GSSL HELP THREAD!!!

[mrcase]

hi all!


has anybody tried the pico 20ledbar meter from roger with the gssl? I successfully implemented the pico 10 led meter (nice!)
but trying to connect the 20ledbar meter the same way didn´t work. I don't know where I should pick up the voltage for the meter in...???
since I´m a total noob - does anybody have an idea?  ;D

thank you all for everything!!!
absolutely love my gssls!

mrcase

EDIT: here`s the link: http://www.picocompressor.com/PicoComp/PCB-Kits/Documents/GR_Meter_20/GR_Meter_20.htm

 

[martthie_08]

it has been a while since I built my first gssl - wow has this thread grown in the meantime!  

finishing up another unit I have noticed that there are still some minor discrepancies in the schematic / pcb layout of the output balancing section:
for the nitpickers
- the schematic has the numbering for the two halves of the NE5532 mixed up
- the schematic shows the 100R output resistor before the decoupling caps, but they actually come after the decoupling caps on the pcb
- the pcb print shows 470R from both inverting inputs to ground reference, I think for pin 3 it should be 10K (as in the schematic)

anyways, it is interesting to see that this compressor design DOES sound quite different with different capacitor types, the one I have on the bench right now has cheap ceramics for (noname) electrolytic bypass and it does behave different than the one I built a couple years ago with ELNA caps and COG bypass ceramics.

cheers, Marten

 

[regularjohn]

- the pcb print shows 470R from both inverting inputs to ground reference, I think for pin 3 it should be 10K (as in the schematic)

HOLY CRAP!  I've never notived that before.
What kind of difference would that make in terms of sonics?

Also, the auto release timing circuit resistors are different on the schematic and pcb.  
I think it's the gyraf schematic that's wrong.
The pcb and the original 82E27 card schematic are the same.

 

[Chrome Heart]

- the pcb print shows 470R from both inverting inputs to ground reference, I think for pin 3 it should be 10K (as in the schematic)

HOLY CRAP!  I've never notived that before.
What kind of difference would that make in terms of sonics?

Also, the auto release timing circuit resistors are different on the schematic and pcb.  
I think it's the gyraf schematic that's wrong.
The pcb and the original 82E27 card schematic are the same.

Thats interesting. Anybody put 10K's in there?

 

[spacemonkeysounds]

Hey guys, I have retrofitted  the DBX202 VCA's in to a couple of my previously 2180 pre-trimmed VCA's.  They sounded cool (one particularly better) but I am now curious if I need to install the distortion trimmers for this set-up.  Thanks.

 

[ricothetroll]

hi !

after experiencing a subtle ripple problem on the output of the compressor I decided to check the +/-15v dc rails with the scope. I disconnected it from the rest of the circuit and measured :

+15v rail has a ripple ("rectified" noise). peaks are about -10mV high and with a frequency of about 100Hz

-15v rails has some kind of a periodic "rounded sawtooth" at nearly 833Hz (where the f*** can 833Hz come from ???) and it voltage is about 70mV peak to peak.

I tried to find the source of those noises by removing the 7815/7915 to keep only the rectifier and the two 1000u filter caps (I also removed the two 10R resistors to get rid of the 78L12/79L12 circuits). I measured perfectly clean +/-21VDC.

I then put back the regulators and I measured again those two phenomenons. How can it be not clean after the regulator when clean before it ? shouldn't it be cleaner ?

So I removed the two 22u right after the regulators and I got rid of the 833Hz. What are those capacitors for ? can I live without them ? how can them create that 833Hz ?

now I'll try the CRCRC filter and see if I get rid of the ripple.

to be continued...

 

[gerardmanvuca]

sorry if this is a silly question but will this led meter work on a gssl?        http://sound.westhost.com/project60.htm

 

[Harpo]

sorry if this is a silly question but will this led meter work on a gssl?         http://sound.westhost.com/project60.htm

Using it as a VU meter - maybe, but this is missing the negative part of an audio signal, if this matters to you.
For showing the amount of gain reduction - no.

