GSSL add-on help thread

[Script]

Where did you get this information ?

Info is in the main thread. You could search for "implementing different vca" " Matt Fischer" "gssl"

 

[Dominique Poinçot]

Info is in the main thread. You could search for "implementing different vca" " Matt Fischer" "gssl"

Thanks a lot, I finally found your post with Matt Fischer's infos ! I did search the main thread, but it was burried in the hundreds of results without the right key words.

 

[timtom]

I'm building a GSSL with two DBX/That 202x VCS's. From the datasheet the resistors around the VCS should be changed as the GSSL is built for 202c's. Anyone has some experience or made a GSSL with 202x's.
It works as well with the GSSL resistors but it compresses way less then it should and also the meter is completely off.

 

[craigmorris74]

I built mine with 202x VCAs, with the components on that data sheet. Works great!

 

[timtom]

I built mine with 202x VCAs, with the components on that data sheet. Works great!

Thanks, I will make those 4 resistors easy switchable and start with the ones from the datasheet.

 

[Coatesy]

Hi Folks - I posted this question a few days ago on the vanilla GSSL HELP thread but realised I should put it here as my current GSSL has a turbo board fitted ………

I just rejoined the forum - I was an active member several years ago and built a couple of GSSL, a dual REDD47, a D-LA2A, a stereo Pultec EQ, A dual Gyraf Calrec EQ, a G7 mic, and an 1176 when I was building up my own home studio.

I have been tweaking one of my GSSL and have a simple question which cannot find by searching anywhere in the GSSL Help thread so far....forgive me if I have missed it.

I'd like to add an externa key/side chain to my current GSSL. It has an expat Turbo board fitted and the whole thing works superbly.

I thought I read that there is an external sidechain input on the gyraf PCB layout. I can’t see any markings or extra solder pads on my boards .

is there a way I can add a switched TRS jack on the front panel so I can patch in an external mono signal from my patch bay to control the side chain - say for ducking the mix slightly for vocals etc ?

is this possible with a Turbo board already fitted, and what about if I wanted to use a stereo side chain input - is that impossible ?

Thanks for any advice.
cheers
PeteC

 

[Script]

I'd think your EXT IN signal needs to be buffered and DC blocked to protect your sidechains.

(1)
You could simply replicate the two balanced Audio INs (simplified) and place them switchable (toggle or relay) before the two 47k resistors. Most versatile solution. Two jack INs plus one switch on faceplate.

(2)
For TRS jack switching you'd still need to buffer the two EXT INs with caps for DC protection of the sidechain (and op amp at unity or for +6dB gain) before the 47Ks.

(3)
Tip and ring of one TRS for L and R might work with both balanced and unbalanced ext in cable/signal (but not versatile), and still needs DC blocking (and buffer) before input of both sidechain paths.

 

[Coatesy]

Thanks for your reply - i need
To think through what you have suggested. I think that having the links to the Turbo board is whats confusing me. I did find one post by Jacob about the unmodded GSSL that suggested buffering wasnt necessary and even mentioned having pads on the board that could be used to tap in a TRS jack for a mono external
Sidechain. I think i need to be able to see it visually to understand how to hook it up really. Anyway thanks for the advice.
Cheers

 

[Script]

You mean following thread, where OP wanted to add a balanced Ext SC Input to a vanilla gssl (i.e. in Aarhus Mode) ?

https://groupdiy.com/threads/gssl-external-sidechain-schematic.70072/
You have Turbo installed (two separate side chains). So using a y-cable for stereo input should work with tip and ring feeding SC L and SC R respectively. Should also work when feeding only mono signal and even when feeding via mono cable (then tip-SC drives the unit, ring-SC is at rest/grounded, both audio path VCAs react to the higher of the two SC signals via diode junction at SC outputs). So okay, I think.

(A balanced mono signal won't work though with above TRS tip-n-ring feed in Aarhus mode, cos summed after 47Ks = silence.) Yours not switchable, right.

Either way, hooking a TRS straight to the SC VCA inputs without any protection I'm not so sure about. It might work 'til the day someone patches the wrong cable.

 

[Coatesy]

Thank you - i am starting to understand how i might be able
to make this work. My unit is switchable between Oxford and Aarhus mode so i need to think about how the switching would be affected.
Cheers.

 

[timtom]

I built mine with 202x VCAs, with the components on that data sheet. Works great!

