GSSL HELP THREAD!!!

[tongenerator]

Hello,

can i use 3 of them to build the gssl?

regards

mark

 

[osterchrisi]

Hello,

can i use 3 of them to build the gssl?

regards

mark

uhm, three of... these pictures?
three of... these beautiful flowers?

three of what?

 

[warpie]

what I can't really understand is why not using ribbon for the pots..
I mean the audio passes through the ribbon (from the main pcb to control pcb) anyway.
Am I missing something?

 

[gyraf]

no audio - only control voltages - go to/from the control board..

Take a look at the schematic

Jakob E.

 

[warpie]

thanks Jacob,

I have to say I'm not very experienced with schematics but as I can see there's only control voltage
goin to the bypass, threshold and makeup pot.
Thus, a ribbon cable can be used for these pots(?)

P.S I keep asking about using a ribbon because I'm planing to use a halfrack encloser and it's important to keep the wire as small and thin as possible.

 

[osterchrisi]

You can use it, but plz also consider that a ribbon wire might be tricky to solder... I don't think you save a lot of space with ribbon cables - but feel free to use them.

 

[warpie]

thanks osterchrisi,

I think I'll go for the ribbon 

 

[warpie]

ok, it's me again... :-[

once upon a time...
I was feeding the SSL input with 4Vpp sinewave (1Khz) from a signal generator. The output of my SSL (bypassed) was outputting 2.6Vpp (approx. as I'm using an oscilloscope). If I've done the maths correctly the output is about -3.5 db less than my input when is bypassed or when the ssl in 'in' mode but makeup gain fully anti-CW.

Then I change the 27K resistor (for unity gain) to a 50k trimmer and adjust it to give me unity gain. The resistance now is 37k instead of 27k.

>>Is it a good idea to use this technique or it will introduce artifacts (like increase to the Noise-toRatio ratio, etc) ? ???
>>Is there the possibility that something else affects my unity gain rather than the 27k resistors?

I'm using 2181LA if it helps

I've read some posts around the unity gain but unfortunately couldn't get an answer to my question.

Any help is much (mush, much) appreciated

 

[trancedental]

Have a problem with the right channel on my finished GSSL. In Bypass the levels are equal with a very slight distortion on the right, when the compression is switched on the right channel gets more distorted & also loses a lot of volume the more compression is applied compared to the left channel???

I 've swapped out VCA's & opamps to rule them out so now wondering what to try next, suppose I'll try sending some test tones in & compare the readings of the channels to each other to start with. :

Any exact ideas on what to look for from the genius minds of the experts on here would be great though? ;D ;D ;D

EDIT Control voltage leaves the TL072 but only gets to one of the VCA's so it's probably something wrong along the way ???

FOUND IT:  ;D After 3 hours messing about, a 1K resistor was faulty no readings going to the VCA! I suppose I'm starting to understand the circuit a bit more anyway now after all this fault finding

 

[marcfrom]

Hi, do i have to using 50K trim whith DBX 202 VCA's?

 

[marcfrom]

Hi, I have build a GSSL whith DBX 202X, I using 27K resistor for unity gain, whith 15K resistor I had something like 5 dB more at the output.

For 100K or 127K resistor for Ratio i don't know, I'm looking for the answer, for the moment i use 127K resistor but i don't know if the Ratio is correct.

If you have information about it, hold me informed.

 

[warpie]

hi,

I noticed that the threshold range of my gssl is aprox. -13db to +23db or so.
Is this possible or the range is always equal for positive and negative voltages (like -20db to+20d or -18dbto+18db, etc.) ?
I'm confused and don't know if it is possible to fix this problem...
any help?

 

[warpie]

anyone???

i can't find any info to my problem?

btw, this threat seems to be pretty 'dead'

 

[museic]

Hey all. I'm looking for a couple final parts...

I need the 79L12 Regulator. Anybody got a link for a U.S. distributor? Digikey says they're out of stock.

Mouser has this one. Would it work?

http://www.mouser.com/Search/ProductDetail.aspx?qs=sGAEpiMZZMvkC18yXH9iIvlH%252b7DLPI6OwbAYhPth1Qo%3d

I also need a rack case... Does anyone sell them in the U.S. with some type of GSSl screenprint on them already? That would be sweet.  I also need some knobs, but I can probably find those on my own. Thanks.

 

[signalflow]

That reg should be fine.  For cases the 10 series from http://www.par-metal.com/10series.htm

Then just send it to http://www.frontpaneldesigner.com/ with one of the GSSL templates from franks site http://www.nrgrecording.de/html/schaeffer.html

-Casey

 

[Harpo]

Hey all. I'm looking for a couple final parts...

