All things G1176 - the new "repost" thread.

[gswan]

Here's my DC voltages for the transistors:
B          C          E
q2 1.038 1.727 0.556
q3 1.727 11.91 1.144
q4 11.91 29.71 11.32
q5 3.453 27.91 3.211
q6 16.28 27.91 28.46
q7 16.28 28.46 29.1
q8 29.71 16.29 15.69
q9 0.7         15         15.68
q10 13.66 12.9         12.9

q12 4.39         14.86 3.84
q13 14.86 29.72 14.24
q14 3.393 16.47 2.824
q15 16.46 29.72 15.9

I have not actually measured the output of each stage, but both input and output knobs seem to be working fine.  I will check this next.

When I try to calibrate, I send a tone out with the unit in bypass, output at about halfway, adjust the input knob so the tone is coming back at 0.
I then attempt to turn the qbias trimmer until I see a 1db drop in level, but nothing happens

You have a problem around Q5. The voltages from here to Q8/Q9 are not right. Check the resistors. Do not bother with calibrations until you have the circuit working correctly.

 

[trapiche2]

Hello everybody!
I have a doubt about the functioning of my g1176.
With piano and electric guitar with fast attack and release it has a sound a bit "harsh."
The harsh sound almost disappears under low attack and / or release ...
Is this distortion normal?
I leave the audio samples so they can listen!

ratio 1:20 fast attack and release
http://www.4shared.com/audio/Qcp1Cg8H/1-20.html

ratio 1:4 fast attack and release
http://www.4shared.com/audio/SfbO62yP/1-4.html

gain reduction disable
http://www.4shared.com/audio/9oIFqV2U/gr-disable.html

Thanks!!!

 

[schrobbelbop]

If I put my G1176 revJ to its fastest attack and releases
is distorts a tiny bit, similar like yours but not that much.

In never use fast attack times so i don't bother it just
sounds great.

 

[dgoszillai]

Thx mac for your answer
again i apologies for my silly questions it's my first DIY and my english is not great specially in electronic

yeah i saw this wireing guide but don't find all answers
in the picture your posted i see R89 & R87 are populated :S
but on mnats guide for little PSU i see they are not .. so hu... what should i do


here is other questions :

on mnats wireing guide i don't see switchs like i have on my panel (ordered from purusha) for bypass-comp / off-on / dual-link what type of switches i need for that ? 2 position but how much poles (3 or 6) is there a guide to wire these switches ?
about those switch again i see a "shaft" value on the shops that sells switches. what is it exactly ? the size of the hole needed to fit the switch in ?

ok last question for now :what (the hell) is :C* C*1 C*2 C*3 C*4 ?
i use OEP A262A2E and little PSU so do i need to populate those ? C*4 seems for power so i don't need it but anyway i can't find C*4 on pcb...

: yeah i realize maybe this diy is a bit hard for me but now that i started ...

 

[schrobbelbop]

Who knows the best way to power my VU led's in an dual 1176?
Do i need some diodes and resistors and take it from the power trans?
or can i just grab the -10V line from my external psu board?

 

[gswan]

Who knows the best way to power my VU led's in an dual 1176?
Do i need some diodes and resistors and take it from the power trans?

Yes. Use a current limiting resistor and a reverse bias diode across the LED for an AC supply.

or can i just grab the -10V line from my external psu board?

No. Don't do this.

 

[schrobbelbop]

So I need to drop down to 12V for the hairball meters i think those 2 leds are connected
in series. What if i put those 2 vu meter each 12 volts in series, i guess i only need an diode?
the 1n4003 should work? anyone made this circuit before?

 

[trapiche2]

If I put my G1176 revJ to its fastest attack and releases
is distorts a tiny bit, similar like yours but not that much.

In never use fast attack times so i don't bother it just
sounds great.

Thank you very much!!!
... Do you think I have something wrong?

 

[aclac]

HI. I wonder, that how important is and WHY have remove R44 an calibration situation as instructions says and when I can put it back? After last calibration or after first, Q-bias cal? Anyway, I have found lots of calibration instructions, but they all are hmm... different and it is hard to get right ones.

 

[gswan]

All the Qbias calibration procedures end up doing the same thing.

 

[aclac]

All the Qbias calibration procedures end up doing the same thing.

YEAH, but some cases no, if I can't trust my cheap VU-meter Can you give some information, that shall I remove R44, as some procedures says, or shall I do like Gyraf says (don't mention on R44 in calibration procedure "four adjustments"). I calibrated mine 2 units (rev J) last winter, and noticed, that second one must recalibrated again... because relase button get it compress -20dB or even more nowdays. There might be something wrong in my unit 2...

 

[cmuller0420]

I finished putting together a Rev J 1176 fom mnats....from intial testing the unit is "working"

I am currently waiting on a VU Meter to arrive to start the calibration or the unit.  From testing so far the input and output level pots, attack, release, ratio selection and the meter select seems to work (for the meter select from no GR to a meter mode enables/disables the gain reduction.

