GSSL HELP THREAD!!!

[Charly_V]

Take the trafo off the circuit, measure AC from side to center tap (should be abut 15VAC) and side to side (should be about 30VAC).

If that checks out, the problem is not you transformer or transformer wiring. If it doesn't, it is.

Gustav

Thanks Gustav, well here are the tensions :

From side to center tap : 17,5 VAC
From side to side : 35,5 VAC

I'm assuming these are correct ?

Turns out there was a bridge between center tap and one side pad.

I'm affraid this might have damaged components since nothing happens when I turn the unit on now, what do you think ?

 

[Gustav]

Thanks Gustav, well here are the tensions :

From side to center tap : 17,5 VAC
From side to side : 35,5 VAC

I'm assuming these are correct ?

Turns out there was a bridge between center tap and one side pad.

I'm affraid this might have damaged components since nothing happens when I turn the unit on now, what do you think ?

Trafo is within expected values for correct set-up, so next step is checking the DC voltages on the board.

I would pull all the ICs first (I never do a first-power up with ICs in) then check them.

A nice trick, if you dont know where to measure which voltage, is to google the pinouts of various components in google image search.

i.e. "LM7815 pinout" - it will show you which pin to measure to see if you are getting 15V out
or "5532 pinout" will show you which pin to measure for positive and negative voltage on that particular IC.

Gustav

 

[Olegarich]

Hey guys, could you point me out how to math parallel resistor for the meter? I have 200uA meter that i would like to use but I'm not sure what resistor I need to use in parallel with meter if it's 200uA. Thanks

 

[Charly_V]

Trafo is within expected values for correct set-up, so next step is checking the DC voltages on the board.

I would pull all the ICs first (I never do a first-power up with ICs in) then check them.

A nice trick, if you dont know where to measure which voltage, is to google the pinouts of various components in google image search.

i.e. "LM7815 pinout" - it will show you which pin to measure to see if you are getting 15V out
or "5532 pinout" will show you which pin to measure for positive and negative voltage on that particular IC.

Gustav

Thanks, I'm getting those values on the regulator ICs

7915 - 15V
7815 - 15,12V
7812 -  12,28V

Those seems fine to me but it seems like there's something weird coming after on the small ones.

78L12 - 15,07V
79L12  - 0V

Where do you think could be the failure ?

I'm not too sure on how I could measure the capacitors, I can also tell you that some resistors around the TL074 show very low impedance. I have a bad feeling about this.

 

[Olegarich]

79L12 - 0, check with meter it's output with ground, you may have solder joint, also you sure that 7915 is 15??, cause it should be
  -15V  as far as I know, cause it is 7915

 

[Gustav]

it seems like there's something weird coming after on the small ones.

78L12 - 15,07V
79L12  - 0V

Where do you think could be the failure ?

Maybe you swapped them?

Should be -12 on the 7912 output pin,  and +12 on the 7812 output pin.  (make sure to obverse the correct sequence of your meter probes while measuring)

Gustav

 

[Olegarich]

Hey guys if I want to use 100ua meter, can put 660ohm resistor in parallel with meter and trim it with 4.7K trimmer?

 

[main repairman]

Hi. I can change disk capacitors to MLCC capacitors? Thanks

 

[Olegarich]

i changed in 'sidechain' those ceramics with no problem.
I've read somewhere that for sound are best silver mica,. In other hand they cost.

 

[main repairman]

i changed in 'sidechain' those ceramics with no problem.
I've read somewhere that for sound are best silver mica,. In other hand they cost.

Thanks

 

[Olegarich]

Just finished Gssl with crc,turbo, sidechain filter and crush&blend ( by Lukas) modes.This is 3 gssl I’ve built and want to say that if you want to put it on master section, crush and blend mod is “must be”. It just gives you much more options and control on sound. Gssl with all  modes definitely  is a beast!!!

