GSSL HELP THREAD!!!

[MiamiBoy]

On the other hand, I should probably use the built in SC.

So the question now is: should I make it permanent by bridging it, like Gyraf suggested?

yes, the wire link must be soldered in if no filter is used. otherwise you don't get sidechain signal.

Or should I connect it to my Turbo board and make it switchable, so it's only engaged whenever the turbo is engaged?
That's how PCBGRINDERS's blog is suggesting

3rd option will be getting 2x SSC boards and order a new frontpanel, drilled for SSC that has those 7 steps markings.
Some say though that SSC is not necessary when turbo is installed!?

I can't decide, don't know the pros & cons for one over the other.

 

[MiamiBoy]

I might even have confused myself further....
Thinking about those 3 options made me wonder some more.

If HPF* is bridged, then signal goes to sidechain?
Will it still low-cut? without a cap..
If not, then putting a cap right on the PCB and avoid the toggle switch, will make it permanently low-cut?

I remember seeing a 0,1µF cap between HPF* and toggle switch, in the guide.
I thought the cap was doing the low-cut.

If the cap is doing the low-cut, then what is the sidechain section doin?

I probably haven't understood it correctly.

 

[Harpo]

Each compressor has a sidechain, controlling threshold, attack, release, ratio, ...
You are talking about a sidechainfilter. Have a look at the schematic.
Sidechain signal coming from TL074-pin7 thru a 22uF cap, followed by two 20k resistors, each to a virtual ground node of the following opamps, so being in parallel, giving 10k. This R/C filter forms a hpf with -3dB cutoff point at 1/(2*PI()*10000*22E-6)=0.72Hz with the additional 100nF hpf provision cap shorted out. With 100nF cap not shorted out by a maybe toggle switch, the 22uF cap is in series with the 100nF cap, giving cap value 99.55nF on paper, that is still followed by the two resistors to the virtual ground nodes, so the hpf -3dB cutoff point rises to ( same 1st order -6dB/oct filter formular with changed cap value 1/(2PI()*R*C) ) 159.87Hz for a 160Hz frontpanel label. A 220nF cap instead of the 100nF cap would have this hpf set at 73Hz, two 100nF caps in parallel instead @ 80Hz, .... just run the numbers and pick the cap value for your wanted hpf frequency.

 

[MiamiBoy]

Thats it, great, thank you! -that's what confused me!

Richardus asked me "don't you want sidechain option, its SUPER useful" when I asked about leaving the HPF* toggle-switch + cap out of circuit.

If leaving the toggle switch out (low-cut), I have to bridge the HPF* or else its not connected to the sidechain section.
And if sidechain isn't connected, that makes the compressor useless (if sidechain is in charge of threshold, attack, release, ratio etc.). Right?
But as you mentioned, if I understood it correctly, theres also a HPF at the sidechain section, right?

Going back, I also see that I've misunderstood Gyraf's answer.

I think im gonna leave the low-cut filter+toggle out and just bridge it,
because one: I don't have space for it on frontpanel, and two: I don't like having my low-cut filter at a fixed Hz.
I rather upgrade later on, with two SSC boards and have the filter toggle/control-knob on my frontpanel (option 3).

I looked at schematic, and even though I don't quite understand them yet, I saw the route you were talking about. I see what you mean.

 

[MiamiBoy]

little feedback. i connected the board with 1M resistors and 50k trimpots surrounding the 202cs. it works just as it should and sounds very nice!

Hey, do you remember if theres anything else that need to be done, other than adding 1M and 50K trim?

 

[MiamiBoy]

Cut the potentiometer?
This is too long for my knob and I want to shorten it.
Is it possible to saw the tip (blue line) off or is there some mechanics inside that solid metal part?

 

[ruffrecords]

You can cut it. It should be a solid shaft.

Cheers

ian

 

[MiamiBoy]

Awesome Ian, it will make my life easier!

 

[Ricardus]

What are you planning on cutting it with? I cut a shaft with something that introduced a lot of vibration down the shaft and into the pot body, and it definitely damaged the pot.

