GSSL HELP THREAD!!!

[khstudio]

Greg, Didn't see your post... So the trim sets the gain of the sidechain filter board?

Is the trimmer still active when set to bypass?
- I think it is but I just want to be sure.

I'm going to attack this CV/Ratio/curve thing as much as I can & when I/we find a good method I'm going to gather ALL the correct info and put it in ONE SPOT to help everyone.

Do you guys think we should continue this discussion in a specific post?

Kevin

 

[Greg]

Yes, the trimmer is still active when the sidechain high pass is bypass.

 

[Dor]

Hello there. I'm ordering my parts for the GSSL off of mouser.com and am running into an issue. i'm searching for part 271-100 but only see 271-100-RC listed at .09 per unit. The 271-100/AP-RC are available but the minimal order is 1000.

Will the 271-100-rc work or do i need the 271-100/AP-RC ?

Thanks,

D

 

[Greg]

Yes, it'll work fine. This happens often to me with resistor values from Mouser.

Also, can you add your location to your profile. Thanks.

 

[Dor]

[quote author="Greg"]Yes, it'll work fine. This happens often to me with resistor values from Mouser.

Also, can you add your location to your profile. Thanks.[/quote]

thanks for the quick response. wasn't sure if I had to have a certain ohm rating ... this is my first DIY :shock:

 

[TornadoTed]

[quote author="TornadoTed"]I've done a bit of searching around and got totally confused. I've found these on the RS components website, you just need to copy the numbers below into the 'Find products' box at the top of the page.

http://rswww.com/cgi-bin/bv/rswww/home.do?cacheID=ukie


Meter - 1968402
Bezel - 1968682
6 way switch (attack and release) - 665196
3 way switch (ratio) - 665219
Copper foil sheets (the enclosure is wood so I've been told I need copper foil to stop RF and such like - 680959

I already have an account with them so sourcing from them is easier than sourcing elsewhjere if these are suitable.

I'd be so grateful if somebody could check them out for me and let me know if they are what I need for the SSL clone in a 2u case. A friend is building the electronics for me but has left me to get these few bits and pieces. I built the case out of maple, looks stunning. Boy I feel out of my depth :roll:[/quote]


Anyone? Please, please, please.

 

[Greg]

The meter, bezel, and switches look fine... not sure about the copper foil sheets. Maybe someone else can comment.

 

[TornadoTed]

Cheers Greg, much appreciated. I can get the case finished off now and delivered to my mate Jake to stuff the boards.

He has a couple of DBX 202 VCA's that he has had 25+ years. What is there a differnece between these and the 202C?

He is making one to spec and experimenting on other so he may use the 202's in the experimental model.

 

[khstudio]

OK,

Been testing my two GSSL's for a few hours & all looks good.

The Control Voltages are perfect on both units.
one has all 2151's & one has all 2180's less trimmer, 68r, 10k & 47r in side chain. I did the 100k to 120k Ratio mod on the one with 2180's & changed the meter resistor to 3k and everything is perfect on that one. The Ratio mod didn't affect the CV at ALL!!! but did fix the ratio's. so all is well.

120mv for 20db compression, 60mv for 10db, 24mv for 4db etc...

Now I'm confussed why some of you had to make adjustments at all?

My last concern before installing Greg/Steffen's sidechain board is:

What's the method of adjusting the distortion trimmers?
I have the audio tester app... can I use that? I would really like to SEE what's going on when adjusted. How?

Kevin

 

[khstudio]

Greg,
Could you check your CV @ pin 3 on the audio VCA's. I'd like to know what your getting there with the sidechain filter installed. I'll be installing & testing mine later tonite after my session. I'll report back.

Also, what did you end up with for the meter resistor? I'm using 1ma linear scale.

Thank's
Kevin

 

[Greg]

Ted: Not sure about the VCAs :roll:

Kevin: I think you need a distortion analyzer to set the distortion trims. I don't have one so my trimmers sit in the middle.

I won't be able to check that voltage for you because both my GSSLs are loaned out at the moment. Also, the sidechain should effect nothing at unity gain. What you can do it put a 12K resistor in for the series 1K and 10K trim.
Basically, this is a simple inverting op-amp configuration. If you aren't familiar with it, do a google search and you'll get tons of info. The gain is -Rf/Rin, where Rf is the feedback resistor and Rin is the resistor at the inverting input. Make these values both 12K and you get gain = -1. :thumb: Or you could put in a 5K and the 10K pot and trim it to exactly -1.