For a gain reduction meter in the gssl you want a linear scale (LM3914 instead of LM3915 or LM3916) to show the amount of negative control voltage at your VCA, so you'll need an inverter in front for a polarity flip. Doing this with a single opamp, make the resistor on its inverting input high enough, so the source can drive this additional load. Adjust the feedback resistor to match your needs for the makeup gain. Another non-inverting buffer in front will prevent this loading of the source and resistor values at the inverting stage could be smaller.

 

[pietro_moog]

hi guys! i'm building a gssl with sidechain board and turbo board.
do i have to change some resistor on the turbo board?
i'm using THAT 2180 on the gssl pcb and on the turbo pcb.
i think i have to change the 3k9 resistor with a 5k1, then?

thanks

 

[regularjohn]

hi guys! i'm building a gssl with sidechain board and turbo board.
do i have to change some resistor on the turbo board?
i'm using THAT 2180 on the gssl pcb and on the turbo pcb.
i think i have to change the 3k9 resistor with a 5k1, then?

thanks

There's LOTS of info on this if you do a search.  I personally have talked about this three or four times in this thread alone.  It's been discussed to death.
Seriously, use the search.

 

[ricothetroll]

well... after removing the +/-15V PSU and a lot of trials I must admit that there are a lot of things that I don't understand !

The schematic I breadboarded that worked the best was that one :
http://www.wuala.com/ricothetroll/public/PSU_test.jpg
Diodes are 1N4003s.

I tried the CRC and CRCRC filters before the regulators without any success (with C=1000u and R=6k8).
http://www.wuala.com/ricothetroll/public/CRC_schem.jpg

The output of the PSU is quite clean on the scope when disconnected from the main board, but as soon as it is connected (especially the GND) I have a lot of noise coming, some hi frequency near 40kHz combined with some symetrical ripple (one positive then one negative then one positive...). I checked for GND loops but I can't detect any. Everything is star-grounded to the mains earth.

I also did some signal tracing, as the ripple appears to be a lot stronger on the left side than on the right side (with the on-board PSU it was the opposive, but whatever, sooooo many things I don't understand) :

- On the right side the signal is correctly clean all way long (nothing so surprising I must admit)
- On the left side the signal is clean until the balancing 5532 : still clean on the inputs (pins 2 & 6) and the there's the same ripple as on the DC rails on the outputs (pins 1 & 7).
- The alimentation on both L & R's 5532 is dirty, but it seems to affect a lot more the left side.

ANY idea that could make me understand those phenomenons and finally get my unit clean all the way long is welcome...

Thanx in advance !

Best regards.

Eric

 

[radiance]

Eric, the idea of the CRC board was to use it with the onboard PSU. When going for an off board PSU (like you bread boarded) I should use
LM337 / LM317 regulators. These deliver a cleaner output than the 7815 / 7915's you have used and there is no need for the CRC boad. The schematic is slightly different to the one you made. Have a look at the LM337 data sheet and you'll get it.

I build all my gssl's with off board PSU's using LM337 / 317 and never had any hum whatsoever....

 

[Harpo]

well... after removing the +/-15V PSU and a lot of trials I must admit that there are a lot of things that I don't understand !

The schematic I breadboarded that worked the best was that one :
http://www.wuala.com/ricothetroll/public/PSU_test.jpg
Diodes are 1N4003s.

Seems right, just as drawn in the gssl schematic, but it is differing from the gssl pcb.
On pcb the 100nF caps in front of the 7815/7915 regulators are missing.
These caps are at input of the 78L12/79L12 instead.
You could fit the maybe missing ones from traceside. Some brands of these regulators behave a little more nervous than others.

BTW the labeling in your schematic seems a little mixed up:
Transformer secondaries V1 and V2 are 15VAC each.
After your rectifying diodes this will be about 21V raw DC.
The 1000uF caps are polarized.
AC-IN1 is +21V DC-IN  and AC-IN2 is -21V DC-IN.

