GSSL HELP THREAD!!!

[dirtyhanfri]

Hi,

I'm having some issues with this build...

The 220k Resistor, after the F point in the 10 pin conector (Main pcb). I can read 12v. varying with the threshold pot in the first (the closer to the molex) leg, but nothing in the other side, I tried lifting up that leg and it reads something near the other leg, but as soon as I put it in the circuit it goes to zero (I tried soldering it to the jumper going to tl072 pin 2)

Something like that is happening on the right channel VCA, In the first 1k resistor going to the  5534 pin 3, on one leg, it reads the same voltage on each channel, on the othe leg it goes near to zero.

Of course I have cheked and replaced resistors cheking for values before soldering., and looked for shorts to ground with no luck...

I have bad sound in the right channel and uncontrolled threshold, so everything makes sense....

Any ideas in what to look at?

Thanks....

 

[MeToo2]

Hi,

I'm having some issues with this build...

The 220k Resistor, after the F point in the 10 pin conector (Main pcb). I can read 12v. varying with the threshold pot in the first (the closer to the molex) leg, but nothing in the other side, I tried lifting up that leg and it reads something near the other leg, but as soon as I put it in the circuit it goes to zero (I tried soldering it to the jumper going to tl072 pin 2)

Any ideas in what to look at?

Thanks....

The other leg of the 220K resistor is connected to the inverting input of an op amp. That's a virtual earth. It'll will always read near enough to 0V that you won't be able to measure it.

Check back earlier in the thread. There are several posts that identify test points and sample voltages to check against by going through the schematic step by step after connecting a test tone to the input. Good luck.

 

[Aleguitarpro]

Hi.
I've decided (a damned day) to modify my GSSL, including a second sidechain with the Expat Turbo pcb.
I've a problem that is driving me crazy...

I've mount the turbo pcb with the switch option, so I have 2 possibilities: use GSSL in a "normal" mode, including the SSC board, and "turbo mod" in which I've put the two 47k resistors in the sidechain before the main board sidechain and the turbo sidechain.

In normal mode it works good as expected (and as before the mod).

In turbo mode, in 4:1 and 10:1 settings it works ok as expected: it reduce equally, both in mono and in stereo operation, feeding it with the same signal (+0 db sine wave of 1k).

In 2:1, with the turbo mode on, channel L (that goes in mainboard sidechain) reduce ,for example, 12 db and with the same signal the turbo pcb (channel R) reduce 16 db.
With a stereo signal it reduce 16 db, following the same gain reduction of the channel that goes in the turbo pcb.
So, the turbo pcb in 2:1 setting reduce more!
WHY???

I've double checked all the resistor, connections, wirings on both the sidechains and they are identical.
What could cause this big difference between the gain reduction of the 2 sidechains?
I've mounted that 2080 in both the sidechains, with the classic mods of the 10k resistor, 5k1 resistor change and without the pin4.

Thanks for help.
Ale

 

[MeToo2]

In 2:1, with the turbo mode on, channel L (that goes in mainboard sidechain) reduce ,for example, 12 db and with the same signal the turbo pcb (channel R) reduce 16 db.
With a stereo signal it reduce 16 db, following the same gain reduction of the channel that goes in the turbo pcb.
So, the turbo pcb in 2:1 setting reduce more!
WHY???

Obvious thing to me would be to check how you wired up your ratio switch for the Turbo board and main board. [It could be either the ratio on the main board or the turbo board that is incorrect] Loose connection or short on the ratio connector on the turbo board or main board? Incorrectly wired ratio switch? Faulty ratio switch? Incorrect ratio resistors on the turbo board or switch board? Solder flux around the high value resistors in the ratio section? Dry solder joint on one of the ratio resistors?

See the turbo installation manual. And check between points 'A' & 'B' on the GSSL schematic on both the main board and the Turbo board [I'm sure you're aware that the Turbo board contains exactly same circuit as the main board sidechain]

You could also check and compare the voltages coming out of the side chain detector on pin 7 of the TL074's to make sure that's the same on both channels before doing these checks on the ratio section, just to be sure that one of the sidechain VCA's isn't acting oddly. But it does look to me from the symptoms that the problem is in the ratio section [between the 22u coupling cap on the TL074 pin 7, and point 'C'] and most probably between point 'A' and 'B' on either the main board OR the turbo board. The control voltages on pin 14 of the TL074 (= at the cathode of the diode connected to point C) should be pretty much identical when comparing the 2 channels for all settings with a mono signal connected to both channels.

From point 'C' onwards looks OK [because the two diodes take the most negative of the two control signals -12dB -16dB before passing this onto the Attack switch, which is correct]

 

[Aleguitarpro]

Obvious thing to me would be to check how you wired up your ratio switch for the Turbo board and main board. [It could be either the ratio on the main board or the turbo board that is incorrect] Loose connection or short on the ratio connector on the turbo board or main board? Incorrectly wired ratio switch? Faulty ratio switch? Incorrect ratio resistors on the turbo board or switch board? Solder flux around the high value resistors in the ratio section? Dry solder joint on one of the ratio resistors?

