GSSL HELP THREAD!!!

[flodjo78]

Hi,

I'm sorry I insist on my problem but I know I won't come with any idea to solve it by myself. 

Changing attack and release values doen't affect the sound very much.

This observation seems consistent with the fact that I don't have the same measurement as Harpo in his guide near the bottom of page 210 of this thread.

As instance, as for Harpo : " TL074 pin8 with release in 4th position will measure about -3.4V at slowest attack up to -5.1V at fastest attack. "

But for me the value range is much narrower: from  -2.17 to -2.45 v. ( 1V RMS 300Hz Sin in right and left  input)

I precise I well observe different values for each 5 release positions, 6 different values for attack.

the different compression ratio are effective

I double checked for resistor errors but can't find any, I also carefully checked for soldering mistakes etc...

Aux supply rails are ok..

The sound is very clear.

Thank you for any idea you could come up with.

 

[angelo2979]

Flodjo, maybe check your resistors between attack switch and Tl072 ? 

Anyways, I'm about to finish another Gssl, and was taking a look at the various mods that came over time...
in particular comparing "new" layouts, which can be found here https://pcbgrinder.com/download/GSSL_11.pdf to the layout (component overlay) I've been following....which appears to be different in many ways.
I attach it.

Aside from it being related to an "old" PCB version, it introduces the mods needed for 218x ... all fine with this.
But then it removes the 10k resistor above the SC Vca - which I found to be needed instead - and has different values of the resistors going to the TL072  - Hey flodjo78 maybe take a look at this too ?
- But the most important differences are in the Input/output section...look!

In sum:
- For INPUT/OUTPUT: 33R instead of 100R, 100K instead of 47K, 100uf instead of 22uf
- to TL072:  127k instead of 120K, 120K instead of 100k

Can anyone help me understand these mods? I thought I was working with updated info, but it seems not... not easy to trace all these in bulk over the forum. Thank you!

...Ah also that 100pf around the L/R VCAs... in red are all the changes to the original Gyraf version

 

[Hobbyist]

.. or recognize this problem.

Wrong thread, but your problem is interupted signal flow from your left side "X"

edit: Please disregard reply. I was referencing another filterboard (there are so many different ones for this project).

No Problem, I'm working with the Super Sidechain from Pcbgrinder.

 

[Hobbyist]

Hey guys,

I'm finishing my first Gssl (mic&mod) and I just added a super sidechain mod.
Everything is connected the same like the picture below from an earlier thread.
I used 3x THAT 2181C on the gssl and changed all resistors based on THAT's datasheet.
First I tested the Gssl (standard) and it was responding as expected.
Now with the super sidechain.. no compression, it behaves like it's bypassed.. 
Only the makeup gain is responding well.

Hope someone can help me out with this or recognize this problem.
Are these symptoms of broken VCAs ? Checking the wires and connections over and over again.

(please ignore the "help" wire, it's connected in my case)

Greets from Belgium.

I had the same problem. Standard gssl was working. Added the super sidechain, no compression. Only passing audio. I solved my problem by soldering all the wires to the bottom side of the ssc board (just as all the other components). Hope this helps, let me know.

Milan

hello ! i have exactly the same problem on my GSSLwith the new SC board inside... No compression when the relay is On and the MAKE-UP not working ! i have test the audio on the board the Sound on the return pin is ok i think is on the IN/OUT relay bypass is the probleme maybe a wrong wiring... ?( i have solder on the back of the board)

on this page : https://picasaweb.google.com/108309409331755720628/GSSLSuperSidechainPCB#5193005367618854546

I can see a different wiring : SC board >> make up pots >> Pots master board ! its a good wiring solution ?

thanks for your help

Do you have a picture of your build? Any other modifications? (Like push buttons, for example).

SC mod really shouldn't cause these problems, so curious to see whats at play.

Gustav

Hello guys, thanks so much for the help so far. I've been searching and searching and unfortunately damaged the solder points of the 47 k's, got the resistors back in and glad it's still working as original.. so I made a new gssl mother board to mount it on the super sidechain. Everything is populated on the pcb and connected according to what i've learned and understood from this forum.
But same thing, no compression.., just like it's bypassed, the make-up gain only has effect. SO I followed the signal starting from the input section on the motherboard and lost it on the last 47k on the Super sidechain, on the pin right before it goes back to the return from the gssl.. Can I make a jumper to keep the signal? Looks like the 47k is taking it down. I tried to (re)sold that point but no effect.

