GSSL HELP THREAD!!!

[signalflow]

2. I'm having problems mounting the Potentiometers for Attack & Release. First off I don't know where wich pins should be sitting. I have a PDF from gyraf.dk where i see the PCB frontside + the back with the connectore lines (sorry don't know how they are called in english). On that PDF, looking at the middle pins of the attack, i see that on the bottom left there should be "A" and on the top right there should be "B". On my potetionmeters though, A & B are next to eachother and not on opposite sides. Maybe someone could just tell me where the outside pins start off so i know where to place my "1".

Also I'm not really sure of how to "Program" the Potentiometers. On the gyraf site it says "relocating the washer/locking pin" when taking off the nut.
I opened the potentiometer and inside are too loose metal parts wich i can move around but i don't really have a clue where to move them so i have it correctly.

I think those are the questions for now ;-) I hope that after those parts i'm done and can test the comp

Phil

Your Attack and Release should only have 2 pins and they should be located diagonal from each other.  If your pot(rotary switch) has more than 2 pins then the wrong parts were ordered.  They should be a 2x6 rotary switch(Pot).  The only rotary switch that should have more than 2 pins is the ratio it need 4.  As long as you line up "A" to "A" then the rotary switch should work just fine.

your release rotary switch needs to be converted to a 2x5.  This means that you need to move the washer with the stop pin, located under the nut, back one position(counter-clockwise).

-Casey

 

[Phil]

thx, yeah i kinda wrote that wrong. thx for the help i got all my pots on the pcb now.

only question left ist about the 750k being a 990k and if that can be a problem

 

[johnmellor]

Hi there another GSSL newbie.

After just finding out that depending on which vca type chosen, you may have to make some alterations to the circuit.
On "Matt's DIY Pages" there are a number of resistors that have to be removed. Of course I have just finished putting in all the resisters, IC's, and jumpers. I've seen a number of clone's with 2180vca's, resistors intact and working fine. Should I remove the resistors suggested?
http://diy.fischerworks.com/gssl_vca.shtml

For opamps are standard Texas Instrument ones good enough for the job? I do want the typical bite of the gssl.

Also I was wondering about the 1k* and 2k* resistors on audio kitchen board. I've read that the 2k should be left free if you are going to use a dist trim for the meter is that correct? 

thanks for your help, enjoying the project so far

 

[pietro_moog]

hi guys!  
everything is fine now on my compressor.
thanks to everyone.

 

[Jazzboms]

Hi
Got some problems with makeup and threshold on my new built gssl. The symptoms are weird. With no threshold, the makeup gain doesnt work until its at max, then it goes to max gain. From zero to max with nothing between. It passes clean audio with, as far as I can hear ,no hum or noise.
With max threshold, and min makeup, I got a lot of distortion, but the distortion decreases when i increases the makeup, but it doesnt make more gain. Again at max makeup, the gain sudden increases to max.(The distortion increases while turning the threshold)  Also the distortion increases when higher ratio. So the conclusion is that instead of compression, it distorts.
With no threshold the unit passes audio nice.
I have checked for shorts, but I cant find any, and my soldiering looks ok. But obvious something is wrong. The op-amps and VCAs doesnt go hot except the TL074 feels a little more hot than the others. Have replaces my opamps and VCA.(Maybe all my extra opamps and vcas also are broken.....)
Havent done any measuring other than checked the main +/- 15/12. The + 15 is 14.77 and the -15 is -15.02.
The meter is not connected.


Thanks for reading!
Best

 

[regularjohn]

After just finding out that depending on which vca type chosen, you may have to make some alterations to the circuit.
On "Matt's DIY Pages" there are a number of resistors that have to be removed. Of course I have just finished putting in all the resisters, IC's, and jumpers. I've seen a number of clone's with 2180vca's, resistors intact and working fine. Should I remove the resistors suggested?
http://diy.fischerworks.com/gssl_vca.shtml

For opamps are standard Texas Instrument ones good enough for the job? I do want the typical bite of the gssl.

Also I was wondering about the 1k* and 2k* resistors on audio kitchen board. I've read that the 2k should be left free if you are going to use a dist trim for the meter is that correct? 

I'd recommend removing the resistors.  It'll still work with em in, but it will be out of calibration.

The originall SSL used 5534's, so TI chips are fine.

You should replace the 2K meter resistor with a 5K trimpot so that you can perfectly calibrate the meter.  Not sure what you mean by distortion trim for the meter???

