All things G1176 - the new "repost" thread.

[Esset]

[quote author="Esset"]
The other one, passes audio, all pots, the meter and switches work, but the audio is heavily distorted and no bass-frequencies.

...

EDIT: Using Lundahl output transformer and IC-based input[/quote]

Any ideas or thoughts about the distortion? It distorts even with all pots fully CCW (and CW if the pots where to be faulty connected)

 

[gyraf]

Esset,

Check the complete signal path again. Trace the signal through the unit to find out where it's going wrong. I think we have a signal-tracing question somewhere earlier.

As you will see if you read this whole thread, nearly all errors are

- Wrong components
- Wrong orientation of components
- Solder bridges shorting on pcb
- Bad wireing
- Bad soldering/left-out solder points

..in more or less that order..

Jakob E.

 

[thedug]

I'm getting distortion on my 1176.

I am running a 1k tone through it and when the signal hits about -6dB on the console I start to hear distortion. This is happening even in bypass mode.

I did the transformer mod.

 

[matta]

Hey Guys,

Does anyone know if I can power up my G1176 without a meter just to check it
passes audio and compresses?

I know that I won?t be able to set the bias without the meter, I?m just
stuck for money now and will only be able to get the meter in December. Do I
need to wait to have the meter before trying the unit out if I have built
the rest of the unit?

Also I noticed in another post that someone mentioned you don?t need the
mu-metal case for the OEP for Mnats boards, anyone tried this? If I can
loose it it would save a few bucks.

Thanks

Matt

 

[FotisGR]

You don't need it for now. You can easily set bias using a software metering. Giving a signal input like Jakob say and just set bias for 1db drop down out on your sound card's meters. Also for reading gain reduction you can use every vu that you want . I always use dc vu meters ( without diodes ) . They work absolutely perfect, exept vu reading. If you want vu reading use sifam or dc vu with diodes etc.

Cheers
fotis

 

[keithcamilleri]

hi guys,

wanted to ask a quick question i've done the mod for the trafo out to be 1:2.

The unit was already calibrated, do I need to calibrate the unit again after the trafo mod?

 

[gyraf]

Nope, calibration stays the same when changing output transformer ratios..

Jakob E.

 

[anneflyr]

Hello.

I've had a lot of fun doing this project. It is all together now. Signal is running trough, and input pot and output pot is working. the problem is that it is not compressing.... :?

I don't have a meter jet, but it should compress without it, should it not?

I have done a lot of testing. All my values seem to be correct. It's spot on or +-1 volt on all measure points. I've read trough all post concerning this project, but I could not find help. I found this answer on another unit that didn't compress.

First of all - does point21 change with signal level?

There is a "threshold" - the negative voltage at point21 - that has to be overcome by input signal level before the FD333 diodes starts to conduct.

Input a loud signal, input at max, and measure changing DC voltage at point21. When this voltage is some +0.6V higher than the DC voltage at point19 (which is set by Q-bias), the diodes conduct, and gain-reduction sets in. Start out with trying different settings for your Q-bias, just in case it is at one extreme.

Does meter and gain change with Q-bias adjustment? This verifies that the FET's and the release circuit is working.

Jakob E.

I have tested point21. It does not change with input; it does change when I regulate the Q bias.
Turning the Q bias, the gain changes slightly when the release is full clockwise, and I have the same slightly change when I turn the release pot.

I've been trough the schematics many times, been lifting out resistors, looking closely on the caps and on the soldering to be absolutely sure everything is correct. I just cannot find any errors.

Does anybody have an idea where to look further?

Andreas

 

[gyraf]

Andreas,

Check thet the FD333-diodes are mounted the right way around. Check signal levels (AC and DC) before and after these diodes - it is here that the audio signal AC is converted into DC for the fet control..

Jakob E.

