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One compressor, What is it doing!>!

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One compressor, What is it doing!>!

PostPosted: Wed Jan 15, 2020 3:37 am
by DC-Choppah
I recently was playing a jazz organ patch into my Yamaha mixing board and the sound would sometimes get into an ugly pulsating distortion.

I looked around and eventually found that the channel on the Yamaha mixer had the one- knob compressor knob at about 50%. Ooops, I never use that. I use this board for recording only. I love it actually, but I don't use this on-board compressor.

So when I turned the one-knob compressor down to zero the sound was fine - no distortion. I could play the Leslie organ as hard as I want and it sounded fine - no pulsating distortion.


So now I keep the one-knob compression at zero. But what the heck is this thing doing? Why does it kick in with my organ and then sound fine at 0. That is really no help at all.

Is mine broke? Or if this the way it works?

Re: One compressor, What is it doing!>!

PostPosted: Wed Jan 15, 2020 9:46 am
by Zukan
DC, clarity dude. Are you talking about the Waves One Knob or something entirely different?

Re: One compressor, What is it doing!>!

PostPosted: Wed Jan 15, 2020 11:34 am
by Hugh Robjohns
DC-Choppah wrote:So now I keep the one-knob compression at zero. But what the heck is this thing doing? Why does it kick in with my organ and then sound fine at 0. That is really no help at all.

It sounds fine at zero because that's effectively switched off!

Real distortion when using a compressor is usually because the attack time is too fast, resulting in transient distortion. This is not uncommon if the compressor is designed primarily as a protective limiter, and when the sound source has a very clean harmonic makeup (eg, flute, organ tones, voice etc) which reveals that transient distortion quite clearly.

However, the pulsating effect you describe suggests a problem with the release time instead (or as well).

A Leslie'd organ will inherently have a modulating amplitude. If the compressor has a fast release (recovery) time (or faster than the Leslie's modulation, anyway) -- and protective compressors of the one-knob sort built into mixing consoles often do -- it will be trying to chase that modulation, and the whole thing will start bouncing around manically in the way you describe.

The same problem can affect efforts to compress bass guitars, where a fast-release compressor tries to track the actual waveform envelope of the low frequency bass notes.

HTH

Re: One compressor, What is it doing!>!

PostPosted: Wed Jan 15, 2020 11:36 am
by Hugh Robjohns
Zukan wrote:DC, clarity dude. Are you talking about the Waves One Knob or something entirely different?

DC-Choppah wrote:...the channel on the Yamaha mixer had the one- knob compressor knob at about 50%"

It's a simple one-knob channel compressor on the mixing console, Eddie...

Re: One compressor, What is it doing!>!

PostPosted: Wed Jan 15, 2020 12:07 pm
by CS70
Er.. it compresses? :) and it does it with a fixed attack and release time, which probably aren’t good for the attack/body/decay of your leslie sound.

By turning the knob you probably lower the threshold (or increase the input to a fixed threshold, which has the same result). Beyond a certain level, the compressor will try to change the sound too fast in either release or attack, resulting in distortion.. the pulsating is likely due to the timing of your leslie with respect to the timing of the attack/release of the compressor.

Re: One compressor, What is it doing!>!

PostPosted: Wed Jan 15, 2020 12:54 pm
by Zukan
Hugh Robjohns wrote:
Zukan wrote:DC, clarity dude. Are you talking about the Waves One Knob or something entirely different?

DC-Choppah wrote:...the channel on the Yamaha mixer had the one- knob compressor knob at about 50%"

It's a simple one-knob channel compressor on the mixing console, Eddie...

Thanks Hugh. Clarifies it for me.

Re: One compressor, What is it doing!>!

PostPosted: Thu Jan 16, 2020 6:19 am
by DC-Choppah
Hugh Robjohns wrote:A Leslie'd organ will inherently have a modulating amplitude. If the compressor has a fast release (recovery) time (or faster than the Leslie's modulation, anyway) -- and protective compressors of the one-knob sort built into mixing consoles often do -- it will be trying to chase that modulation, and the whole thing will start bouncing around manically in the way you describe.

The same problem can affect efforts to compress bass guitars, where a fast-release compressor tries to track the actual waveform envelope of the low frequency bass notes.

HTH

It's an ugly distortion on the jazz B3 organ with Leslie that this one knob compressor generates. Not musical at all. I tried other sources and they just compress normally. So if I put in straight guitar into the mixer and am not hitting it very hard, then bring up the one-knob compressor, it just starts to sound compressed - but not distorted.

