A Multiband GSSL !

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Cardinen

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Feb 11, 2008
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101
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Italy
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)







 

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Rocinante

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Jan 17, 2014
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Minnehopeless
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.
 

Rob Flinn

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Jun 3, 2004
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Sussex, UK
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.
 

Cardinen

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Joined
Feb 11, 2008
Messages
101
Location
Italy
Rocinante said:
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

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

Thanks Gold  ;)


Rob Flinn said:
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...
 

Gold

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Jun 23, 2004
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Brooklyn
Rocinante said:
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.
 

mjrippe

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Dec 27, 2011
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Location
Brooklyn, NY
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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