GSSL HELP THREAD!!!

[Siegfried Meier]

Just finished my fourth SSL - works great. Thanks to everyone for the help.

I'm sure this has been covered, but I can't seem to find the info. I've noticed all the SSL's have a gain boost of around 4-6 dB when simply patched in - bypassed or not. How do I get rid of this, so that the unit is passing unity gain when bypassed or engaged?

Thanks.
Siegfried

 

[khstudio]

[quote author="Siegfried Meier"]Just finished my fourth SSL - works great. Thanks to everyone for the help.

I'm sure this has been covered, but I can't seem to find the info. I've noticed all the SSL's have a gain boost of around 4-6 dB when simply patched in - bypassed or not. How do I get rid of this, so that the unit is passing unity gain when bypassed or engaged?

Thanks.
Siegfried[/quote]

Change the two 15k resistors (just outside the main VCA's) to 27k & it will defeat the 6db boost your getting.

 

[Siegfried Meier]

Thanks for the info. Could you point out in a pic exactly which ones to replace?

Thanks.
Siegfried

 

[Siegfried Meier]

Just curious - are these the exact resistors you're recommending be changed in order to get rid of the 6 dB boost? Where in the chain is it dropping the level down? On the output?

Thanks!

 

[khstudio]

I'm sorry I've been away for a few days & don't know why nobody helped you by now but YES, they are right!

 

[Siegfried Meier]

Haha. No worries. I guess since they figured you replied to me first, you'd do it again.

Thanks so much!

Siegfried

 

[gyraf]

[quote author="Siegfried Meier"] Where in the chain is it dropping the level down? On the output? [/quote]

Naa - look at the schematic again. The 15K resistors are voltage-to-current converters at the input of the (current-controlled, current-input) VCA's.

Jakob E.

 

[Purusha]

Hi,

I have a few more questions before I buy all the resistors and capacitors and this kind of things. Can you give me some info on your personal changes or if you replaced something or added for getting your ratio or threshold or whatever adjustments needed for your G-SSL. I will use the 2181LB VCAs. This will help me a lot so I can buy the right things from the start.

1.) Can someone explain the unity (-/+ 6dB) thing with G-SSL? Do I need to change anything here? Some are complaining about it so I thought I need some more knowledge here.

2.) I bought the Farnell meters which Gyraf recommended (METER, EDGE 100uA) Do I need to put some resistors in the chain to get the 10dB meter scale working properly?

3.) What is the optimum power supply for the G-SSL if I put some extra LEDs or maybe power and bypass square knobs with light bulbs inside like in the original design? Toroid 15V or more power, what is the optimum here?

Gyraf, Greg, anyone please? :idea:

 

[Greg]

Regarding the ratios, you'll have to do it yourself... that's it I already explained that to you.

1) If you want unity/balanced, use 27K resistors in place of the 15K... circled a few posts up.

2) Take a look at the schematic and you will see that for a 100uA meter, you need to shunt the meter with a 330R (IIRC). If you want to change the scale further, change the 2K meter series resistor. But this is done after the unit is built. Just use the 2K and see where this gets you.

3) It's not really the voltage to worry about. It's the current the lamps/LEDs will draw and the VA rating on the power tranny. A 30VA power tranny should be plenty of juice, but if you need DC I'd pull it pre-regulation as to not stress the regulators. You'll also need the appropriote series resistor.

 

[Purusha]

Thank you Greg.

I have one more question regarding THRUST filter. I am very bad at reading schematics. Does anyone of you have a PDF list of parts needed for this filter?

 

[Purusha]

Hi everyone,

I have more questions:

1. Is the make-up gain bypassed by default Gyraf schematics when bypass switch is on or I have to make some additional modification to bypass it when bypass is on?

2. Are IC sockets necessary or can I just solder all those semiconductors directly to the PCB? I would like to get the best possible contact. Some believe there is a loss in sound quality if IC sockets are used. Anyone tested this yet?


I am a newbie here so please be patient with me :grin:

 

[Greg]

1. On Gyraf's PCB layout PDFs, he shows how to hook up the bypass switch to defeat make-up in bypass mode.

2. Use sockets... you'll thank me later if you have any problems with the build. Sockets make contact just fine for me... :wink:

 

[Purusha]

Thanks again Greg :thumb:

I may also take out all the sockets later, they don't cost much anyway :idea:

 

[khstudio]

I've been researching & testing my GSSL comps for days now to get a grip on the sounds of the different VCA's & the ratio's.

Am I right to come to the conclusion that the CV of 50mv to 6mv isn't really a problem & that the ratio problem is about the same for both. I read the THAT's data sheets on upgrading to 218x from 215x & it shows & says NOTHING about compensating for the CV difference. The whole time I've been jammed up about this, thinking that the CV change would make the newer VCA's compress more or not the right way bacause of this.


Also, I have one unit with all 2151's & one with 2180LA's. I tried using each in the sidechain of the one fitted with the 2180 & it is a lot more trasparent & also reacted totaly different to frequncy & seemed to be much faster & smoother with the 2180 in the sidechain (less 47R when installed)... even in bypass, which seemed strange.


1 more thing. Is there any way to speed up the seond half of the AUTO release... when hit hard it takes a very long time to open back up, just a hair too long for me even on moderate threshold settings?

Kevin

 

[gyraf]

Is there any way to speed up the seond half of the AUTO release... when hit hard it takes a very long time to open back up, just a hair too long

The auto release is really just two added time-constants, a fast one for rare transients, and a slow one for frequent transients. There is a 0.47u tantalum cap that runs the fast part of the timing, and a 6u8 that runs the slow part. Put in lower value caps to get faster timing, higher values to get slower. Maybe make a 6'th step on your release switch for this.

Jakob E.

 

[khstudio]

Maybe make a 6'th step on your release switch for this.

Dude... What a great idea!

:thumb: :guinness: :guinness: :guinness:

 

[Purusha]

Maybe make a 6'th step on your release switch for this.

I like this idea also. Is it difficult to wire this one properly?

 

[Greg]

hey Purusha:
Before attempting modications, Jakob (and myself) always recommend building the unit as is then modify to taste if necessary. :wink:

 

[khstudio]

Jakob,
Can you or anyone more experienced than me help with my other Q's in my last post concerning the VCA - CV - 6 & 50mv?

 

[Purusha]

[quote author="Greg"]hey Purusha:
Before attempting modications, Jakob (and myself) always recommend building the unit as is then modify to taste if necessary. :wink:[/quote]

I understand this. But I am building 6 of them for me and my friends and would like to buy as much as possible in one place at once to get the best possible price.