JAY X

vumeter rectifier as compressor sidechain?
« on: September 13, 2018, 10:56:37 AM »
Hi!

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

Jay x



abbey road d enfer

Re: vumeter rectifier as compressor sidechain?
« Reply #1 on: September 13, 2018, 11:42:00 AM »
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.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

JAY X

Re: vumeter rectifier as compressor sidechain?
« Reply #2 on: September 15, 2018, 08:13:31 AM »
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


abbey road d enfer

Re: vumeter rectifier as compressor sidechain?
« Reply #3 on: September 15, 2018, 09:42:22 AM »
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.

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

Quote
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.

Quote
I will post a schematic, to make it clear. ???
That is cruelly necessary.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

abbey road d enfer

Re: vumeter rectifier as compressor sidechain?
« Reply #4 on: September 15, 2018, 09:43:09 AM »
A picture of the sidechain
This is 404 to me.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

JAY X

Re: vumeter rectifier as compressor sidechain?
« Reply #5 on: September 15, 2018, 10:30:47 AM »
ok, a new picture...

abbey road d enfer

Re: vumeter rectifier as compressor sidechain?
« Reply #6 on: September 15, 2018, 12:08:07 PM »
ok, a new picture...
OK, it works. You must be aware that the sum of L+R may be smaller than expected, due to possible phase cancellation, resulting in less compression than expected. Depending on your application it may be an issue or not.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

JAY X

Re: vumeter rectifier as compressor sidechain?
« Reply #7 on: September 15, 2018, 01:30:58 PM »
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

abbey road d enfer

Re: vumeter rectifier as compressor sidechain? New
« Reply #8 on: September 15, 2018, 05:11:30 PM »
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.

Quote
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.
« Last Edit: September 16, 2018, 07:47:07 AM by abbey road d enfer »
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

 

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