 

[regularjohn]

Hi
Got some problems with makeup and threshold on my new built gssl. The symptoms are weird. With no threshold, the makeup gain doesnt work until its at max, then it goes to max gain. From zero to max with nothing between. It passes clean audio with, as far as I can hear ,no hum or noise.
With max threshold, and min makeup, I got a lot of distortion, but the distortion decreases when i increases the makeup, but it doesnt make more gain. Again at max makeup, the gain sudden increases to max.(The distortion increases while turning the threshold)  Also the distortion increases when higher ratio. So the conclusion is that instead of compression, it distorts.
With no threshold the unit passes audio nice.
I have checked for shorts, but I cant find any, and my soldiering looks ok. But obvious something is wrong. The op-amps and VCAs doesnt go hot except the TL074 feels a little more hot than the others. Have replaces my opamps and VCA.(Maybe all my extra opamps and vcas also are broken.....)
Havent done any measuring other than checked the main +/- 15/12. The + 15 is 14.77 and the -15 is -15.02.
The meter is not connected.


Thanks for reading!
Best

Your opamps and vca's are fine.  something is wired wrong somewhere.  recheck your wiring and check for solder bridges or incorrect component values.

 

[Phil]

________
EDIT:

I thought i had to bend the 4th pins on my VCAs but i have the THAT2181 so i bent them back.
I'll test it tomorrow. But are there some measurepoints where i can measure to see if everything is correct?

And also - the trim pots at the VCAs - what exactly can i calibrate with them?
_________


hey, i got my ssl all soldered up now.
I just tested it and at least it passes the sound .. but it's not working correctly.

The meter reacts really weird. I tried running a drum bus through the comp and it reacted pretty hard - i didn't really notice HARD compression though. I seemed as if the snare was making the comp work hard so i tried soloing the snare but then it didn't react at all.
Same when it tried vocals. When i had 2 vocals coming through it reacted very hard but when only the main voice came nothing happend, even when i turn up the volume of the vocals very loud. It only reacts when both vocals come..

I soldered the bypass button wrong i think since when i turn on the bypass i can use the makeup and when i turn it off i can't use the makeup. I'll change that now but i guess that doesn't have much to do with my problem, does it?

at least u got no noise or hum .. ;-)

Is there some kind of measuring plan where i can measure at some points to go for some error-searching?

phil

 

[regularjohn]

make up gain doesn't work in bypass mode.
The bypass is simply a sidechain mute (you're still running through the audio path), and since the make up gain control is part of the sidechain circuitry it does not work in bypass.

 

[Phil]

i know - i connected it wrong. now everything works.

Still i'm not sure if anything changes when using the trim pots. plus even when having a high signal coming in my meter starts moving only when i'm already up half of the threshold... so is there a way i can measure if everything is correct electricity wise?

 

[pietro_moog]

hi guys!

so there are 2 version of the circuit, one is the classical circuit which is printed on the pcb and the other is the one at page 187.

which is the best? and what is the difference?

 

[regularjohn]

i know - i connected it wrong. now everything works.

Still i'm not sure if anything changes when using the trim pots. plus even when having a high signal coming in my meter starts moving only when i'm already up half of the threshold... so is there a way i can measure if everything is correct electricity wise?

The trimpots next to the vca's are THD trimmers.  I'd be surprised if you can hear what they do under most circumstances.  You need test equipment to properly calibrate them.  

If your voltage rails are correct and it's passing audio I wouldn't worry about checking any other voltages.

GR usually starts around 12 o clock on the threshold knob.  The only way to verify if your meter is correct is to run signal into the comp, and run the comp into an external set of meters (I use my Otari 2 track for this purpose).  This way you can see if the gain reduction on the meter equals the actual amount of gain loss.  If you replace the 2K resistor with a 5K trimpot you can perfectly calibrate it.
I also normally replace the 15K resistors at the front of the output section with 20K trimmers to perfectly calibrate unity gain, and I also replace the 127K ratio resistor with a 200K trimpot to perfectly calibrate the ratio.

 

[regularjohn]

hi guys!

so there are 2 version of the circuit, one is the classical circuit which is printed on the pcb and the other is the one at page 187.

which is the best? and what is the difference?

There's a lot more than two versions.  Everyone and their mom has mods and circuit changes for this thing, myself included.

If you're using DBX202 or THAT2150 go by the pcb silkscreen.  If you're using THAT2181 or THAT2180 you'll need to make changes to accomodate those VCA's.  That's the reason for the resistor changes near the vca's.  Other resistor or cap value changes are done for personal taste.

 

[Phil]

The trimpots next to the vca's are THD trimmers.  I'd be surprised if you can hear what they do under most circumstances.  You need test equipment to properly calibrate them.  

If your voltage rails are correct and it's passing audio I wouldn't worry about checking any other voltages.

