GSSL SuperSC board

[vertiges]

Thank you Joachim !!!

eD)))

 

[barclaycon]

Yes that's right.
22uF electrolytics for the power supply caps.
Basically the electrolytics are to give power when it's needed and the 0.1uF caps are for RF rejection.

Joachim post has covered your queries in his post.

 

[vertiges]

Thank you barclaycon !

eD)))

 

[crisotop]

IC1 gets extremely hot in my unit (I can touch it with a finger for no longer than half a second) and my unit stopped compressing. it passes audio fine, but there is no gain reduction happening, makeup gain is still working. I'm able to trigger the comp with an external signal through the ssc board. any quick hints before i plug in a scope # frequency generator?

thanks
christoph

 

[Harpo]

Hi Christoph,

check if R16 (100R) connects to the tip of your rca plug and not to gnd, else check for shorts around ic1 and R16/R17.

 

[crisotop]

check if R16 (100R) connects to the tip of your rca plug

harpo, can't quite follow - my ssc boad is wired directly to the main ssl pcb. "send" (left of R16) of the sc board goes to the "bottom" of the two removed summing resistors on the main pcb.

will check the rest tomorrow morning
christoph

 

[Harpo]

[quote author="crisotop"]

check if R16 (100R) connects to the tip of your rca plug

harpo, can't quite follow - my ssc boad is wired directly to the main ssl pcb. "send" (left of R16) of the sc board goes to the "bottom" of the two removed summing resistors on the main pcb.

will check the rest tomorrow morning
christoph[/quote]
No! "send" goes to an external send with the corresponding return, most often wired to a stereo rca plug with ring as send and tip as return. It's like an insert plug in your mixing desk. Useful to plug in another filter for deessing or maybe a kickdrum signal.
The "bottom" of the two removed summing resistors (comming from the gssl input buffers) connect to "In-L" and "In-R". The other side of the removed resistors (dice it out, doesn't matter) connect to "Out", leading to pin 1 of the sidechain-VCA.
-Harpo

 

[crisotop]

sorry, my bad - it'S coneced like you described, I just mixed up my wiring when I looked at the picture of the sc board and not my actual build.

will check back later once I'm back at my unit
christoph

 

[crisotop]

what a shame - I'd rather not describe the fault in public, I could kick my own ass . During the finishing touches I installed shorter PCB standoffs, so that the big lytics wouldn't touch the top lid - same for the ssc board, for a cleaner look. what I didn't see is, that i forgot to cut the wires coming from the switch to the ssc board - the were sticking through the pcb and now - because of the shorter standoffs - touching the case....

Luckily nothing got damaged, unit is working fine again and sounding fabolous

thanks
christoph

 

[ask]

Would there be any chance of adopting this circuit back to it's "roots" - I'm thinking of two of PeterPurpose's 525-style comps with a S/C filter and thr*st, along the lines of an API 2500...?
But maybe the superSC is in the black book of DIY, so it's not an option?

 

[barclaycon]

I logged on to this thread because it looked similar to mine in Black Market.
I did a super sidechain PCB because I needed something to match Purusha's front panel and to tie up all the GSSL loose ends (i.e. IN/OUT switching, meter illumination etc.)
The hookup information is here:
http://picasaweb.google.com/barclaycon/GSSLSuperSidechainPCB

 

[clintrubber]

[quote author="ask"]Would there be any chance of adopting this circuit back to it's "roots" - I'm thinking of two of PeterPurpose's 525-style comps with a S/C filter and thr*st, along the lines of an API 2500...?
But maybe the superSC is in the black book of DIY, so it's not an option?[/quote]
:?:
I'm not sure I fully understand, but if there's some suited place in the 525-sidechain to insert a filter then this could work I guess. I have no idea how much the 2500 & 525 differ though.

 

[bassculture]

hi,

i've built 2 12afael / clintrubber sidechain boards.

i also got a turbo board, wich is not connected for the moment.

so i connected the two boards (ins & outs @ the 47K summings resistors on the gssl pcb), 1 for left, 1 for the right channel.


1/ i'd like to know if there is any change to the 20K resistor at the input and/or 47K resistor at the output on the sidechain card
because those cards were designed to received L+R at the input & not only one channel.

2/ i'd like to know how to set up the trimmer that control the output level (VR10) of the sidechain card.
to increase the gain should the R9+R10 high or low ?
i tried to adjust VR10 while compressor was on & i didn't notice a change.
(but maybe that's normal because the output of the two cards are summed...

3/ my question 2 is because i can mesure a AC at the input, but when i try at the output i get a value that decrease to 0 very fast (less than a second)
i mesure this against audio input or output ground.

