All things G1176 - the new "repost" thread.

[byoung]

I've got my G1176 completed, actually it's been completed for a while, but now I'm wondering if it is either not working as it should, or is miscalibrated.

I never had a chance to use a real 1176 until recently, just the bomb factory plugin which I heard didn't emulate it well.  I was always wondering what this 'distortion' and 'british mode' was all about until I tryed a real 1176(I think it was a reissue, looked pretty new). With the real 1176 I was able to dial up a saturation type distortion(almost a bit like mild tube overdrive) very easily and change the timbre of it with the attack and release knobs, it was really interesting, I could keep it clean by keeping the Input level roughly below 10 o'clock, and then when I pressed in all buttons I was quickly reminded of a fuzz bass sound I have heard so many times on old rock tracks.  I can't get anything like that with my g1176.

When I got back to my studio I tried my 1176 emulating plug ins and the closest I can come to the 1176 hardware unit I used was the Bomb factory Purple 76, yet my G1176 sounds like the McDsp compressorbank Solid state.

My G1176 compresses and is extremely clean, the only way I can get any distortion on this thing is to bypass the gain reduction and turn the input up really high with the output down so I don't kill my converters. I've checked my wiring for the nuke setting and it all checks out but it doesn't seem to do anything soundwise more than the 20:1 setting. So am I crazy or is this what I should be hearing?

Brian

 

[byoung]

Can anybody tell me if there is a way to know that my 'all buttons' mode is working properly on my unit?  I've quadruple checked my wiring and it seems to be right. What should I be hearing?  Also when I select 'all buttons' mode my meter will just peg as high as it will go until it gets a signal, then I have no idea if the gain reduction being displayed is accurate. Is this how it should be behaving.

 

[casrec]

Can anybody tell me if there is a way to know that my 'all buttons' mode is working properly on my unit?  I've quadruple checked my wiring and it seems to be right. What should I be hearing?  Also when I select 'all buttons' mode my meter will just peg as high as it will go until it gets a signal, then I have no idea if the gain reduction being displayed is accurate. Is this how it should be behaving.

    This is completely normal. In all buttons in mode there is no real accurate way to see how much gain reduction is taking place off the meter. All buttons in mode is basically 7,500;1 ratio. With the input turned to about 1 o'clock or higher the source should start to sound squished and depending on timing settings you should start to hear it pump. This is a great effect for drum room mics and even parallel bass mix's to get nice fat distortion sound behind the bass. Sounds like you have calibrated right. Mess around with it and experiment!

Brandon

 

[orangerec]

ok, I really tried to troubleshoot this on my own. Yes, I have searched the forum. This is the 3rd 1176 I've built but with an issue. It's an mnats Rev J with Lundahl in/out xfrmrs. The input is wired normally and the out is at the 1:2. My voltage -10 and +30V are spot on. My main issue is it has really low output. It is compressing but for troubleshooting purposes, I have it on bypass, just running through the amp stage and I have to crank the output all the way up to be as loud as the source. I have replaced Q1-9 already in the preamp and line amp stage and their voltages are within limits. I have also experimented with jumping pad  15 to 17 feeding the preamp directly into the line amp, feeding the output and still low gain and a bit of distortion. Calibrating the Q Bias is for the gain control amp, correct? This shouldn't have an effect if the unit is in bypass and I'm just concerned with the line stage, or is this incorrect?

Thanks in advance,

Tony

 

[gswan]

Calibrating the Q Bias is for the gain control amp, correct? This shouldn't have an effect if the unit is in bypass and I'm just concerned with the line stage, or is this incorrect?

Incorrect. The calibration of Qbias is done in bypass mode, and is necessary to place the FET just into conduction. If this is done incorrectly, or with a leaky or damaged FET then it is possible your input will be severely attenuated. Pull the FET out and check the gain of the unit in bypass mode.

 

[orangerec]

Thanks for replying gswan. I pulled Q1 Fet out and the level definitely gets louder but with distortion. Sounds like odd order harmonics, clipping.

 

[gswan]

Pull out the scope and start probing. Check the signal at the input pot, the output pot and the output to find out which stage is giving you problems. Then you can start looking at components in that stage.

 

[orangerec]

Thanks, I got to get a scope. Building gear without a scope is probably not the best thing. I will figure this out.