However there are a few issues:

Q2          Q3          Q4          Q5          Q6            Q7            Q8            Q9            Q12        Q13          Q14              Q15
B 1.01V  B 1.76v    B 12.0V    B 4.92V    B 28.18V    B 28.74V  B 14.45V    B 13.22V    B 4.52V    B 15.11      B 3.46V        B 16.81
C 1.76    C 12.0    C 29.9    C 28.18    C 14.45      C 14.45                                    C 15.11    C 29.9      C 16.81        C 29.9
E 0.52                  E 11.39    E 4.48      E 28.74      E 29.39    E 13.87      E 13.82      E 3.922    E 12.5                          E 16.24


It seems that most values are down by 400-500mV, which could be accounted for by the +29.9V/-9.80V supply rails instead of the 30.3 on the schematic given.

The 2 issues I have found is that I have a loew frequency rolloff starting at aroun 700Hz, gradual but by the time it get doen to 200hz and below it is quite framatic.  I ran a 1kHz sin wave through the 1176 and scrolled from 20Hz, to 20kHz ..the top end is fine

I am running an unbalanced signal in from my signal gen and am coming in on the positive pin of the input XLR...and the output signals are different by alot...

with 0.775V coming in (and output and input level set to match the input level on the output - pin) I am getting on the negative pin 0.775V (approx)  and 1.128V on the positive output pin (using lundahl output xfrmr)...and I have no idea why other than possibly  biasing issue with my measured voltage levels being off.  I have gone through and checked all of the biasing resistors and found 1 or 2 bad ones nd they have been replaced.

Other than these two issues the unit seems to be functioning okay so far

 

[dgoszillai]

huu... if anybody can answer one of there  ;D would help alot
http://www.groupdiy.com/index.php?topic=646.msg499983#msg499983

 

[aclac]

HI. I have done calibration mine rev.J (2 unit, OEP), and they work well... exept one thing. Other unit start compress -6 dB, when I turn relase- knob from right (fast) to up or more left (slow) side...? I have calibrated it many times as the other unit and no idea, what is wrong? Maybe Q10 and Q1... maybe they should be more like 'matched'?

 

[mac]

Hey Dgoszillai - sorry I missed your post...

in the picture your posted i see R89 & R87 are populated :S
but on mnats guide for little PSU i see they are not .. so hu... what should i do

Sorry - Pic is misleading - you dont need to be populated if you are using off board PSU, I left them on mine but it shouldnt matter if the reg is removed.

on mnats wireing guide i don't see switchs like i have on my panel (ordered from purusha) for bypass-comp / off-on / dual-link what type of switches i need for that ? 2 position but how much poles (3 or 6) is there a guide to wire these switches ?
about those switch again i see a "shaft" value on the shops that sells switches. what is it exactly ? the size of the hole needed to fit the switch in ?

There is no details for every different way of controlling these features, and I dont know how your front panel is laid out but if you re-read Gyrafs docs things will make more sense. For mine http://www.groupdiy.com/index.php?topic=646.2580 (middle of page) I used DP3T switches and for the Link switch I just used a single pole DT toggle, and for my bypass / compress I used a DPDT toggle. READ PAGES 126 - 130 OF THIS THREAD to see how I figured mine out.

ok last question for now :what (the hell) is :C* C*1 C*2 C*3 C*4 ?
i use OEP A262A2E and little PSU so do i need to populate those ? C*4 seems for power so i don't need it but anyway i can't find C*4 on pcb...

From memory the "*" components are optional and I had C* and C*1 as 100uf /35v electrolytics,c*2 and c*3 as 0.1uf poly - I dont remember C*4...

hope this helps a bit...


Mac

 

[aclac]

HI. I have done calibration mine rev.J (2 unit, OEP), and they work well... exept one thing. Other unit start compress -6 dB, when I turn release- knob from right (fast) to up or more left (slow) side...? I have calibrated it many times as the other unit and no idea, what is wrong? Maybe Q10 and Q1... maybe they should be more like 'matched'?

OK, I changed Q10, and... HEUREKA! This problem went the other kind. I first calibrated my unit. And then turn release from CW to CCW, VU-meter get +5 dB more, BUT it doesn't effect the output anymore? Maybe somebody can get the point of this and tell me what is going on?

 

[myker]

hey guys, i hope im not being rude by not reading the entire 150+ pages of this thread before asking...

1. do we have an accepted standard test for the rev J for the gain reduction tracking?

2. When i push the GR button with signal running through the compressor the needle just goes to 0, isnt it supposed to keep dancing around indicating the amount of GR?

Thank You,
Mike

 

[gswan]

1. do we have an accepted standard test for the rev J for the gain reduction tracking?

Yes.

2. When i push the GR button with signal running through the compressor the needle just goes to 0, isnt it supposed to keep dancing around indicating the amount of GR?

Yes.

 

[myker]

very very cool, thank you

1. where can i find this info? link or page number?
-mike

 

[gswan]

Try here. This is a bunch of stuff I put together specifically for this project.

http://www.axtsystems.com/index.php?option=com_content&view=category&id=34:1176ln&Itemid=62&layout=default