.com/img/s10/v16/p707096027-4.jpg)

(http://studio939.zenfolio.com/img/s3/v38/p857716982-4.jpg)


Well, there it is.  Now that I'm done taking pictures, I can try to figure out what is broken with the 1st Cascode type input amp and build my 2nd kit.  I learned a lot from this project.  It was the 1st time I used a scope.  I was trying to figure out why the math all didn't work until I figure out unity is 4dB not 0dB for this equipment.  I learned a bit about output transformers and floating ground.  And I learned hot to use my Hakko 808 desoldering tool a lot better :P

Well, I hope this gives everyone a getter look at the F76 project.  Most of the calibration steps can be done with a volt meter or plugged into a DAW.  One step (dist adjustment) is best done with scope.  I chose to use the scope for many of the calibration steps because it's a new thing for me to learn to use.

I'd say this project mechanically is not the simplest and there are a few mechanical tolerance oddities and more general futzing than some other kits, but in the end, I think the final product if carefully assembled polishes out really nicely.  The internal component arrangement is slick, and the feature set is awesome.  2:1 ratio and true relay bypass is awesome.  The metering is a treat to use.  I really like the way Igor set up the physical metering and programming to drive the meters.  Very intuitive in use.  I can't wait to get this module into the studio and hear it in a good listening environment.




Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on March 16, 2012, 03:45:35 PM
Congrats,that is very impressive,and you've done this pretty well!
Now that teases me to build some on my own ;D

Cheers,have fun with the new toys,

Udo.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: jensenmann on March 18, 2012, 05:55:20 AM
Great pictures!!!
Yesterday I mixed the first show with my new 51x-F76 on bass and leadvocals. They certainly do the 1176 thing, exactly what I wanted them to do.
Thanks a lot, Igor, for that great project!
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: briomusic on May 17, 2012, 03:58:09 AM
Does anyone know the correct way to wire the B111048?

Currently I have primaries and secondaries in parallel, but this seems to result in low output.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: zayance on May 17, 2012, 05:58:49 AM
Does anyone know the correct way to wire the B111048?

Currently I have primaries and secondaries in parallel, but this seems to result in low output.

I wired in parrallel as well as Rev. F/G, using original Amps, no signal loss on my side...
On my build the low output i had on my second module, was a wong resistor on the ratio side
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: briomusic on May 17, 2012, 08:07:54 AM
thanks zayance, I am using the ic output, which apparently noone else here does (I am tied to 511 specs for this build).
I am not quite sure what sort of level I should be seeing pre-transformer....
Was your ratio-board fault also noticeable with the ratio switch set to off?

cheers
brio

Does anyone know the correct way to wire the B111048?

Currently I have primaries and secondaries in parallel, but this seems to result in low output.

I wired in parrallel as well as Rev. F/G, using original Amps, no signal loss on my side...
On my build the low output i had on my second module, was a wong resistor on the ratio side
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: zayance on May 17, 2012, 08:17:17 AM
Quote
Was your ratio-board fault also noticeable with the ratio switch set to off?

not sure about that....
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: qmp audio on June 05, 2012, 05:04:44 PM
IM nearly complete w/ 2 units.   i went to calibrate and both units seem to pass signal directly thru the units with no power.   I just plugged into my test card,  sent a sine wave and the signal passed right thru.   Almost like the input/output is shorted.   is this supposed to happen?  anyone have any idea whats going on?   the same on both units,  eveything looks ok though.

using balanced line receiver, b11148,  +-16v (500 spec)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on June 05, 2012, 10:52:13 PM
IM nearly complete w/ 2 units.   i went to calibrate and both units seem to pass signal directly thru the units with no power.   I just plugged into my test card,  sent a sine wave and the signal passed right thru.   Almost like the input/output is shorted.   is this supposed to happen?  anyone have any idea whats going on?   the same on both units,  eveything looks ok though.

using balanced line receiver, b11148,  +-16v (500 spec)
Hi

Don't know this piece yet,but looking on the pics it has got relais as well as a bypass switch on the front.Now guess..... ;)

Udo.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: qmp audio on June 06, 2012, 12:37:05 AM
IM nearly complete w/ 2 units.   i went to calibrate and both units seem to pass signal directly thru the units with no power.   I just plugged into my test card,  sent a sine wave and the signal passed right thru.   Almost like the input/output is shorted.   is this supposed to happen?  anyone have any idea whats going on?   the same on both units,  eveything looks ok though.

using balanced line receiver, b11148,  +-16v (500 spec)
Hi

Don't know this piece yet,but looking on the pics it has got relais as well as a bypass switch on the front.Now guess..... ;)

Udo.

yes i see the relays are opening the circuit like a hard bypass.   These relays aren't receiving the signal to close.   I'm having this issue with and without the GR board connected.   both units are functioning the same,  so whatever the issue is it persists across both modules.   I'm looking closely at the solders and components and everything looks right (comparing w/ chunger's photos).   I'm getting the proper voltage readings  (step one of igor's test procedures).  Anyone familiar with this have any idea where to look,  or where to start w/ this?
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on June 06, 2012, 01:05:26 AM

yes i see the relays are opening the circuit like a hard bypass.   These relays aren't receiving the signal to close.   I'm having this issue with and without the GR board connected.   both units are functioning the same,  so whatever the issue is it persists across both modules.   I'm looking closely at the solders and components and everything looks right (comparing w/ chunger's photos).   I'm getting the proper voltage readings  (step one of igor's test procedures).  Anyone familiar with this have any idea where to look,  or where to start w/ this?
I´m not sure if I really get you right,but I did a quick look at the schematics some minutes ago.The relais bypass circuit is shown at the upper right corner.
See it as toggle switches with a single "input" to two "outputs",this is also called "failsafe mode".The unit powered off causes the relais to connect the inputs to the outputs.This is the default condition of the relais.Therefore it is correct that the board passes audio when not powered up!Looking good so far,don´t worry.

Hope to have helped,

Udo ;)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: qmp audio on June 06, 2012, 01:28:18 AM

yes i see the relays are opening the circuit like a hard bypass.   These relays aren't receiving the signal to close.   I'm having this issue with and without the GR board connected.   both units are functioning the same,  so whatever the issue is it persists across both modules.   I'm looking closely at the solders and components and everything looks right (comparing w/ chunger's photos).   I'm getting the proper voltage readings  (step one of igor's test procedures).  Anyone familiar with this have any idea where to look,  or where to start w/ this?
I´m not sure if I really get you right,but I did a quick look at the schematics some minutes ago.The relais bypass circuit is shown at the upper right corner.
See it as toggle switches with a single "input" to two "outputs",this is also called "failsafe mode".The unit powered off causes the relais to connect the inputs to the outputs.This is the default condition of the relais.Therefore it is correct that the board passes audio when not powered up!Looking good so far,don´t worry.

Hope to have helped,

Udo ;)

Yes thanks Udo for looking into this.   The issue i'm having is the signal is still bypassed when i power up.   Im testing the voltage and the amps are getting power and the leds are lighting up,   but the bypass still active when powered.  Been studying the schematics and pcbs and can't seem to find why this is happening when its powered up.

(http://xohol.com/diy/f76-q1.jpg)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on June 06, 2012, 02:04:30 AM
Can you hear the relais cicking when you toggle the bypass switch?
Maybe just the switch miswired?
Measure if the control voltage is there at the relais corresponding to the switch position?

As said I don't know this piece yet and therefore haven't built one.

Maybe somebody who has already built them could chime in?

Udo.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: zayance on June 06, 2012, 04:39:07 AM
Even when you add the jumper on the 10 Pin connector without the control board?


EDIT: wait, you forgot to put R95, a 1/2W resistor, check the BOM and Schematic for an explanation on this, because the value depends on Coil resistance.
I see you use kit from Igor, so the coil resistance of his relays must be 1K (check it tough) That means that R95 should be about 330 ohms 1/2Watt.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: qmp audio on June 06, 2012, 09:54:45 PM
EDIT: wait, you forgot to put R95, a 1/2W resistor, check the BOM and Schematic for an explanation on this, because the value depends on Coil resistance.
I see you use kit from Igor, so the coil resistance of his relays must be 1K (check it tough) That means that R95 should be about 330 ohms 1/2Watt.

Good eye!  Thanks!  Calibrated and functional!   Thanks Everyone on here for your notes and info,  and Igor this things great.

My second unit is getting the same V reading Chunger had on the input amp (~13v).  So just ordered some new bd139s to test.

