All things G1176 - the new "repost" thread.

[living sounds]

There is a PDF of the overlay posted on my site. The topic of the two pad 18s is also covered in my troubleshooting FAQ.

Damn, I overlooked that.  : Expected it on the left side of the page or something. Anyway, the boards are great and the compressors are working perfectly now.

 

[Le Roux]

Hi

The Lorlin CK2377 for the ratio board is out of stock at mouser and cannot find another one.

Would this one work in its place?

CK2394
http://ca.mouser.com/Search/ProductDetail.aspx?R=CK2394virtualkey12200000virtualkey10WA155

Anyone have a ck2377 they could sell me?

Thanks

 

[skal1]

Ok lads i am a bit confused about the gate and source terminals in the schem, are they connected together ? and are they both tied to ground.

I am using a bf245 fet


cheers

skal

 

[Echo North]

Source is at ground.  The gate receives a variable negative voltage.

Are you referring the the circuit symbols arrow position?  That's just the common symbol for an N channel JFET.

Mike

 

[skal1]

Are you referring the the circuit symbols arrow position? 

Mike

yes

Hi thanks Mike


skal

 

[JerryAnthony]

So i've spend some time using the search function but i could not find anything about my problem.
I'm still waiting for my VU meters to arrive, but even so it seems that the attack and release pots are not working at all. They are connected like they should be and tested for connection. The input and output pots are working just fine.

Before i spend a huge amount of time fixing this problem i'll ask it over here: What are the most common problems when the attack and release pots are not working?

J.

 

[gyraf]

i'll ask it over here: What are the most common problems when the attack and release pots are not working?

Basically four possibilities:

1) Attack pot shorted. This leaves you with fastest attack time constant always.
2) Attack pot open. This stops the 1176 from compressing, as the attack pot passes the DC for the gain-reduction.
3) Release pot open. This will give you a fixed, very-very-long release time, compressor will seem "stuck" at high GR.
4) Release pot shorted. Fixed very-short release time. Distortion on low-frequency compression.

...but don't get fooled by the 1176's attack time control - it ranges only from very-fast to ridicously-fast. Release action has a wider range, and can be checked by watching the GR-meter.

Jakob E.

 

[JerryAnthony]

A few minutes after my post i received my VU meters. Yeah!

I've connected it to my MOTU audio interface and giving it a 0db 1khz oscillator sound trough Logic.
First thing i noticed is that the q-bias trimpot isn't doing anything at all. And yes it is properly soldered/connected.
So i gave it some audio input to see a moving vu meter.

In vu GR mode, nothing is happening it stays at +1db. Not moving at all. Wont respond to anything. (trimpots, pots, input, output)
In +4 mode audio passes trough. But wont respond to attack, release or any of the trimpots. It works for input and output.

Time for some troubleshooting...

 

[dgoszillai]

hi i'm finally trying to wire my dual 1176 revJ
i have a question about the output pot.
i use this pot that is different from the one on picutre..
as i am super master noob of the universe i'm not sure how to deal with it.
on this picutre i see the outer shield is connected to the left pin but i don't know if it's the same on my pot + i'm not sure on the pcb wich "wiper" and "cw" are

i tried to read this but as my english is not great i'm not sure i understand : "comes to rest" / "where the wiper is closest to"

cw=counter-clockwise - the contact where the wiper comes to rest if the shaft is turned all the way to the left when the pot is viewed from the front; wiper=the middle contact; cw=clockwise - the contact where the wiper comes to rest if the shaft is turned all the way to the right. If you have any doubt, turn the shaft all the way to the end stop and measure the resistance from the middle terminal to each of the other lugs. The one that shows the lowest resistance is the one where the wiper is closest to. It should read very close to zero ohms.

dam ...  :

 

[ricothetroll]

Hi,

Here's a post to share my experience with the G1176.

I had some large inconsistencies with the meter display, and just couldn't fix it. I also had the "meter deflection with the release pot" issue.
I solverd it in a simple but yet efficient way : my fets were socketed. I removed the sockets and soldered the trannies directly on the PCB, and now those problems have disapeared !
The user manual gave me a clue : "In extreme cases it may be necessary to replace the sockets that holds Q1". It seems like moisture is the issue : I calibrated the unit at work where we have air conditionned, let it there a few days trying to switch it on from time to time and it seemed stable, but then 2 days later when switching it on at home the meter calibration was highly inconsistent...
I soldered both the GR and the meter fet.
When the unit is cold, the release pot still has a great influence on the meter reading, but after 10 minutes or so the needle only move of about 1/10 dB, that seems ok to me. With gain reduction occuring the release pot still has an influence, of 1-2dB.

