GSSL HELP THREAD!!!

[Gustav]

I'm specifically referring to Gustavs new board which has the side chain built right onto the main PCB.

Not a new board, just the version Jakob did with the components for the single freq side chain included with a new assembly guide

Sorry if that was somehow overstated (I thought SC ed had a subtle ring to it).

Gustav

 

[Gustav]

.. I have finished the assembly of my second compressor GSSL and found some problems ...

Since you are lucky enough to have a working unit, I would use the first/working unit to compare.

Gustav

 

[Jimmy1980]

Hey all,

I'm still working with my clipping output problem. Just wondering if anyone knows if a bad TL072 or TL074 could be the source of the problem. All DC voltages look good on them, though....

Thanks,

 

[Harpo]

I'm still working with my clipping output problem. Just wondering if anyone knows if a bad TL072 or TL074 could be the source of the problem. All DC voltages look good on them, though....

maybe, but questionable with your measuring methods.

When the compressor is powered off I can send 0.775vac (1k tone at 0dbu) from my DAW and 0.775vac will show up on the output XLR pins (I'm not sure if this should be happening).

Some Kohms additional impedance, but signal will make it from input to output in this circuit. The internal protection diodes inside the opamps (not all opamps have these) hopefully will prevent damage with input voltage (your signal) exceeding the chips supply voltages (nada with missing power supply).

When the power is on I'm getting about 5vac at the XLR output pins. This confuses me as it seems like I'm getting a much louder signal on the output compared to the input. Could this explain why everything I run through it sounds distorted?

5VAC at XLR-out-pin2 and/or pin3 in respect to 0V reference voltage or between XLR-out-pins2/3 ? Lots of reasons (wanted or unwanted) to get there.

When the compressor is powered on, I can trace the 0.775vac cleanly to the left and right 2181 IC's in the VCA sections where I find a slight bump up to around 1.1 vac on pin 8.

The VCAs are current-in/curent-out devices, not voltage. You fitted these VCAs with correct orientation? They won't survive, once powered reversed.

These are my approx VAC readings at my output NE5532 pins from my +XLR pins

maybe a language thing, but I would want to know the opamps AC and DC voltage readouts in respect to 0V reference voltage, not in respect to whatever +XLR pins.

I removed the 2180's from the left VCA section and jumped pins 1 and 8, which made the left channel sounds great but no compression.

With the VCA (with changed type) bypassed, the controlling element is missing, so no compression happening is correct. Clean audio with audio-VCAs bypassed as well shows input and output section probably operating correctly, so fault will be located in the sidechain section including its +/-12VDC supply or the audio-VCAs might be broken. (please be more exact with your numbers. What type of audio-VCAs and sidechain-VCA are on board for real, THAT2181 (A, B or C) or THAT2180 (A, B or C) ?

I'm getting continuity between pin 2 of the sidechain's 2180 and the 470R.

Checking for continuity might be useful for sorting non-coded multicore wires, but you almost never use this multimeter setting for any electronic devices. Use the 'Ohm' setting for measuring resistance. A short will give a zero or close to zero readout (your measuring leads and pcb traces have resistance as well).

I'm only measuring about -2.8v dc at pin 5 of the sidechain 2180 when I believe I should be measuring -15v dc

There is a 5K1 resistor between the negative supply rail and each audio-VCA-pin5. With no signal, -2.8V at 2180-pin5 is close to perfect (for the audio-VCAs, powered from +/-15VDC rails. The sidechain-VCA is supplied from +/-12VDC with a 3k9 resistor in between -12VDC and VCA-pin5).

Question: When I send 0.775 AC voltage (1k tone at 0vu) from my DAW and trace the voltage through the PCB, I've noticed I can measure 0.775 AC at ground. Even on front panel of the chassis. Is this normal?

