All things G1176 - the new "repost" thread.

[gswan]

E is an exponent.
ie 100x10^-6

 

[Gege]

I answered to myself ... my case is not "electrically connected" .

Bye bye humm

 

[Luca]

I just finished populating rev j board!
I have a question... Why c*1 c*2 c*3 and c* are not present in mnats bom? what they do? What's the difference to have them on the board or not?
Thank you!

 

[Gege]

If you see the gyraf bom, all the * cap are optionnals

I don't know why it's optional, but personnaly, for the missing parts I'm refered to Jakob PCB and i have fully populated PCB, maybe useless, but after some troubles, my G1176 rock's !

I Let pro-diyers answer you

 

[Luca]

can you give the values of those caps?
in gyraf bom i can't find any *...

 

[Gege]

http://gyraf.dk/gy_pd/1176/1176.pdf

I put the value in the jakob pcb.

 

[seavote]

gyrafs site has the PCB PDF. that shows component values on it.  Mnats boards have the component numbers listed on the PCB.  now that my board is populated and i need to troubleshoot i cant see the component numbers(the components obscure them). is there a layover diagram available on the web with the component numbers listed on the PCB? i cant find one !!
8) 8) 8) 8)

 

[s2udio]

Why not troubleshoot from the schematic as any tech would do ?

 

[sr1200]

I have one ill send it to you.

 

[seavote]

thanks sr . but just found oneat atx web site.
8) 8) 8) 8) 8)

 

[sr1200]

cool man, if you want a shot of the board too lemme know.

 

[mpk]

Hi,
just finished this great board! I've a couple of questions, though!

At the moment I'm waiting for the enclosure so it's working "on the table", anyway it's all working just fine but it seems to me that there is too much distortion on the output. I'm testing this way: unbalanced input signal from mac jack, unbalanced out to ampli+ns10. With the input all the way up, snare or vocal tracks, 4:1 compression, fast attack, the output sound is very, very distorted (somehow saturated...). I was expecting some dirtiness from a 1176 but not so much. And with the input pot full cw like that, the GR doesn't reach -20dB very often (or at least as someone would expect it...). I tried a more common setup on voice, with GR around -4/-7 dB, but it seems to me that there is always too much distortion (not like at the maximum compression).
It could be a wrong q bias calibration? I've done all the calibration following the original urei manual, so q bias set using Output pot full cw, input all the way down and q bias all the way up till the vu meter doesn't move anymore to the right. Than set the input pot (if I recall correctly) to +1 dBU and setting the q bias for a 1dBU drop (0 on the vu meter).
I've done some measurement with oscilloscope, 1KHz -6db signal, 20:1 compression and full CW input; I attached the oscilloscope pic. It seems that the wave it's a bit square (don't know how to say it in english, but it's pretty clear from the pic!), maybe the compression FETs saturating, don't know...

Any suggestion it will be very appreciated!
Thank you!

Edit: The input trasformer (OEP) was installed in the 2:1 config, now i reverted it to 1:1.
Just forgetting the essential thing! With the gr disabled, the unit doesn't add any distortion! I just finished checking all the values and it's all right... I did one more test, disconnected the positive output cable, I used it as a "probe". I attached it at the emitter pin of every fet and the output is always distorted, from every single fet... Any ideas?

 

[mpk]

So, the problem is solved! Bad solder, damn it!! Now it sounds great!

 

[gswan]

Also remember that the unit has a lot of gain (36dB). So feeding a line level signal into it and turning it all the way up is going to overload right from the start.

 

[mpk]

Also remember that the unit has a lot of gain (36dB). So feeding a line level signal into it and turning it all the way up is going to overload right from the start.

I don't get this, what kind of level am I supposed to feed in? A line level I suppose, because a 1176 doesn't have a mic pre stage! Considering that a line output of a Mac it's consumer line level, so -10dBV, and that the line level one usually gonna work with is +4dBU, I'm pretty far from that value with my Mac output...
Anyways now I reverted the input transformer to step down, also switched the output transformer the same way. It's working very well, even at max comp (max input) there's no distortion, as it should be... I'm very satisfied with the results! Thanks mnats!

 

[gswan]

A line level input is fine. Just don't turn up the input and output all the way, or your output (without gain reduction) will be line + 36dB!

 

[sedit1]

I need some help with my second g1176 rev J
(Not building stereo one, I have different cases).

The unit is passing audio just fine and the voltages are spot on but I dont get any compression.
I tried to replace the q1 fet and checked the wiring with skylars wiring guide, everything were right and all the cables made connection to board like they should. I also checkd all the resistors and possible solder bumps/bridges, nothing.

The meter is acting normally, in vu mode it works like it should and in gr mode it sits nicely in 0 but no movement after that. The attack and release pots are't doing anything in gr mode, totally "dead".

I'm using hairballs ratio/meter pcb's and also checked the resistor values there.

Do you have any advices where to look, I'm out of ideas?

Thanks! 

 

[gswan]

Is the -10V rail OK? Check Vgs with no signal to see if the FET is biased correctly.
Check that signal is getting to the input of the GR amp section and trace it through the GR amp to the rectifiers at the output.

 

[sedit1]

Thanks a ton it'a working now, just some finishing touches to do! The FET was not biased correctly it was way off! I don't know what I was thinking this was so easy solution (This time I had bourns multiturn trimmers and I didn't think that things could be so way off)

 

[Arthurelletson]

Hi all,
I have been building a rev g 1176 from mnats and hairball and I have got everything together on the pcb and hooked it all up but no sound will pass through it, now I have been through all the support threads and read everything I can find and can't get an awnsering to why it is not working.

I have found out that I can get a signal to pass through the entire unit when there is nothing plugged into to output xlr but as soon as I hook up the output to my ad convertor the signal stops at IC2

Can anybody help me with this
Thanks
Arthur