GSSL HELP THREAD!!!

[beatnik]

i think that first you need to identify wich regulator is causing latch-up. the 12V regulators are cascaded after the 15V regulators.

you need to measure which voltages are wrong when latch up is present.

in my case I had latch up problem with the 15 regulators, and fixed that by adding capacitor and diodes on the back of the pcb. but now i also have problem with the +12v regulator, so i try to fix that or change to another brand.

about the unbalanced connection, probably if in your mixer inserts connection the negative input is connected to ground, this causes problem to the IC input/output stage, which maybe the transformers don't suffer. but you can easily try and see.

 

[rainton]

Ok I will check both of the regulators first

Regarding the unbalanced connection: All the inserts from the console are soldered to the patchbay and negative is shorted to ground there.
So I read somewhere in this tread that this is ok for the input but not for the output of the GSSL...and that it is required to disconnect (-)signal at the output(?)

...but how can I solve this without loosing 6db? I already thought about transformer-balancing the signal before it reaches the comp.

Sorry if this is a dumb question but I'm kinda new to this.

Thanks again!!

 

[Harpo]

Maybe are you sending unbalanced signal to the GSSL?

Well, my GSSL sits indeed on the unbalanced inserts of my console's master bus. I didn't think that would be a problem - but I just realized all the other gear I occasionally use on the master bus is transformer balanced...

...so what are my options here. I googled it and found another GroupDIY  thread about this topic and the conclusion was to either solder special-cables where only (+) and (0) is connected or to disconnect (-) from the XLR-pins in the GSSL (?)
But then I would still experience the -6db drop, right? Is there any way to avoid this?
Help would be highly appreciated!

A second question:
I also went through some of the 280pages of this thread last night because I also experience the "latch-up" problem when switching on the GSSL. And since the LED of the meter stays off when the comp doesn't boot correctly the problem has to be with the +/-12V regulators. I checked Harpo's anti-latch-up solution:
So I get where the diodes need to go - but harpo wrote:

The 100nF caps in front of the 7815/7915 are already shown in the schematic, but are in front of the 78L12/79L12 on pcb instead.

Where exactly do I need to put the 100nF caps in this case?

Might help if the 7815/7915 regulators should oscillate. Not needed if your +15 and -15V rails are working.
[quote author=beatnik]i think that first you need to identify wich regulator is causing latch-up. the 12V regulators are cascaded after the 15V regulators.[/quote]
They are not cascaded after the 15V regulators.

Ok I will check both of the regulators first

and checking all four regulators (78L12, 7815, 79L12, 7915) would only take max.10 seconds longer ...

Regarding the unbalanced connection: All the inserts from the console are soldered to the patchbay and negative is shorted to ground there.
So I read somewhere in this tread that this is ok for the input but not for the output of the GSSL...and that it is required to disconnect (-)signal at the output(?)

...but how can I solve this without loosing 6db? I already thought about transformer-balancing the signal before it reaches the comp.

: All of your questions have been covered within the last pages (279/280) of this thread ...

 

[mokkinger]

This has been beaten to death. A simple 'unbalanced' or '6dB' in the [Search within topic] would have given you the last 30 related questions/answers.

hi harpo, thanks a lot - and, yes, I could have searched for that unbalanced thing... will check that asap and give feedback again
great help!

 

[wartornrex]

I'm building my first GSSL Clone and I'm having trouble with the transformer placement. Originally I bought the wrong voltage for the US. I have the correct one now (thanks to this thread) and I was told I'm mounting it in the wrong place.  How do the 4 wires go into the 3 holes for the external transformer?  I originally had it mounted in the square area and was told that's not correct.  I really have no idea what I'm doing but so far I'm very proud of my work.  I just need to figure out the transformer and I'm done.  I would also like to try a side chain.  Is there a link that shows how to do it?  Sorry for the simple question. You can see what I've done so far at:

The photos of my project can be seen at:
http://www.gearslutz.com/board/so-much-gear-so-little-time/817504-gssl-clone-help.html#post8804021

The images were to large to post here. 

 

[MeToo2]

I'm building my first GSSL Clone and I'm having trouble with the transformer placement. Originally I bought the wrong voltage for the US. I have the correct one now (thanks to this thread) and I was told I'm mounting it in the wrong place.  How do the 4 wires go into the 3 holes for the external transformer?  I originally had it mounted in the square area and was told that's not correct.  I really have no idea what I'm doing but so far I'm very proud of my work.  I just need to figure out the transformer and I'm done.  I would also like to try a side chain.  Is there a link that shows how to do it?  Sorry for the simple question. You can see what I've done so far at:

The photos of my project can be seen at:
http://www.gearslutz.com/board/so-much-gear-so-little-time/817504-gssl-clone-help.html#post8804021

The images were to large to post here.