GR usually starts around 12 o clock on the threshold knob.  The only way to verify if your meter is correct is to run signal into the comp, and run the comp into an external set of meters (I use my Otari 2 track for this purpose).  This way you can see if the gain reduction on the meter equals the actual amount of gain loss.  If you replace the 2K resistor with a 5K trimpot you can perfectly calibrate it.
I also normally replace the 15K resistors at the front of the output section with 20K trimmers to perfectly calibrate unity gain, and I also replace the 127K ratio resistor with a 200K trimpot to perfectly calibrate the ratio.

Hey john, ok thx for the tips and info on the trimpots!

Unfortunately after testing it and hearing it working yesterday i have a new problem today:

When I have both input-plugs plugged in i get not compression (meter is not jumping and i hear no compression) - if i put one plug (doesn't matter wich side) completely away or only half way out i get the compression to work. of course i only hear the left or right side..

I dunno why this problem occurs - I've switched the input OPs but it's still the same. It seems that if both plugs are plugged, the comp is bypassed.. can that be? maybe i have my bypass switch connected wrong? (eventho i think that can't be cause yesterday i remember testing the compression and turning on the bypass to hear before & after results)

I've changed the input cables on the pcb but nothing changed either. i'm kind of running out of ideas...

UPDATE:

Ok I think i had soldered the bypass switch bad. It compresses now BUT when i have the cables fully plugged in only very very little and if i pull them out half way it compresses "hard". I still have the feeling that i can't "destroy" anything with overcompressing. I ran some Drums over it and it compressed hard but not too hard. I also tried vocals and i only got them compressed so far that it souneded good but i never got it to compress it in a bad way (i turned attack fast and also release and the threshold full)

Also for some reason i managed to switch the ratio button - wich means that left is 1:10 and right is 1:2. I don't think that would be the problem tho, would it?

hope somebody can help

thx

 

[schrobbelbop]

Hi there,

im finishing my gssl! thanks gyraf! thanks Dan for the panel! thanks chef for the pcb's.

but there is a problem

Audio is fine, but when compression kick in there is a DC-hum on both channels and no audio anymore.
I noticed that the -12 0 +12V line tot the turbo pcb measures 4V and 14V.
What could be wrong? seems to me something like a PSU failure somewhere.

Also if i connect the turbo pcb the voltage drops and my meter led is almost out then.

also gain makeup only does about 3db's extra and responds a bit slow on potmeter movement.

i'm using 2181 vca's with the resistor mods etc.

Where to begin?!?

 

[mac]

Sounds like you start by removing the turbo board and check voltages on the main board. Problem might be wrong component on the turbo board??
Is it wired as per the expat document with the dc supply coming from the mainboard?

Mac

 

[schrobbelbop]

Sounds like you start by removing the turbo board and check voltages on the main board. Problem might be wrong component on the turbo board??
Is it wired as per the expat document with the dc supply coming from the mainboard?

Mac

I already removed the turbo board with noluch. with the turbo board in the voltage drops even more and my meter led dims..

 

[schrobbelbop]

Sounds like you start by removing the turbo board and check voltages on the main board. Problem might be wrong component on the turbo board??
Is it wired as per the expat document with the dc supply coming from the mainboard?

Mac

I already removed the turbo board with noluch. with the turbo board in the voltage drops even more and my meter led dims..

Might this be the problem? im using LM79L12ACZ  and LM78L12ACZ and i've read in the thread the pin-out is diffrent?

 

[schrobbelbop]

Sounds like you start by removing the turbo board and check voltages on the main board. Problem might be wrong component on the turbo board??
Is it wired as per the expat document with the dc supply coming from the mainboard?

Mac

I already removed the turbo board with noluch. with the turbo board in the voltage drops even more and my meter led dims..

Might this be the problem? im using LM79L12ACZ  and LM78L12ACZ and i've read in the thread the pin-out is diffrent?

Sorry this was spam, it's correct, read it wrong having sleepless nights!

 

[Harpo]

... the voltage drops even more and my meter led dims..

Your meter LED (sure its an LED and not a light bulb?) should not be supplied by the +12V or -12V rails.
Maybe reconnect your meter LED ( 0V -->|--1K2-- -15V ) or ( +15V -->|--1K2-- 0V ) for a blue LED with typical VF3.3V @10mA.
You already have double checked parts values and parts orientation?
Power down, disconnect the turbo board, temporary remove the sidechain VCA, TL074 and TL072 on main pcb, power up and check for correct +/-12V voltages, else replace the broken 78L12 or 79L12 regulator.
Power down and put the chips back in one by one. Power up and measure rail voltages again after each chip. If a rail now drops in voltage, the last chip you put back in is probably broken. Now reconnect the turbo board as described by Expat Audio.