One other question,  my GR meter seems pretty calibrated,   except it goes crazy w/ the slam switch engaged.   is this expected?  pretty much goes the full range of the LED,  where as all other GR settings go from 0 down appropriately.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: zayance on June 07, 2012, 03:53:38 AM
Quote
One other question,  my GR meter seems pretty calibrated,   except it goes crazy w/ the slam switch engaged.   is this expected?  pretty much goes the full range of the LED,  where as all other GR settings go from 0 down appropriately.

expected
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: qmp audio on June 10, 2012, 01:50:50 AM
Hello again everyone.   I'm having trouble tracking down the issue w/ one of the ig se-cascode input amps.   the measurement on the amp is ~15V.  (I'm testing on a 16v lunchbox ps).   I saw changer had a similar problem,  so i replaced the bd139s as it had worked for him.   Same 15V measurement.   I double checked resitances,  and examined for any shorts etc.   everything seems to match my working on.   Could this be an issue w/ t1, t2, or t3?   the values are right,   could one of these components be bad?

Also,  does any know what kind of other input amps can be used? (16v)
Thanks for any insight.   I have one module finished!   the second is keeping me stuck on this non-functioning input amp.
qmp
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: wowi on June 24, 2012, 12:28:45 PM
Similar problem as gunpoint recording. Measurement at the ig input amp is 22,85 V with 51x. I checked everything and like gunpoint recording i replaced the BD139s. I build two 51X-F76 and got the same Measurement on both !

Any ideas ?
Wolfgang
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: qmp audio on June 24, 2012, 10:02:50 PM
Similar problem as gunpoint recording. Measurement at the ig input amp is 22,85 V with 51x. I checked everything and like gunpoint recording i replaced the BD139s. I build two 51X-F76 and got the same Measurement on both !

Any ideas ?
Wolfgang

Hello Wolfgang.   I never did figure out the problem w/ my 2nd ig input amp.  One specced just fine and worked,  the other did not.   i replaced the transistors and checked every component.... same ~16v measurement.   Keep me posted if you figure anything out.   In the meantime i ordered 2 ( http://www.digikey.com/product-detail/en/AD711KNZ ) IC opamps and extra pins for use with the IC input option.   You could get the opa604 for that.   I want to revisit the ig input and try to figure that out,  but for now 16v IC input and sl2520 output's working great for me.

I have read posts about people receiving faulty/counterfeit bd139s,  and that a large number of fakes may have entered the market.   Though i find it hard to believe that each of the 6 bd139s i tried are faulty ( i ordered in the US from digikey ).   However... i can't think of anything else that could be wrong w/ the amp  :-\
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: chunger on July 03, 2012, 02:40:21 AM
hey guys,

Sorry you're having problems with the Cascode opamp.  I figured there were only 5 transistors on there, so I started replacing them one at a time until it worked.  I'm not electronically literate, but going over the schematic with a friend indicated the BD's were likely suspects.  I hope you're able to get it sorted out.

Long-term report. . . we have been using one of the F76 units in the studio for a few months now configured as built in this thread.  input/output pots, Cascode input amp, IC receiver, original output amp, Lundahl output transformer, and it's been working really well on vocals and guitars at the studio.  It is a bit thin and overdrives a bit too early and gritty for heavy things like bass.

I brought a 2nd unit into the studio recently configured with an APP2520E which loves to run at +-24V as output amplifier trying to decide which configuration we like better for a matched pair.  This setup ended up being smoother with a lot more bottom and a silkier top end.  Great for bass, snare, kick, but on vocals, we liked the way the original output amp breaks up and gives a hint of bite to female vocals.  Ended up leaving them in different configurations.  Maybe i will have to build another one if i want to run a stereo pair.

But, I know Igor prefers his Albatross amp in this device.  Alternately, for a more pristine sound with lots of headroom, the APP2520E available in the white market might be something to consider.  Note: Do to the height of the potted opamp, I had to cut a little bit of the F76 upper PCB with a file to fit, but no problems.  That part does not have any components even close.

We use the 2:1 ratio all the time making F76 do things the original would not be able to do.  VERY nice feature.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on July 11, 2012, 05:59:19 PM
Any folks who have a pair of these who live in NYC??  I'd like to compare mine and see if you can help me see if i have them properly set up.    Send me a PM if you do.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: odfull on July 15, 2012, 03:08:54 PM
Hi,

I'm building a 51x76 with a B11148 output transformer. I'm not an electronics engineer and I'm afraid to make a mistake. Does anyone can tell me if it's the right way wiring it like this:
- Brown and Orange on out_tr+1
- Red and Yellow on out_tr-2
- Green and Violet on out_tr+3
- Blue and Grey on out_tr-4

Another question from a newbies:
on mother board, in the detector section, 6.8Uf electrolitics caps are used for C19 and C20. On a previous BOM I read 6.8....10uf tan tall caps. I have 10uf tantall caps. Can I put them, or is it preferable that I follow the last version of docs and put 6.8uf ?
For my knowledge, what's the difference? Is the detector more sensitive with 6.8uf or anything else?

Thanks
Thierry
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: briomusic on August 03, 2012, 06:18:23 AM
That's the way I have my B11148-500 wired (both sides parallel). Unfortunately there is no technical info on the hairball site, I found a quote from Ed Anderson on this board:
Quote
the b11148 is a 1+1:3.5+3.5 ratio, with something like a 150 ohm primary impedance.  it is not gapped, so there must be a cap or some other means to block DC from flowing in the primary.
With this wiring I have a gain of +41.5dB with both pots on maximum. I am not sure if this is ok or too much.
I also don't know if a Load Resistor and/or Zobel network is required.


Hi,

I'm building a 51x76 with a B11148 output transformer. I'm not an electronics engineer and I'm afraid to make a mistake. Does anyone can tell me if it's the right way wiring it like this:
- Brown and Orange on out_tr+1
- Red and Yellow on out_tr-2
- Green and Violet on out_tr+3
- Blue and Grey on out_tr-4

Another question from a newbies:
on mother board, in the detector section, 6.8Uf electrolitics caps are used for C19 and C20. On a previous BOM I read 6.8....10uf tan tall caps. I have 10uf tantall caps. Can I put them, or is it preferable that I follow the last version of docs and put 6.8uf ?
For my knowledge, what's the difference? Is the detector more sensitive with 6.8uf or anything else?

Thanks
Thierry
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on September 24, 2012, 03:26:17 PM
Hi Igor,

have sent a mail to your yahoo adress concerning my order.

Cheers,

Udo.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on September 24, 2012, 06:02:51 PM
Yes, shipped. It sometimes goes with delay to answer forum-related things, but I try to do my best :)
May take some time due to local holidays, crazy time - half week, everything is dead, then, day-two of work, than, back.
Mostly caused by happy penguins (don't mess with Linux), we celebrating 5773 New Year.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on October 05, 2012, 12:28:36 PM
Hello Igor,

package received today,but.......

Have sent an email to your yahoo adress.

Best regards,

Udo.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on October 06, 2012, 12:53:55 PM
Answered by mail. In case of whatever: should be 2 packages, and black anodised Aluminum fronts will arrive separetely.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on October 06, 2012, 12:55:52 PM
Answered by mail. In case of whatever: should be 2 packages, and black anodised Aluminum fronts will arrive separetely.
Thanks Igor,

did you put the Alps switches in as well?

Cheers,

Udo.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on October 06, 2012, 01:12:22 PM
Yes, at 2nd package. You told you're in hurry with the comps, so, we shipped all possible stuff asap, and the rest for a week later.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on November 01, 2012, 10:59:32 AM
So I finally got (most of ) the parts here and will start assembly.
And here's my first question:
C3 and C4 on the motherboard are specified at 200pf in both bom and schematics.I'm not able to find them in igor's baggies.The closest to source from here is either both at 180 or 220pf as styrenes or silver mica.If nothing else works I must parallel 2 x 100pf...an ugly solution.
Any recommendations on them?

Thank you in advance,

Udo.

Edit:Found 4 wima caps in parcel number three at 220pf-will they work? (4 pieces because I have two kits here).
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on November 01, 2012, 12:11:28 PM
220pf 5% were supplied in baggies, IIRC.
These caps can be in 180pf - 220pf range but should have close (5% is ok) values.
As well, a parallel trick with 2x100 pf styrenes should work fine.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on November 01, 2012, 01:10:33 PM
220pf 5% were supplied in baggies, IIRC.
These caps can be in 180pf - 220pf range but should have close (5% is ok) values.
As well, a parallel trick with 2x100 pf styrenes should work fine.
Thanks Igor.
Which baggies do you mean,the one in my third parcel I guess since there are 4 pieces of Wima at 220 pf/5%/100v.
i was just wondering since on all the pics i have seen (incl. yours) there were styrenes in this positions.
Will take the wimas then.