So your case ground is connected to 0V reference voltage and you mixed up probe wires.
Use your black wire probe that is plugged into your multimeters [COM] terminal for the 0V reference voltage connection (the center pin of the aux.12V relay/lights connector might come handy) and keep it there for nearly all measurements (except FI when measuring transformers primary or secondary voltages). You probe around with your red wire probe that is plugged into your multimeters [V/Ohm/...] terminal and your multimeter set for AC volts or DC volts in a range higher than expected.

 

[Jimmy1980]

I'm still working with my clipping output problem. Just wondering if anyone knows if a bad TL072 or TL074 could be the source of the problem. All DC voltages look good on them, though....

maybe, but questionable with your measuring methods.

When the compressor is powered off I can send 0.775vac (1k tone at 0dbu) from my DAW and 0.775vac will show up on the output XLR pins (I'm not sure if this should be happening).

Some Kohms additional impedance, but signal will make it from input to output in this circuit. The internal protection diodes inside the opamps (not all opamps have these) hopefully will prevent damage with input voltage (your signal) exceeding the chips supply voltages (nada with missing power supply).

When the power is on I'm getting about 5vac at the XLR output pins. This confuses me as it seems like I'm getting a much louder signal on the output compared to the input. Could this explain why everything I run through it sounds distorted?

5VAC at XLR-out-pin2 and/or pin3 in respect to 0V reference voltage or between XLR-out-pins2/3 ? Lots of reasons (wanted or unwanted) to get there.

When the compressor is powered on, I can trace the 0.775vac cleanly to the left and right 2181 IC's in the VCA sections where I find a slight bump up to around 1.1 vac on pin 8.

The VCAs are current-in/curent-out devices, not voltage. You fitted these VCAs with correct orientation? They won't survive, once powered reversed.

These are my approx VAC readings at my output NE5532 pins from my +XLR pins

maybe a language thing, but I would want to know the opamps AC and DC voltage readouts in respect to 0V reference voltage, not in respect to whatever +XLR pins.

I removed the 2180's from the left VCA section and jumped pins 1 and 8, which made the left channel sounds great but no compression.

With the VCA (with changed type) bypassed, the controlling element is missing, so no compression happening is correct. Clean audio with audio-VCAs bypassed as well shows input and output section probably operating correctly, so fault will be located in the sidechain section including its +/-12VDC supply or the audio-VCAs might be broken. (please be more exact with your numbers. What type of audio-VCAs and sidechain-VCA are on board for real, THAT2181 (A, B or C) or THAT2180 (A, B or C) ?

I'm getting continuity between pin 2 of the sidechain's 2180 and the 470R.

Checking for continuity might be useful for sorting non-coded multicore wires, but you almost never use this multimeter setting for any electronic devices. Use the 'Ohm' setting for measuring resistance. A short will give a zero or close to zero readout (your measuring leads and pcb traces have resistance as well).

I'm only measuring about -2.8v dc at pin 5 of the sidechain 2180 when I believe I should be measuring -15v dc

There is a 5K1 resistor between the negative supply rail and each audio-VCA-pin5. With no signal, -2.8V at 2180-pin5 is close to perfect (for the audio-VCAs, powered from +/-15VDC rails. The sidechain-VCA is supplied from +/-12VDC with a 3k9 resistor in between -12VDC and VCA-pin5).

Question: When I send 0.775 AC voltage (1k tone at 0vu) from my DAW and trace the voltage through the PCB, I've noticed I can measure 0.775 AC at ground. Even on front panel of the chassis. Is this normal?

So your case ground is connected to 0V reference voltage and you mixed up probe wires.
Use your black wire probe that is plugged into your multimeters [COM] terminal for the 0V reference voltage connection (the center pin of the aux.12V relay/lights connector might come handy) and keep it there for nearly all measurements (except FI when measuring transformers primary or secondary voltages). You probe around with your red wire probe that is plugged into your multimeters [V/Ohm/...] terminal and your multimeter set for AC volts or DC volts in a range higher than expected.

