GSSL HELP THREAD!!!

[Eurocide]

So, I've started my GSSL for the first time without ICs.
Unfortunately the +DC rail gives a wrong voltage.
(see picture)

The output AC from the transformer is 17V.
The -15 V line works fine but the +15V and both of the 12V lines show only 4.xx V

I've already exchanged the diode bridge with the same result.
Could it be the 7815?

I hope it is just a silly question. :wink:

 

[gyraf]

Don't run it without ic's installed - regulators needs some load to work properly. Read this thread - I think we've had this question before..

Jakob E.

 

[Greg]

[quote author="khstudio"]Are you guys saying to use the 2180 (Pre-trimmed) over the 2181?

Roger, can I use a volt meter @ the CV input. Now, this is just for the main (Audio) VCA's & not the sidechain? or do I have to adjust for that also?[/quote]
I'd say yes, use 2180 over 2181. Seems to be less hassle. However, I'd recommend 202 over all, but they're hard to get and more expensive.

I don't like measuring low voltages with a meter. I'd recommend a scope. Whenever measureing small AC, or even AC in general, I like to see the waveform. There could crossover distortion or some oscillation/ringing in there that you won't be able to "see" with a meter.

 

[Purusha]

[quote author="Greg"]
I'd say yes, use 2180 over 2181. Seems to be less hassle. However, I'd recommend 202 over all, but they're hard to get and more expensive.

[/quote]

Greg, can you please explain one thing to me regarding the 2180 over 2181. I have a special VCA "color" option in mind for the 8 SSL units which I am building. I will put one extra rotary switch for two different settings of two sets of THD trimmers. So that at the end I can choose a cleaner or dirtier sound of VCAs. That is why I ordered THAT2181LBs, they are not pre trimmed. I can still change the order to THAT2180LBs. My question is - would 2180 VCAs cancel my "color" option from the design because they are pre trimmed or can I still build my SSLs with more or less color option by using the extra trimmers with the 2180?

 

[Eurocide]

[quote author="gyraf"]Don't run it without ic's installed - regulators needs some load to work properly. Read this thread - I think we've had this question before..

Jakob E.[/quote]
I've put all ICs in.
-15V OK
+15V shows now 2.xx V
-12 V shows 2.xx V
+12 V shows +17 V(!)

I hope I haven't blown any IC now!

 

[gyraf]

..So you either have bad regulators or shorts on the board. Shorts are by far the most common..

 

[Purusha]

I'll repeat my dilemma since topic moved to next page...

Can you Greg or anyone else, please explain this thing regarding the 2180 over 2181. I have a special VCA "color" add-on option in mind for the 8 SSL units which I am building. I will put one extra rotary switch for two different settings of two sets of THD trimmers. So that at the end I can choose a cleaner or dirtier sound of VCAs. That is why I ordered THAT2181LBs, they are not pre trimmed. I can still change the order to THAT2180LBs on Monday but my question is - would 2180 VCAs cancel my "color" option from the design because they are pre trimmed or can I still build my SSLs with this color option by using the extra trimmers with the 2180?

One more thing regarding the release:
0.1 sek, 0.3 sek, 0.6 sek, 1.2 sek, 2.4(Auto) ...the last 2.4s is actually in Auto mode, yes?

I need to know because I am doing the design for the front panel.

 

[Greg]

Purusha: I cannot answer that question, since I think you're doing something custom. But if you use the 2180, it won't trimmable, if that's what you're asking. I've only built two units without the 2180 and on those I just left the distortion pot in the middle position. So I can't really even comment how that really effects the sound. I guess I don't really care all that much...

I don't know where the 2.4s came from, but the fifth position is the Auto release.

PS - Got the WU today. Also, you don't have post again just because it went to a seperate page... I'll read all posts I haven't already read. :wink: Member my patience comment... I was helping my dad pull some new coax through the walls at his house since we had to re-wire the entire place since it flooded.

 

[Purusha]

[quote author="Greg"]Purusha: I cannot answer that question, since I think you're doing something custom. But if you use the 2180, it won't trimmable, if that's what you're asking. I've only built two units without the 2180 and on those I just left the distortion pot in the middle position. So I can't really even comment how that really effects the sound. I guess I don't really care all that much...[/quote]

I suggested the idea of having one extra potentiometer on the front panel to regulate the THD of the VCA for color here in one thread and got even better idea from somebody to use two set of trimmers inside and just point to them with 2 step rotary switch. It's a simple mod thing, isn't it?
But I guess this would not be possible if I use the 2180 VCAs...

[quote author="Greg"]I don't know where the 2.4s came from, but the fifth position is the Auto release.[/quote]

From Gyraf's SSL website... copy paste - 0.1 sek, 0.3 sek, 0.6 sek, 1.2 sek, 2.4(Auto)

 

[Greg]

Yup, it's a simple mod, and could definitely be a nice feature, except you wouldn't need a rotary. You could use a toggle and that would save front panel space.

 

[Purusha]

Yep, this is also true, but I already bought them and it makes a nice looking design with many buttons :grin:

 

[Purusha]

The idea for the black on gold front panel design. Comments please :twisted:

 

[Purusha]

It looks like I'll be the most frequent visitor in this thread for next few days or even weeks :grin:

For the external sidechain connections, do I need balanced or unbalanced 1/4 connectors?

 

[Greg]

Purusha, you need TRS connectors. One contact for send, one for receive, and the sleeve for ground reference. :thumb:

 

[Purusha]

Oh yeah, what a stupid question, I completely forgot about send/return. Stereo is the way to go then. :thumb:

Greg, what do you think about my design?

 

[Greg]

I think your design is top notch... looks great !!! :green:

One thing, just in case you didn't think of it. You won't be able to mount the switch daughter board to the front panel because of the location of the ratio switch. So you'll have run wires from the daughter board to the attack, release, and ratio... kind of a pain of the ass, but I've seen several units built like that.

 

[Purusha]

One thing, just in case you didn't think of it. You won't be able to mount the switch daughter board to the front panel because of the location of the ratio switch. So you'll have run wires from the daughter board to the attack, release, and ratio... kind of a pain of the ass, but I've seen several units built like that.

Yes, I know. Distances between pots are also smaller because of few more switches. BTW I don't care about more wires, I like soldering! :green:

 

[khstudio]

Greg,
I just finished loading my 2 sidechain boards & need some help.
Roger talks about adjusting the CV but never mentions having a sidechain installed... did you ever check your CV like Roger recommends & what did you come up with? Having the sidechain installed would change things a bit I'm sure.

And just so I can get this straight, the CV & Ratio's needs to be checked & adjusted for both - 215x & 218x :?: That seems to be what Roger is saying.

I'm sure the info is here somewhere but what's the trimmer for?

Just for the record, I've been leaning towards the newer VCA's - 2180LA, with the 100k to 120k ratio mod it's very nice. I was going to leave 1 unit Gyraf/Stock with 2151 x 3 but the more I listen to the adjusted one I don't like the other as much... maybe I just need the Ratio mod on that one too :?

Anyway, thanks for your help & the boards :thumb:

Kevin

 

[Greg]

I personally have not done the "ratio curve" test but when I install my sidechain filters I'll mess around with it a bit.

The sidechain filter shouldn't change much regarding the channel VCAs. Also, the trimmer in there will work kind of like a threshold adjustment. Or it be used the set the highpass exactly to unity gain if that's what is wanted.

It's basically a "set to taste" trim pot.

 

[khstudio]

Roger,
I'm on it.
I come back after I check.

Again, thank you for a more detailed responce.

Kevin