ruckus328

Blendable GSSL/Turbo Sidechain?
« on: March 11, 2011, 03:39:22 PM »
OK, keep thinking about it and trying to wrap my head around this, figured this would be a good place to discuss.  Is it possible?  This is what I've been brainstorming:

OK, so going to need a pot (maybe a dual pot), and probably want to buffer the signals.

In the one extreme - L & R signals would each be going to their respective sidechains.....

In the other extreme - L & R signals would be summed and go to a single sidechain.  Ahh.... now it's getting confusing (for me anyways).  I can't think of anyway to achieve this.  Only thing I can think is to sum the signals and send the summed signal to both sidechains, which I think would give me the same results. With res/cap tolerances, one of the sidechains would always (slightly) dominate the other anyways, since both sidechains would be seeing the identical summed signal, in sense it would still be operating in gssl mode.

Enter roadblock.  I keep going through the "well what if I.............nope", "well maybe if I............ehh nope", "well if they both...........damnit.......nope"  Maybe this is simpler than I'm making it out to be.....or maybe not.

Ideas & input are welcomed & appreciated.
Serpent Audio™ - SB4000 & SA-3A Boards & Parts Kits / SB4001 Preorder / Send 'N Blend

www.serpentaudio.com


mikefatom

Re: Blendable GSSL/Turbo Sidechain?
« Reply #1 on: March 11, 2011, 04:28:45 PM »
Couldn't you mix in the GSSL (SUMMED L+R) sidechain signal with each of the Turbo sidechain signals with a dual-ganged pot?  It'd be like using the SnB in stereo mode but with sidechain signals.

I'm not sure if that's very clear.  I can draw something up at home later if it helps.

Cheers,

Mike

MikeClev

Re: Blendable GSSL/Turbo Sidechain?
« Reply #2 on: March 11, 2011, 04:43:21 PM »
You could build it as a normal turbo'ed version and feed each sidechain a single channel at one extreme of a pot and a sum of left and right at the other extreme?
Soldering burns: No pain, no gain.

If my opamps can't be discrete, I at least try to keep them discreet.

ruckus328

Re: Blendable GSSL/Turbo Sidechain?
« Reply #3 on: March 12, 2011, 03:58:28 AM »
3 Mike's in a row...  ;D

I think you're both basically saying the same thing.....far as I can tell, yea it would work, it's actually the first thing I went and looked at when I started brainstorming this.  The thing is, seems like massive overcomplication, there's gotta be simpler way.  For the SnB, you're dealing with 4 different signals (Left Clean, Left Compressed, Right Clean, Right Compressed).

For this, it's just 2 signals, and really you're trying to either pan them in (summed) or pan them out to thier respective sidechains.......just how to do it I can't quite put my finger on it yet.
Serpent Audio™ - SB4000 & SA-3A Boards & Parts Kits / SB4001 Preorder / Send 'N Blend

www.serpentaudio.com

MikeClev

Re: Blendable GSSL/Turbo Sidechain?
« Reply #4 on: March 12, 2011, 06:00:58 AM »
3 Mike's in a row...  ;D

I think you're both basically saying the same thing.....far as I can tell, yea it would work, it's actually the first thing I went and looked at when I started brainstorming this.  The thing is, seems like massive overcomplication, there's gotta be simpler way.  For the SnB, you're dealing with 4 different signals (Left Clean, Left Compressed, Right Clean, Right Compressed).

For this, it's just 2 signals, and really you're trying to either pan them in (summed) or pan them out to thier respective sidechains.......just how to do it I can't quite put my finger on it yet.

I'm NOT saying the same thing!

I'm saying Build a normal GSSL plus turbo. The only modification you make is a control that lets you feed either a summed Left and Right audio signal into both the Left and Right sidechain VCAs -OR- a separate Left audio signal into the Left Sidechain VCA and separate Right audio signal into the Right sidechain VCA, or any blend between the two extremes!

That way each sidechain is either getting the mono feed or either the left feed or the right feed.

