vumeter rectifier as compressor sidechain?

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JAY X

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Joined
Jan 9, 2009
Messages
683
Hi!

¿is it possible to use a peak detector vumeter rectifier as a compressor sidechain? with some mods perhaps... ;D

Jay x

 
JAY X said:
is it possible to use a peak detector vumeter rectifier as a compressor sidechain? with some mods perhaps... ;D
Why would you want to do that? Do you have such a thing and want to use it for another usage? Anyway there are many different types of meter rectifiers, some may be suitable, some less so.
 
Hi!.

Ok!.  I will skip that idea for now.

I 'm trying now with a 4305 rms detector.
From the datasheet, it is not clear if the RMS input, is an inverting input.
If it is, i could control 2 vca with it.
If it is not inverting, maybe i could use the inverting input of the vca inside this chip to sum the input signal from other two vca's... And then, attack the input of the rms converter...

I will post a schematic, to make it clear. ???

Jay x

 
JAY X said:
I 'm trying now with a 4305 rms detector.
From the datasheet, it is not clear if the RMS input, is an inverting input.
What do you mean, inverting. The input signal is rectified, so the absolute value is measured, then logarithmically converted.

If it is, i could control 2 vca with it.
You can control several VCA with one RMS detector, but most of the times, an opamp is used to provide scaling and threshold.

If it is not inverting, maybe i could use the inverting input of the vca inside this chip to sum the input signal from other two vca's...
I don't really understand what you think you want to do, but remember that summing logarithms results in multiplication.

I will post a schematic, to make it clear. ???
That is cruelly necessary.
 
ok, a new picture...
 

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  • 4305 STEREO COMPRESSOR v4.jpg
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Hi!

Ok. Another question, is if the vca in the sidechain should be at unity gain, i suppose.. And Ec- should be tied...to gnd?

Jay x
 
JAY X said:
Another question, is if the vca in the sidechain should be at unity gain, i suppose..
  It's not mandatory; if the gain was different than unity, it would just change the threshold, which can be adjusted elsewhere.

And Ec- should be tied...to gnd?
Yes.

BTW, you don't need all this, because the input of the RMS detector is also a virtual earth input, so you can sum up signals there just as well.

However, proper implementation for a bus compressor: uses both RMS detector (one on each channel), then tie their output together (their output is open-emitter, so tieing them together makes it an analog OR) and use a single "Threshold/Ratio/Gain" circuit.
 

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