By the way, I also solved some "very slight but still annoying" buzz issue by implementing an external PSUwith LM317/337 regulators, and wiring grounds along Rane.com & ESP 's specifications : pin1 of all XLRs connected directly to the enclosure, earth connected to the enclosure directly to the mains input, audio ground separated from the earth with a 10R / 100n / diode bridge groundbreaker network. The unit is now dead silent.
http://sound.westhost.com/psu-wiring.htm#s2.2
http://sound.westhost.com/earthing.htm

Hope this will help.

Best regards.

Eric

 

[gyraf]

Thanks Eric - this is the kind of information that we like in this thread!

Jakob E.

 

[ricothetroll]

Hi,

So I took it to the lab at work to see if the fet/meter calibration is stable and... it is, but at -4dB ! I did all kinds of measurements with a Neutrik A2 and everything is fine, both channels even track very well at +/-0.25dB, with and without the stereo link (Hairball). I brang it home yesterday and switched it on this morning : both meters track at a perfect 0dB ! ;D

So, removing the sockets was anyway a huge improvement : the behaviour of the copressor is much more predictable and thus stereo use is now possible. Still there's this difference between when I'm at work and when I'm home, I'll check the mains on both places, maybe it's low at one place or the other, and then my LM317 has a kinda low input.... My power trafo is 2x24VAC for 230V, that makes 23V rms for 220V, thus a peak voltage of 32.2V, that is kinda low for a 30V configured 317... I also added a CRCRC with 4R7 / 1000u so maybe with the drop across the resistors I'm even lower that that. 30V trafo might be the way to go.

To be continued...

Best regards.

Eric

 

[mnats]

The effect of contamination around the FETs is documented and well-known. So I have to ask - did you try thoroughly cleaning the sockets and PCB before your tried removing them completely? It's hard to believe the sockets themselves were conductive enough to cause problems. Contamination seems a more likely culprit.

 

[ricothetroll]

I cleaned the PCB but not the sockets themselves, and as my fets are matched well, removing the sockets is actually getting rid of another source of problems... For sure the contamination was in the sockets but I don't know how to make sure they're totally clean. Soldering seems like the most reliable solution.
As I searched for clues on the forum to solve my problems, I didn't find any mentioning the sockets, that's why I though it made sense to mention it, then other people that have the same kind of problem can also have that clue.

 

[mnats]

I cleaned the PCB but not the sockets themselves, and as my fets are matched well, removing the sockets is actually getting rid of another source of problems... For sure the contamination was in the sockets but I don't know how to make sure they're totally clean. Soldering seems like the most reliable solution.
As I searched for clues on the forum to solve my problems, I didn't find any mentioning the sockets, that's why I though it made sense to mention it, then other people that have the same kind of problem can also have that clue.

Fair enough. The usual alcohol and toothbrush would probably do but in stubborn cases an ultrasonic cleaner is useful.

 

[ricothetroll]

Fair enough. The usual alcohol and toothbrush would probably do but in stubborn cases an ultrasonic cleaner is useful.

I'm quite a stubborn case myself, but do not have any ultrasonic cleaner 

 

[kquick]

I would like to add a bypass switch to my stereo 1176-J  build.  Would shorting pad 22 with a toggle switch to ground work? Or does any one have a better solution.

Thanks
Kim

 

[ricothetroll]

Hi,
That's about what the "GR disable" switch does, right ?

 

[audiophreak]

Hi All,
      ok ... I think I have found some sort of success  ;D   
 
    After checking everything several times, resistor values  , voltages etc.  and not finding anything amiss ,  I could not get the meter to drop when GR enabled for the Gain Reduction Meter Tracking with a -10db 1k signal - I read on the Gyaf page to change input " Source Signal "  ... that  didnt help , .... then I found and watched mnats fantastic calibration video which states to use a 0db 1k  input signal - so I tried that and ... success !!!  had to fiddle with the input and output pots extensively  , but was able to meet all conditions and move on to finish the calibration procedure 

    I think I'm good now , but wanted to share what I did , and ask ... do I now have this right ??

  Thanks to all,
                      Chip

 

[audiophreak]

ok ...
    have now calibrated both channels , I think I will eventually change out the in and out  pots to LIN , with LOG they get very touchy . 

  need some advice / suggestions
                                                I am using Haiball push button meter switches , and planed on using them for power too , however now that I have everything in the case , not sure I want mains power going to and from two places on the front panel - sooooo , was thinking about using a main power switch on the rear panel to  power mnats PSU board, permanently  wiring the 0v to the Rev.J boards and switching the +30v / -10v with the Hairball switches from the PSU board to the REv.J boards.
 
  Is this advisable ??  any problems with doing it this way ??

  Thanks,
              Chip