GSSL HELP THREAD!!!

[Harpo]

lol. ok, the problem was finding spindel ø6mm. The others seemed like ø10, but I'm not too sure.

These Lorlin CK-series rotary switches only come in 6mm or 6.35mm spindle diameter.  Your ø10 number is the M10 bushing diameter for the ø6mm spindle.

 

[G-Sun]

These Lorlin CK-series rotary switches only come in 6mm or 6.35mm spindle diameter.  Your ø10 number is the M10 bushing diameter for the ø6mm spindle.

Ah.. thanks a lot for helping me out!

 

[totemst]

Hi, all. I have a problem with my GSSL. I build it few month ago with THAT2181 VCA's. The only mod i have done is a relay bypass. Relay powers exactly like in Jackob's schematics.The compressor sounded great and everything was OK until i changed the VCA's to 202xt. It was interesting to hear the difference. Now it's really loud buzz when compressor works. It passes audio and compresses, but its too noisy. Buzz level and audio level changes with makeup rotation. I disconnect relay board from inputs and outputs - no changes. Buzz is much louder when relays are powered. It seems like power supply or grounding issue. Any ideas? Sorry for my english. :'(

...until i changed the VCA's to 202xt.

...requiring more than 10 times (typ.26mA) the current of previously installed THAT2181s (typ.2.4mA) per VCA, next to different values of input resistors in front of your 202XTs and feedback resistors in the VCA following I2V stage, ... for a comparable result.
You are aware of the possible difference between '202XT VCA's and 'known working 202XT VCA's ?
The type of illumination  (LED/light bulb) in a single status display or GR-meter might draw more current than the complete GSSL. Anything shining built in your unit ?
Can your power supply deliver the required amount of voltage and current ?

Maybe this information would be helpful for someone. After hours of digging forums, i have not find the the answer to my question. I notice that buzz level is dependent of power supply load. More load(current) - more buzz. I find my old oscilloscope and see some interesting things. This is a picture of my 15v rail (after regulators).

Impulse amplitude ~10mV. Higher load- higher the impulse amplitude. No load - no impulses.
But real problem is ground wire. You can see almost the same impulses on ground wire. Ground wire is a reference point for all measurements in schema, so any fluctuations on ground will break operation of the device. This fluctuations caused by big psu  capacitors charging current. Higher current causes higher fluctuation. So, until psu is not loaded with current consuming devices (lamp, relays) everithing is Ok and compressor works well. Increasing the psu load causes noticeable buzz in audio path.  It seems to bee a pcb layout issue. My pcb is rev7, if im not mistaken.
The decision is separate psu. So  i build a dual rail psu and take out the 15v power rail parts from GSSL pcb.
Now the power rails picture is absolutely flat. No fluctuations on ground wire. The compressor is quiet. No buzz with makeup knob at fully cw position. Now my gssl with additional power supply looks like this

Maybe i miss something. Please correct me if im wrong.

 

[gyraf]

Increasing the psu load causes noticeable buzz in audio path

Yes, if you get dirty rails because of too high current consumption, you will need to upgrade the powersupply.

But dirt in power lines also has to do with transformer secondary voltage and "sag" - noise often comes from under-voltage transformers.

The most important rails to keep clean are the +/-12V that are used for reference at makeup and threshold pots.

Jakob E.

 

[totemst]

Increasing the psu load causes noticeable buzz in audio path

Yes, if you get dirty rails because of too high current consumption, you will need to upgrade the powersupply.

But dirt in power lines also has to do with transformer secondary voltage and "sag" - noise often comes from under-voltage transformers.

The most important rails to keep clean are the +/-12V that are used for reference at makeup and threshold pots.

Jakob E.

Thanks for reply, Jackob.
Its nothing special about power consumption in my clone. No lights. Just a pair of LEDs for indication. Additional load is 40mA for relays plus 80mA for 202VCAs.  Power transformer is 2x15 volts 15VA. Its 500mA per rail.  +/-21V on regulator inputs. Everything seems to be normal. Onboard GSSL PSU seems to be good enough to power up the compressor. This is another kind of problem. PSU capacitors charging current share part of ground wire with another components.
And new PSU is build from almost the same components. Just another layout.

 

[Potato Cakes]

Hello Everybody!

During my painful journey through the classic quest of "Why Doest Thou Compress Not?" I found that I was getting about -7VDC on pin 5 of the side chain VCA. The resistor in line with the -12V rail feeding it on the schematic is 3.9k but the PCB layout shows 5k1. I switched to 3.9k and the voltage was about -8.5V, so I then switched to 2.2k and it got it up to -10V. So I put it back together thinking I would then get Ye Ole Compression, but still nothing. However, a new fun thing emerged.  Before trying to fix the voltage issue, the unit would pass audio clear and fine. But after I swapped out resistors hoping increasing power to previously mentioned VCA pin would prove fruitful, I now get normal levels on the left side and Mach 5 on the right.  I swapped the resistor back to the original 5k1 as listed on the PCB layout, but still the right side is way super hot.

I'm going to back through to recheck all of the voltages on the IC's, but right now I would appreciate if anybody had some fresh ideas of where to look for problems regarding the original issue of why it is not compressing. I've done my due diligence of checking and for errant soldering and continuity between connections and fervently searching this thread to find the answer. I'm using THAT 2180 VCAs with the pin 4 removed and I'm going to order more VCA's and TL072's to replace the ones I currently have in case they are the culprits.  I did have a brief moment where the VU meter started moving intermittently like it was trying to work after one of many sessions of scouring for and redoing solder joints that might have been suspect, leaving me to believe that I might be getting close, but then it stopped and hasn't exhibited that behavior again. Like I said, any new direction or idea of where to look would be greatly appreciated as I keep going in circles and it's becoming quite maddening.