All the best.
Michael

 

[Harpo]

... SO I followed the signal starting from the input section on the motherboard and lost it on the last 47k on the Super sidechain, on the pin right before it goes back to the return from the gssl. Can I make a jumper to keep the signal? Looks like the 47k is taking it down. I tried to (re)sold that point but no effect.

... so this part of circuit is maybe operating correctly when connecting to a virtual ground node. (after current to voltage conversion, pin7 of the TL074 on GSSL main board should show up your "lost" signal again.) If you would replace this 47K resistor (value of this resistor is dependant on how many 1/2/.. filter boards are connected) with a jumper/zero ohm resistor, this will make sure that the sidechain VCA most likely will NOT survive this abuse.

As already asked, "Do you have a picture of your build?" This pic might show what (maybe different type/parts value/manufacturer) part(s) you have used and how they connect. (FI relays don't come with all the same pinout, ...)

 

[angelo2979]

Hi again,
I didn't want to put mess with my post above and/or interrupt troubleshooting of other clones... I've just realized how useful is the "print" function with such long threads, it makes it easier to gather all of the precious infos here...!

Still, though, if anyone could answer without much bother, I'd really be thankful... i'm building this clone to understand it better and move on, but I have no teachers and and I'm not so skilled 

talking about the resistors in the sidechain section, right above the TL072, I guess 127k has been brought to 120K for better ratio response (makes sense??) - and what about that 100K close to it, what does it do?..my old notes suggest a 120K here, why?

And most of all, the input/output section:
- I have 33R instead of 100R, before and after NE5532s
-  100K instead of 47K
-  100uf instead of 22uf, the first capacitors after L/R input 
- 22pf instead of 100pf (output section)
(see the layout I've attached in my last post above, the red marked mods)

these values were suggested like 7 years ago in a different old forum which now is down.
And now I keep asking, would these improve or make things worse? 

... In my (little) knowledge:
bigger capacitors improve HF (?),
100K instead of 47k, I guess it means higher output impedence (?), why would this be desirable ?
33R, can't see why. But on the components overlay there's a note saying 100R may be smaller with "output tx". Does it mean...?
22pf - no idea

Please apologize both my curiosity and my ignorance, I really think that anyone more experienced then me could clear this mess in a metter of minutes - if not seconds.

Thank you!

 

[Hobbyist]

... SO I followed the signal starting from the input section on the motherboard and lost it on the last 47k on the Super sidechain, on the pin right before it goes back to the return from the gssl. Can I make a jumper to keep the signal? Looks like the 47k is taking it down. I tried to (re)sold that point but no effect.

... so this part of circuit is maybe operating correctly when connecting to a virtual ground node. (after current to voltage conversion, pin7 of the TL074 on GSSL main board should show up your "lost" signal again.) If you would replace this 47K resistor (value of this resistor is dependant on how many 1/2/.. filter boards are connected) with a jumper/zero ohm resistor, this will make sure that the sidechain VCA most likely will NOT survive this abuse.

As already asked, "Do you have a picture of your build?" This pic might show what (maybe different type/parts value/manufacturer) part(s) you have used and how they connect. (FI relays don't come with all the same pinout, ...)

Hey,

Seems like i've solved the problem.. I re-tinned almost all the points on the super sidechain, renewed both of the 3532p, and now it works correctly. Just need to calibrate the ratio, TM/TL correctly.. i'm sure i'll find the know-how here somewhere on the forum.
Next one i'm gonna make is with turbo and c'n'b.
Here is a  raw picture from it anyway.

Thanks so much for the advice.

Michael

 

[angelo2979]

It's curious... First Gssl I made (I was 17 and 10 times a noob then I am now), there happened to be some faults that just got solved with no apparent reason, maybe right in the process of tracing the circuit! That build was a real mess, but it still works now.
That's how, after other small projects and upgraded knowledge, I'm coming back to this. I think I can do it better, make more logical decisions and learn more...Still, I wish I had the knowledge to give my contribute here... or to make working units on the first try  ;D

Anyways, aside from the knowledge questions I've posted above, I'd like to introduce you to the troubles of my current build 
That is, If my ignorance and/or my attempts of speaking english are not annoying anyone. I apologize for that in advance.

