GSSL HELP THREAD!!!

[onlymeeee]

Welcome sircletus,

How are your 12v rails doing? Are you getting the power for your relay from the regulated 12v rail or before? You want to keep the 12v rail as clean as possible. When you tested without relay, was it completely removed from the 12v rail along with anything else on there. Lamps, Leds etc?

Any chance of some audio files?  Is it a subtle distortion?

 

[sircletus]

OnlyMeeeee:

Thank you for the reply.

My 12v rails read consistently around +/-11.89 or so.  I'm not taking the relay supply from the +12v rail.  I'm actually taking it from the regulated +15v rail, to allow for a bit of voltage drop through the current limiting resistor and indicator LED located in the switch.  The relays are only "on" (closed) when in bypass; when the circuit is "in," the relays are open and draw no current, as the switch/indicator LED is upstream.  So +15v just sits on the switch and draws no current when the circuit is "in". I assumed this would have no negative impact on the audio supply.

I AM, however, pulling my meter backlighting (2 BRIGHT blue LEDs) from the +12v rail.  Could those be the culprit?  Also, I'm using off-board 7812/7912 in TO-220 package, wired into the PCB through about 4" of wire for what it's worth.

I will upload some files tomorrow to demonstrate the distortion.  I don't find it subtle at all.  I had the GSSL across my rhythm guitar submix and was able to pick out the distortion even in a busy mix.  It's less obvious with transient material, but on sustained stuff (keys, guitars) it's pretty obvious.

Thanks again!
SirC

 

[onlymeeee]

Perhaps the LEDs could be causing it. 
Not recommended to take much from the 12v rails.
It's better to take it from the unregulated dc.

Try it with the leds disconnected and let us know

 

[sircletus]

Disconnected meter backlight LEDs from +12v rail.  Still distorting.  Files on the way soon.

Question:  Are these control voltages sensitive enough that +11.86v is too far out of spec?  I can't imagine that would be the case...but that's what's coming off the 7812.  The 7912 is putting out a perfect -12v.

 

[sircletus]

Here's a link to an mp4 file containing examples of the distortion:

http://www.enfuegoaudio.com/GSSL_Distortion.m4a

There are four segments of a stereo rhythm guitar stem with the following settings:

1.) GSSL bypassed
2.) 2:1 ratio
3.) 4:1 ratio
4.) 10:1 ratio

Attack and release are at their fastest settings on all examples.
Threshold and Makeup Gain are both set at zero on all examples.

Again, the distortion is at its worst at the fastest attack settings.  Changing release setting has no effect on amount of distortion.

 

[onlymeeee]

Are your voltages at all the op amps ok?
What are you seeing at point c?

 

[sircletus]

OnlyMeee:

All op amp supplies are fine:

TL072/74 rails read +11.86v and -12v even.

Audio path op amps are +15v and -14.97v.

I'm seeing 0vDC at point "C" regardless of settings when NO signal is present.  I assume this is correct, as there is no AC signal to rectify.  I'm also assuming that with signal present it should be nice clean DC, but HOW clean should it be?  How much ripple is acceptable?  I'll scope it tomorrow.

 

[onlymeeee]

Long shot.. but have you missed the small wire link on the control board near the the 10pin?
Tripple checked component value/orientation? And shorts?
What changes have you made because of the 2180 vca?  eg. http://diy.fischerworks.com/gssl_vca.shtml

 

[sircletus]

Yes, the jumpers are all installed.  I've definitely triple checked orientation and values.  The only thing I have NOT done, however, is replaced the 3k9 resistors on the VCAs with 5k1s...

Here's what I see when scoping the CVs when feeding both channels a sine wave:

- At pin 3 of the audio VCAs, I see a nice, flat, essentially zero ripple DC CV that varies just a bit when I twiddle the makeup and threshold knobs
- At point "C", I see some ripple of about .1mV P-P
- Just on the other side of that diode, at pin 14 of the TL074, I see a VERY asymmetrical sine wave of about 1V P-P

Is that healthy/normal?  I'm just about ready to scrap the whole thing and start over.