Thanks so much Harpo,

When measuring the VAC through the compressor from my DAW, I am connecting to XLR input Pin 2 with my black probe and using my red probe throughout the components on the PCB.

I am using three THAT2180B in all slots.

Thanks,

 

[AdoreaRecordingStudio]

Changed my multi meter batteries and yet I'm still getting a reading of +\-30.5vDC at my +\-15vDC rails.

This is the current stock kit from Frank purchased through the micandmod site. Absolutely no parts have been subbed, and I am operating on 120v service - and believe the transformer is wired accordingly? Any thoughts folks?

 

[mukole]

Are you measuring this voltage across both of your rails or are you measuring each rail from earth? If your measuring across both rails you will see about 30 volts as that is both + and  - 15v in series. I cant really figure out how your voltage could be that high if you have the correct regulators installed otherwise.

 

[rearturo]

Hi everyone

Can someone be kind enough (and maybe patient) to briefly tell me the applications of the different capacitors on the GSSL kit? I know what a capacitor is and what the different kinds are (ceramic, tantalum, etc.) (and their properties), but I just want to know why for example tantalum caps are only used on the switch board.
I couldn't find enough information on Jakob's construction page with regards to my question so I'm asking here...

Thanks a lot!

 

[Harpo]

When measuring the VAC through the compressor from my DAW, I am connecting to XLR input Pin 2 with my black probe and using my red probe throughout the components on the PCB.

: XLR input pin2 is a moving target (AC signal voltage from your sending device) in respect to 0V reference voltage. You never use this pin2 as a reference. Maybe read my last reply again.

 

[AdoreaRecordingStudio]

Are you measuring this voltage across both of your rails or are you measuring each rail from earth? If your measuring across both rails you will see about 30 volts as that is both + and  - 15v in series. I cant really figure out how your voltage could be that high if you have the correct regulators installed otherwise.

Wow, I really can't believe that's what I was doing all night...  Apparently someone forgot to take the "coffee break" in the build guide* 

Now I believe I only have the issue of the supplied dpdt pushbuttons not illuminating & the VU meter being froze half way up. I'm going go insert a 5k trim pot in the "meter sens" and check my resistance value. I'm hopeful that I just have to swap out the 2.2k resistor I have in there currently. My bigger concern is neither the power or compressor lights wprking ... Seems I only see a brief "flash" of light upon switching off. After a night of reading this thread I can only find other folks talking about the same problem but no hints at solutions.

Anyway- thanks all

 

[AdoreaRecordingStudio]

Absolute strangest thing just happened... I accidently double tapped the power button and lights turn on! All the sudden the meter reads normal, the compression light works too!? But I have to double tap the power for it to work?? What is going on here? ?

Ps-my voltages across both rails read exactly as they should (+\-15 & +\-12)

 

[weiss]

Absolute strangest thing just happened... I accidently double tapped the power button and lights turn on! All the sudden the meter reads normal, the compression light works too!? But I have to double tap the power for it to work?? What is going on here? ?

Ps-my voltages across both rails read exactly as they should (+\-15 & +\-12)

yes, this is because of the 3 pin voltage regulators, don't use ts rectifiers (taiwain semiconductors) but e.g. ti or fairchild. Just replace uA7815, ua7915 for the TO220s and ua78L12, ua79L12 for the TO92s and it will work on the first try

weiss

 

[AdoreaRecordingStudio]

Absolute strangest thing just happened... I accidently double tapped the power button and lights turn on! All the sudden the meter reads normal, the compression light works too!? But I have to double tap the power for it to work?? What is going on here? ?

Ps-my voltages across both rails read exactly as they should (+\-15 & +\-12)

yes, this is because of the 3 pin voltage regulators, don't use ts rectifiers (taiwain semiconductors) but e.g. ti or fairchild. Just replace uA7815, ua7915 for the TO220s and ua78L12, ua79L12 for the TO92s and it will work on the first try

weiss

Think these will work?

http://www.mouser.com/Search/m_ProductDetail.aspx?Fairchild-Semiconductor/LM7812CT/&qs=sGAEpiMZZMtUqDgmOWBjgC5jv%252bsRCBsGZyYOsz27OnY=

Along with the LM7915 & LM7815?