Problem:

I have the Left channel not working. Well, it's got an ultra low output.  Everything looks good on the right side.
I've tried to compare the 2 channels, but they really look specular.  Then, I've measured AC on both, and I realized audio is not even coming to the left VCA, and, as it looks, not even to Pin 3 of  the NE5534 on the input! That of course means there's no output at pin 6, where on the Right channel, I can measure AC on both pins.

It seems like I loose signal after those DC blocking - coupled caps on the input, right at those 22k resistors. I can't see the reason. I have signal at the capacitors legs, but it disappears after them.

These 22k resistors look good from color coding, but maybe I should not trust that ? I keep wondering if there's anything I'm not considering or I do not know! ..It looks like I can measure AC on the right side, about that same spot, but not on the left.
...Traces look good, solder joints too. I even re-heated them to be sure there were no bad contacts.

Also, If I try to move cables on my patchbay, and I only insert the "Left Input" bantam to the tip, I can get signal to the Left channel, out of phase of course. I guess it's because I'm shorting the tip to the ring, which apparently works good on the clone.
DC voltages look good. +-15v and +-12v are nice all over, on all sockets. I've tried to exchange L/R NE5534s, but nothing happens;
...actually now, after the exchange, my ne5534 on the right (working channel) got really hot and sounded distorted so I had to replace it - but I guess I could have damaged it by taking it out from the left socket (unless my left channel is guilty of frying things  :)

I'd really bet it's something simple. but I can't see it. Any suggestions?

Again, apologize my ignorance!

 

[angelo2979]

anyone?... Please, I'm a good guy, any word would be appreciated!

 

[angelo2979]

just to update readers... today I power up, and left channel magically appears, but around 6db lower then R and with a lot of hum, (-80dbFs at 50hz + odd harmonics and a couple of high sparkles at 10k and 18k.... like 40 db higher then what R channel noise).
Swapped all ICs. voltages are good, joints do look good too, and no resistors apparently wrong (based on the layout posted above, old PCB revision). 

minor, not related concerns:
- Compression is fine, and controls respond well, but it seems like 4:1 is lowering the treshold, so that it always compress, and
the meter jumps up with GR, whatever value I set the treshold to. But gain reduction responds to treshold variations, and acts right in every other aspect. I have a turbo board here, wonder if this means anything.
- I 've my meter's led connected to the 1k resistor on the control Pcb, in place of the power led, which I'm not using. Meter is standard 1ma type from Hairballaudio... Leds are all the same right? this shouldn't stress the circuit anyhow, I suppose...




 

 

[Gustav]

just to update readers... today I power up, and left channel magically appears, but around 6db lower then R and with a lot of hum, (-80dbFs at 50hz + odd harmonics and a couple of high sparkles at 10k and 18k.... like 40 db higher then what R channel noise).
Swapped all ICs. voltages are good, joints do look good too, and no resistors apparently wrong (based on the layout posted above, old PCB revision). 

minor, not related concerns:
- Compression is fine, and controls respond well, but it seems like 4:1 is lowering the treshold, so that it always compress, and
the meter jumps up with GR, whatever value I set the treshold to. But gain reduction responds to treshold variations, and acts right in every other aspect. I have a turbo board here, wonder if this means anything.
- I 've my meter's led connected to the 1k resistor on the control Pcb, in place of the power led, which I'm not using. Meter is standard 1ma type from Hairballaudio... Leds are all the same right? this shouldn't stress the circuit anyhow, I suppose...

If the meter light is a bulb and not an LED (do people generally say A Led or an L.E.D. ? Ive been awake at night wondering about this recently...sorry, back to the original thought), it will not work like that. Its probably not a bulb, but since you ask, its best to cover all bases and check.

If you're losing input before the input differential, the path to search is extremely short. Even if you should have little experience reading schematics (I am not saying you do, just "if"), you should be able to trace it. Start on the top left of Jakob's schematic, see how that sits on the PCB.

Soldering work ok? Just by the description of this, and your first build (problems magically disappearing), I picture a lot of wobbly joints connecting at the whim of how the board is bent.

It would be good seeing a picture fo the solder side of the board, and the input XLR to board connections, just to get a feel of where you're at, then taking it from there.

Gustav

 

[angelo2979]

Thank you Gustav!

