GSSL HELP THREAD!!!

[ReggieReddog]

Check the usual stuff like solder bridges etc. Make sure you have the Sidechain VCA installed correctly (opposite the other 2 VCAs). Go back through the building process and make sure you put every component in correctly. If you can't find the prob, just put a pretty front panel on and it can at least look pretty in your rack. :green:


Hey I have a question of my own: What are you guys using to measure THD or whatever to know how to adjust the trims? I downloaded that DazyWebLabs Oscillator, but I can't seem to figure out what I need to do.

 

[csonics]

Luny Tune, thanks for the advice. I pretty much went over the whole thing. No solder bidges, and the vca's are in the right direction.

For what its worth, my meter does show the side chain compressing. And you can here it happening in the audio but what should be a smooth compressed signal is a whole lot of distorted gurgly (sp?) junk.

Any one have any other suggestions?

 

[csonics]

Ok, I feel like a moron but I found a jumper that was missing. I get a LOT more clean signal now but I still get that farty distortion when it compresses hard. Especially when I set the attack to fast.

Now we're getting somewhere. Does anybody know what that could be or where I should start?

Thanks again

 

[gyraf]

Csonics,

Best advice is probably to read through this thread - e.g. your missing jumper (at the control board, just where the cables come in) has been seen several times before..

Jakob E.

 

[Luny Tune]

It does sound like something that's been discussed already I think.

Having said that it should be noted that very fast compressors are actually capable of creating a "farty" effect on some material when you, in case of the GSSL, turn both the attack and release switches fully CCW. It's not a faulty cirquit, but faulty operation for that particular material. With the release mod mentioned elsewhere on this forum you create a release time on the sixth position which i think can create a near-invisible but very effectful compression for a vocal singing, but completely useless for speech because of the farty effect that kicks in at lower frequencies.

I discovered this first with my RNC comps and the SSL comp actually has an attack time twice as fast as the RNC....and that's fast! :shock:

 

[csonics]

Gyraf - Your my hero!! Thanks man. I will check it out tonight.
Luny Tune - Thanks for the input thats good to know.

You guys rock!

 

[csonics]

Well, the bad news is that I already have that jumper in place. And...well I guess theres no good news. I've pretty much surfed through this entire thread and I can seem to find anything.

What else could cause that sort of effect? Any ideas?


Thanks,

 

[Luny Tune]

My limited expertise stops there. Sorry!:?
But I'm sure help is near.

 

[gyraf]

Are you absolutely sure that you actually have a malfunction still?

Jakob E.

 

[csonics]

Gryaf- Actually I'm just a *******...turns out that the one thing I didn't check was to see if I wired the ins and outs correctly. I had them reversed- right going to left and left going to right! It seems to work great now (besides the hum...but I don't have it properly grounded yet).

Out of curiousity now that I have a clear signal to judge, it seems like my gssl has some coloration. I've never used the original so I can really say what sounds normal. I notice that the signal looses some of its high frequencies after passing through the unit. Is this normal? Is it supposed to have a darker sound?

I'm guessing that the humm could be affecting the signal output too so maybe thats it.

Thanks guys for your patience with me!

 

[csonics]

rf,

Thanks for the suggestion. I don't really mind it that way. I just want to make sure that it sounds like it was designed to.

Thanks,

 

[csonics]

I am using THAT vca's. Hmmm... something to think about. The one thing that I noticed is that its dark both with the bypass on and when its compressing. I would think that there would be little to no effect if the bypass was turn on.

 

[gyraf]

..If you take a calculation on the HF stability ceramic caps, you'll see that they're far beyond the audio range. No lack of top-end from this, surely.

Jakob E.

 

[csonics]

Guys, thanks for the info. I'm taking carefull notes here for future builds. So from what it sounds like I am thinking I might have a bad cap or something. I don't notice a lack per se of "hi's" but I do notice a darker coloration to the audio.

Thanks again.

 

[Greg]

What type of electrolytics did you use?

In general, I would not describe either of my GSSLs as transparent, so mine have coloration as well. But I don't see that as a bad thing.

 

[gyraf]

Yep, I'm pretty sure about the 100p in the emulation part (btw, this is for control-voltage only!)

And the 100p//15K at the current-to-voltage opamp following the VCA gives us a bit over 100KHz bandwidth, which should be sufficient..

Jakob E.

 

[csonics]

Just wanted to say thanks guys for all the knowledge you've shared with me. I've managed to figure out a few more things including some miss wiring. But I've still got this ongoing problem on my left channel.

When I have the compressor in or on standby the left channel makes this crazy popping noise now. Like when your listening to a thunderstorm on an AM radio without a signal coming though. Could it be a bad Cap in the signal path?

Thanks,

 

[gyraf]

If the problem follows the bypass switch, then look for the dc path from the TL072 through the 202-emulation-5534 and into the CV input of the VCA.

Maybe scope the CV pin of the two VCA's to compare.

Maybe switch VCA's and/or emulation-5534's to exclude broken silicon

Jakob E.

 

[caps]

Ok...

Could anyone put me on the trail of where this problem might be coming from..

I have a 1 -2 db difference in the stereo output of the gssl. Strange...

Maybe adjusting the VCA trimmers? Something else ? :shock:

 

[gyraf]

Maybe adjusting the VCA trimmers

Nope - those are for THD, not level..

That is a large difference (are you sure that it is in the clone?) - you could check tolerances of resistors around the VCA's

Jakob E.