In order to provide any useful advice, we need either the model number of your particular transformer, or the color coding of the various leads. These are not in any way standard. Plus we need close up photos of your board and your chassis showing the transformer connections. You can't see well enough on the ones you posted on gearslutz exactly which PCB pads you used, and what other components you fitted e.g. which bridge rectifier, fuses, on/off switch, safety earth....

 

[wartornrex]

The new transformer I bought is the TE62063-ND from digikey.  Here is the link: http://www.digikey.com/scripts/DkSearch/dksus.dll?WT.z_header=search_go&lang=en&keywords=Te62063-nd&x=0&y=0&cur=USD
I got this from the beginning of this thread.  The components on the board are from this bom list:  http://www.nfaudio.com/wp-content/uploads/GSSL.pdf
I changed some of the resistors and the larger caps to be the correct values of 1000uF x 63v.

Do I need the bridge rectifier in both places or just next to where I mount the transformer? 
I have yet to do any grounding cause that was going to be my next question.  How do I do the grounding? 
I will have to transfer some pics to my other computer to reduce the size to post.  I hope this is enough info and sorry for so many questions.

 

[MeToo2]

The new transformer I bought is the TE62063-ND from digikey.  Here is the link: http://www.digikey.com/scripts/DkSearch/dksus.dll?WT.z_header=search_go&lang=en&keywords=Te62063-nd&x=0&y=0&cur=USD
I got this from the beginning of this thread.  The components on the board are from this bom list:  http://www.nfaudio.com/wp-content/uploads/GSSL.pdf
I changed some of the resistors and the larger caps to be the correct values of 1000uF x 63v.

Do I need the bridge rectifier in both places or just next to where I mount the transformer? 
I have yet to do any grounding cause that was going to be my next question.  How do I do the grounding? 
I will have to transfer some pics to my other computer to reduce the size to post.  I hope this is enough info and sorry for so many questions.

The color code on the data sheet does not match your photographs posted on gearslutz (datasheet shows dual primaries. Photo shows single primary).
http://media.digikey.com/pdf/Catalog%20Drawings/Transformers/ART-SERIES%2062000%20SCHEMATIC.jpg
http://www.gearslutz.com/board/so-much-gear-so-little-time/817504-gssl-clone-help.html#post8804021

So what have you actually built right at this moment?

It's vitally important that you be absolutely 100% crystal clear about this, because you are dealing with mains voltages here, which are potentially lethal.

 

[wartornrex]

Oh, I should have been clear that the one pictured was the incorrect Australian one that was switched with the one from digikey.  I checked the digikey specs and they do match what I now have.  Ill be able to load up pics when I can get to my computer.  I'm sorry, I was thinking I needed to clear that up right after I posted.  Ill try to be more clear in the future. 

 

[dirtyhanfri]

Unsolder the two 47k resistors from the board.  Solder both 47k to a lead going to switch COM.  Solder lead from OFF position to the 15k resistor at the sidechain input.  Solder capcitor across the switch from ON position to OFF position.  Pretty basic.  Only need one capacitor with mono sidechain.

.047uF = 225Hz
.068uF = 156Hz
.1 uF = 106Hz

Sorry, but sometimes searching a simple answer about gssl is becoming quite hard...

Will this work finely with mono Sidechain? I will use rotary switch with OFF (No cap) and some cap values. It's ok? or do I need something else, I don't need extreme filtering, just some bass roll-off (using just a cap it should be 6db/octave right?)

Also, adding an external SC signal should be as easy as unbalance a mono signal (as the input) coming from a specific connector and run it to the 15k resistor (some tricky switching can be used here) instead of the signal coming from the filtering caps?

 

[wartornrex]

Oh, I should have been clear that the one pictured was the incorrect Australian one that was switched with the one from digikey.  I checked the digikey specs and they do match what I now have.  Ill be able to load up pics when I can get to my computer.  I'm sorry, I was thinking I needed to clear that up right after I posted.  Ill try to be more clear in the future.

I just found this on about page 9 of this thread.  It's very difficult to search a specific thing so I'm going page by page. 


115v,220v AC.
15v,15v
25VA

Tubejay:

My toroid is actually an Avel from Parts Express, but yours will do just fine. Here's what you need to do to wire it.

On the primaries:
Tie yellow and red together and that goes to your common (not GND).
Tie black and violet and that goes to the hot (115VAC/120VAC).

On the secondaries:
Tie red and brown together...
Then measure between green and blue and you should have approximately 30VAC.

When you go to connect to the Main PCB, the red/brown (which are connected together), go to the middle point of the three. Connect green to the outside and blue to the one on the inner part of the board.