Meanwhile the jazz B3 at the same level distorts as soon as you kick in some one-knob compression. I'm talking Jimmy Smith style jazz organ. It just hates the one-knob!

Spread the word!

Re: One compressor, What is it doing!>!

PostPosted: Thu Jan 16, 2020 9:04 am
by Wonks
There will be a difference between signal level and average signal power. It sounds like the compressor is working on RMS, rather than peak, level detection, and the RMS value of an organ signal will be much greater than that of a guitar. So the compressor will be working a lot harder on the organ than the guitar signal, despite similar peak values.

Re: One compressor, What is it doing!>!

PostPosted: Thu Jan 16, 2020 11:37 am
by Hugh Robjohns
There could be a number of different reasons, and without hearing and using it, it's impossible to say for sure from the remote silence of a forum... ;-)

Wonks makes a very good point about the side-chain level sensing system, and depending on the voicing the organ may well have a much smaller crest factor than a guitar or voice (ie, RMS level much closer to peak level). So the compressor may be trying to introduce more gain-reduction for the same control setting and running out of headroom internally.

It could also be that there is a very strong bass content in the organ sound which is either fooling the compressor into too much compression, or it's trying to track the LF waveform because its release time is too fast.

Or it could be too fast an attack time, as already mentioned.

Or a general gain structure problem in the signal path through the console.

Or a combination of any of the above.

H

Re: One compressor, What is it doing!>!

PostPosted: Thu Jan 16, 2020 11:57 am
by Tim Gillett
A band I've played in has one of these Yamaha mixers with the one knob compressors on each channel strip, or at least some of them. From memory, increasing compression also added some make up gain. Its usefulness is limited obviously but in a live band situation it helped me smooth a ragged vocal out somewhat.

Re: One compressor, What is it doing!>!

PostPosted: Thu Jan 16, 2020 3:28 pm
by James Perrett
DC-Choppah wrote:It's an ugly distortion on the jazz B3 organ with Leslie that this one knob compressor generates. Not musical at all. I tried other sources and they just compress normally.

It sounds like you are using an organ sound without many overtones. Any non-linearity in the signal chain is going to be far more apparent on that sound compared to most other sounds which have overtones or harmonics going up to a few kHz. A compressor is non linear when its gain changes so, if the gain changes are fairly rapid, you'll hear that as distortion.

It is often interesting to feed pure sine waves into various bits of kit and hear what comes out - some things aren't as clean as you think they are.

Re: One compressor, What is it doing!>!

PostPosted: Sat Jan 18, 2020 8:53 pm
by DC-Choppah
One-knob at zero

https://drive.google.com/open?id=1DObWB ... hQhXwWYGPs



One knob at 5 (12 0-clock)

https://drive.google.com/open?id=17T8uA ... DibToyWCV4


This is recorded with my Tascam handheld recorder listening to the Adam studio monitors in the project studio. This is all-analog monitoring with the keyboard DI into the Yamaha mixing board.

Nothing is clipping in the chain. The levels on the Yamaha mixer are set using its simple procedure where you push the PFL button and set the levels of the track.

The distortion comes from the one-knob compressor itself - like a fuzz box sound effect.

If you set the knob higher than 5, the fuzz gets much louder quickly.

Re: One compressor, What is it doing!>!

PostPosted: Mon Jan 20, 2020 1:28 pm
by Eddy Deegan
If you reduce the volume of the organ (at source, on the organ itself) with the compressor knob at 50%, and make up the gain on your monitoring does the distortion remain the same or does it reduce as the input signal from the organ gets lower?

Re: One compressor, What is it doing!>!

PostPosted: Mon Jan 20, 2020 2:28 pm
by Hugh Robjohns
DC-Choppah wrote:One knob at 5 (12 0-clock)...

That sounds to me like too fast an attack time on the compressor, but it could also be an internal gain structure thing. Do you have any idea how much gain reduction it's actually applying at that setting?

Re: One compressor, What is it doing!>!

PostPosted: Mon Jan 20, 2020 2:35 pm
by DC-Choppah
Eddy Deegan wrote:If you reduce the volume of the organ (at source, on the organ itself) with the compressor knob at 50%, and make up the gain on your monitoring does the distortion remain the same or does it reduce as the input signal from the organ gets lower?

The distortion reduces.

You have to hit it pretty low, and use a lot of make up gain. Seems like the threshold of the one-knob is pretty low. You have to keep the one-knob from doing anything. As soon as it kicks it it distorts.