GSSL HELP THREAD!!!

[monobass]

Good tip. So if they were in reverse and Live was connected and Neutral wasn't what would happen? I have a CRC board also.

 

[dennisp]

Ahem... Then there would be power on Neutral all the time and if a short would happen with your self involved it will get enpleasant at least 

If both pins were disconnected power would be cut completely 

Positive regards
Dennis

 

[supiarmando]

Hi there,

maybe very stupid question:

Today I have finished my first GSSL build. All went fine and I have worked very careful and checked after while soldering each solder that it is fine. Voltages are running fine (as the should), but

If I lower threshold ALL SOUND IS TERRIBLE DISTORTED. Bypass all audio is good.

I cannot find anything in the thread. Has anybody the same problems? This affects THAT2181B and 2180B. Where should I start to check? I am using all caps and resitors like in gssl docs from gyraf. http://www.gyraf.dk/gy_pd/ssl/ssl.pdf

I hope anyone has an idea or could help me. Thanks

 

[dirtyhanfri]

Hi

I'm having some issues on my GSSL, no Bypass or Turbo boards, 2181C's... (Resistors changed as suggested some posts ago) Looks like working fine

First of all, I've got 6db of gain in it, bypassing it or not, maybe I have to look the Input/output IC's.

Also, I have read somewhere the gain pot was from 0 to +20db, I can measure about 15db (50k pot), it is more than enough for me, but I'm thinking maybe it could be related with my +6db issue...

More.... The Meter, it looks fine, more or less accurate, but putting a 330R resistor between the pins makes it almost don't move... maybe a lower value? anyway, without any resistor it looks fine, even reading a bit less than the in my DAW meter.

Then, I got a Hum noise, something like -60dbfs. I've connected the jack's ground one with another (L-R) and then to the pcb, also I'm using metal spacers and screws for the pcb, maybe some kind of grounding issue? Lifting the mains ground from the chassis doesn't make any effect.

Last of all, in the 3rd release position I have no compression, I looked for bad sodlerings and found nothing, have to look closer for wrong resistor values or cap orientation...

Any ideas?

Thanks

 

[monobass]

First of all, I've got 6db of gain in it, bypassing it or not, maybe I have to look the Input/output IC's.

There is a resistor value that will give 6db of gain as standard I think, but you can drop it back to 0db by swapping it. I read about it in this thread yesterday.

easiest way to find it is hit that 'print' button top right, which shows the entire thread, and then keep searching on '6db'.. you'll find it in a minute or so

 

[Harpo]

First of all, I've got 6db of gain in it, bypassing it or not, maybe I have to look the Input/output IC's.

Double check resistor values of input resistors in front of the audio-VCAs (27K from schematic) and feedback resistors at the audio-VCAs following current_to_voltage converter stage (15K from schematic). In a balanced-out config Rfb should be half the value of Rin (2x 27K in parallel=13K5). In an unbalanced-out config (leaving XLRs-out pin3 or R from a TRS jack disconnected, not shorted to gnd) Rfb would be same value as Rin (27K).

Also, I have read somewhere the gain pot was from 0 to +20db, I can measure about 15db (50k pot), it is more than enough for me, but I'm thinking maybe it could be related with my +6db issue...

not related to your +6dB issue and amount of makeup gain is not related to the voltage divider pot value. Tweak to increase makeup gain by decreasing the 620K between pot wiper and opamps inverting input or increase the 620K for decreasing max.makeup gain.

More.... The Meter, it looks fine, more or less accurate, but putting a 330R resistor between the pins makes it almost don't move... maybe a lower value? anyway, without any resistor it looks fine, even reading a bit less than the in my DAW meter.

What type of meter do you use? The 330R shunt across the meter coil is used for a 100uA FSD meter. Leave this resistor out for a 1mA FSD meter.

Then, I got a Hum noise, something like -60dbfs. I've connected the jack's ground one with another (L-R) and then to the pcb, also I'm using metal spacers and screws for the pcb, maybe some kind of grounding issue? Lifting the mains ground from the chassis doesn't make any effect.

NEVER lift mains safety ground from a conducting metal chassis. You might make a connection between your case ground and 0V reference voltage switchable, called ground lift.
Hum most probably at double mains frequency will be ground loops from your both side connected cable shield between pcb and whatever type of jack you use (XLR-pin1 or TRS-sleve). Cable shield is only an extension of the case. Connect XLR-pin1 or TRS-sleve by a short connection to your case. Cable shields other side doesn't connect to pcb. The balanced line receivers exclusivly operate the potential difference between XLR-pins2/3 or T/R from a TRS jack. Your metal standoffs will make 3 additional connections to your case ground when conducting to the 0V reference voltage pcb traces at the mounting holes that might form a ground loop. You don't want more, if any, than exactly one connection between 0V reference voltage and your always safety ground connected case.

Last of all, in the 3rd release position I have no compression, I looked for bad sodlerings and found nothing, have to look closer for wrong resistor values or cap orientation...

Most likely a wrong resistor value (560R or short instead of 560K ?)

All been covered to death.

 

[12dbLow]

Hi guys,
finally i also registered here. I nearly completed the GSSL project from the documents. Even so, i encountered some questions:

- I found the same meter as 100mA and 200mA. Do they work ???
- Would it be convenient to put a switch on the front for the 47K threshold resistor, in a modern DAW environment? (Still, i have some synthesizers with a low signal)
- I have the THAT 2180LB (Pre trimmed). Do i HAVE to bend away the 4th pin? Or could I use the trimpots for a tiny bit of harmonic distortion? Its only a guess, tell me what you would do

Greets from Germany,
12dbLow!