At one end of the pot:
Left Sidechain VCA: receiving only Left audio input signal
Rght Sidechain VCA: receiving only Right audio input signal

At other end of the pot:
Left Sidechain VCA: receiving Left and Right summed audio input signal
Rght Sidechain VCA: receiving Left and Right summed audio input signal

No crush and blend style mixing, no duplication of expensive parts. Just a pan style potentiometer affecting only the mix of signals reaching the sidechain VCAs.

Soldering burns: No pain, no gain.

If my opamps can't be discrete, I at least try to keep them discreet.

mikefatom

Re: Blendable GSSL/Turbo Sidechain?
« Reply #5 on: March 12, 2011, 07:53:52 AM »
I did mean exactly what MikeClev said but he has done a much better job at explaining it.  8)


MikeClev

Re: Blendable GSSL/Turbo Sidechain?
« Reply #6 on: March 13, 2011, 10:02:44 PM »
Where did ruckus go? I want him to say 'good job gang, its going in the next version of the SB4000!'

:D
Soldering burns: No pain, no gain.

If my opamps can't be discrete, I at least try to keep them discreet.

ruckus328

Re: Blendable GSSL/Turbo Sidechain?
« Reply #7 on: March 13, 2011, 11:20:31 PM »
Where did ruckus go? I want him to say 'good job gang, its going in the next version of the SB4000!'
:D

Sorry, busy weekend.

Good Job Gang!  But..........

We're not done yet  :(

This is exactly what I was saying at the beginning of my post:

1 Extreme - Both CV signals summed and go to both sidechains.

Other extreme - Left CV goes to Left Sidechain, Right CV to right sidechain

But we still haven't figured out how to achieve this.  You couldn't do it with just a single Pot.  Think about it, one side of Pot goes to the left CV, Other End of the Pot Goes to the right CV, the wiper goes where???  Soon as you start to draw it up you'll see what I mean.  It might maybe be possible to do it with a DUAL pot, something like this:



Not quite sure that would work as is though.
Serpent Audio™ - SB4000 & SA-3A Boards & Parts Kits / SB4001 Preorder / Send 'N Blend

www.serpentaudio.com

MikeClev

Re: Blendable GSSL/Turbo Sidechain?
« Reply #8 on: March 14, 2011, 08:52:28 AM »
Its basically like a pan circuit for mixing consoles, and you want a constant power law fade between one extreme and the other...

See attached NY Dave partial schematic:

The R2 resistors bend the law slightly to steer it close to a constant power so you don't get a loud spot in the middle and quieter extremes

This means you would need a 4 gang linear pot for the mix pot
« Last Edit: March 14, 2011, 08:56:38 AM by MikeClev »
Soldering burns: No pain, no gain.

If my opamps can't be discrete, I at least try to keep them discreet.

Kingston

Re: Blendable GSSL/Turbo Sidechain?
« Reply #9 on: March 14, 2011, 09:18:23 AM »
There's still the issue of compensating between the level differences of single and dual sidechains. I hope you realise it can't be done. You can only estimate some average that you expect the signal will always be and it'll work in that range. Then someone inputs, lets say, very left-heavy material and your single/dual crossfade turns into a 6dB level dropper. For free!

That's four Mikes in a row.


mikefatom

Re: Blendable GSSL/Turbo Sidechain?
« Reply #10 on: March 14, 2011, 09:50:49 AM »
Could this be done using a summing amp block and a custom 4 gang pot?

MikeClev

Re: Blendable GSSL/Turbo Sidechain?
« Reply #11 on: March 14, 2011, 01:17:39 PM »
There's still the issue of compensating between the level differences of single and dual sidechains.

Well you're not likely to go changing this setting in the middle of a song are you? its the same issue as panning laws and mixing down to mono, there is no perfect rule that satisfies everybody...
Soldering burns: No pain, no gain.

If my opamps can't be discrete, I at least try to keep them discreet.


 

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