 

[trancedental]

I've just installed the super sidechain board on my previously working GSSL, but seem to have some problems

LED & compression on/off switches work, but nothing else no makeup, threshold, no meter readings, the compressor just seems to be in bypass, can't hear any compression even on the SSC off position on the Lorlin 8 way switch.

I've checked continuity from the Super Sidechain PCB to the Lorlins & other connections & also checked the switching positions on the Lorlin.

I've checked & found the DC return signal (VCA control voltage) coming out from the sidechain board, back to the main PCB and all the way to the TL074 various outputs, 7 & 1 OK but after the next output pin 14 the DC signal goes dead just before the bypass section judging by the GSSL schematic. I don't know exactly how the bypass relates to the relay / SSC as I can't find a schematic for that board!

Any advice would be great

(Post moved into the SSL thread)

EDIT swaped in a new TL074 no difference, looks like I'll have to order a new relay? ???
Luckily it all works OK with the Pot A / B & COM ON OFF connections wired up as normal, with the SSC still in the circuit when switched in.

 

[mrcase]

Hi Everyone!

First of all I`m quite new to the forum! Thank you all! This is just great!
AND I`ve finished my first DIY Project - the GSSL! and it works! so coooooool!!!!! ;D ;D ;D ;D

I`ve set up a little blog with some pics, its german only at the moment though...

here you go! : http://justincase.soup.io/

now the only thing left is getting it racked, and supersidechain!

Thanks to everybody again!
I´ll have a drink now! 

cheers!

 

[sircletus]

Congratulations, Mr. Case!

UPDATE on the distortion I've been experiencing:

It turns out that my choice of SIP sockets for the VCAs was the culprit - I was using Mil-Max sockets with round holes.  Obviously, those don't mate well with the flat pins of the 2180s.  Eliminating the sockets altogether cleaned everything right up.

 

[Stagefright13]

Great job mrcase I hope you enjoy it! The super sidechain is exactly that. Super! Never tried the turbo board tho. The sidechain board gives it everything I need.

John

 

[Jagle]

heya guys. new here.

got most of my parts, stuffed the PCB's.
just about to order the final bits and pieces.
anyone be able to tell me if this meter is ok? and if what resistor i need to use for the meter..

thanks
http://ie.farnell.com/jsp/search/productdetail.jsp?sku=1262059

 

[trancedental]

Jagle, That meters OK with a 330R shunt resistor for details look in the schematic, looks nice but maybe a tight squeeze on 1U? BTW you can save money by using  Farnell product code 143509, and the PCB (shown on the layout ) meter resistor is 20K instead of 2K for 100uA.

Happy St Patricks Day ;D

 

[Jagle]

haha thanks, i do love our special day..
im using a 2U case with that meter, havent decided yet between the two..

thanks for calming my nerves trancedental

 

[tongenerator]

Hello,

i have a question  :

i buyed the 2181LB to build this GSSL Kompressor.

How reliable are the given resistor values of this page for the 2181LB  ???
http://diy.fischerworks.com/gssl_vca.shtml

If it says jumper... i could also just use an isolatet short wire?  ;D

thanks

mark

 

[trancedental]

A cutoff resistor leg does the job just as well as a jumper ;D

 

[Oli]

Hey guys !

I have just finished assembling a GSSL clone that looks really nice but there seems to be a problem about it:

It appears to be something related to the Threshold value.

When I give him some feed from a source, the meter needle seems to hold according to the value of the Threshold. so the needle moves when I turn the treshold knob, but it always stays at one point.  If I play a bit with more, at one point, it suddenly peaks and go back down at its point.  At that precise moment, it seems to clip sound wise.

Other than that, sound comes out "normally" but it doesn't seem to be compressed that much, with or without the bypass.  I've try a different control board/inputs/outputs/power from another GSSL, and same problem happens so the pots should not be the issue here. It should definitely be something wrong in the board. Could it be a burnt 5534N chip, or something else? 


Please help !!!

Oli

 

[tongenerator]

well i am not an electrician... but i think that your amplifier chip is not burned...
if so, there schould not even a signal come into your compressor...

what the issue relatet to ur problem might be ??? dont know... i am a noob  :

edit:

i just see... does it meight be that there is a problem with ur dc meter...
as far as i know u need a 1mA dc meter. maybe it just shows wrong because u
have diffrent dc meter.