I need the 79L12 Regulator. Anybody got a link for a U.S. distributor? Digikey says they're out of stock.

search digikey 79L12 and only select TO92
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MC79L12ACPGOS-ND current stock 3,778
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=LM320LZ-12-ND current stock 574
Your Mouse Part should also fit the bill.

 

[Harpo]

anyone???

i can't find any info to my problem?

btw, this threat seems to be pretty 'dead' 

mike

have a look in the gssl meta or
select the search tab at the top of this page and enter gssl+threshold

 

[sircletus]

Okay, all.  I'm a first-time builder of this particular project, but a hobbyist for a few years.  I just completed my first GSSL build but I'm having a somewhat familiar issue:  distortion at fast attack times at the 4:1 and 10:1 ratios.  Here's EXACTLY what's happening:

1.) Distortion occurs in both channels.
2.) It's only audible at 4:1 and 10:1 ratios.
3.) The faster the attack time, the greater the distortion.
4.) Release time does not seem to affect the amount of distortion.

SO, more compression = more distortion.

I've only made a few modifications from the original circuit:

1.) Using THAT2180 VCAs.
2.) Relay true bypass.
3.) Increased sidechain mix resistors from 47K to 100K.
4.) Jumpered (and therefore bypassed) the on-card bypass switch option.

Aside from these small changes, I followed what was on the PCB.

Here are some steps I've taken to troubleshoot:

1.) I have extensively tested the audio path: the issue is in the sidechain.
2.) I have extracted the audio path VCAs and jumpered pins 1 and 8 to ensure integrity of audio signal path.
3.) Even checked with a scope and gen at 1kHz and 10kHz to look for distortion.  None present when sidechain NOT engaged.
4.) I thought perhaps switch wiring was to blame, so I got rid of ribbon cable and rewired ALL switches with higher quality 20 gauge teflon stuff.
5.) Ended up pulling both attack and release switches and hardwiring a jumper for each so that as I test, the compressor is "stuck" in the fastest attack and release settings - this eliminates those switches as culprits altogether.  Remember, it's only at the fastest attack settings that distortion occurs.
6.) Just for the sake of testing, I removed relays from the equation – no change, as I suspected.
7.) Made sure ALL components attached to pin 4 of ALL VCAs were removed AND bent pin 4 on each VCA just to be sure.
8.) Removed ribbon cable that connects control board to main PCB and rewired with individual wires.
9.) TRIPLE checked all sidechain/timing component values.
10.) Just to be sure, I attached the 47K resistor in series with the positive leg of the threshold pot.  Distortion still present.
11.) Changed out sidechain VCA, TL072 and TL074.
12.) Changed 100K sidechain-summing resistors back to 47K. Distortion still present.
13.) All of my tantalums are properly polarized.
14.) All diodes properly biased and measured.
15.) Yes, all jumpers are in place (and continuity checked), including the one just before the meter (which is a 1mA meter, btw).


So, there you have it.  Really at a loss.  I'm sure it's something stupid that I've been overlooking this entire time. The one area that's particularly suspect to me is the on-card bypass switch that I bypassed and makeup gain pot connection.  I assume they're wired correctly as I've traced the circuit on the PCB and makeup gain works just fine.

This brings me to a couple of questions:

1.) Could slightly changing values of audio path components be responsible for this?  I assume NOT, as I've tested the signal path without the sidechain as many times as possible, with both OLD schematic-specified and PCB-specified audio path feedback capacitor values (I seem to recall there being a SLIGHT difference...)

2.) I have no idea what the control voltages are supposed to look like or measure at.  I ASSUME they should be nearly ripple-free, but I'm not sure HOW ripple-free they should be.  The CV going to the audio VCAs has some ripple when I scope it in AC.  But again, I've changed BOTH the TL072 AND the TL074 AND double-checked all sidechain resistor/capacitor values.

I'm perplexed and incredibly frustrated.  Anyone have any thoughts on the matter?

SirC

 

[warpie]

anyone???

i can't find any info to my problem?

btw, this threat seems to be pretty 'dead'

mike

have a look in the gssl meta or
select the search tab at the top of this page and enter gssl+threshold

hi Harpo, thanks for replying. I've have already been through all these posts and I think I couldn't find the answer.
Also I assume tat the answer to my question is more like 'yes' or 'no'

 

[museic]

Hey thanks for the links guys! One step closer to seeing if this gadget works  ;D