Thanks!

Paul

 

[Potato Cakes]

So I found that I am getting just over -12V on pin 7 of the right output NE5532 with puts about -8V on the positive leg of the the output XLR. Hilarious. I'll look at it again in the morning. I either ruined a capacitor somewhere or magically created a solder bridge.
Place your bets!

Paul

 

[Potato Cakes]

Further found that when I removed the NE5532 I do not get the -12V on pin 7 but I do when I put it in. I swapped opamps to see if that was the problem, but it is still showing voltage on pin 7. When both opamps are removed, the Left side (properly working) has about 0.2V on pin 7 and the right side has 0.9V. I'm back to suspecting an capacitor problem so I'm going to stare at the schematic and see if it reveals itself.

 

[Potato Cakes]

Found the voltage problem! It seems that the 2180 VCA chip went bad somehow. Swapped it out and presto pants! Now if I could just get to compress...

 

[Graph]

Hi! Well i made my GSSL, but it is still not working.

What i did wrong:
1. From 7815, two legs had a little bridge solder, which burned up a 10r resistor.
2.  I forgot to make a bridge in the PCB (well.. the one that gives -15v)
3. 1 That 2180b (not the one for each channel) was placed backward, so i removed and changed it from Left channel(leaving Left channel without 2180).  I know it should be considered death, but now it works the same as the other channel(bad)

Sound is passing through but VERY distorted. Also, Controls for GR are not working. Only Bypass is working(which it doesnt change anything, but it will bypass the signal). I have checked all components and there doesnt seem to be any bridge out there, checked every solder, every resistor, every cap.

Should the 7815 be changed because of 1? Could any IC got damage from this? I have bought anyways replacement for all Regulators and VCA. If i should change anything else. It will be arriving in 3 weeks

Thanks i have tried searching but couldnt find many answers, all switchs are all the way left. The only thing, is when Make Up Gain is set hard left, audio goes out of the GSSL, it is like it was a bad contact(or a bad pot maybe...)

EDIT:  Well.. i got not working audio, but a cool thing. If i send the signal before, at -70dBs, the signal is perfectly clean, after -65dBs it becomes quite messy. But... no control is working, maybe there is some short in the VCA control? Where should i look for?

Edit 2: I removed TL072, and placed it back, compressor started working, but with a very VERY odd behaviour, Just listen! I think i must leave it like this for sound design (just kidding)

https://soundcloud.com/grahf-1/ssl-compressor

Are the VCAs burned out?
Edit 3: The most amazing thing now is that i stopped music, and it keeped doing the same!! (until i changed some gr controls) Its now a synthesizer and a looper!!

 

[Humner]

Hi,

I'm looking through my parts bin to see what I might be able to use for a GSSL.

I found some small 500ua FSD meters - can these be used? What adjustments would I need to make to be able to use these?

 

[Potato Cakes]

Does anyone know what voltage you're supposed to get on Pin 5 of the side chain VCA? I'm getting just under -8V and I keep thinking this may be my problem of why it's not compressing. If this is the correct voltage then it must be a soldering error that I am unable to find at the moment.

I'm so close I can feel it!

Thanks,

Paul

 

[mike76]

Hey guys,

I'm planning to build an GSSL soon and habe just ordered the PCB an the parts. I war wondering, what kind of cables do you suggest for the wiring? Oft course, for the power supply I'll use 1,5mm^2. Do you think I can take some Multicore for the other wiring vor should I take some thicker gauge? Thanks.

 

[bernbrue]

http://www.musikding.de/Platinen-Steckverbinder-10-polig

Very easy to solder with moles connectors (plug& jack)  ready to go.
Bernd

 

[mike76]

http://www.musikding.de/Platinen-Steckverbinder-10-polig

Very easy to solder with moles connectors (plug& jack)  ready to go.
Bernd

Thank you very much. Thats exactly what I was searching for

 

[bernbrue]

they have 5 pol for input/output as well.
Bernd

 

[mike76]

they have 5 pol for input/output as well.
Bernd

Already ordered!

 

[Graph]

Hi Again, i am trying to get my GSSL working.

I just tried removing TL072, which.. it wont get a signal to VCAs and other things. Audio is Clear, but meter goes up to 20gr

If i put TL072 again, its like i have a 60/80dBs Amplification of the signal, giving me, a LOT OF NOISE and a VERY distorted signal(well, if i put a -60dBs signal it sounds clear, but with some noise).  There is not actual bridge there, and resistor values are fine.

Any ideas why it is giving me +60/80dBs?

Thanks in advance

 

[Potato Cakes]

Graph, do you have any spare TL072 or VCA chips? I had a similar problem and it was a bad VCA chip.

 

[Graph]

Mmmm i replaced a TL074 and it is working better, i dont have any TL072 or VCAs. Right now, first Attack goes to 20dB GR,  and depends on the release, it slowly goes back... but each one hit, respondes somehow when GR is activated.

Example

https://soundcloud.com/grahf-1/compressor-test-v2

I guess this is my last problem

Edit: Replaced a TL072 for a TL052(i had some spare left from other project, and it is pin compatible) and same problem.. i guess it is related to something close to TL072/074, but couldnt find anything wrong there yet... like it gives the action to compress a LOT more than it should..(Voltages are fine, Attack, Ratio, Release, Makeup and threshold are responsive)