I feel stupid... I've just followed your advice, and with the benefit of a better light I've found a joint in the L input section that was not that good. Actually because the metal plate at the base was detached... probably too much heat there. I replaced the connection with a wire jumper.

below is the link to the photos of my clone; sorry I could not rotate the board further, cause my Audio wires are hard soldered to the board  : Notice the wire jumper I put in the Input section. The same happened between spot "D" and pin 10 of TL074 - and the resistor as well; I have a couple of jumpers there too, because when I soldered the control board that little plate melted easily.

https://www.dropbox.com/sh/j07ssex0770rcms/AABCgujAah8oVdtmw-s-4w_6a?dl=0

But now that I have both channels, I still get these problems:

- L channel still has 50hz hum (10 db lower then before), where R looks good. This is annoying, it also makes bad low end definition.
- Ratio still has that same strange behavior at 4:1.
2:1  and 10:1 are good, and they do compress about the same, as the clone is supposed to adapt to changing ratios... but 4:1 compresses a lot!

I'll be thankful to any comments!

P.S. Gustav, about your grammar doubts, I found this interesting discussion hehe https://www.englishforums.com/English/ALedVAnLed/kgggr/post.htm

P.P.S When I finish this, my wish is to take a walk to your online store

 

[angelo2979]

...first impression with the unit is it's increasing the lows (or maybe cutting the highs).
It could also be pleasant, but I feel I'm lacking definition and clearness. I wonder if this is normal, or due to the problems I still have.. or a completely new, different, kind of problem. 

 

[Gustav]

...first impression with the unit is it's increasing the lows (or maybe cutting the highs).
It could also be pleasant, but I feel I'm lacking definition and clearness. I wonder if this is normal, or due to the problems I still have.. or a completely new, different, kind of problem.

I'd argue that writing reviews should probably come after you've gotten the unit working properly, but dulling is not an uncommon byproduct of adding compression to any type of program material - depends on how much, of course.

If you already built and used one, you may also be able to come up with ways to do a comparison of the two.


Now, the soldering work looks sort of ok, but it does look like you have some cold solder joints, maybe not obvious, since you are pretty generous with the amount of solder you use. Remember, if you are not getting a conic shape on the joint, and flow throughout the pad, you are not getting heat to both the component terminal and the pad. Looks like heat to the terminals should be a focus.

Also, your iron may be too hot. These pads can usually take quite a beating, so lifting them off like that suggests they were slightly abused and/or took a bit of excessive heating.

..and make sure to snip the terminals off close to the pad - you dont want to create any shorts by unnecessary terminal tips bouncing around.

For the ratio, try taking a look at Jakob's schematic again. On the third line (starts with L/R SC in) at the end of the line, the switch for the ratio is drawn. There are two components switched into play on the middle ratio setting. Can you see which ones? If the other ratios work, it would follow logically that your problem is localised to those two components.

Take another look at the solder work, wiggle some stuff around, see if the solder joints are wiggly.

Check and recheck your XLR connections. I only caught an out of a focus glimpse, but they dont look entirely healthy. Remember, when you have stripped off the plastic, you should tin the wire before making a joint. That may make things easier, prettier and healthier for you.

Get back to the hum problem when that is done - if its still there.

Gustav
.

 

[Gustav]

I'm sorry I insist on my problem but I know I won't come with any idea to solve it by myself. 

Changing attack and release values doen't affect the sound very much.

This observation seems consistent with the fact that I don't have the same measurement as Harpo in his guide near the bottom of page 210 of this thread.

I found Harpo's guide (A direct link rather than written directions will make it easier, and faster, to check your reference).

http://groupdiy.com/index.php?topic=47.msg483540#msg483540

I have my own VECA on the bench, and Ill poke around for some values if needed, but as I see it, Harpo gives very specific advice "in case of deviant measurements".

Since you are going by these voltages, did you disconnect the meter and jump the VCA as described? (I figure you wouldn't see any voltage reading on the referenced nodes if you didn't jump the VCA, but I dont know enough to be sure, so I am just asking to make sure we dont overlook anything due to my shortcomings).

Are you feeding the unit the prescribed 20dBV, 0.1V RMS, 0.14V pk?

Since you are using those voltages for reference, checking for measuring error seems prudent.

It would also be nice to hear how you set up the VCA circuits, and if you have any mods installed.

It seems very odd that you are not hearing a difference in attack and release settings if compression, threshold, make-up and ratio is working.

If all the above checks out, and you really arent hearing any difference when turning the release and attack (It should be obvious, but since you are focused on the meter readings now, just go back to listening mode for a minute to make sure) I would...