See the turbo installation manual. And check between points 'A' & 'B' on the GSSL schematic on both the main board and the Turbo board [I'm sure you're aware that the Turbo board contains exactly same circuit as the main board sidechain]

You could also check and compare the voltages coming out of the side chain detector on pin 7 of the TL074's to make sure that's the same on both channels before doing these checks on the ratio section, just to be sure that one of the sidechain VCA's isn't acting oddly. But it does look to me from the symptoms that the problem is in the ratio section [between the 22u coupling cap on the TL074 pin 7, and point 'C'] and most probably between point 'A' and 'B' on either the main board OR the turbo board. The control voltages on pin 14 of the TL074 (= at the cathode of the diode connected to point C) should be pretty much identical when comparing the 2 channels for all settings with a mono signal connected to both channels.

From point 'C' onwards looks OK [because the two diodes take the most negative of the two control signals -12dB -16dB before passing this onto the Attack switch, which is correct]

Thanks for your very useful suggestions.
Today I've decided to disassemble al my GSSL: I've resoldered all the contact of the RATIO switch and resistors of the control board.
Then I've changed the resistor of the pin5 of THAT 2180 in the sidechain of the mainboard because it seems not be working, I don't know why (5k1 resistor). Now all works correctly!

Thanks. It's a joy use this compressor with his new turbo mode!
Ale

 

[Holiveira]

When I shot the 2 47k (pin 1 vca sidechain) the compressor works in strange ways but it compresses.

You want these 47K resistors in circuit, else you will blow your sidechain VCA. (These VCAs are current-in/current-out devices. VCA-Pin 1 is current in, VCA-pin 8 is current out. No voltage to measure here).

I use the That 2180BL08 with 4 pin up. I changed the 3k9 by 5k1 in VCAs.

VCA-pin5 current source to neg.rail change 3K9 to 5K1 only in the DBX202C substitution circuit. The 3K9 value at the sidechain VCA is correct (this 3K9 connects to the -12V rail).

I have 10k between pin 3 and pin 5 in the side chain and VCAs.

Take these out for THAT218x VCAs. (these 10Ks between pins 3/5 once have been a try to get modulation down for DBX2150/2151 type VCAs).

Double check resistor values, especially the 47ohms at VCA-pin 3 (your R47=0.47ohm probably being a typo), the 100ohms at TL072 pins 1+7 and the opamps feedback resistors.

Hello Harpo and Metoo2,


I've been a long time without appearing in the forum.
I solved my problem, I had 2 VCA damaged.

My SSL is working very well

Thanks
Hugo

 

[burglar]

Hi all,

I have found a company here in the UK with the THAT 2181 VCA's.  However, they have 2181 AL, BL or CL.  The A being the most expensive and the C the least.  Apparently these brandings are related to harmonic distortion. 

I don't want my comp to be too transparent so would I be better off going for a lower grade? say Cl or Bl?

 

[RATMNL]

If you'd take 2180's (not pre-trimmed) you can set that for yourself with the trimmers, you could make it sound any way you wanted.

Oh crap, wanted to post theese a long time ago: exterior pictures of my first build GSSL:

http://www.twin-x.com/groupdiy/thumbnails.php?album=505

(couldn't get the pictures to be at thumbnail size in the post... so that's the link)

Thanks all for Helping out! On to the dane-tate-de-esser-building!

 

[frazzman]

Hi guys,
One my GSSL's with turbo is doing something strange... it works fine 99% of the time, but occasionally after having moved the unit around or what not, it stops compressing. The makeup gain still works but the needle on the meter stops moving and theres no compression. If I shake the unit around it starts working again and seems to be fine -- even if I start shaking the unit around again it keeps working. Obviously there is a loose/bad connection somewhere... I've checked for continuity across all the connecting wires between the control PCB + mainboard and the turbo board to mainboard and I can't find a problem. Initially I thought it was a bad connection at point 'c' where the turbo wire and wire from the control board join the PCB, but it looks fine. I know that if this connection is bad that the compressor will stop compressing, is there anywhere else that could be a volatile place and could result in the unit intermittently stop compressing? As I said, it works fine most of the time and I can't find a problem
Thanks!

