Multiband Compressor Idea

[JohnRoberts]

Hi,

For multi-timing parallel sidechain inspiration, might be worth reading thru the white paper about the Safe Sound Audio - Dynamics Toolbox. Clever design: single band compressor with three different side chains, interlinked (see attach).

I didn't read the white paper but that is how de-essers pretty much have always worked. Separate side-chain that bangs the same one full range VCA (likewise for hard limiter and downward expansion all controlling the same one VCA).

About the bandsplitting: How about using a subtractive VCA approach, where the main path is full range unfiltered, and the band-splitted blocks are mixed in out-of-polarity when they are used? This means, no processing in one band = no unwanted artefacts in that band. Of course the gain law is unconventional using subtractive technology, but I believe in mastering applications the amount of needed gain reduction would be rather modest...

I used that (subtractive***) topology back in the 80's for a SENR (single ended noise reduction). An additional important benefit of that topology is unfettered transient response. Classic HF NR systems struggle to open up quickly enough to cleanly pass HF transients. Also the "straight wire" dry path is lowest possible noise and distortion, a feature for a high performance NR.

JR

**** This century I proposed to a friend (now RIP) to use the subtractive VCA for a gain control path with superior 0dB (unity gain) performance. It worked as promised and he may have used it in a product for some modest limiter gain reduction. Not practical for full range gain control.

I believe we have not yet seen this implemented in a DIY design, would be a nice educative discussion

PS about the (derivative) crossover for the band splitting, there is lots of info in Douglas Self's 'The design of active crossovers'. Most interesting reading!

Best Rogy

 

[RuudNL]

I was just thinking about the Behringer Combinator (MDX8000).
It was a 4-band compressor.
As far as I know it has never been a success.
(I have modified a couple of them, and they had some serious problems in the design.)

https://www.youtube.com/watch?v=DmyFnFQMD7U

By the way: I have the full schematics of the MDX8000... 

 

[Gold]

I was just thinking about the Behringer Combinator (MDX8000).
It was a 4-band compressor.
As far as I know it has never been a success.
(I have modified a couple of them, and they had some serious problems in the design.)

https://www.youtube.com/watch?v=DmyFnFQMD7U

By the way: I have the full schematics of the MDX8000... 

I can't tell what it's doing by looking at it. I'm not surprised is was not popular. I can't find the manual but it doesn't look like it has repeatable settings or the ability to know how a band is set.  Most multi band compressors sound terrible anyway. I can count the good sounding ones I've tried on one hand. Hardware and software. The design looks terrible from an ergonomic standpoint unless I'm not getting the functionality from looking at it. It doesn't inspire confidence in the sound of the uint.

 

[JohnRoberts]

I can't tell what it's doing by looking at it. I'm not surprised is was not popular. I can't find the manual but it doesn't look like it has repeatable settings or the ability to know how a band is set.  Most multi band compressors sound terrible anyway. I can count the good sounding ones I've tried on one hand. Hardware and software. The design looks terrible from an ergonomic standpoint unless I'm not getting the functionality from looking at it. It doesn't inspire confidence in the sound of the uint.

Maybe figure out whose unit they copied.... 

JR

 

[Rogy]

Hmmm... Both the colour scheme and the buttons look a lot like the Aphex Dominator...

 

[Gold]

Maybe figure out whose unit they copied.... 

They usually copy things that sell. I have a feeling this was an original design by someone(s) who has no experience as an operator of such a device.

 

[alexc]

With respect to multiband processing ...  Im' a 'Finalizer'  guy 

I have a couple  .. I use them daily forever now ... 

They're unique and good  and one can get quite good at operating them, in detail. One can get a little over the top too, no doubt.

I'm fairly basic in my usage,  but they're a lot of value in 1RU  Especially when you need a few of them.

mbGate is the best gate I've used. Especially for 'hum' management with tube gear. Hands down best.

mb Comp/Limiter is very interesting. Again, some time at the controls is important.

I'm quite simple, but 'my friend' who did the 'small studio' thing for a living was quite flash with it.

If I had the cash, it would be tubetech for sure!  But that's very high end, so yep.

One could try it with some 'discrete' rack units ... a couple of crossovers and even more vca compressor units  ..  plus a mixer!

...

I can do something like that with my old yam 03digital desk and some external crossovers  ..  but mostly didn't.

The Finalizer has to be somewhere in the 'multiband' figuring ...

 

[Gold]

The Finalizer has to be somewhere in the 'multiband' figuring ...