Basically we're connecting the primaries is parallel and the secondaries in series.

If this is corrects for the transformer I just bought (all lead colors match) all I need is the grounding.  Is there sn in depth explanation of the grounding? 

 

[tnerbsivraj]

Finished building a gssl clone and am hoping someone can help me with a couple bugs

The left channel seems to work great in all regards but the right channel only outputs the bypassed signal. When I fed a signal to the right channel alone it appears on the meter to be compressing and varying with changes of threshold, ratio etc... but the output stays the same as if in bypass.

I thought I had messed up the switch but checked it and from what I can tell it looks ok. The switch however has different labels than the component layout diagram. Where the diagram indicates on / off going to C1 / C2 my switch goes from 1 - 12 so I've got on / off going in 7 / 8.

 

[wartornrex]

Just finished my first GSSL clone and it works Great!!!  The sound is amazing.  I'm blown away.  I was able to find every answer to every question I had by starting on page one of this thread and reading till I found what I was looking for.  This thread is so helpful. 

I read a bunch of solutions to problems with one channel functioning and the other not.  Start on page one and you will find it.

My first clone has no side chain or any mods (just the two basic PCB's). I'm about to start my second with a turbo side chain and VU meter mod.  Ill post pics of my projects when I can get to my computer. 

 

[gyraf]

The left channel seems to work great in all regards but the right channel only outputs the bypassed signal. When I fed a signal to the right channel alone it appears on the meter to be compressing and varying with changes of threshold, ratio etc... but the output stays the same as if in bypass.

Right channel VCA does not get a sidechain control signal - check output voltages at the 5534 driving the VCA control input, compare L and R while compressing.

Then look for errors around R VCA

Jakob E.

 

[qwerty8787]

I'm still in trouble with a distortion issue in my GSSL.
Distortion is present in each channel.
I managed to get that it's a sidechain related thing and not an audio path issue.
Shorting pin 1 & 8 of audio VCAs I get perfect audio from in to out.

I see with my scope that on pin 7 of TL052 I have a strange behaviour.
With threshold @ max position (as to get no compression) I see about -1.8 Vdc
With threshold @ min position (as to get max compression) I see a strange waveform, some kind of half-rectified sinewave (frequency related to the sin on the inputs) with a 10KHz (frequency independent from the inputs) sin wave summed on it. Total magnitude of this crap is about 2Vpp.

Refer to this image to see the behaviour:

Parameters:
Input signal: 200Hz sine wave
time div. 0.5ms
Ch.1 2V/div ---> Audio out
Ch2  1V/div ---> pin 7 TL052

As long as I can understand, I should expect only a DC value on this net, or am I wrong?
Anyway this strange behaviour on "CV TO SC CTRL" net is wasting all the signal as soon as compression kicks in.

I already triple checked resistor values and all other things. DC rails are ok.
Hope someone can give me a hint on this, because this whole thing is driving me crazy by months

thanks in advance to anyone who will come in

 

[qwerty8787]

I tried to pull out the 100Ω resistor connected to PIN 7 of TL052, and I connected an external regulated power supply to the common point of the two 1K resistors going to Audio VCAs CV. Changing this voltage from 0v to about -3V let the output properly changing in amplitude. So the audio path (and the audio VCAs) should be free of problems.

That crappy oscillating behaviour should be related only to sidechain part.

Any thoughts?

 

[MeToo2]

I tried to pull out the 100Ω resistor connected to PIN 7 of TL052, and I connected an external regulated power supply to the common point of the two 1K resistors going to Audio VCAs CV. Changing this voltage from 0v to about -3V let the output properly changing in amplitude. So the audio path (and the audio VCAs) should be free of problems.

That crappy oscillating behaviour should be related only to sidechain part.

Any thoughts?

TL052??

Maybe that's your issue right there. Should be a TL072. TL052 is faster, and phase shift versus unity gain is quite different (and thus might oscillate)

That 2180 datasheet: "A typical opamp's output imped-ance is therefore inductive at high frequencies. Excessive inductance in the control port source impedance can cause the VCA to oscillate internally. In such cases, a 100 R resistor in series with a 1.5 nF capacitor from the control port to ground will usually suffice to prevent the instability."

 

[qwerty8787]

already tried 072 with no significant changes.
Anyway tomorrow I'll go double check that searching for any little changes, with the scope.

 

[qwerty8787]

Tried TL072, TL082, TL062 with no success. Same oscillating behaviour....

 

[qwerty8787]

Also, the picture I posted was taken with ratio @ 10.
With ratio 4 the 10Khz oscillation is less prominent.
With ratio 2 the oscillation disappears but it appears anyway as "soft" clipped on the tops (just like the photo, but without the little waves).