Cheers,

Udo.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on November 01, 2012, 01:26:23 PM
We used both styrenes and Wimas in our builds. I cannot notice any sound differencies.
Same about measurement - I check every unit's distortion on analyzer. 220pf 5% will work fine. IIRC we used FKP type Wimas.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on November 03, 2012, 01:10:48 PM
Hello everybody,

while reading through this thread again I found that quite a few of you had trouble with Igor's input amps.Still nobody seems to have found what the issue is except our friend chunger who swapped all transistors out step by step until it worked.Also one can read here that the bd139 could be suspects.
So before building I started measuring some parts including these-and was surprised: While one reads a hfe of 52 the other has a hfe of way over 100!I know this is within the specs,but..........
Could this be the point to look at and if so should we match them a "little" closer?
I ordered a bunch of 20 now,they're pretty cheap and try to find some better matching pairs.

Anyway,did anybody of you ever solve this issue and could post a bit about it?

It would be highly appreciated!

Cheers and have fun with your builds,

Udo.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: qmp audio on November 03, 2012, 07:28:45 PM
Anyway,did anybody of you ever solve this issue and could post a bit about it?

I never did get 1 of my 2 igor input amps working.  i tried swapping w/ 2 new bd139s TWICE,  w/ no luck.  so i was in the assumption it could possibly be one of the other transistors.   I plan to get back to it but haven't gotten to it yet.   However,  i am using a pair of the f76 and love them.   using an IC input amp and gar2520s on the outputs.  rev F style otherwise.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on November 03, 2012, 08:20:49 PM
Hi,

thanks for the reply.You haven't measured the bd139 by accident?
You have the gar2520 as output amp,does that mean you're running it on  +/-16vdc like a lunchbox or so?
I'm going 51x so that's sadly no option for me (except setting the jumpers and cutting goldfingers).
About ic input amp,would you prefer more this one or igor's cascode amp?
Don't want to go on your nerves,I'm just collecting possibilities and ideas,so mea culpa ;)

Cheers,

Udo.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on November 04, 2012, 08:41:09 AM



For use with input IC amp, INSTALL R11' = 560k.

This resistor IS installed on "my" or "original" input amp PCB.
Hi all,

what does that mean for IJ input amp?
This question was asked before but never answered I think.
Can't find this 560k neither on his DOA pcb nor in the corresponding schematics or the bom.
So I "guess" r11' must be soldered in,right?

Can anybody confirm this please?

Thanks in advance,

Udo.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on November 04, 2012, 09:56:55 AM
560k is resistor which pulling the input of first amplifier to ground or to its bias.
With IJ amp, no need for 560k, because it has own bias circuitry at its input already.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on November 04, 2012, 09:59:22 AM
Anyway,did anybody of you ever solve this issue and could post a bit about it?

I never did get 1 of my 2 igor input amps working.  i tried swapping w/ 2 new bd139s TWICE,  w/ no luck.  so i was in the assumption it could possibly be one of the other transistors.   I plan to get back to it but haven't gotten to it yet.   However,  i am using a pair of the f76 and love them.   using an IC input amp and gar2520s on the outputs.  rev F style otherwise.
BD139 shouldn't be a problem. Check all other things, maybe, wrong value resistor or put 2484 instead of 4250, etc.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on November 04, 2012, 10:05:56 AM
560k is resistor which pulling the input of first amplifier to ground or to its bias.
With IJ amp, no need for 560k, because it has own bias circuitry at its input already.
Cool,

thank you very much Igor!

Udo.

...and thank you for explaining,it's way clearer now to me ;)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on November 04, 2012, 10:22:12 AM
BD139 shouldn't be a problem. Check all other things, maybe, wrong value resistor or put 2484 instead of 4250, etc.
That would mean that quite a few guys here have similar problems,right?
O.K.,for easy swapping the other transistors (T1-T3) I think I will put in sockets,just to be save.

Thanks again,

Udo.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on November 04, 2012, 10:52:39 AM
Some progress in solving the mechanical stress on led alignment,bent motherboard and GR switch.

I did it this way (after some trials):

1)Align the leds exactly as described by Igor!!!
2)Cut off the six little plastic pins from the underside of the alps switch (for GR);it´s easy since it is just soft plastic.
3)Now put on the actuator cap and assemble the pcb to the L-bracket temporarily.The cap will "guide" the switch itself to a nearly perfect position!
4)Catch one(!) of the outer switch pins with a solder blob.By reheating it (not too long of course) you can make a final alignment although it is nearly unneeded then.
5)Solder the opposite outer pin then to make it "save".
6)Now disassemble the mainboard from the bracket and solder the remaining pins-done!

This will give you a perfect line-up without any stress on the board like our friend chunger had problems with.

Attached a pic to proof this,I took it half an hour ago.

All the best to you guys,

Udo ;)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on November 09, 2012, 05:18:14 PM
Hi all,

Me again.
I'm using LL1524 as output transformer.
Can somebody please tell me the correct values for the zobel network meaning R101 and C100?
I have 1k (R84) as load as stated on the bom and schematics.

Thank you in advance,

Udo.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: chunger on November 09, 2012, 06:56:25 PM
I used:

R101 469R
C100 4.7nf

It has worked well enough.

(http://studio939.zenfolio.com/img/s11/v37/p75873719-3.jpg)

Hi all,

Me again.
I'm using LL1524 as output transformer.
Can somebody please tell me the correct values for the zobel network meaning R101 and C100?
I have 1k (R84) as load as stated on the bom and schematics.

Thank you in advance,

Udo.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on November 09, 2012, 07:08:24 PM
Thank you very much chunger,

have read that in this thread,but I am a bit confused because it says 469r here and 460r in another place.May I ask how you ended up in these values?
Tried a search for zobel network,seems quite complicated.

Best,

Udo. ;)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: saxmonster on November 30, 2012, 10:31:54 PM
Anyone make a stereo pair of these yet?  Did you have to match resistors or any parts when you built them or is the matching of a stereo pair done in the calibrating?

-Scott

Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: chunger on November 30, 2012, 10:40:46 PM
I'd be the wrong person to ask.  I believe Igor suggested a range of values, and I selected the cap and resistor value inside that range that would attenuate the treble response least from a phone conversation with a friend squinting at the schematics.  I do not have much understanding of how the circuit works, but that was the value that I used for this transformer, and I can't complain about the resulting sonics.

Thank you very much chunger,

have read that in this thread,but I am a bit confused because it says 469r here and 460r in another place.May I ask how you ended up in these values?
Tried a search for zobel network,seems quite complicated.

Best,

Udo. ;)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on December 01, 2012, 12:11:31 AM
@ chunger:Thank you very much for taking care!Meanwhile I got the information that Lundahls are not sensitive to this,so I'll leave them out first.In case if they will be needed I've put sockets to these positions.I have the 1k as load resistor.

@ scott:I'm close to finishing my pair.From what I understood Q1 & Q10 should be matched for stereo operation,Igor states this in the bom.I have his kits here,and these transistors came packed in aluminium foil.Don't know how this will work out at the moment,will see when I come to final setup and calibration.

Best,

Udo.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: chunger on December 01, 2012, 12:25:31 AM
Very good. .. . that was actually what my friend first suggested.  "Why don't you just leave the zobel network out?"  But I was trying to build it close to how Igor's production units were set up.  Igor seems to have a funny way about doing things, but the results are fantastic.  The F76's are used heavily in the studio.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on December 01, 2012, 12:43:18 AM
Great to hear that they're in heavy use!
The guy from whom I got the info about the zobel from is a live-engineer doing quite big shows,he's a forum member here.I'm about to using them in my next musical shows,live of course.The rehearsals will be a nice "platform" for checking things out,especially in the early rehearsal stage.
I think I'll build all of the doas and do some experiments,have done some APP992s as well.
Will keep you posted,promised!

Cheers,

Udo. ;)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: tonycamp on December 01, 2012, 11:19:43 AM
Anyone make a stereo pair of these yet?  Did you have to match resistors or any parts when you built them or is the matching of a stereo pair done in the calibrating?