 

[realitycontrol]

Throughout this thread there have been plenty mentions of the following two pages to follow for calibration.
http://groupdiy.silentarts.net/martthie_08/gssl/calibration.html
http://homepage.mac.com/marten.thielges/gssl/calibration.html

Both of these pages are no longer online, does anyone happen to have a copy?

 

[Olegarich]

Was that about meter calibration?

 

[realitycontrol]

I'm not certain, I've never seen it.
I'm about to finish up a build and was hoping there was a one stop shop for calibration recommendations/instructions (meter, ratios, VCAs).

 

[Olegarich]

As far as I know there is no calibration needed for the ratios. Unless you did it with some modification. If you're using pre trimmed VCA (THAT2180), then no calibration is needed  for them too. Only calibration as far as I know needed for the meter. Basically if you have 4K7 trimpot where in the old version there was 2K resistor (just before the meter on schematics) you need to calibrate that one.
1.  Turn Threshold fully clockwise (No compression)    !!No Make Up gain (fully CCW)!!
2.  Send 0db to your compressor
3.  Now measuring output signal start rotate threshold pot until you'll get on the output -10db
4. Now calibrate 4K7 trimpot until meter is on 10
Pretty much it.  There was video on youtube showing it but now I can't remember where exactly, sorry.

 

[Miguel Cohen]

Hello! This is my first post in a forum, so if you notice something wrong in my reply regarding the forum's rules please make sure to mention it!

I'm trying to build the holy GSSL and for that I want to send some gerber files to a board manufacturing house. I've done copied the schematic and am almost finishing the board layout, but the Pinouts for the two NE5532 don't seem to match...

I've read that you need to "transpose" the pins, but I'm not sure I fully understand that statement. What exactly do I need to do? Swap the two halves of the IC in the schematic? Or maybe just connect it as the board layout on the gyraf site suggests?

Thank you for your time and knowledge you all share in this forum!

P.S.: English is not my native language, I'm from Portugal

 

[Olegarich]

Hey Miguel, welcome to the this forum, you’ll defenitely will love this place.
As I understand you are making your own layout? If yes, then you should defenitely was hink about mods (turbo, sidechain HPF, crush&blend)

Now due to your question of op amps, yes you just need to swap 2 halves of opamp.  Schematics don’t match those pinouts on Gyraf layout.

Only I wonder why would you want to make your own layout? Last revision of layout is pretty good.

 

[Miguel Cohen]

Hey Miguel, welcome to the this forum, you’ll defenitely will love this place.
As I understand you are making your own layout? If yes, then you should defenitely was hink about mods (turbo, sidechain HPF, crush&blend)

Now due to your question of op amps, yes you just need to swap 2 halves of opamp.  Schematics don’t match those pinouts on Gyraf layout.

Only I wonder why would you want to make your own layout? Last revision of layout is pretty good.

Thank you for the warm welcome!

I'm making my own layout so that I can have it made at a professional boardhouse (better results than etching) and also to do the external board mods in the same board, as opposed to having to buy the additional boards.

I've since got it all figured out, just need to find some board connectors on mouser with the cable already crimped in (I don't have the tools to do it), and I'm ready to start building!

 

[Olegarich]

You defenitely want to have cnb mode and turbo mode.

 

[angelo2979]

Hi! I've just finished another Gssl, I did some testing today and everything looks working...except for a problem in the left channel. Could you help me figure it out?

The left channel is rolling off bass below 100hz . Actually at 100hz the Left channel is 0.5 db quiter, and  down at 20Hz it gets 6db quiter then the right channel! Testing in pro tools with some white noise and sinusoides...

Also, with no audio signal passing, noise is fine in the Right channel (linear, -130db or so), but the Left shows 22db more noise peaking at 40/50Hz. It's not audible but it's there, and maybe related to the rolloff above....

Everything else works fine!

Do you have any suggestions of what should I look for before I open it?
Thanks!