Compressor meter doesn't match the output meter

fuzzyoctaves

fuzzyoctaves

Inspired
I have a compressor block just before my main output block. My output block's meter is reading ~ -1db or so. The compressor block's meter is reading ~ -11db. I know this because I have a hard knee and set the Threshold to -11 to see where the compression starts to kick in. Is there some misunderstanding on my part?

FWIW, I am using the compressor as a brick wall limiter to keep an analog delay pedal in self oscillation from clipping.
 
FractalAudio said:
The compressor meter is the amount of gain reduction, not the output level.
Click to expand...

Sorry. I meant the matrix display in the compressor block.
With the threshold set to -10.5, it is not showing any gain reduction and the yellow dot is just below the knee. The output block right after is showing -1db.

Compressor settings:
Ratio = 20
Attack = .1
Lookahead = 0
Hard Knee
 
fuzzyoctaves said:
Sorry. I meant the matrix display in the compressor block.
With the threshold set to -10.5, it is not showing any gain reduction and the yellow dot is just below the knee. The output block right after is showing -1db.

Compressor settings:
Ratio = 20
Attack = .1
Lookahead = 0
Hard Knee
Click to expand...
What’s a matrix display in the compressor block?
 
Turn off the Auto Makeup setting to keep the output level the same relative to the threshold. Otherwise it gets boosted up to keep the block output more consistent.
 
Sounds about right. The output block is normalized to -12 dB. This is to provide adequate D/A headroom.
 
Yeah, 0 dB on the output meters = -12 dBFS for the digital signal level going to the D/A converters or digital outs (USB/SPDIF/AES).
 
FractalAudio said:
Sounds about right. The output block is normalized to -12 dB. This is to provide adequate D/A headroom.
Click to expand...
This is true only for out1 and out2, right?
Cuz some time ago I did exactly the same thing as the OP, a brickwall limiter before the out block, but I used it on out3 and out4 and it works perfectly with the threshold set near 0dB.
EDIT: oops, I realized now you were talking about the output meter and not the out level, nevermind.

PS: a little wish.
Could we have a simple brickwall limiter built in on each output block?
Or maybe some kind of saturation, something that distorts the signal in a pleasant way to avoid digital clipping?
 
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So the idea is that it's ok to clip earlier in the signal chain, but not at the output? I guess that makes sense if internal processing is floating point, since the output DAC does have a finite max level.

Compression early on controls level through the whole signal chain, and optimizes signal to noise ratio too.
 
Smittefar said:
@DLC86 I do this with a combination of compressor block and Tape Drive. If you add lookahead to the studio compressor with 20:1 ratio it is very close to a brickwall limiter
https://forum.fractalaudio.com/thre...spiky-transients-on-very-clean-sounds.167866/
Click to expand...
Yes I've already tried that but the problem is also that, at this point, my patches are almost maxed out CPU-wise and I can't add another drive block. Also, using the studio compressor as a limiter is probably not the most efficient solution since its algorithm probably contains some quirks of real studio gear too.
A simple hard clipper/limiter baked in the out blocks might be more efficient for this scope.

PS: and as yek pointed out in that discussion, the drive block sums to mono.
Using the preamp in the cab block instead (with two null IRs if cab sim is not needed) might be a solution to this but even less efficient.
Smittefar said:
Yes, and as I said, I activated it to make it work - But it actually still lets a few peaks through
Click to expand...
I've experimented a bit with this and managed to make it work, I don't remember exactly atm but I think I had to set the threshold a few dB lower than 0dBFS so as to leave a bit of headroom to the compressor and to those peaks.
I'll share my settings as I get home
 
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DLC86 said:
I've experimented a bit with this and managed to make it work, I don't remember exactly atm but I think I had to set the threshold a few dB lower than 0dBFS so as to leave a bit of headroom to the compressor and to those peaks.
I'll share my settings as I get home
Click to expand...

See my attached screenshot for my current settings. I have a Carbon Copy in the out/in loop 4 in self-oscillation. Considering what it still lets through, -15.4dB keeps Out2 under 0dB.

Screen Shot 2020-12-13 at 4.17.48 PM.png
 
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