-Scott

i believe Igor will give you matched set of FET quads for a stereo pair for an extra charge? The +- of the suggested resistor values shouldn't matter, but what the hell do i know ;D
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on December 01, 2012, 04:56:15 PM

i believe Igor will give you matched set of FET quads for a stereo pair for an extra charge? The +- of the suggested resistor values shouldn't matter, but what the hell do i know ;D
I got a quad of fets with my kits,seems Igor automatically does that when ordering them as a pair.
Have opened the aluminium foil some minutes ago,they're packed in two pairs.Each pair has a label on it with "Audio" and "GR" written on.So it seems that the both functions have to use matched fets,not Q1 matches Q10 in the build.Mine are 2N5457 although BF245 is written on the foils outside.
He didn't ask for extra money in my case.
Maybe Igor can tell us the specs?

Cheers,

Udo.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Axelerator on December 02, 2012, 06:40:32 AM
Hi igor, will there be another Batch for those DIYers have been late   8)   ??
greets
Axel
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: saxmonster on December 02, 2012, 02:24:17 PM
yes, igor I could use a pair, thanks.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on December 05, 2012, 10:35:24 PM
anyone here replaced the in/out pots with stepped switches?   I know Jeff makes a little PCB/Switch kit that is perfect for this.   I'm wondering what the values are for the resistor settings and am unsure how to come up with them. 
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: indiehouse Recording on December 06, 2012, 09:28:37 AM
I would like to order a pair of these. Any idea if they will be in stock again?
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on December 07, 2012, 05:32:41 PM
So I started final steps and did voltage checks,all very very well in specs (on one LM337 I even got -9,99 vdc,the other 9,89vdc).
That made me happy.
Happiness stopped immediately when I put in igor´s amps:I have the same issues than a lot of you guys,can´t get readings lower than around 5,2 vdc-on both builds,pots completely bottomed out!Have the transistors on sockets,swapped them,no change at all!
I even selected the BD´s prior to assembly as an "apocalyptic prevention2 from a bunch of 30,no luck at all.
This is getting on my nerves now.....will take a sleep first,then install the 560k´s (r11) tomorrow and try other configurations.
I´m pretty sure I will not spend any time on the cascode amps anymore because I must get them started very soon.
Have built all amps and do have some others ready for checking here,so I have a few choices still.

Will keep you posted (if interested),

Udo :-[
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on December 09, 2012, 07:12:43 AM
Hello,

audio part is o.k. now on both boards,I get nice gains of +37,1 dB,clipping is around +30 dB (1K sine) unloaded,very nice.
But then the next issue came up:
While I managed to get one build fully working is the second doesn´t work correct when ARR board is attached.
At the point of trimming the -10 for the meter in GR mode I figured out that I´m not able to get the difference of 10dB comparing off mode and ratio setting to 4.Even dialing both input and output level to max. gives me only a difference of roughly 6 dB.
So that´s wrong.
I can state that the fault is on the ARR board because it follows when swapping them out between both units.
Having them side by side I measured the values of the resistors more than 5 times,and I´m unable to track this issue down.
I thought it is around the ratio switch connections or so because there´s one strange thing happening when I switch ratio to higher rates,starting at 1:8 etc........the level measured on output starts to increase instead of constantly decrease on higher ratio positions!
I still haven´t found it.......

I decided that it might be the best to build a new ARR board,but they are part of the pcbs/kits.Have found they´re sold out on Igor´s homepage-Great....... :-[
Now how can I proceed,is it possible to get just this board from you Igor?
Or even better:Does anyone have a nice and elegant idea to track this issue down?

I´m completely lost now,this build is no fun anymore....my time is running and I have the feeling that this all won´t work out until rehearsals start.......seems I´m losing another chance to test them in a professional high class live situation.....

Udo.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: wowi on December 09, 2012, 01:37:13 PM
Hi Udo,

if you get an error when connecting the ARR board, the error is not necessarily on the ARR board.
Check the detector area around the TL074

Wolfgang
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on December 09, 2012, 01:53:18 PM
Hi Udo,

if you get an error when connecting the ARR board, the error is not necessarily on the ARR board.
Check the detector area around the TL074

Wolfgang
Thanks Wolfgang,

but the error moves with the arr board when attaching to the other unit.

Udo.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Igor on December 12, 2012, 04:28:40 PM
Hi Udo! In general, I have a feel like something is shorted somewhere at your att/rel board.
Or, maybe, wrong value resistor etc. You have to pass on every component with multimeter and check.
Or...maybe....what about stop pins for ratio switch?

For cascode input amps - do you run the unit at +/-24V?
No need for 560k input resistor with cascode amp
Feels like a same mistake on both pcbs. Maybe, wrong resistor, reversed polarity of diode/zener/etc. Maybe zener replaced by diode.
We built about 30 of F-76 for now using same pcbs from same batch; if everything soldered correct, it simply works.
So... let's try by way of hi-res pictures, maybe, I will find something.

Matched fet's: quad fet sets were coming with stereo kit. Better matched for audio, "less better matched" but within same specs, for GR.
Written BF245, 2n5457 inside, dats right. On PCB it is written BF245, too. 5457 should face back to silkscreen (reversed) vs 245.
Just check the BOM and docs, I already wrote about 5457 here.

For kits requests: if there are more than 10 kits, can do small run; won't be fast - if pre-order and 3-4 month delivery is ok with you, possible.

Replaced pots with stepped switches - search this forum for excel stepped attenuator calculator in excel or switch to pot excel calculator.
The rest is your time. I did pair of UN-76 units (same but in 2RU, with Neve output stage and our output trafo's) with ELMA switches for input/output.
Takes exactly 2 min to get all values and it is your homework.
Input/output pots values (in case of our input stage and balanced line receiver) are 10k log.
I used to add 100R from ccw to gnd to get 40db range on these pots (more precision scale).
Steps of 3db for input and 2db for output should work.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on December 13, 2012, 11:45:39 AM
O.K.,thanks for posting Igor.
Will go over it at the weekend,again.....
Maybe I made more mistakes while swapping things/boards between the units than I wanted due to my disappointment.
I have the feeling too that it must be on the arr board,and as said there's one thing that is pretty strange:while I'm on adjusting ratio to 4:1 and toggling between this and compressor off position I can not get a difference of more than 6 to 7 dB,even with output level fully up.
Also after the 4:1 ratio,so 8:1 etc. the output level starts to increase again instead of decreasing with higher ratios!That can't be right I think.........

Anyways I must have this up and running in general before I can go back to repairing doas.As said motherboard readings on audio are pretty fine at the moment,troubles start when attaching arr board.

Thanks for watching,

Udo.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on December 15, 2012, 09:40:13 AM
Hi Igor (and those who are interested)!

Some huge progress today."Faulty" ARR board is now working correctly.Patience was the key.
A couple of days ago I went into some kind of disappointment,I have been stressed heavily by my real work as an audio engineer,time is running and I had caught a heavy cold.No good combination at all ;D
In one of my trials and errors while I was swapping boards and re-adjusting stuff again and again i certainly missed the point to pull the fets again and then putting them in prior to setting the "-1dB-point".So I trimmed the bias on that ARR board to somewhere in nirvana or so.
Readjusted the whole thing from start again today (I have 2 days off-horray!) and yes-it works,at least my measurements tell me that,both units behave the same now,pooooooooohhhhhhh........The board was never faulty!My apologies for causing trouble here!

O.K.,next step is my issues on the cascode amps,I posted before that I´m not able to bring them down to less than 5,6vdc both.


For cascode input amps - do you run the unit at +/-24V?
No need for 560k input resistor with cascode amp
Feels like a same mistake on both pcbs. Maybe, wrong resistor, reversed polarity of diode/zener/etc. Maybe zener replaced by diode.
We built about 30 of F-76 for now using same pcbs from same batch; if everything soldered correct, it simply works.
So... let's try by way of hi-res pictures, maybe, I will find something.

So yes,I´m running them on +/-24V,I didn´t have the 560k soldered in.
Maybe someone can see an error in the picture?

Thanks again,

Udo.

P.S.:The transistors are mounted on sockets.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on December 15, 2012, 01:23:29 PM
Oh, I forgot to post a pic-here´s (are) the blue(s),nice look,no?
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on December 16, 2012, 04:33:23 AM
...and another one (to proof that I´m not only showing frontpanels and knobs ;D)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mulletchuck on January 04, 2013, 04:01:25 PM
Woohoo!!  For anyone interested, i used Jeff's VP gainswitch PCB and grayhill switch, with resistor values taken from the Switch/Pot spreadsheet floating around the forum.    Also of note, the pots that these switch assemblies were replacing had a lot of variance in their values.   the 4 pots were: 7.5K, 9.2K, 10.3K and 9.59K, and they're supposed to be 10K.    each switch assembly is 9.93K, so my units should match much closer.   This might also explain why my voltage values were never identical to the test procedure values. 
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: ramshackles on September 23, 2013, 04:10:01 PM
Hi
Sorry for hijacking this thread; I didn't exactly know where to put this.
I'm looking for someone who bought the original PCB set to confirm the price of the PCB set only (not PCB + hardware kit/parts kit, just the PCB set):
Was it $90 ???