 

[guitarguy12387]

Hey everyone,

Well i just got a chance to compare my g1176 to a UA reissue the other day and i was looking to make a few small modifications to mine. First, the output level of mine was still pretty weak. I AM using a lundahl on the output wired 1:2, but it still seems a little lacking. I think i read that lowering R33 would increase the gain. Anyone tried this? If it works, what value should i change to? Also, i was hoping to get a little faster release times. Looking at the schematic, if i increase R79, that should increase my release time constant, correct? Any suggestions on what value i should use? Thanks!

 

[orangerec]

Hi guitarguy12387,
As you could see in my previous post, I'm experiencing a low output also. Especially compared to my RevA, RevD and an original 1176. I'm building a dual Rev J and have swapped out almost everything, my voltages are perfect but low gain and distortion if driven a little hard. I'm starting to wonder if this is a G1176 or RevJ, which I think are the same beast, thing? Anyone who's built different Revs want to chime in?

 

[casrec]

Hi guitarguy12387,
As you could see in my previous post, I'm experiencing a low output also. Especially compared to my RevA, RevD and an original 1176. I'm building a dual Rev J and have swapped out almost everything, my voltages are perfect but low gain and distortion if driven a little hard. I'm starting to wonder if this is a G1176 or RevJ, which I think are the same beast, thing? Anyone who's built different Revs want to chime in?

  As I am aware of it, mnats rev J is the G1176 slightly modified, and the G1176 is based off Rev F and K from the Urie schematic. I have built the mnats rev J and and two of my own design. Neither had a low output and they acted as a 1176 should. sounds to me like something is faulty or not wired right.

Brandon

 

[herrmann]

Hi everyone,
I've build a stereo 1176, and since a few weeks, one channel have lost high frequencies and starting to buzz. I've checked voltages, all seems to be fine.
It's a Mnats rev J board, with 1540 transfo In, and OEP Out.
Perhaps a transfo is dead? How to test it?
Thanks

 

[guitarguy12387]

Thanks guys. Yeah, in the meta, there's a thread addressing the low gain and it suggested that the g1176 does in fact have 6db lower gain than the original, but this is addressed by putting the output lundahl in backward (1:2). I did this from the start.  And the comp still works just fine otherwise... just tryin to bump up the output a bit. I'll double check a few things and go from there.

 

[gswan]

Hi everyone,
I've build a stereo 1176, and since a few weeks, one channel have lost high frequencies and starting to buzz. I've checked voltages, all seems to be fine.
It's a Mnats rev J board, with 1540 transfo In, and OEP Out.
Perhaps a transfo is dead? How to test it?
Thanks

Unlikely to be a transformer, however that depends on what you've been doing to them.
Inject a signal and run the usual test diagnostics through the stages and see where the problem is.

 

[orangerec]

aggghhhh...
I'm ordering a scope next week. this 1176 is driving me crazy. I can't sleep or concentrate an anything else. Curse the DIY! :'(

I just finished calibrating it again and it sounds fine with snare but it can't handle low Hz info. A bass with about 4dB of GR @ 4:1 distorts. A 50Hz tone does the same. All my voltages across all transistors and FETs are within .5-1V. I'm assuming this is tolerable? I want to think it's in the pre-amp section but won't know for sure till I have a scope.

-venting

 

[gswan]

Does it distort when GR is bypassed?
0.5-1V can be quite a difference, what % difference are the bias voltages to their nominal values? Anything more than 5% may deserve scrutiny.

 

[orangerec]

Yes it does distort in bypass, even worse because there is no GR. I have started measuring the transistors again and there either spot on or off by 5%, except Q8 and Q9. I will swap it out again, third time, and recheck. This may be it, maybe it's not Q8 Q9 but what's leading to them. I'm at work, will check later. Thanks.

 

[casrec]

This might be a stupid reply but have you checked the distortion trimmer pot?

Brandon

 

[orangerec]

CAN YOU SAY R40 & R41!!!!!!!!!
4.3 OHMs not 4.3 kOHMs!!!!!! Bangin' head against the wall. Big dummy!!!!! I can't believe how much I've learned through this.
It sounds EFFIN great. Thanks for the support guys.  ;D

Tony

 

[gswan]

'tis an easy mistake to make. Always measure (with a meter) the resistance before insertion and save your head (and the wall).