1. Set meter to continuity to check for shorts on those
2. Make sure you programmed your switches correctly. Sometimes, a switch is caught on the wrong side. (Would probably sound awful, but it would be good to have it ruled out).

Gustav

 

[angelo2979]

I want to thank you all for your patience and help in this forum and in particular in this thread, Harpo, Gyraf, Gustav and anyone else who has completed this project and now is giving help and supporting, making it possible to keep this thing alive.
I can only imagine how boring it is to face these topics every time, with noobs like me, and to help, some times with a word, some times with a full featured doctor's recipe...I want you to know I have deep respect and admiration for your work and passion, and I hate 90% of my posts hehe for my noobness and bad english.

I will try to get a sense out of my clone...actually I am not able to say which of my joint is colder, and could be causing the problem(s), I 'm a bit scared of remaking soldering work where there's no need of it.  They all look similar to me.

As for the ratio, the only difference with the 4:1 setting is those 2 resistors, right? I doubt I have them wrong, but I should check again; I wonder...I have a turbo board connected to the ratio selector, could it interfere with my 4:1 setting....but the problem is there both in turbo and gssl mode. Better check those 2 resistors first.

about hum, could it be caused by a stupid grounding... I have Xlrs linked togheter and connected to the chassis, and from that same link, 4 wires to my board, 2 for the input, 2 for the output.  I'm going to check that too, and report.

thank you again.

 

[patzo]

Can I  replace  the four 22uf input Electrolytic Cap with 10uf film caps.  They are quite large. But I'll find a way to place it.  Would it be better with them ?

 

[angelo2979]

In my small knowledge...Like many years ago I've been suggested to put 100uf there (see posts above).
In my small knowledge, higher values should improve frequency extension of audio content - if 22uf is high for you I guess mine are a mountain. For dc blocking purposes internet suggests ceramic caps are best, but for higher values like mine electrolytics are still more practical, and what I have seen so far in these clones.

Interestingly enough, there's documentation in this forum about completely removing the bypass 100nf caps around, as this should give better HF extension. I would love someone to clarify that, if it's worth trying and if are there any considerations to take before simply leaving those empty.

 

[patzo]

I did a small experiment with condensers of 1, 2, 10 and 100 uf. With 1 uf there is -4db cut at 20 hz and the line is getting straight at 70 hz. With 2 uf there is -2db cut at 20 hz and the line is getting straight at 70 hz too. With 10 and 100 uf the line is completely straight till 20 khz, so I think that with 10 uf cap wouldn't change the frequency response.

 

[Harpo]

I did a small experiment with condensers of 1, 2, 10 and 100 uf. With 1 uf there is -4db cut at 20 hz and the line is getting straight at 70 hz. With 2 uf there is -2db cut at 20 hz and the line is getting straight at 70 hz too. With 10 and 100 uf the line is completely straight till 20 khz, so I think that with 10 uf cap wouldn't change the frequency response.

Driven from a low impedance source, the 22uFs in conjunction with the 22K resistors at input of the balanced line receivers set a 1st order (-6dB/oct. or -20dB/dec.) HPF in Hz @ 1/(2*Pi()*R*C) with Pi()=3.14159..., R in ohms and C in Farad. This HPF frequency is the point in the audio band where signal has dropped by -3dB, or phase response tested at this frequency is -45°. With given values 22uF and 22K, this HPF is set for 1/(2*Pi()*22000*22e-6)=0.329Hz. With these parts values and tested at 20Hz, signal will have dropped by 20*log(1/(sqrt(1+power(0.329Hz/20Hz;2))))=-0.001dB.
Your different frequency responses let assume, your signal source -whatever this might be- has a cap connected to its output, so there are caps connected in series. Just for examples sake, if this assumed cap value would be 1uF, the resulting series capacitance from 1uF at outputside of your signal source + 22uF inside the GSSL would be 1/(1/1e-6+1/22e-6)=0.956uF=0.000000956F=956nF=0.956e-6F=0.956*10^-6F (whatever writing you like best). Substituting the 22uF with this series caps result in the formula above will give a HPF @ 7.56Hz and signal will have dropped by -0.58dB when tested at 20Hz.
For more usual signal sourceimpedances, your 10uF film caps will do fine if you can make them fit on pcb without overheating these more soldertemperature sensitive parts.