Thanks
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: kante1603 on September 24, 2013, 01:25:42 AM
Hi
Sorry for hijacking this thread; I didn't exactly know where to put this.
I'm looking for someone who bought the original PCB set to confirm the price of the PCB set only (not PCB + hardware kit/parts kit, just the PCB set):
Was it $90 ???

Thanks
Hello,

yes,in that area at least.Prices changed from time to time.Must do a search on my old bills.

Best,

Udo.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: ramshackles on September 24, 2013, 01:41:32 AM
Thanks a lot. I thought so...that comes out at ~£56 which is fairly pricey for just PCB's (IMO).
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: taliska on February 06, 2014, 06:14:49 AM
Hello folks.

(Resurrecting this thread as the boards are available again and this seems the most appropriate place).

So I've got a couple of these F76s in progress finally, and need to check some (potential) component issues. FWIW, I'm building the re-issues that ramshackles now sells, but I believe they're identical to the last ones that Igor put out (v1.4 with the exception of fewer i/o Amp choices).

I built my component list by using the ramshackle BOM doc, comparing it with Igor's original BOMs, and also using Chunger's build guide for visually checking that my choices were consistent.

Anyway, there are two carbon resistors specified in Igor's original BOM: R95 on the main board, and R46 on the attack/release board. However, in the ramshackle BOM they're both listed as metal film, and as I overlooked the difference when originally ordering, those are the ones I have.

So the question is:

Is it essential that these are carbon composition or will metal film be ok too? What differences if any, will result?

I believe the values concerned are: R95: 330R, 1/2 watt, R46 10M 1/4 watt.

Thanks for the help!

Kaz
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: taliska on February 07, 2014, 06:59:16 PM
Anyone? Anyone?

Bueller?

(I was having trouble procuring the carbon 1/4 watt 10M resistor, which is why I originally asked the above question, but today I managed to source a couple of them, so it's more or a curiosity now than anything else...for those of you based in the UK having similar issues...try www.hificollective.co.uk)

Kaz
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: ramshackles on February 08, 2014, 10:58:55 AM
there should be no problem fitting metal film resistors. May have an effect on the sound (subjective)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Harpo on February 08, 2014, 02:44:05 PM
Is it essential that these are carbon composition or will metal film be ok too? What differences if any, will result?

I believe the values concerned are: R95: 330R, 1/2 watt, R46 10M 1/4 watt.
High ohm value (probably anything above 1M will do) R46 in parallel to resistor network at the ratio switch is only used for bridging the switch while switching to prevent/reduce popping between switch positions. Carbon or metal film type doesn't matter.
Voltage dropping/current limiting R95 value and min.wattage needed is dependant on supply voltage (+/-16V or +/-24V) and coil resistance of your bypass relais. Again carbon or metal film type doesn't matter.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: taliska on February 08, 2014, 07:32:44 PM
Is it essential that these are carbon composition or will metal film be ok too? What differences if any, will result?

I believe the values concerned are: R95: 330R, 1/2 watt, R46 10M 1/4 watt.
High ohm value (probably anything above 1M will do) R46 in parallel to resistor network at the ratio switch is only used for bridging the switch while switching to prevent/reduce popping between switch positions. Carbon or metal film type doesn't matter.
Voltage dropping/current limiting R95 value and min.wattage needed is dependant on supply voltage (+/-16V or +/-24V) and coil resistance of your bypass relais. Again carbon or metal film type doesn't matter.

Thanks for the detailed response Harpo! Hopefully it will be useful for other builders here too at some point, who like me notice the BOM discrepancy. As it happens I've put the carbon ones in anyway (and have metal film spares), but am unable to go any further due to a long lead time for the grayhills at digikey. Just waiting for those (due end of March) and some lundahls and should be able to finish them and post some pics! ;-)

Kaz
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: ramshackles on February 09, 2014, 05:35:58 AM
You can also get grayhill switches off audiomaintenance. I dont remember off the top of my head which ones a required for the f76, but they might be there (you can always get a switch with too many decks and take out the last deck).
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: qmp audio on February 10, 2014, 12:55:42 PM
i usually have good luck w/ greyhills from allied:

http://www.alliedelec.com/switches/rotary/?navigation=4294862273-4294965262&mkwid=swVDUtnI3&pcrid=19895068099&pkw=grayhill&pmt=p&gclid=CJTDg8aPwrwCFaZAMgodhX8AFg (http://www.alliedelec.com/switches/rotary/?navigation=4294862273-4294965262&mkwid=swVDUtnI3&pcrid=19895068099&pkw=grayhill&pmt=p&gclid=CJTDg8aPwrwCFaZAMgodhX8AFg)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: taliska on February 10, 2014, 04:42:38 PM
You can also get grayhill switches off audiomaintenance. I dont remember off the top of my head which ones a required for the f76, but they might be there (you can always get a switch with too many decks and take out the last deck).

Funnily enough, I actually already have a number of grayhills from AML, because I just finished building a pair of EQNs. However, it's worth mentioning that the ones from AML have bushings that are too large for the front panels and brackets that frank makes.

While it's not super convenient, I don't mind the wait from digikey providing they arrive eventually! ;-)

Kaz
Title: Can't figure out strange problem
Post by: qmp audio on February 15, 2014, 02:37:39 PM
My f76's have been in service for a couple years now.   Love them and they work great,  except for 1 issue i cannot figure out the source of.

The units function as expected.  However,  after they have been on for a long time ( like 8 hours or more ) the signal is low output and crackly.    They work fine for many hours.. but then all of the sudden... low/crackle output.

A simple power off for a few seconds,  and power back on and they are like new.... at least for another 8 or so hours.

I have changed the opamps and module slots on this several times over the years,  and the same issue persists.  So i believe it is not related there.

Does anyone have any idea what could cause this issue?  A simple power off/on fixes it.

It is also a very hard issue to reproduce for testing... as i need to leave the module on overnight, at least, for the problem to happen.

Also,  it only happends to the f76's ( both of them ).   However,  no other modules are effected so i do not think it is the power supply.

Thanks for any insight.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: johnnyscotch on February 16, 2014, 01:32:58 AM
Where are the boards available again??
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: ramshackles on February 16, 2014, 02:30:36 AM
ramshacklerecording.com
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: taliska on February 19, 2014, 08:35:25 AM
Hello all,

So I decided to go through the initial testing procedures for my first F76 as my main board is now fully populated and I thought I might as well get it out of the way while I wait for my grayhills to arrive.

Anyway, so the first test was fine...I had -9.79 vdc at the output of the regulator, so I went ahead and populated all of the ICs, installed the jumper to engage the compressor, and installed the amps too (IC output amp & albatross input amp). Forgot to connect the i/o pots, and powered up the rack.

What followed was some smoke! Specifically, the resistor below JP2 at the back of the main board fried, but I don't know whether anything else is screwed. Visually it only looks like that one resistor, but who knows...

Anyone got any ideas what I got wrong? I've included a pic which shows the problem area...

Thanks for any help,

Kaz
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: taliska on February 19, 2014, 08:37:31 AM
Here's another pic showing the exact config of the board when I was testing it...

Kaz

Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: culteousness1 on February 19, 2014, 08:45:18 AM
What followed was some smoke! Specifically, the resistor below JP2 at the back of the main board fried, but I don't know whether anything else is screwed. Visually it only looks like that one resistor, but who knows...

Maybe you could give us the descriptor of the fried resistor? Without having the schematics at hand,
I ASSume that this resistor is/was a 10Ω current limiting resistor on either the +16 V or -16 V rail.

Did you check for shorts after installing the ICs? Could be a IC in backwards or a faulty DOA.

Best,
Carsten
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: taliska on February 19, 2014, 09:13:26 AM
What followed was some smoke! Specifically, the resistor below JP2 at the back of the main board fried, but I don't know whether anything else is screwed. Visually it only looks like that one resistor, but who knows...

Maybe you could give us the descriptor of the fried resistor? Without having the schematics at hand,
I ASSume that this resistor is/was a 10Ω current limiting resistor on either the +16 V or -16 V rail.

Did you check for shorts after installing the ICs? Could be a IC in backwards or a faulty DOA.