 

[DaxLiniere]

I would guess that the best way to align the gain for the SuperSC board is to feed a signal into the GSSL which is above the filter frequencies, 1kHz will probably do.
With the sidechain filter bypassed, adjust threshold for, say, 6dB of attenuation (gain reduction). Then switch the filter in, any of the standard HPFs should do.
Then adjust the trimmer so that the GR meter is still showing -6dB.

I would also test this in a couple other filter positions, it should be all the same, except for the thrust positions, which are a bit different.

 

[bassculture]

thanks.

my previous post was messy -  :-\


i connected the two sidechain boards (ins & outs @ the 47K summings resistors on the gssl pcb), 1 for left, 1 for the right channel.

problem :
i got the sidechain output trimmer set fully clockwise (to get the highest output signal) & with the 47K engaged (i made this switchable) on the treshold pot (with treshold at -20 - ie 8 o'clock) , i compress but it's a really light treatment - far not enought for single instrument / drumbus.

i suppose there is not enought level at the output of the sidechain card

question :
i'd like to know if there is any need to change the 20K resistor at the input and/or 47K resistor at the output on the sidechain card
because those cards were designed to received L+R at the input & not only one channel.

 

[DaxLiniere]

I'm kinda busy right at this moment and I don't have the schematic in front of me either, but I would try halving the values, first on input of SSC board, then on output.

Also, bypass the SSC with aligator clips (using correct resistor values) and use my test procedure (Set for -6dB, then change a part of the circuit to see which way it goes)

 

[Harpo]

hi,

i've built 2 12afael / clintrubber sidechain boards.

i also got a turbo board, wich is not connected for the moment.

so i connected the two boards (ins & outs @ the 47K summings resistors on the gssl pcb), 1 for left, 1 for the right channel.


1/ i'd like to know if there is any change to the 20K resistor at the input and/or 47K resistor at the output on the sidechain card
because those cards were designed to received L+R at the input & not only one channel.

2/ i'd like to know how to set up the trimmer that control the output level (VR10) of the sidechain card.
to increase the gain should the R9+R10 high or low ?
i tried to adjust VR10 while compressor was on & i didn't notice a change.
(but maybe that's normal because the output of the two cards are summed...

3/ my question 2 is because i can mesure a AC at the input, but when i try at the output i get a value that decrease to 0 very fast (less than a second)
i mesure this against audio input or output ground.

1) Value should be 10k, else your signal will drop by 6dB. If you have both 20k's already placed on your sidechain board, keep them and feed both inputs/resistors with 1 signal (2x 20k in parallel=10k).

2/3) The 47k at output of the sidechain board is the summing resistor, substituting the 2x 47k at the gssl mainboard. Sidechain Out is the summing node/virtual ground of the following stage, so measure the signal level just before this 47k resistor on the sidechain board with preferably sidechain switched to bypass, else with a signal above cutoff frequency (see previous post by DaxLiniere), and adjust the trimmer to match input with output level.

 

[DaxLiniere]

preferably sidechain switched to bypass, else with a signal above cutoff frequency (see previous post by DaxLiniere), and adjust the trimmer to match input with output level.

Yeah, that's right. When I said "With the sidechain filter bypassed" I meant, the bypass position, not a hard-wired, physical bypass.

 

[bassculture]

that's crystal clear !!!

thanks a lot !!!!! ;D ;D ;D

 

[Dr nEon]

Hi guys !

1) Value should be 10k, else your signal will drop by 6dB. If you have both 20k's already placed on your sidechain board, keep them and feed both inputs/resistors with 1 signal (2x 20k in parallel=10k).

2/3) The 47k at output of the sidechain board is the summing resistor, substituting the 2x 47k at the gssl mainboard. Sidechain Out is the summing node/virtual ground of the following stage, so measure the signal level just before this 47k resistor on the sidechain board with preferably sidechain switched to bypass, else with a signal above cutoff frequency (see previous post by DaxLiniere), and adjust the trimmer to match input with output level.

Does this issue also apply to barclaycon's pcb?  I'm using two of these barclaycon pcbs with a turbo board . I have one 20k fitted on each board. I'd read this thread and wondered if I should change the 20ks to 10k from the outset , but decided to fire up for the first time with the stock 20ks in , and check out how the levels are with hpf in/out .

With about 8dB compression showing,on a 1kHz tone  there is no difference switching the hpf in/out ... this suggests that everything is fine , and the 20ks can stay as they are . 

Can anyone confirm this? Does the barclaycon pcb differ somehow from the 12afael / clintrubber sidechain boards??

[BTW - sounds EXCELLENT , and potentially VERY useful.....even tho the turbo brings us back to the ssl dual s/c that we all know and love , I think the hpf is still a welcome addition!]

cheers

nEon