I installed trimmers and set them to the values from the datasheet. It worked as well.
But gave me 6db more signal. Adjusted them so I have unity gain.
Unit still compresses less then my other Gssl and meter is still very off.

 

[craigmorris74]

I installed trimmers and set them to the values from the datasheet. It worked as well.
But gave me 6db more signal. Adjusted them so I have unity gain.
Unit still compresses less then my other Gssl and meter is still very off.

How much compression can it do, and how are you measuring it?

Did you install the trimmer before the meter?

 

[timtom]

How much compression can it do, and how are you measuring it?

Did you install the trimmer before the meter?

I installed the trimmer for the meter.

The 127k resistor for the VCA control voltage I replaced with a pot and now I can adjust more or less compression. This allows me to match more a less the reading on the meter.
But still the meter shows more compression than actually happening.

 

[craigmorris74]

I installed the trimmer for the meter.

The 127k resistor for the VCA control voltage I replaced with a pot and now I can adjust more or less compression. This allows me to match more a less the reading on the meter.
But still the meter shows more compression than actually happening.

Sorry, been I while since I've built this. Looking at the schematic, where is the 127K resistor?

 

[timtom]

Reading through the MixBuzz500 thread those resistors have to be changed.

Sorry, been I while since I've built this. Looking at the schematic, where is the 127K resistor?

 

[craigmorris74]

Reading through the MixBuzz500 thread those resistors have to be changed.

View attachment 104040View attachment 104041

If you’ve lowered the resistance in the CV path, I’m not sure what’s going on. Someone with more electronics chops will have to chime in.

 

[JerryPbury]

Try this

 

[MiamiBoy]

I have a CRC board and Turbo from Expat Audio.
I want to add a voltage switch (115-230V) to my gSSL so I can use it globally.
This is what I need help with:

1. Trafo: solder which wire to each other (primary / secondary ?!) by color.
2. and how to wire the trafo to Voltage switch -what to wire to what (it has 6 pins).
3. From there, what to wire to IEC ON/OFF switch.
4. what to wire to CRC board?

Thanks Jerry, I really appreciate your time & effort.
But unfortunately, this is gibberish to me.. I cannot read schematics. Also, I don't know which of my many questions this schematic answers?

I will try to be more clear: I need it to be explained like im a 5yr old, please consider my lack of knowledge/experience. Im not an electrician or a technician with electricity training. Im just a record producer who's good with a soldering iron I need guidance / explanation with any answer/solution you come up with... im a noob and still learning! Please be kind... der skal være plads til alle.

 

[JerryPbury]

Thanks Jerry, I really appreciate your time & effort.
But unfortunately, this is gibberish to me.. I cannot read schematics. Also, I don't know which of my many questions this schematic answers?

I will try to be more clear: I need it to be explained like im a 5yr old, please consider my lack of knowledge/experience. Im not an electrician or a technician with electricity training. Im just a record producer who's good with a soldering iron I need guidance / explanation with any answer/solution you come up with... im a noob and still learning! Please be kind... der skal være plads til alle.

Ok….your power switch has 2 connections. Couldn’t be simpler. The voltage switch is numbered like the picture. Your power tranny has a sticker that shows the voltage or a paper that shows which colors are 0 volts and 120 volts. Do one wire at a time. Other than doing it for you, I don’t know a better way to describe it. The only difference between you and 90% of the people on the board is that we aren't afraid to mess things up. We see it as a learning opportunity. That’s how we learn.

 

[MiamiBoy]

On the back of my powerswitch, it has 8 pins.. What do you mean "2 connections" ?

Taking a closer look, I see some letter on the power switch: L, N W, E.
The L is LOAD/live, N is NEUTRAL and E is EARTH/ground.
But what is W ? it's right above the N

On the other 4 pins, it doesn't say anything (behind the on/off switch).

And on the voltage switch there's 6 pins:
2A · 2 · 2B
1A · 1 · 1B
Im guessing, there are some bridging that needs to take place?

On the The trafo it says:
Primary: 115V yellow/white 115V or-purple
Sec. I: 15V black-red 1,0 A
Sec. II: 15V or-blue 1,0 A
out of all of the colors, only orange isn't mentioned. And there's 2 orange wires.
I'm afraid that I don't have anymore info on that trafo. There's no sheet-data on their website.