Best,
Carsten

Hi Carsten,

Yeah, it was a 10R value between pin 17 (+24v) and one of the big capacitors at the back. Apologies for not being able to be more specific...can't locate that section in the schematics at the moment, so just verified that by looking at the traces on the back...

I believe all the ICs are in their correct orientation as the notches all seem to line up, (edit) the previous posted pic shows most of them best. I'll remove the DOAs and visually inspect them to check. Will need to locate some more 10Rs and replace I guess before attempting any more testing...

Kaz
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: culteousness1 on February 19, 2014, 09:25:17 AM
The original Igor Docs contained a PCB overlay that might help you.
You can probe with your DMM at the fried resistor's leg and check for
a short to GND.

Remove one IC after each check to locate the faulty one.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: ramshackles on February 19, 2014, 09:28:31 AM
before turning power on again, do some resistance checks to make sure there are no shorts/bad soldering.
Then test voltages without IC's & DOA's installed..
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: taliska on February 19, 2014, 09:37:18 AM
The original Igor Docs contained a PCB overlay that might help you.
You can probe with your DMM at the fried resistor's leg and check for
a short to GND.

Remove one IC after each check to locate the faulty one.

Thanks for pointing me back at the docs Carsten...I somehow managed to miss the power supply schematic in my panic! I've attached it for reference, but looking at it, is seems that in this design, the 24v rails are dedicated to the DOAs with everything else using the 16v rails (that's certainly what I get from looking at the schematics, but then I'm not very good at this stuff!).

I'm hoping that means that Igor's design has saved me from worrying about having fried any components except ones in the DOA path, which would be great if that's true. It would certainly make debugging it easier...

Does that seem right to you? Oh, and thanks for the help Carsten, I'm not exactly a wizard when it comes to this stuff... ;-)

Kaz
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: taliska on February 19, 2014, 10:17:27 AM
before turning power on again, do some resistance checks to make sure there are no shorts/bad soldering.
Then test voltages without IC's & DOA's installed..

Will do. Might seem like a stupid question, but I just tested the resistance on the fried resistor and it seems ok...is it a bad idea to power up without replacing it? (as I don't have a replacement handy...)

Kaz
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: taliska on February 19, 2014, 11:37:06 AM
So I've carried on investigating, and seems that the problem is down to the (aptly named) albatross input amp.

Clearly I've used either a wrong component somewhere or installed something backwards. I checked both of my albatross builds, and they both exhibited the same problem, though the second one started smoking too which I guess is due to the 10R resistor being less effective at doing it's job due to fusing or something like that...

Anyway, I thought I'd post a pic of my albatross DOAs as an example of how not to build them! ;-)

If anyone can suggest what I got wrong that would be good, though my current thinking is just to use a different doa for the input amp for the time being... (FWIW, my current guess is that I installed the BD139s backwards...though now that I think about it, they're placed consistently with respect to the BD139 And BD140 on the IC output amp, and the modules with those amps in, don't smoke, so...)

Has anyone tried alternative DOAs for the input amp, and did they have any problems with them?

I picked up a couple of DIY-990s from hairball a while back which are supposed to be suitable for 24v operation with a couple of resistor swaps so I'm thinking I'll try those at some point...

Cheers,

Kaz
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: taliska on February 19, 2014, 01:54:03 PM
Ok, so I think I've isolated the problem with the albatross DOAs, but would appreciate confirmation of this as an issue or not, as I'll be building some new ones at some point, and I'd prefer to get them right this time! ;-)

So after examining the data sheet for the central semi 2N2484, I think that the emitter and collector might be switched with regard to the albatross DOA...

I've attached a grab of the data sheet for reference purposes composited with the top view of the albatross which I believe confirms it. Can anyone else confirm that they had to reverse their 2N2484s?

<edit>

Oh, and what are the chances that I've screwed the other components on the doa? I've ordered some new albatross pcbs, so I can build new ones if I need to, but if I can get away with just replacing the 2N2484s, then that would be awesome...

</edit>

Cheers,

Kaz
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: culteousness1 on February 19, 2014, 02:15:13 PM
I'm hoping that means that Igor's design has saved me from worrying about having fried any components except ones in the DOA path, which would be great if that's true.

Igor's design probably saved your PCB from being damaged, BTW.

And yes, it seems like your 2N2484 has a wrong pinout, i.e. emitter and collector swapped.
If you have any spares, you can put in a new one with the two pins changed. But used some
shrink tube for isolating the crossing leads. Maybe that's it.

Cheers!
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: taliska on February 19, 2014, 02:20:34 PM
I'm hoping that means that Igor's design has saved me from worrying about having fried any components except ones in the DOA path, which would be great if that's true.

Igor's design probably saved your PCB from being damaged, BTW.

And yes, it seems like your 2N2484 has a wrong pinout, i.e. emitter and collector swapped.
If you have any spares, you can put in a new one with the two pins changed. But used some
shrink tube for isolating the crossing leads. Maybe that's it.

Cheers!

Thanks for the confirmation. The bizarre thing is that I made the same mistake on my ic output amps too just because I'm using the same part, though for some reason they didn't go up in smoke...

For now, I guess I'm going to try and locate some of the pn2484s that have a better pinout as unfortunately I only order what I need per build...

Oh well...live and learn I guess. Hopefully this will stop someone else from making the same mistake at least! ;-)

Thanks for the help!

Kaz
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: taliska on March 23, 2014, 05:59:53 PM
Hi all.

Looking at my F76s again as my grayhills from digikey will be shipping this week, so I should be able to finish my units off and am looking at changing my input/output pots. The ones I've got are citeks that I ordered from Farnell in an attempt to mimic the original BOM, but they ended up being a bit tight fitting and I want to use something smaller.

Anyway, I've been looking around and found some potentially great pots from alpha (small and 5% tolerance!), but I'm a bit concerned about their power rating.

Can anyone tell me what minimum power rating I can get away with for the input/output pots?

I've looked at the audio schematic and it seems like they're just being used as voltage dividers after the THAT1246 and input amp respectively, but that's pretty much where my ability to work out what's going on ends!

I've looked at the THAT1246 data sheet, and it says "The 1240-series devices are typically capable of supplying 25 mA into a short circuit", but obviously that's the short circuit case they're talking about and I don't know what that says about normal operation. Assuming straightforward usage, the THAT1246 is probably configured for -6 dB operation. The data sheet also says: "For example, with ±18 V supply rails, the 1240-series parts have a maximum output signal swing of +23 dBu". Now I don't really know my decibel related units at all, so I just had to google for a calculator like this one: http://www.sengpielaudio.com/calculator-db-volt.htm (http://www.sengpielaudio.com/calculator-db-volt.htm) and type in some numbers which gave me 30.947147054 volts peak to peak. Now I know that P = IV, so that suggests that power = 31 * 0.025 for the short circuit case, which is 0.775 watts but that seems pretty huge. Can anyone help me with the methodology? I'd rather know how to work this stuff out so that I can feel confident about the result rather than just choosing a suitably big potentiometer with regards to power rating and trusting to luck...

I've also had a think about the output of the IJ input amp stage, but I'm at a loss with this one unfortunately. Help on what power rating the pot should have would be appreciated...

It seems like the smaller ones have lower power ratings, so I just want to make sure they can handle it. Obviously bigger power rated pots are available, but they tend to be larger in size too...

FYI, the ones I'm looking at are these: http://uk.mouser.com/ProductDetail/Alpha-Taiwan/RV120F-10-15F-A10K/?qs=%2fha2pyFadugrQN9O93rLvSvPxd4VhM3GzU2Z7E8cvnKWhZmlVeObpw%3d%3d (http://uk.mouser.com/ProductDetail/Alpha-Taiwan/RV120F-10-15F-A10K/?qs=%2fha2pyFadugrQN9O93rLvSvPxd4VhM3GzU2Z7E8cvnKWhZmlVeObpw%3d%3d)

but notice that their power rating is only 40 mW (but their tolerance is 5%!).

