How to connect the Turbo board + 2x Super SC (drawing, post #15) **revised

[stereokillah]

also, this is the only switch/pot in the unit which needs to be 2 decks, right?

YES

Sorry don't have link but i think you may find it on ebay

 

[ncoak]

thanks....this one should work eh?

http://search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=GH7324-ND

 

[stereokillah]

yes you need 8 position by  each deck for the SSC

 

[Alessio]

When I connect the TURBO only at one end of the 47k resistor (that needs to be removed) do I need to make a bridge with the hole on the other end?

Thank you,
Alessio

 

[Harpo]

Alessio, did you change your mind and took out the SSCs or is this for a different build ?
From your previous post you seemed to build a GSSL with 2 SSC boards and an always connected Turbo board. With SSC board in front, the Turbo does not connect to one of the lifted 47k resistors on GSSL mainboard but to the output of the SSC board.

do I need to make a bridge with the hole on the other end

The opamp stage, connected to this point will hate you just for the idea of frying its input stage.

 

[Alessio]

Hi Harpo,
is still the same project 2SSC and an always connected Turbo board.
I've followed the draw that you post on the "GSSL SuperSC board" thread... All the switches and LEDs are working, the makeup is working. When is in bypass the makeup is disabled. I've check all the voltages on the main PCB on the TURBO and on the 2 SSC everything is OK. I've insert all the opamp and VCA in the right places and right orientations.
Now this is what is happening:
When I turn on the unit the audio pass through but when I engage the compressor the threshold is not working and the meter doesn't move (NO COMPRESSION!!!) when I move the ATTACK to POS 1 the meter jumps up (the same for the other positions of the attack!)... What the hell is happening???
I can't understand... The control PCB seems fine...

I wired the LEFT (removed 47k resistor close to the bridge) SSC with the TURBO board and the RIGHT (removed 47k resistor close to the left vca) SSC with the main board.
On the SSC boards I use only the LEFT input and I've soldered only 1 10k resistor (the one connected to the L) instead of 2 20k resistors, because I dont use R. Is that right?

TURBO: the "C" is connected to the main board, the S/C C.V. is connected to the 100ohm resistor (on the main board) and the S/C INPUT is connected to the RETURN of the LEFT SSC which L is connected to the removed 47K resistor close to the bridge. Is that correct?

I've tryed to re-check you draw and I dont understand where the problem is... It must be something stupid... ??? I'm soooo close!!!!


Any idea?

Thank you,
Alessio

 

[stereokillah]

and your switch for sidecahin filter is correctly wired ?? check all your voltage +- 12 and -+15 perhaps something around

 

[Alessio]

I've wired the SSC rotary switch following this draw: The voltages seem to be correct...

 

[Alessio]

I've solved one part of the problem! (I had soldered the rotary switches in the wrong way : ).
Now the LEFT SSC is connected to the TURBO and the RIGHT SSC to the main board.

This is what happens.
If I disconnect the power of the TURBO board: the RIGHT channel work perfectly, meter, compression, SSC filter... everything perfect!
If I connect the power of the TURBO board: the meter jumps up and nothing works except the make up...

So I think I've located the problem... There must be something wrong in the wiring of the LEFT channel (TURBO board + SSC LEFT).
I just dont know what... Any idea???


Thanks very much!
Alessio

 

[Alessio]

Everything works!!!!
I had the turbo board connected wrong!!! ;D

Thanks everybody for your help!

I'll post pictures!!!!

 

[Alessio]

Ehm... I still have a little problem...
This will be the last one I hope ;D

So... My left channel (where the turbo board is connected) compress the double amount of dB compared to the right channel...

 

[SSLtech]

Scope. Compare the two channels. You have to start by finding out where they're the same, and where they become different.

Keith

 

[Alessio]

It seems like a need a resistor before the turbo board???

On both channel then, when the threshold is at 0 (so it should not compress) and I switch the compression on I still compress 1dB on the right channel and 2.8dB on the left channel (where the turbo is connected). If I move the threshold down (so I'm compressing) the difference between the 2 channels increase as well...

Does this have something to do with the 2x20k resistors at the inputs of the 2 SSC? Because now I solder only 1 10k because I use only 1 input (the L input) on both SSC...

I'd like to have this unit perfectly calibrated I can use trimmer resistors I just dont know where :


Thanx,
Alessio

 

[Harpo]

It seems like a need a resistor before the turbo board???

Yes, but you already have placed this 47k on the SSC board. Nothing to add or to change in this spot.

On both channel then, when the threshold is at 0 (so it should not compress) and I switch the compression on I still compress 1dB on the right channel and 2.8dB on the left channel (where the turbo is connected). If I move the threshold down (so I'm compressing) the difference between the 2 channels increase as well...

Does this have something to do with the 2x20k resistors at the inputs of the 2 SSC? Because now I solder only 1 10k because I use only 1 input (the L input) on both SSC...

I'd like to have this unit perfectly calibrated I can use trimmer resistors I just dont know where :

Double check ALL resistor values for same resistance L+R channel, beginning at GSSL input thru the SSC boards, thru Turbo board and back to GSSL board. Might be easier to measure at the corresponding opamp output pins where levels drift apart when GSSL input L+R is fed with same signal. 
Nothing to do with your 10k. With 10k feedback resistor at the SSC summing stage (1st.opamp) you want this 10k for unity gain as SSC input resistor for your Turbo/Oxford build. Connecting to SSC L or R input doesn't matter, as this is a summing stage. (For GSSL/Aarhus mode these SSC-input/summing resistors are program depending 2x 20k up to 2x 14k1).

 

[Alessio]

Ok, I'll check all the resistors and see if I put something wrong. I'll let you know!

Thank you,
Alessio

 

[Alessio]

I've checked all the resistors on the main PCB and they are all right.
I've swapped left and right SSC and the problem is always on the left channel (where my TURBO is connected). So I think the problem is not in the SSC boards.
I swap TL074 from the TURBO to the main PCB and the problem was still on the left channel (a little bit less). So I assume is not the TL074.

Now I have: when compressor is engaged but threshold at 0, -0.25dB on the right channel (that is acceptable) and -2dB on the left (that is wrong) this difference increase a lot when I move the threshold down. Left channel compresses much more than the right.

So, correct me if I'm wrong, I think the problem is on the TURBO board. I just dont know where.


Is this makes sense? I'm learning a lot doing troubleshooting, I'm still new to this kind of things...



Any idea?

Thank you very much!
Alessio

 

[stereokillah]

check the signal between your controle board ratio and your turbo ratio under the board i think you have a bad way in your ratio connetion with turbo

 

[Harpo]

check the signal between your controle board ratio and your turbo ratio under the board i think you have a bad way in your ratio connetion with turbo

Well spotted, this just might be it. Have a 2nd look at the TurboInstallationManual.pdf, page 6.

 

[Alessio]

The ratio connections seem fine. I'll check better...
For now the only difference that I can see between the turbo and the main board is that on the main I've switched the 3.9k resistors close to the VCAs to 5.1k but in the Turbo is still 3.9k. This can be the difference of compression? Should I change this to 5.1k?

Thank you,
Alessio

 

[Harpo]

I doubt, this is the reason for your mismatch, but use 3k9 for both Turbo and sidechain VCA, both being powered from +/-12V supply. I'd keep 5k1 for the audio VCAs, powered from the +/-15V rails.
Did you already measure the opamp output pins, so you'd know where levels drift apart? (IE. feeding both inputs with maybe 1V 500Hz sine wave, both NE5534 pin6 at the input stage would measure 1V, ..)