What is Spectral Compression ?

[Gone To Lunch]

Exactly what is spectral compression as advertised in this new product smart:comp from sonible ?

https://www.sonible.com/smartcomp/

[Hugh Robjohns]

It's a multiband compressor with a heck of a lot of independent bands and some intelligent processing control algorithms. So the idea is it compressors only the loudest individual elements within a complex mix, rather than affecting larges sections of the bandwidth. I guess the idea is that the resulting dynamic control sounds less obvious...

Sounds a very interesting idea, anyway....

[Dennis J Wilkins]

Hello,

Having just spent the past few months beta testing Sonible smart:comp I can explain in a bit more detail. Spectral compression, as they have implemented it, analyses the input track in real-time, across more than 2000 frequency bands (I'm guessing 2,048 but haven't tried to count them!) and uses the levels detected at each frequency to act as a high-resolution multiband compressor. Not only a multiband compressor that adjusts compression based on the spectral content of the music, but also can use the "smart" part of the processor, using a “profile” developed for different styles/tracks (standard profile for general use, and profiles for both female and male vocals, bass, drums, kick, snare, keys, and guitar).

The capability that really excited me is using the spectral compression with a side-chain input. This enables ducking the controlled track based on the spectrum of the controlling track. So a bass track can duck the kick track only at the current frequency of the bass rather than duck the entire kick level. Although I've been able to do similar selective ducking for years with some REAPER tricks, this makes it extremely easy.

Anyway, it's one more great audio tool that digital processing and powerful, affordable computers have made possible.

[Sam Inglis]

'Spectral compression' seems to be one of those terms that can apply to all sorts of processors.

I am a big fan of HOFA's IQ-Comp which implements a rather different sort of 'spectral compression'. I'll be trying out this new Sonible compressor soon too.

[Gone To Lunch]

Hello,

Having just spent the past few months beta testing Sonible smart:comp I can explain in a bit more detail.

Thanks, that was very helpful.

[Martin Walker]

Hello,

Having just spent the past few months beta testing Sonible smart:comp I can explain in a bit more detail.

Thanks, that was very helpful.

Agreed - fascinating info The Sound Guy

Martin

[James Perrett]

This thread prompted me to have a play with the compression option in ReaFIR - something I'd never thought of trying before. The idea of spectral compression seems very interesting but it is also easy to see how it could be misused (or maybe used creatively). While the effect was very interesting, I found it easy to end up with bubbling sounds or distortion if I pushed things too far. I get the impression that Sonible have implemented more sophisticated control compared to ReaFIR which would make their plug-in much more easy to use and more versatile.

[awjoe]

While the effect was very interesting, I found it easy to end up with bubbling sounds or distortion if I pushed things too far.

I'd like to hear an A/B of Smart.Comp when it's working well compared to a compressor plugin I have at my disposal. Reafir, for instance. Or Ozone, for instance. I know Ozone way better than Reaper. I think I have me a test. Now, let's see... do I really want another compressor?

[Dennis J Wilkins]

Hello again,

I have ReaFir which has been of good use at times, but as James noted, you can get some rather odd artifacts, bubbling or burbling with it. The spectral compression in smart:comp does not create such artifacts, and is very transparent. And spectral compression is an option - you can just use the compressor as a normal broadband device, with or without its smart function. Even as a basic compressor it is very flexible with comprehensive adjustments for attack and decay times/slopes (even hold times for each) and a frequency 'focus' control (separate from the spectral mode) that I've found excellent for focusing control on specific frequency bands. Definitely worth trying. And I think it's still on sale if you find you find it as useful as I do.

Have a great summer!

[Zukan]

Apart from its automated detection feature (which reminds of the Gullfoss eq) how is this any different to a dynamic equaliser?

I couldn't find anything in the specs about variable slopes. Most multiband compressors have fixed slopes but dynamic equalisers have variable slopes but this one doesn't mention anything about it which does seem a little odd. For me the slopes and crossovers are critical specially when it comes to mastering.

Finally, does this MB offer any expansion? FabFilter MBC can be used for expansion as well as compression and has variable slopes. So, apart from the automated detection feature what does this offer me above say FabFilter or a dedicated dynamic equaliser?

[Dennis J Wilkins]

Hello,

I think smart:comp's key contribution is the automation of compressor settings, and the spectral compression is a nice addition, and actually a very powerful one. I often use NOVA GE from those great Tokyo Dawn guys, and it offers multiple bands of dynamic EQ that can both compress and expand, and do so both in upwards and downwards modes. But the bands in NOVA (and I believe in Fab) are a fixed frequency (though with extreme 'slope' control).