Since I can tell you like things exact, you might want to put something like 5K and the trimpot in the feedback path so can set the gain to exactly -1.

 

[khstudio]

Greg,
I wouldn't say exact... this DIY stuff is a great hands on learning tool with great rewards. I've built MANY guitar amps but the LA-2a & above all this SSL comp really opened me up to working with IC's & the VCA's. I've learned so much & love it. To me it's just as much about learning as building, then having more cool equipment for my studio. When you guys say just build it & move on, I'm not with it... I want to dig in a little & learn so the next time I don't have to ask so many questions... not to mention, be more creative in how I mod or adjust my gear.

Isn't the trim there to adjust the gain already?

BTW, I got a lot out of your last post... I don't know ANYTHING about how to set up IC's & their gain's but I'm getting there.

Basically, I just like my gear to work right. The small adjustments I've made so far made the GSSL better for me. Now after measuring the CV & adjusting the meter I've got it to a point where I know it's right & can now move onto the sidechain filter without any added confussion - meaning I'll know where the problem will be (if there is any) without running around the whole board.

If anyone that has the sidechain filter installed can check their CV I'd love to know what your getting to compare. I'll post my results soon.

Thanks again :green:
Kevin

 

[khstudio]

OK, I just looked at the schematic & see you can only get 11k total in the feedback as is... so, your saying to increase to 12k to be at unity?

Also, the cap value in the feedback, how does that work? Do higher values add or reduce the higher frequencies?

 

[MRP]

I haven't read about this problem yet, so I'm posting it. I built two GSSLs, neither of which work. The first isn't even close to functioning properly, but the second one seems promising, even though it's still acting strangely. Here's what's up with the second

Bypassed, it's nice and clean, makeup gain works fine.
When engaged, all the knobs/switches "work", in that they affect the compression as they should, but the actual compression is crazy. As I turn the threshold CCW, the audio level goes down, and the meter goes up accordingly. This is more like turning down the volume though. When the compression does engage, it totally reduces the gain to nothing, and the meter spikes. The attack and release controls do affect the speed of the respective spiking timings. Changing the ratio also makes the meter spike. Basically, it seems like i'm getting super negative ratios, and it's not tracking properly, as the gain reduction swings are barely related to the source material I'm running through it.
My 15 and 12 voltages seem fine. C and D voltage spikes with the meter/compression. Diodes are oriented correctly. Any ideas?

 

[khstudio]

I don't think the Make-up Gain should work in Bypass :?

 

[giantbenny]

Hi how are you? I too have had a few minor dramas with a couple of ssl's, i came up with these conclusions but i'll just give them to you in my language. (idiotnamese)

I added a 22k resistor to pin 3 of the threshold pot (as per advice in this forum) That settled the threshold issues, next i attached a variable 1k lin pot to the cv 1k resistor located at the bottom of the pcb nearest the vca outline (there are two of course) I then used the pot to isolate the correct resistance that i needed to give me a 2 db drop between the ratio settings by passing through a 1k tone. My perfect cv resistance was 600R this gave me a much better compressor. I did tell you i was an idiot and spoke strangely, so if this is wrong, then ah well i tried.

all the best.

ben

 

[MRP]

I've got my make-up gain bypass jumpered on the control board until I get everything to work.

 

[MRP]

Alright, now a new phenomenon has cropped up. With no input, the meter is spiking every 4 seconds or so. Then I put signal through, and it kind of stabilizes, and minutely reacts to the signal, although the baseline of the meter is still inversely proportional to the threshold knob position. I turn the signal off, and the needle holds and doesn't spike. Then I test the range of the threshold knob, and the intermittent spiking begins anew.
After the first GSSL didn't work, I was putting my faith in the second. Now I want to shoot myself in the face.

 

[khstudio]

You have 1 option... Shut it off!

Take your time & go over every little thing. There are a lot of components that have a specific direction - Caps, IC's, Diodes etc...

I built 2 that worked right away but took the time to test EVERY components value before installing. There are soo many things it could be so its going to be hard to help you without a lot more details.

BTW, don't give up, it's probably something small that you're missing.

 

[Purusha]

Just to make the right change of 100pF to 100nF. Is this the right spot? If yes, than I need to change two of them in both VCA sections on one PCB?