 

[Script]

Vibration, dust and heat (when dremelled) all can damage it. How short does it have to be? An extra nut on inside shortens it too.

 

[MiamiBoy]

I’m gonna a use a regular metal hand saw.
The knob is the problem, it ain’t deep enough.
But okay, I’m gonna try buy some nuts and see.

edit: no can do with nuts. See the spacing distance from frontpanel to knob?

 

[MiamiBoy]

All better now.. not perfect, but better than before.
I've put washers on the inside but the nut on the outside, between panel and knob is still too thick.

The question is, was the pot damaged during the process?

Thanks for your inputs, guys!

 

[MiamiBoy]

Any guess why my MakeUpGain is affecting the meter?

 

[Harpo]

Any guess why my MakeUpGain is affecting the meter?

With your red and green wire hooked up wrong (they need to be separate from the other part of the bypass switch), makeup-gain affecting the meter is your least concern. You need a little luck that your tantalum timing caps now fed with 0..+12VDC reverse voltage have survived this abuse...

 

[MiamiBoy]

I’ve now removed them to the other side and also removed the LED out if the circuit completely. Performs normal now.


That sounds serious with the cap. Is it gonna sound obvious if it’s broken or should I run some kind of a test/measurements?

Wonder how I should wire the LED now, for illumination..

 

[MiamiBoy]

Threshold doesn't do anything between +15 and 0 (1 o'clock / 12 o'clock) with 2:1. Is that normal?
im using unbalanced cables.

When increasing threshold to -15, the meter just shows "more compression", but the compression sound doesn't really change from when it's at 0.
The whole "glue sound" is not there, only gain reduction but no compression / minimal compression. I'm using 202C gold cans, + added two 1M resistors and 50K trimmers.
Make-up gain isn't super loud either, even at max.
Is this expected?

Please, if theres some tests or audios I should run, to confirm if my unit is behaving normal, let me know

EDIT: i'm getting these measurements (unit is ON, without audio running)
Power input: 230 VAC
center tap: 17.6 VAC on each

LM 7915:
G: 0
In: -22.000
O: 14.972

LM 7815:
In: 21.838
G: 0.0002
O: 14.825

Op-Amp/VCA from top left to bottom right:
5534: (7): 14.826 ·|· (4): -14.974
5534: (7): 14.827 ·|· (4): -14.975
5532: (8): 14.828 ·|· (4): -14.977
5532: (8): 14.826 ·|· (4): -14.978
tl072: (8): 12.121 ·|· (4): -12.100
tl074: (4): 12.121 ·|· (11): -12.097
THAT: (7): 12.121 (2180B SideChain)

Without op-amp/VCA (sockets only):
5534: (7): 14.798 ·|· (4): -14.974
5534: (7): 14.798 ·|· (4): -14.974
5532: (8): 14.798 ·|· (4): -14.974
5532: (8): 14.797 ·|· (4): -14.974
tl072: (8): 12.127 ·|· (4): -12.117
tl074: (4): 12.127 ·|· (11): -12.117
THAT: (7): 12.127 (2180B SideChain)

MakeUp-Gain Wiper pot & 620K resistor:
Left pin: 0.0003
Mid pin: CCW: 0.0004 |12 o'clock: 5.9359 | CW 12.139
Right pin: 12.141

Threshold Wiper pot:
Left pin CCW: 0.3975 | 12 o'clock: 0.7360 | CW: 0.4411
Mid pin CCW: 0.3975 | 12 o'clock: -5.427 | CW: -12.100
Right pin: -12.100

10 pin MainPCB:
+:12.121 | F: -11.551 | E: 12.121 | G: 0.0005 | D: 0.0026 | -: -12.098 | 0: 0.0002 | A: 0.0003 | B: 0.7403 | C: 0.0026

I don't have voltage at "optional relay & light power" (only 0.0018) I should be getting 12V - trying to illuminate meter-LED.