 

[Svart]

i've been using my dual mono 1176 for a while and it is wonderful! one problem is that I used a dual VU meter and it barely moves. set to VU mode it moves a small amount and under much higher levels it moves more.. it's obvious that I need to adjust the drive to the meter..

so my question is: how do you figure out how much drive you need from measurements taken from the meter and how would you make sure that it is indeed correct?

yes i know this is not much information..

 

[anneflyr]

It is compressing :grin:

First I have to say. There are two really educating periods during a project. Part sourcing and error tracking. Specially the last really makes you go through the unit you're building teaching your self how it works.

I checked around the fdh333, and also the whole signal path. Suddenly out of nothing it was compressing. My guess it faulty wiring, I resoldered all the wires paying special notice to point 7, 19, 20. It is working!! It is always something stupid, is it not.

You are a angel Jacob to answer all this questions about your projects.

Don't know if you remember, I offered you some Tore Seem schematics some months ago. I'm sorry, but I only have block diagrams, no in depth schematics. Trying to get hold of some, if I get them you'll be the first to know.

Thanks for a superb compressor, now calrec is next. :green:

 

[gyraf]

:thumb:

 

[bradb]

I've got the optional input transformer and I'm finding that there isn't a single location for info on how to wire this thing. I've got the mnats board. his instructions on his website are regarding different ratio/meter boards.

Some questions, confirmations:

R* and R*1, these 10kohm resistors need to be added when I use the optional transformer, correct?

BUT, if I add these resistors, I can't mount the Lundahl flush to the PCB.

Do C* and C*1 need to be added as well? what are these values?

With the optional input tranny, Input pin 1 needs to be run to 1* next to point 22?

Just want to also confirm that pin 4 on the meter board goes to pin 4 on the ratio board.

Thanks all!

Brad

 

[bradb]

Thank you!,

Just to confirm:
C* is 1000uF/35V
C*1 is 100uF
C*2 is 0.1uF
C*3 is 0.1uF

I think I'm on track. I am following some of Mnats advice in using shielded cable to wire certain points and grounding at one end.

 

[mikeyB]

Now that electrovalue got bought out and then the stock up in smoke!! grrr!!! - does anyone know where to get 4M7 and other high value pots - all i can find are presets and my eyes are beginning to bleed! I'm UK based - by the way!

 

[louder]

alo mikey
think digikey carries 5M pots.
best regards
pedro

 

[Svart]

Hey, sorry to repost this but i'm still wondering about it:

i've been using my dual mono 1176 for a while and it is wonderful! one problem is that I used a dual VU meter and it barely moves. set to VU mode it moves a small amount and under much higher levels it moves more.. it's obvious that I need to adjust the drive to the meter..

so my question is: how do you figure out how much drive you need from measurements taken from the meter and how would you make sure that it is indeed correct?

 

[Greg]

Did you do the calibration procedure on Gyraf's site?

 

[Luny Tune]

Hi all,

I'm building my first G1176 and at the same time I'm making a complete shopping list for all parts in Denmark. (Some of the webshops do ship internationally so I'll publish the list here too of course.)

Now, I've come to the same stop a lot of others have. I can't find the BD517 anywhere. I have seen that BD517/518 can be replaced by BD135/136 and that you just have to bend their legs to fit them correctly into the PCB as they're not directly compatible. It's not too hard really.

I've read many pages and comments but I have two questions still.

The first one is of general interest I think. Is there any audible difference at all between the BD517/518 and BD135/136 combinations?

The second question arises because I have already soldered in the BD518 I found, and I didn't know it would be a problem to find the other one. Can I solder in a BD135 as a substitute for the BD517 and just leave the BD518 in, or well I have to replace the BD518 with a BD136 as well?

I found the question about the sonic difference asked before, but I couldn't find an answer.

 

[gyraf]

There will probably be very little sonic difference between the two types, but I haven't A/B'ed them. Use BD135/136 or BD517/518 pair-wise, don't mix. You want decent complimentary action..

Jakob E.