Smart:comp, on the other hand, figures out the frequencies on the fly, both for internal and external side-chain control. It can follow an input frequency from an external side-chain, and then process only a small frequency range around the side-chain frequency. So it can react to a bass guitar track and only duck any frequency that occurs in the bass track, but apply the ducking to the controlled track. I don't know of another compressor or dynamic EQ that can do that, though I have rigged up REAPER's "infinite" routing and modulation functions in the past to accomplish a similar effect.

As for the variable slopes, I was referring to the detection circuit response, the slopes being related to to attack and release times (which also have a shape adjustment and hold times for each). The bandwidth of the spectral comp effect is "automatic", depending on the control signal - and it's not just one frequency (or a few selected frequencies) like a MBC, it's whatever frequencies are present in the control signal, subject to any focus or range you select with some auxiliary controls. Smart:comp is only a compressor, so no expansion, but I've found it plenty useful as is.

Free to try out, so no trouble if it's not want you want.

[Wonks]

Just want to point out that the TD Nova GE centre frequencies are fully adjustable (within the allowable setting limits). But although you get a lot of bands (for an EQ/dynamic EQ) you certainly won't get anywhere the number in a spectral compressor.

Once you get to a certain number of bands, it really becomes impossible to implement individual adjustable slopes and thresholds - especially when you are talking 2000+ bands.

Different tools for different jobs.

[Dennis J Wilkins]

Wonks » Wed Jul 10, 2019 8:51 pm
Just want to point out that the TD Nova GE centre frequencies are fully adjustable

Yes, adjustable to a fixed frequency (actually up to six different frequencies using all the bands) unlike smart:comp's bands that respond to the frequency of the control signal dynamically and automatically. But you cannot vary the width ('Q') of the smart:comp bands and they are a moderate 'Q' level, so you can't notch out a narrow band.

I've used NOVA GE for years (I was a beta tester for the new 2.0 version) and find it an excellent tool, which can do things smart:comp cannot (at the same time expand on one frequency band and compress another, provide very narrow peaks or dips, etc.), but smart:comp can do things NOVA cannot (automatically apply a useful set of compressor parameters, apply spectral compression, etc.).

And if you haven't tried Tokyo Dawn Labs Kotelnikov GE 1.5 compressor, you should. It brings some fascinating control possibilities with its frequency dependent ratio (FDR) control and it ability to combine peak and rms detection. Overall it's a very flexible compressor with different abilities from other compressors.

The problem today is not a lack of good tools, but the time to fully master them!

[Zukan]

I thin k it's best I demo it. Looks interesting though.

[Mike Senior]

Hmm. Not tried this yet, but already it looks like it doesn't have dedicated side-chain EQ controls, which would be one of the first things I'd want -- a bit like the facilities in Sound Theory Gullfoss or the Oeksound plug-ins.

The side-chain thing sounds like Wavesfactory's Trackspacer, and would indeed be useful. It also has the advantage over ReaFIR that the time constants are variable.

As an aside, though, I like the fact that ReaFIR can be so brutal in its processing -- great for reining in frequency peaks.

Thinking about it, I reckon Melda MSpectralDynamics might also be able to provide this kind of functionality, although I've not got round to trying that yet...

[ef37a]

Or, as I did a week ago, it is when you sit on your reading glasses.

Frames totally borked and they don't stock it anymore so I have to stump up for a new set of specs!

Dave.

[James Perrett]

As an aside, though, I like the fact that ReaFIR can be so brutal in its processing -- great for reining in frequency peaks.

I wonder if it would be good to have a magazine article on ReaFIR? I'd never explored the compression option at all before trying it after seeing this thread and it looks like it could offer some really interesting sounds. I wonder how many other people are aware of its power?

[Dennis J Wilkins]

by Mike Senior » Tue Jul 16, 2019 6:02 am

Hmm. Not tried this yet, but already it looks like it doesn't have dedicated side-chain EQ controls, which would be one of the first things I'd want.
_____________________________

Yes, the detection circuit, whether used on the direct input signal or using a sidechain input, has a feature called Focus that is a graphically controlled 'bandpass' filter with a low and a high 'handle' that can be set while observing an overlay of the detection signal spectrum, so you can see just what is being used for detection. There is also a 'switch' to listen to the detection signal after EQing it. Further, the spectral compression, if used, applies the focus band of the detection circuit to the controlled signal, rather than ducking the full frequency range. And the spectral compression system, another graphical control with a kind of spectral display of its own, has its own focus control to further adjust what/how is being compressed.

I's say its worth checking out, but give it some time since there are a lot of features that can interact in useful ways.

[Dennis J Wilkins]

Make that "I'd say its worth checking out, but give it some time since there are a lot of features that can interact in useful ways." One more amazing result of digital audio.