Thanks for any and all help,

Kaz
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Harpo on March 28, 2014, 08:52:17 PM
"For example, with ±18 V supply rails, the 1240-series parts have a maximum output signal swing of +23 dBu". Now I don't really know my decibel related units at all, so I just had to google for a calculator like this one: http://www.sengpielaudio.com/calculator-db-volt.htm (http://www.sengpielaudio.com/calculator-db-volt.htm) and type in some numbers which gave me 30.947147054 volts peak to peak.
..giving a max.15.5V peak voltage across the pot. The 10Klog pot will need a power rating of at least 15.5V^2/10Kohms=0.024W, so your 40mW rated pot will do.
"The 1240-series devices are typically capable of supplying 25 mA into a short circuit" tells you the chips max.drive ability. The min.resistive load to not exceed the chips limits would be 15.5V/0.025A=620R. Your 10K input volume pot in its CW position is in parallel to the series connected resistors R6 and R8, giving 1/(1/10000+1/(27000+10000))=7872R, so no problem expected.
Quote
I've also had a think about the output of the IJ input amp stage, but I'm at a loss with this one unfortunately. Help on what power rating the pot should have would be appreciated...
Output voltage of the preceding stage will not be higher than its supply voltage. Worst case steady clipped signal might be (more unlikely, there will be diode drops within the preceding amp stage) at the +18/-18V supply rails, the pots min.required power rating would be 18V^2/the pots resistive value, maybe again 10K, giving 0.0324W. Again your 40mW rated pot would do, if its example value would be 10K. Just substitute your values for voltage and selected pots resistance with previous example values to run your numbers.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: taliska on March 29, 2014, 05:47:24 PM
"For example, with ±18 V supply rails, the 1240-series parts have a maximum output signal swing of +23 dBu". Now I don't really know my decibel related units at all, so I just had to google for a calculator like this one: http://www.sengpielaudio.com/calculator-db-volt.htm (http://www.sengpielaudio.com/calculator-db-volt.htm) and type in some numbers which gave me 30.947147054 volts peak to peak.
..giving a max.15.5V peak voltage across the pot. The 10Klog pot will need a power rating of at least 15.5V^2/10Kohms=0.024W, so your 40mW rated pot will do.
"The 1240-series devices are typically capable of supplying 25 mA into a short circuit" tells you the chips max.drive ability. The min.resistive load to not exceed the chips limits would be 15.5V/0.025A=620R. Your 10K input volume pot in its CW position is in parallel to the series connected resistors R6 and R8, giving 1/(1/10000+1/(27000+10000))=7872R, so no problem expected.
Quote
I've also had a think about the output of the IJ input amp stage, but I'm at a loss with this one unfortunately. Help on what power rating the pot should have would be appreciated...
Output voltage of the preceding stage will not be higher than its supply voltage. Worst case steady clipped signal might be (more unlikely, there will be diode drops within the preceding amp stage) at the +18/-18V supply rails, the pots min.required power rating would be 18V^2/the pots resistive value, maybe again 10K, giving 0.0324W. Again your 40mW rated pot would do, if its example value would be 10K. Just substitute your values for voltage and selected pots resistance with previous example values to run your numbers.

This is really great. Thanks for the guidance Harpo!

I completely failed to notice the max. voltage across the pot will be the half wave (must have been half asleep).

The rest of your calculation seems to be from P = IV & I = V / R, which gives P = V * (V/R), which is obviously just P = V^2/R. I'm new enough to this stuff that I'm struggling to think things through properly, so I really appreciate the pointers.

So, as you said, the 10K log pot should be fine for the input control, as the balanced line receiver is only running at +/-16v anyway. Just for others building this, here's a link to the pot in question which is nice and small with good tolerances.

http://uk.mouser.com/ProductDetail/Alpha-Taiwan/RV120F-10-15F-A10K/?qs=%2fha2pyFadugrQN9O93rLvSvPxd4VhM3GzU2Z7E8cvnKWhZmlVeObpw%3d%3d (http://uk.mouser.com/ProductDetail/Alpha-Taiwan/RV120F-10-15F-A10K/?qs=%2fha2pyFadugrQN9O93rLvSvPxd4VhM3GzU2Z7E8cvnKWhZmlVeObpw%3d%3d)

The output pot comes after the input DOA, which in my 51x rack will be running at +/-24V, so I think using your logic and calculations that comes out a bit too high to use the same pot as the input pot. 24^2/10000 = 0.0576W. Luckily, I've already ordered and received some replacement pots which are suitable to use instead. They're a bit more expensive, but they're nice and small with 1.5W ratings and 10% tolerance, so I'm going to use those for the output controls.

For the benefit of other builders, the other 10K pots I'm going to use for the output control are:

http://uk.farnell.com/jsp/search/productdetail.jsp?id=8795762&Ntt=8795762 (http://uk.farnell.com/jsp/search/productdetail.jsp?id=8795762&Ntt=8795762)

Notice that the heading on that linked pot says linear, but that the description and product code confirms that it's actually a log pot. I've got pots like these ones (vishay/sfernice PRV6s) in the past from mouser for the EQN build, so you can probably find them there if you want to get all the pots for the project in the one place (I generally do all my ordering with mouser because their project management stuff is better than farnells, but got them from farnell in this case as it was just a small order to make up for my own mistakes!).

Anyway, thanks again for the help Harpo. With any luck I'll have my two F76s running by the end of the weekend! ;)

Kaz
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: bruce0 on April 08, 2014, 03:22:04 PM
Finally built my stereo F76 modules.

Definitely read Chunger's excellent advice on http://studio939.blogspot.com/2012/08/ij-research-f76-compressor-build.html (http://studio939.blogspot.com/2012/08/ij-research-f76-compressor-build.html) it helps a lot.   Build is straightforward, but having the pictorial guide and suggestions really helped with the fit.

Here is my build so far.  Sill missing some parts, but I am awaiting them eagerly.
(http://i1221.photobucket.com/albums/dd463/Bruce0/2%20-Build%20Logs/F76%20build/B5F2F616-EABE-4382-BBE9-69E8A256C568_zpsvky6pqvq.jpg)

Builders that bought from Ramshackles are lucky, the service is better, they get fast shipping from Ramshackles and the board are nice.

PS:  If there are remaining poor souls that bought the kit from Igor, I have a list of the missing components in that kit.  PM me and I will provide that list, which will save you some time.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: ramshackles on April 10, 2014, 02:56:17 PM
Thanks for the BOM updates Bruce.
Igor seems to have been a little lax in the accuracy of BOM's and I have not yet built all his projects that I sell boards for, so if you do find discrepancies or odd bits that you dont understand please give me a shout and I will have a look at it.

Also, if you are building from an old version of the docs, do have a look on our website at the docs - we have updated docs/easy-to-read BOM's for most of the projects and on some projects there are additional docs that Igor didnt release initially.

We also maintain & update a 'hard-to-find-parts' and replacements guide so have a look there (and give us more suggestions!)

Chungers guide(s) are really awesome, so this project is lucky to have one for it.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: bruce0 on April 30, 2014, 05:37:08 PM
Adjusting my "Bias" I find I am a bit confused.  The idea if I understand it is to do the following:

Feed it a -20dB signal
Max the input
Adjust Attack for Min (fastest? right?)
Adjust Release for Max (slowest? right?)
Adjust output for a 1.23V RMS

THEN
install the 2 FETs and adjust the BIAS trimmer for -1dB.

The problem I am having is the confusing use of dB scales.
 
Am I always using 0dB=1.228V RMS?
in that case the Bias would be adjusted to output 1.094V RMS and the input signal would be 0.123V RMS
That is what I have done for now.

Or should I be using the other scale in which case I output +4dB (1.228V RMS)
and the Bias would be adjusted to output .690V RMS and the input signal would be 0.078V RMS


Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: slegg on May 27, 2014, 07:21:04 AM
Hi everybody,

I've got a question .... for Cascode OPamp, 2SK170 BL or GL ?

Thanks thanks !!
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: taliska on May 30, 2014, 07:06:16 PM
Hi everybody,

I've got a question .... for Cascode OPamp, 2SK170 BL or GL ?

Thanks thanks !!

I used GR...seemed to be what Chunger had when he built his F76 and his kit came straight from Igor...so...
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: slegg on June 01, 2014, 04:08:21 AM
Thanks taliska,
I'll build one with BL and one with GR. I'll tell you the difference if I hear it !!!!
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: KDE on July 12, 2014, 02:38:19 PM
Selling some hardware kits that i had made up for these that i am no longer using. http://groupdiy.com/index.php?topic=56693.0 (http://groupdiy.com/index.php?topic=56693.0)


(https://imagizer.imageshack.us/v2/960x640q90/819/4xk9.jpg)

(https://imagizer.imageshack.us/v2/960x640q90/829/ewlr.jpg)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: qmp audio on July 23, 2014, 01:36:41 AM
Hello all!  i have successfully built 2 from igor's kits.   i am now sourcing parts to build another 2 from igor's pcb.

1.  does anyone have a US source for the ribbon cable and connectors?  i'm having a hard time finding those.

