Cardinen

A Multiband GSSL !
« on: March 31, 2020, 09:06:59 PM »
Hi all,

For some time I had this crazy idea in mind,  inspired by this thread https://groupdiy.com/index.php?topic=70580.0

The idea was to make a multiband compressor with 3 Gssl and a simple 6dB/Oct crossover with variable frequency.

I used some old gssl pcb (rev.7) with a few mods:

- THAT 1246/1646 for in-out
- Relay True Bypass  and Mute
- Adapted Attack and Release time for each band
-  Make up gain 5dB with 0.5dB steps
- Ratio 1,5:1 added
- LedBar meter reduction
- Sidechain link between compressors (still to be done)

The crossover is based on single pole R-C filters with 2 buffers at input and output for each band, the frequency is changed by the resistor values;  At the moment i have only set a fixed position at 100hz for the low and 5khz for test purpose.
I've used super matched pairs of Styroflex and Polypropylene caps for the filters.

I admit that at the beginning i was a little skeptical about this project, as a mastering engineer i was afraid of phase issues or flat response of the crossover, i have to say that when I listened to it the first time all the fears passed  :)

I'm very happy with the result, the unit is very clean and the crossover is imperceptible with no gain reduction or make up gain,
in the past I have happened to work with the Maselc Mla-3, and i have to say the workflow is very similar.

It took me several months of work to complete it, it was a fun but also frustrating project at times ... but hey! this is DIY!  8)







SSLtech:  "Because not all that matters can be measured, and not all that can be measured matters."


Cardinen

Re: A Multiband GSSL !
« Reply #1 on: March 31, 2020, 09:07:39 PM »
Inside photo
SSLtech:  "Because not all that matters can be measured, and not all that can be measured matters."

Cardinen

Re: A Multiband GSSL !
« Reply #2 on: March 31, 2020, 09:08:30 PM »
Inside photo 2
SSLtech:  "Because not all that matters can be measured, and not all that can be measured matters."

Rocinante

Re: A Multiband GSSL !
« Reply #3 on: March 31, 2020, 10:20:27 PM »
This is great but it feels like you would want more control over narrower bands. Still I am certain it would be a great tool.
If there's a harder way to do this, I haven't found it yet.

Gold

Re: A Multiband GSSL !
« Reply #4 on: April 01, 2020, 01:46:43 AM »
Looks great. I’m glad to hear that style crossover is transparent.

Rob Flinn

Re: A Multiband GSSL !
« Reply #5 on: April 01, 2020, 06:24:42 AM »
Looks great.  Did you not think of adding the turbo boards ? With my single band version I find myself never using it much out of turbo mode.
« Last Edit: April 01, 2020, 05:47:05 PM by Rob Flinn »
regards Rob

Cardinen

Re: A Multiband GSSL !
« Reply #6 on: April 01, 2020, 08:35:35 AM »
This is great but it feels like you would want more control over narrower bands. Still I am certain it would be a great tool.


Yes bands could be narrower but i find it very useful this way for tame an harsh hi-hat or stop an uncontrolled sub, it’s a great tool.
Wide bands give me good feeling about transparency

Looks great. I’m glad to hear that style crossover is transparent.

Thanks Gold  ;)


Looks great.  Did you not think of adding the turbo boards ? With my single band version I find myself never using much out of turbo mode.

It was not planned to add turbo boards on this but will see in the future...
SSLtech:  "Because not all that matters can be measured, and not all that can be measured matters."

petermontg

Re: A Multiband GSSL !
« Reply #7 on: April 01, 2020, 08:45:32 AM »
Congrats C, Long may it serve you.

Script

Re: A Multiband GSSL !
« Reply #8 on: April 01, 2020, 09:55:16 AM »
What are you using for summing amp?

Cardinen

Re: A Multiband GSSL !
« Reply #9 on: April 01, 2020, 03:32:35 PM »
What are you using for summing amp?
Nothing so special, just an inverting configuration OPA based (opa2134)

Congrats C, Long may it serve you.
Thank you!  ;)
SSLtech:  "Because not all that matters can be measured, and not all that can be measured matters."


Gold

Re: A Multiband GSSL !
« Reply #10 on: April 01, 2020, 03:48:20 PM »
This is great but it feels like you would want more control over narrower bands. Still I am certain it would be a great tool.

A 6dB/oct filter is the only order that will do a perfect mathematical sum. Steep filters won’t . For a narrow frequency band you would need steep filters.

For frequency dependent compression of a narrow band I think a dynamic EQ would be a better choice. That way you can dial in what you want without using steep filters.
« Last Edit: April 01, 2020, 03:56:01 PM by Gold »

Script

Re: A Multiband GSSL !
« Reply #11 on: April 01, 2020, 03:51:04 PM »
Quote
Nothing so special, just an inverting configuration OPA based (opa2134)
Thanks. Well, that is more special than a TL07X for summing duties.

mjrippe

Re: A Multiband GSSL !
« Reply #12 on: April 02, 2020, 01:34:21 PM »
That is fantastic!  I love the layout and the use of different color LED bar meters for each band.  If I was still recording I would lust after one of these.


 

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