 

[Harpo]

Maybe working, but not for the GSSL. Neither the TL072 nor the +/-12V supply for this part of circuit has enough beef to drive these 100mA or even worse 200mA meters to FSD.

 

[12dbLow]

Ok thanks.
And what about the other issues?

PS: Does the meter have to be AC or DC ?  For example this one?

 

[monobass]

what AWG of wire should I use for the star ground?

 

[12dbLow]

PLEASE Guys, I need some answers...  I finished my GSSL today and i encounter the following problem:

- The Threshold has (barely) no influence. it does have the 47k resistor.
- The Makeup Gain also has no influence

EDIT:
It seems everythings working. But its a pain in the arse when the unit just had some problems a few minutes ago and now its supposed to work.. You always hear some things that sound "wrong" ^^

 

[dennisp]

what AWG of wire should I use for the star ground?

I just used a 0.25mm² wire and my GSSL is silent as the grave (or at least below the noise floor of my Soundcraft Ghost LE which is very silent).

- The Threshold has (barely) no influence. it does have the 47k resistor.
- The Makeup Gain also has no influence

Those problems I actually had when I didn't have the wiring for the on/off/com right - perhaps a loose connection somewhere on the switch?

Positive regards
Dennis

 

[12dbLow]

No, but thanks everythings working now! Now I can order the frontplate.

edit: and the parts for the 1176  haha

 

[kante1603]

PLEASE Guys, I need some answers...  I finished my GSSL today and i encounter the following problem:

- The Threshold has (barely) no influence. it does have the 47k resistor.
- The Makeup Gain also has no influence

EDIT:
It seems everythings working. But its a pain in the arse when the unit just had some problems a few minutes ago and now its supposed to work.. You always hear some things that sound "wrong" ^^

Wondrous self-healing?
When threshold has barely no influence and makeup hasn't worked I wonder what it was,did you change anything?

Best regards,

Udo.

 

[12dbLow]

Sorry, i must have edited that sentence away..

I had the pots solderen incorrectly. Mine had 4 pins. I haven't had that before. Now everything works. But one more question: Is it normal that the GSSL tends to clip or make agressive noises when in more extreme settings? (Like distorting the bass?) My problem is that I dont have experience with hardware compressors, so I can only guess if mine works correctly. Though i've had very fat results today. (Drum group in parallel compression)

 

[kante1603]

Sorry, i must have edited that sentence away..

I had the pots solderen incorrectly. Mine had 4 pins. I haven't had that before. Now everything works. But one more question: Is it normal that the GSSL tends to clip or make agressive noises when in more extreme settings? (Like distorting the bass?) My problem is that I dont have experience with hardware compressors, so I can only guess if mine works correctly. Though i've had very fat results today. (Drum group in parallel compression)

O.K.,got it.
The pots:The fourth pin is most likely a connection to the metall housing.
GSSL tends to make noise:what does "extreme settings" mean?
Do you know the input level,maybe you are driving it too hard?
Does it have the turbo modification?
Since you are not experienced with them practice for a while,a GSSL can make a lot of different sounds.Start with one ratio,say 1:3,then work with the threshold and dial it in,listen to how the compressor affects the signal,then play with the time constants.It takes a while to get a feeling for it.
The makeup is for bringing back the output to an adequate level since the compressor reduces the original dynamic,therefore takes some level away.
A GSSL is an awesome tool especially on drums,it's a "rocker".
When you have played enough with it I'm sure you'll find your sound.
Parallel compressing is a last step to bring back some life if overcompressed.

Hope to have helped,

Udo.

 

[12dbLow]

Yes you're right I'll keep on trying. no modification yet. The sound also got better, I just tweaked around a little bit and always have to be carefull not to clip my interface. It outputs a pretty hot level, doesn't it? I always have to use the pad button on my interface.

 

[kante1603]

Yes you're right I'll keep on trying. no modification yet. The sound also got better, I just tweaked around a little bit and always have to be carefull not to clip my interface. It outputs a pretty hot level, doesn't it? I always have to use the pad button on my interface.

pardon,but you're talking about a pad which is normally to find on mic inputs.
If so then it is wrong,you must return the signal to line since compressors have line level outputs!

Udo.

 

[monobass]

what AWG of wire should I use for the star ground?

I just used a 0.25mm² wire and my GSSL is silent as the grave (or at least below the noise floor of my Soundcraft Ghost LE which is very silent).

Thanks Dennis.

I notice some people use bare tinned copper wire, quite thick gauge. Is that overkill then? Is having it bare anything more than a economic consideration?

 

[dennisp]

I notice some people use bare tinned copper wire, quite thick gauge. Is that overkill then? Is having it bare anything more than a economic consideration?

I think that using a bare wire is probably an economic consideration, but I like to have mine protected from accidental shorts - I didn't really take great care in cutting it at precise length for it to lay on a straight line out of harms way  :

As for the gauge - the thicker the wire the lesser the resistance and of course you would want the least resistance but this is still just low frequent audio signals (Hz to KHz) so any moddest thickness will do I'm sure.

I also stripped off paint on the sides, corners and screw holes where there is a connection between the plates forming the casing - but right now it stands on the table without a top on it and it is still very silent.

Positive regards
Dennis