2.  does anyone have a US source for the toggle switches?  i can't find a US source for the MULTICOMP switches in the BOM.  these look close,  but I'm unsure if they will fit.
http://www.mouser.com/ProductDetail/NKK-Switches/M2012S2A2G30/?qs=sGAEpiMZZMvudeGI7i40XM9lbS6CChc2ssS0Egwjy%252bw%3d

3.   same with the LEDs... anyone gotten those flat leds from a US source?

4.  the IGOR bom lists 10k pot for output.  the 1176f schem lists 100k pot.   curious why the f76 uses a 10k pot.   

5.  I'd like to make the controls function as close as possible to a revF, so i'm planning on using pots for the attack/release (5M and 25k).   i understand it as the f76 has SLOW at the CW position.  To make these function like an 1176 so that FAST is at CW,  is it as simple as reversing the connections?

6.   the bom lists TL074P for IC6.  will any TL074 work there? ( can't find a P version ).  Like this one?
http://www.mouser.com/ProductDetail/Texas-Instruments/TL074ACN/?qs=sGAEpiMZZMtCHixnSjNA6P3Ssczg4flJ4b0Fos4RBXg%3d

Thanks much everyone.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: taliska on July 23, 2014, 02:59:31 AM
Hello all!  i have successfully built 2 from igor's kits.   i am now sourcing parts to build another 2 from igor's pcb.

1.  does anyone have a US source for the ribbon cable and connectors?  i'm having a hard time finding those.

I got mine from Farnell in the UK, but was feeling helpful so I tried finding some on mouser. I think this is what you need for the header:

http://uk.mouser.com/ProductDetail/FCI/66506-001LF/?qs=sGAEpiMZZMs%252bGHln7q6pmxAVkKtOEC39x%252bMZRvPovBI%3d

And this would be the female part:

http://uk.mouser.com/ProductDetail/FCI/66900-310LF/?qs=sGAEpiMZZMs%252bGHln7q6pmxAVkKtOEC3902NCbcFrx9I%3d

And perhaps this for the cable (or something like it!):

http://uk.mouser.com/ProductDetail/3M-Electronic-Solutions-Division/3365-10-CUT-LENGTH/?qs=sGAEpiMZZMsJiFh04Lj2rqE9WUkL5fzVjO%252b525M71nY%3d

But obviously I haven't used those myself, so you should check the datasheets just to be sure. ;)

Quote
2.  does anyone have a US source for the toggle switches?  i can't find a US source for the MULTICOMP switches in the BOM.  these look close,  but I'm unsure if they will fit.
http://www.mouser.com/ProductDetail/NKK-Switches/M2012S2A2G30/?qs=sGAEpiMZZMvudeGI7i40XM9lbS6CChc2ssS0Egwjy%252bw%3d

I seem to remember there being some digikey part numbers in the original BOM for those, but haven't got it to hand myself...

Kaz
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mtw on July 23, 2014, 12:57:01 PM
2.  does anyone have a US source for the toggle switches?  i can't find a US source for the MULTICOMP switches in the BOM.  these look close,  but I'm unsure if they will fit.
http://www.mouser.com/ProductDetail/NKK-Switches/M2012S2A2G30/?qs=sGAEpiMZZMvudeGI7i40XM9lbS6CChc2ssS0Egwjy%252bw%3d

Looking very very closely at Chunger's build photos I think I was able to determine a proper part and found these switches on Mouser:

http://www.mouser.com/ProductDetail/CK-Components/E101MD1AGE/?qs=%2fha2pyFadui7fmXg5D5VHzeYUMlC3Wv6jFoQNk4twq0%3d

Maybe take a look at the datasheet and measure the lead spacing?  I'd do it myself but I'm at work and the PCBs are at home.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: qmp audio on July 23, 2014, 04:32:46 PM
Thanks!  Very helpful.  What value for output pots did any of you use?  The BOM states 10k,  but the digikey PN txt lists a 100k.   Igor mentioned in this thread he used 10k w/ a resistor for <40db attenuation.  I suppose i could try both and see which I like better.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: taliska on July 27, 2014, 06:24:37 PM
Thanks!  Very helpful.  What value for output pots did any of you use?  The BOM states 10k,  but the digikey PN txt lists a 100k.   Igor mentioned in this thread he used 10k w/ a resistor for <40db attenuation.  I suppose i could try both and see which I like better.

The two I built used 10K logs for input and output, and grayhills for everything else, so strictly by the book and work perfectly and sound great to me.

I love these compressors...just wish I had a need for more than two of them! ;)
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mtw on July 29, 2014, 12:00:58 AM
2.  does anyone have a US source for the toggle switches?  i can't find a US source for the MULTICOMP switches in the BOM.  these look close,  but I'm unsure if they will fit.
http://www.mouser.com/ProductDetail/NKK-Switches/M2012S2A2G30/?qs=sGAEpiMZZMvudeGI7i40XM9lbS6CChc2ssS0Egwjy%252bw%3d

Looking very very closely at Chunger's build photos I think I was able to determine a proper part and found these switches on Mouser:

http://www.mouser.com/ProductDetail/CK-Components/E101MD1AGE/?qs=%2fha2pyFadui7fmXg5D5VHzeYUMlC3Wv6jFoQNk4twq0%3d

Maybe take a look at the datasheet and measure the lead spacing?  I'd do it myself but I'm at work and the PCBs are at home.

OK - I took a look at the data sheet and measured the holes on the PCB - these should fit.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: qmp audio on July 29, 2014, 03:29:17 PM
OK - I took a look at the data sheet and measured the holes on the PCB - these should fit.

Excellent.  Thanks for checking, that is very helpful.    Ok,  i have my entire mouser bom put together... except I am not skilled enough to now how to choose replacements for the transistors on the igor cascode amp.  I may just end up using 'original' amps,  but would like to try the cascode amps also.

the following seem to be unavailable.   What have you all been using?  will bc550 replace the 2484 if reversed?  What about a replacement for the 2SK170?
2SK170
2484
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mtw on July 29, 2014, 03:43:10 PM
I just sent payment for 2 x 2SK170 to the fellow that runs https://sites.google.com/site/diypartsstore/catalog/transistors-diodes

As far as the 2484 goes I think this Mouser part number will work? 610-2N2484
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mtw on July 29, 2014, 04:14:06 PM
Whoa there!

I was just re-reviewing this thread, and it looks like Taliska found that the emitter and collector on the Albatross PCB are swapped with regards to the Central Semiconductor pinout:  http://groupdiy.com/index.php?topic=43338.msg706062#msg706062

so... caveat applumbator!!
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mtw on July 05, 2015, 05:39:25 PM
Hi All,

Wow, this is one of those projects that has dragged on for ages for me...

Anyway I'm working on getting one of my units calibrated, which I'll call unit A.

Here's what I've done:


I'm using a JE-990 output DOA from Hairball configured to work at 24v.

While I was double checking the board, C15 and one of the 2484s on the output DOA blew out. (Loud POP from the capacitor and the 2484 is leaking some fluid.)

So... I have no idea what to do about this 8V output issue. Unit B exhibits similar behavior so I've obviously done something incorrectly on both motherboards, but I don't even know where to start looking.

Has anyone seen this behavior before? If so, did you debug it and figure out what was wrong?
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: mtw on July 05, 2015, 06:15:13 PM
some further debugging:

I removed the output DOA and left the input, turned input pot to max and measured the OUT terminal of the input DOA with the following (1k sine) signals (and results):

IN voltageOUT voltage
0.01V RMS0.2V RMS
0.1V RMS1.8V RMS

I then turned the output pot all the way up and measured +IN at the output amp terminal - it reads the same as the OUT terminal.

I also removed R11' (560k resistor on the underside of the mother board) - similar results.

Seems to me the problem probably lies with the 990 DOA.

Do these values seem sane?
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: baloubass on November 15, 2017, 01:41:40 AM
Hi guys, does anyone have the documents for this build? The link in post 1 are dead.
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: ramshackles on November 15, 2017, 12:12:59 PM
Ill get them online soon
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Mike Havok on September 12, 2019, 02:46:07 PM
Apologies for the necro, but does anyone have the build docs for this?
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: TillM on September 12, 2019, 03:52:17 PM
Chunger do a guide on his page.
http://studio939.blogspot.com/2012/08/ij-research-f76-compressor-build.html
Title: Re: 1176 in 51x/500 format, or 51X-F76 Build Support Thread
Post by: Mike Havok on September 12, 2019, 05:10:20 PM
Thanks