 

[weiss]

every rectifier will work matching the specifications and the build type (except the ones i told you)

 

[Dannytech]

Hello!

I have 2181B VCA, but I don't know what kind of resistors and trimmers do I have to use to the "%" places. (Now, they are empty, but it works fine.)

Photo: https://www.dropbox.com/s/8i73p5kzzf6ylot/IMG_1408.JPG

Daniel

 

[weiss]

Hello!

I have 2181B VCA, but I don't know what kind of resistors and trimmers do I have to use to the "%" places. (Now, they are empty, but it works fine.)

Photo: https://www.dropbox.com/s/8i73p5kzzf6ylot/IMG_1408.JPG

Daniel

don't need any of them!

 

[Dannytech]

don't need any of them!

Cool, thanks!

 

[finbase]

Hello folks!

Yet another n00bie just about to finishing his first GSSL. Nevertheless, I countered a problem with the bypass switch. I'm just too dumb to wire it correctly...

I'm using Gustav's GSSL 2nd ed. kit and PCB, plus the Super Sidechain PCB. The switch template is like on the frontpanels.de  GSSL frontpanel with Sidechain and TL, TM.

The switch I'd use (if I could...) as the bypass control is Lorlin CK Rotary Switch, 4 pole / 12 turns, turns limited to only two.
How to wire this thing? Wires from where to where?

Please see the attached jpg picture, the bypass switch is depicted in the upper right side. I'd like wire it the way that the compression would be in the active mode in the position 1 and in bypass mode in the position 2... So my unschooled guess is that a wire should go from the SSC PCB's point "TO" to the center pole A, and then there should be wires from the pole/turn 1 to the SSC PCB's point "Ret" (return), and from the pole/turn 2 to the chassis ground. Am I correct?

If I'm correct, how would you suggest to attach that chassis ground wire?

So anyone, any compassion for an inept n00b?

(PS. Hopefully you can follow me, I'm not a native...)

 

[AdoreaRecordingStudio]

Absolute strangest thing just happened... I accidently double tapped the power button and lights turn on! All the sudden the meter reads normal, the compression light works too!? But I have to double tap the power for it to work?? What is going on here? ?

Ps-my voltages across both rails read exactly as they should (+\-15 & +\-12)

yes, this is because of the 3 pin voltage regulators, don't use ts rectifiers (taiwain semiconductors) but e.g. ti or fairchild. Just replace uA7815, ua7915 for the TO220s and ua78L12, ua79L12 for the TO92s and it will work on the first try

weiss

Okay, so I swapped out the supplied components as previously noted for the ones you suggested and the following happened.. My lights still won't turn on for either the "power" dpdt or the "compression" dpdt switches & my voltages went completely out of whack for both the +15rail (jumped to +22.1) and the -15vdc rail (dropped to 0.0vDC).

So I then decided to pull the TO220's and reinstall the 7815 & 7915 but I left the TO92's in place of the 79L12 & 78L12.  My voltages are now back to the correct levels - however my damn lights still don't work!! lol


Sincerely,


Palm + forehead

 

[weiss]

Okay, so I swapped out the supplied components as previously noted for the ones you suggested and the following happened.. My lights still won't turn on for either the "power" dpdt or the "compression" dpdt switches & my voltages went completely out of whack for both the +15rail (jumped to +22.1) and the -15vdc rail (dropped to 0.0vDC).

So I then decided to pull the TO220's and reinstall the 7815 & 7915 but I left the TO92's in place of the 79L12 & 78L12.  My voltages are now back to the correct levels - however my damn lights still don't work!! lol


Sincerely,


Palm + forehead

okay, this is weird.. did you check your wiring of the lights?