I tried the CRC and CRCRC filters before the regulators without any success (with C=1000u and R=6k8).
http://www.wuala.com/ricothetroll/public/CRC_schem.jpg

If value of your R=6k8 wasn't a typo, this would have to be expected. (Use R=6.8 instead, this value is close to 7 ohms.)
With 21V raw DC feed and your maybe 6k8 in series, the max.availiable current for each rail would be limited to 3mA.

The output of the PSU is quite clean on the scope when disconnected from the main board, but as soon as it is connected (especially the GND) I have a lot of noise coming, some hi frequency near 40kHz combined with some symetrical ripple (one positive then one negative then one positive...). I checked for GND loops but I can't detect any. Everything is star-grounded to the mains earth.

I also did some signal tracing, as the ripple appears to be a lot stronger on the left side than on the right side (with the on-board PSU it was the opposive, but whatever, sooooo many things I don't understand) :

- On the right side the signal is correctly clean all way long (nothing so surprising I must admit)
- On the left side the signal is clean until the balancing 5532 : still clean on the inputs (pins 2 & 6) and the there's the same ripple as on the DC rails on the outputs (pins 1 & 7).
- The alimentation on both L & R's 5532 is dirty, but it seems to affect a lot more the left side.

ANY idea that could make me understand those phenomenons and finally get my unit clean all the way long is welcome...

I'd try a different brand of regulators if the prementioned caps from traceside couldn't stop oscillation.
Another source for a ground loop might be metal/unisolated pcb standoffs.
You could use a different psu instead, as suggested by radiance.

good luck

 

[ricothetroll]

Thanx a lot for your answers !

I tried the CRC and CRCRC filters before the regulators without any success (with C=1000u and R=6k8).

My mistake ! I wrote 6k8 instead of 6R8, but I used 6R8 on my breadboard trials.

I have a couple of LM317/LM337 in stock, I'll try those instead of 78xxs. Such a waste of time only for bad regulators ! I hope that's the problem. I still don't understand how can a regulator make the DC rail dirty when you feed him with a clean DC voltage...

To be continued...

Best regards.

Eric

 

[ricothetroll]

Concerning the voltages on of the generators on LTSpice, they're 21V peak-to-peak, that corresponds to the 15V RMS of my "real world" toroid trafo.

 

[pkarr]

Hi, I'm building my 1st DIY project. I use THAT 2180LA for the VCA. I removed the resistors around the VCA like on this website: http://diy.fischerworks.com/gssl_vca.shtml
I changed the 2x15k by 2x27k, the the 100k by a 127k and the 2x3k9 by 2x5k1. Do u think I should remove the 2x47k? I haven't Sidechain mod or Turbo mod. I started by building the simple version of the GSSL. Thank you for your help.

 

[radiance]

Do u think I should remove the 2x47k?

Leave them in.....

 

[pkarr]

Ok, thanks Radiance. I don't remove them.

 

[pkarr]

Hi, my name is ALex, I'm from France. I need your help for my threshold and Vu meter. When my Threshold button is completely on the left, the Vu meter is blocked in the middle "i don't play music when it's like that, no signal" I just turn on the compressor. THen I turn the Threshold at 1/4 and the Vu meter diminish on the left and it is blocked, it doesn't move. Then i can turn the threshold in the middle or on the right, it doesn't change, the Vu meter don't move and it is blocked on the left. I added the 47k on the Threshold pot. THe sound volume doesn't change when the threshold is in the middle or completely on the right. THe sound Volume changes when i start my threshold on the left until the middle but the Vu meter is strange. I don't understand why it goes on the left and stay blocked. Normally it should move. Please Need help. Thanks alot

ps: the link of my vu meter
http://fr.farnell.com/sifam/19w0-1ma0-100/galvanometre-0-1ma/dp/1262061?Ntt=1262061

 

[MikeyT1987]

Hello all,

I really want a big fat meter like regularjohns build! I'm putting mine in a 2U case.

I'm really new at this, will this meter work?

http://www.mouser.com/ProductDetail/Simpson/04610/?qs=JX1bQUixcTnt%2fTjEkNc3Ig%3d%3d

Is there anything I need to do to make certain meters work?

Thanks for your help!