 

[imo]

I have a GSSL with the turbo mod that has been working well. Loaned it out to a friend and it came back sounding like the whole thing is through a fuzz face.
I checked for obvious problems, voltage rails seem to be right and voltages at +- on the chips are all right as well. The unit is unchanged whether i "bypass" or not so i figured it must be in the main left and right channels. Tried replacing the 5532 and 5534 just for grins, but no luck/.
i do have a scope and sig generator, but limited skills beyond finding signal.
Are there any obvious places that you guys would start looking in this situation? Am i right to think that the sidechain shouldn't be the culprit if it is distorted in bypass as well?
Any tips on looking at the opamps with the scope and what to look for?
Thanks
Ian

 

[Aniol1349]

could anyone tell me how can I fit the diodes on Super Side Chain board? the holes are too small for them, and I can't manage to fit them in.

also I have problem with the 200R resistor, the one I have seems to be quite big, but the value is right so theoretically it shouldn't be a problem, can someone just confirm that I could use this? (look the photo below)

 

[spase]

its to big becouse that is 5W resistors ) you dont need that resistor you just need 200ohm 1/4W metal film in there )

 

[Grag38]

Hi boys.

Just a question about stange thing. I realised 2 years ago 2 SSL clone compressor with the expat turbo mode extension.

Both works quite well. But a friend told me about a problem so I decide to do some checks.

And here is the trouble with the both ssl.

I turbo mode :

If I apply 1khz signal on left and right : compression is ok
if I mute left channel : compression is ok (same level as 2 signal together)
if I mute right channel : no compression at all...

And this stange thing is on the 2 ssl I made...

If I dwitch back to 'Normal mode', 1khz signal on left or right channel is operating compression.

I check everything and nothing seems false. (power is ok

So from (I'm french froggy people), where can be my mistake ?

voltages are ok on both tl072, continuity also. I read carrefully expat instructions...

Connections between expat and de main boards are :

+12/0/-12V ok
Ratio solders : ok I've checked them.

C is soldering on main board on the #10 pin the C one.
the lifted resistor 47k is going to the common of the switch.
one leg of the switch goes to the SC Input on the expat board.
other leg is comming back on the 47k still soldered next to the one which is unsldered...
SC CV is connected to the 100 ohm resistor next to the 072...

I checked it 5 times and all seems ok. But the effect is on the 2 SSL I've made.

If someone as an idea of solving it...

Best regards

 

[MeToo2]

I checked it 5 times and all seems ok. But the effect is on the 2 SSL I've made.

If someone as an idea of solving it...

Best regards

Your turbo boards are clearly not working properly (assuming the left channel goes through the Turbo board).

The way to find out where the problem is located is indeed to insert mono tones into the left and right channels, and mute the channels in turn.

Then step through the schematic and compare AC and DC voltages between the left and right channels at the same points on main board and the Turbo board (they are the same circuit).

Start at the sidechain VCA input (left side of 47K) to check input signals are being properly routed.
Then TL074 pin 4 (+ve supply)
Then TL074 pin 11 (-ve supply)
Then TL074 pin 7 (sidechain VCA out)
Then TL074 pin 14 (compression control voltage out)
Then point C (lower of the two compression control voltages L and R)

AC and DC voltages should be near enough identical on both channels.
If they aren't the same, your problem lies between the last good value and the first bad value.

 

[Aniol1349]

once again..

how I can fit the diodes on ssc board if the diodes legs are too large to fit?

 

[Harpo]

once again..

how I can fit the diodes on ssc board if the diodes legs are too large to fit?

This is still a DIY forum (and btw the gssl thread, not the ssc thread), so sometimes you might need to get a little inventive.
Some options to solve your 'problem'...
a) use a drill to enlarge the hole to the required diameter.
b) use some resistor snip offs that fit thru the holes, solder these to the pcb and solder the diodes to these snip offs from component side.
c) turn the pcb around and solder the diodes from traceside.

 

[Aniol1349]

Thanks Harpo for solving this for me!

It's my first build, and I'm learning fast but still the basics are sometimes problematic.

 

[amaurythewarrior]

I've had a similar problem when doing my green psu ... with the huge legs of the bridge rectifier. turns out the good, cheap, and easy solution was just to use a drill bit of appropriate size with my hand.

i have a question. i notice the 1mA meter for the GSSL are usually pretty expensive where i find them ... there are some pretty cheap meters on ebay, less than $10 is that good enough ?

 

[dirtyhanfri]

Hi

Finally my GSSL is going on, I had a bad conection in one of the wires going to the control pcb, so my threshold issue is solved, but now, I got some kind of white noise coming from one channel, swapping 2181's, 5534's &32's didn't make any difference, I had no time to look for bad solderings, I think the problem is coming from the VCA section.

The good news is my left channel sound & compress nicely, so I think It's a minor issue...

Any ideas on white noise? I used the sear function with no luck....

I started this project thinking it would be a nice and easy project, well, has been lots of troubleshooting work for me... I just finalized a poor man's pultec with tube make up gain stage (my first tube project actually) with many less issues than this one, It's curious how the life slaps you sometimes...

 

[Spaturno]

Hello everyone,

i manage to finish my SSL clone... somehow i get +12 0 -12 +14.9 0 -20.4
The voltage regulator are all ok, the Bridge rectifier also.
No IC is plugged. The TRAFO is 2x18V - 4.8VA
Somebody can help... thanks in advance.