A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"

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Gold
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Re: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"

Post by Gold »

I’m glad you are working on a Pico replacement. I’m not enamored with my Pico builds. I have them only in variable A/R mode. I don’t think that VAR circuit was tweaked out as much as it could be. It always seems like too little or too much. I’ve wanted to switch them over to using the timing caps but don’t want to have to take these out if service. New boards for a new build would be very welcome.
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Re: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"

Post by emrr »

I'll add that over time I find I'm using non-linear mode the most with Pico's in pop music, acoustic Americana, etc. I rarely ever use adjustable attack/release, it's NL or RMS. Never the peak mode. I think the waveulator is a better approach for transients.
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Doug Williams
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mediatechnology
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Re: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"

Post by mediatechnology »

emrr wrote: Wed Feb 07, 2024 12:07 pm I'll add that over time I find I'm using non-linear mode the most with Pico's in pop music, acoustic Americana, etc. I rarely ever use adjustable attack/release, it's NL or RMS. Never the peak mode. I think the waveulator is a better approach for transients.
I agree. Using an "RMS" compressor to control peak level is like driving a screw with a hammer. It's the wrong tool.

The RMS tool optimizes power: The peak tool optimizes crest factor.
Together they both optimize crest factor.

I'm dog-sitting a geriatric dog this week for my daughter and have not had a chance to actually hook the detector up to VCAs in order to listen to it.
Gold
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Re: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"

Post by Gold »

emrr wrote: Wed Feb 07, 2024 12:07 pm I'll add that over time I find I'm using non-linear mode the most with Pico's in pop music, acoustic Americana, etc. I rarely ever use adjustable attack/release, it's NL or RMS. Never the peak mode. I think the waveulator is a better approach for transients.
I probably should have built it that way but I don’t like a kitchen sink of controls. I know some like the ‘ it does everything’ approach but I’m the opposite. I like li limited set of features. I just picked the wrong features.
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Re: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"

Post by emrr »

Gold wrote: Fri Feb 09, 2024 12:41 pm
emrr wrote: Wed Feb 07, 2024 12:07 pm I'll add that over time I find I'm using non-linear mode the most with Pico's in pop music, acoustic Americana, etc. I rarely ever use adjustable attack/release, it's NL or RMS. Never the peak mode. I think the waveulator is a better approach for transients.
I probably should have built it that way but I don’t like a kitchen sink of controls. I know some like the ‘ it does everything’ approach but I’m the opposite. I like li limited set of features. I just picked the wrong features.
I’d say if you have space, it’s easy enough to add the parts and switch(es). I understand not wanting to take them out of service.
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mediatechnology
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Re: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"

Post by mediatechnology »

Doug what does NLC bring to the table for you that you don't get with RMS? Less distortion on low frequencies?

I did some digging to find out how dBx and THAT settled on the typical 10 µF, 7.5 µA, 35 ms log-domain tau, 120 dB/s decay rate used in almost every app note and schematic since the beginning of time and found this in DN-107:

Image

I'm looking at a variable rate of 600 dB/s to 60 dB/s as a trial range.
Quadrature power summing should reduce audible ripple artifacts significantly at the faster A/R rates which should make NLC unnecessary.
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mediatechnology
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Re: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"

Post by mediatechnology »

I just started doing listening tests late yesterday and so far I really like the variable capacitance multiplier.

I need to put on the 'phones and do some critical listening but before I do I wanted to verify, with tone, the benefits of Quadrature Power Summing.

A quick FFT with a 100 Hz tone shows that at the slowest setting, 60 dB/s, the reduction in HD-3 is 20 dB.
At 600 dB/s the reduction in HD-3 is over 30 dB.

What I'm finding is that due to reduced detector ripple the attack/release can be made much faster when its needed.
I may expand the range from 10:1 to 20:1.
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Re: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"

Post by JR. »

Lower distortion should always be good.

Does it impact the waveform distortion caused by fast release on pure low frequency tones?

While it is unclear that this mechanism is an audible problem with real world complex waveforms.

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Re: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"

Post by mediatechnology »

On pure sustained tones at 100 Hz I can hear various degrees of distortion at almost every setting of the capacitance multiplier when QPS is switched out and don't hear any change in timbre at any setting when QPS is in. HD-3 is near the same residual level as the VCA's HD-2 with QPS.
At 50 Hz HD-3 dropped over 40 dB.

QPS allows some crazy-fast attack-release that almost makes it a peak limiter at 600 dB/s.

I ran some Stanley Clarke bass through it and used a ratio setting and the fastest response that was over the top musically in order to try to and break it. What I heard admittedly had too much compression but not much audible distortion with QPS and lots of crunch and breakup without QPS.

I think I want to try an even faster setting maybe 1200 dB/s for drums.

The cool thing about the capacitance multiplier is that, at least theoretically, it's still power-responding whereas a modified A/R isn't.

I found the link to Fred Floru's AES paper on the RMS detector and its very math-heavy. My eyes glazed over.
Gold
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Re: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"

Post by Gold »

emrr wrote: Mon Feb 12, 2024 9:17 am I’d say if you have space, it’s easy enough to add the parts and switch(es). I understand not wanting to take them out of service.
I don't have space. It's two units with VAR boards in a 1RU case. It's jam packed in there.
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