The first multiband I used was MD2 in an M5000. That’s where I learned to like them. Mostly because it was all I had.  I know an ME who uses one.

 

[fazer]

I have a composer friend that sprung for tube tech multi bands for his 5.1 music delivery Stem mixing.  I would love to play with a pair.  Some serious coin was spent on those.  He loves them.  He also has great ears IMO.  Audio Designed Recording used the multi sidechain detectors but don’t remember a multiband.   

I’ve never been happy with plug in multibands across a mix.  I like them best on instrument tracks.  (But that is with the ones I’ve tried).  It seems like trying to get peak and rms detection on the same multiband VCA,Vari Mu, is bound to have sonic penalties.  It might be best to solve in two separate pieces. 

Al Schmitt uses Tube Tech multibands across the mix.  That’s good enough for me.

 

[Gold]

It seems like trying to get peak and rms detection on the same multiband VCA,Vari Mu, is bound to have sonic penalties. 

The GML does it as well as others. If you turn the knobs the wrong way it's bound to sound bad. I don't see any inherent problems with the concept, but I'm not doing the circuit design.

 

[gyraf]

I'm sorry if I misunderstand or is slow at understanding, but what/where is the new idea?

Not to criticize this thread or your intentions, but it looks to me more like a wish-list of features that are already existing, without dealing with the "hard" questions or generating not-yet-existing.

Don't get me wrong - I like wishlists - but I can't seem to extract where the new idea hides in all this..

Jakob E.

 

[Gold]

I'm sorry if I misunderstand or is slow at understanding, but what/where is the new idea?

Not to criticize this thread or your intentions, but it looks to me more like a wish-list of features that are already existing, without dealing with the "hard" questions or generating not-yet-existing.

Don't get me wrong - I like wishlists - but I can't seem to extract where the new idea hides in all this..

Jakob E.

I guess it depends on what you mean by new. Most of audio is rearranging the puzzle pieces.  There is nothing new  on a circuit design level. That’s on purpose. I want to see this built and I want it to be relatively straightforward to design. It can be done from the THAT app notes. The new part is the choice and arrangement of controls. It will produce results not possible with current offerings.

 

[JohnRoberts]

I guess it depends on what you mean by new. Most of audio is rearranging the puzzle pieces.  There is nothing new  on a circuit design level. That’s on purpose. I want to see this built and I want it to be relatively straightforward to design. It can be done from the THAT app notes. The new part is the choice and arrangement of controls. It will produce results not possible with current offerings.

I didn't get 9 patents rearranging puzzle pieces...  : (Actually invention is kind of rearranging known means, to realize a novel and useful result.)

This (dynamics processing) is a fairly well worked over area of interest... The beauty of DIY is you only have to please yourself, not sell a full production run, so go for it.

JR

 

[Gold]

I didn't get 9 patents rearranging puzzle pieces...  : (Actually invention is kind of rearranging known means, to realize a novel and useful result.)

This (dynamics processing) is a fairly well worked over area of interest... The beauty of DIY is you only have to please yourself, not sell a full production run, so go for it.

Using your definition of invention I think this qualifies. It will realize a novel and useful result using known means. A better mousetrap is still a mousetrap. This is not DIY. This will only happen with a production run. They will sell.

 

[gyraf]

but, if I may continue, what is the essence of  the new thing - can you describe what you expect to find, as a result of what  controllability?

Is it the dual/individual timing on peak/rms you expect qualitatively new results from? remember that the significant "sound" of rms-detection is caused by the inherent log-domain timing: should be reachable through current-controlled timings (like e.g. NTP)

again, not trying to dis your idea, I just don't get it...?

 

[Gold]

Is it the dual/individual timing on peak/rms you expect qualitatively new results from?

Yes. Lets take the Finalizer as an example. It has a three band compressor with a limiter in each section. On the face it may seem similar to what I have proposed but it differs significantly form an operational standpoint. First the thresholds are tied together in that there is only a ceiling threshold adjustment for the limiter. Second there is no ratio choice for the limiter.

Now lets take a case where you want to control a snare drum transient and even out a vocal in a mid band. With the Finalizer since the limiter is stuck at a 10:1 ratio it's going to stomp all over the mix by the time you get the threshold set for the compressor to catch the vocal. With my arrangement you could use a lower ratio and lower threshold on the  peak detector to grab the snare and tune the compressor to catch the vocal without adversely affecting the setting for the snare.

Lets take a low end example. Lets say there is a big floppy bass with a bass drum that has a large transient. Its the same kind of thing as above. You are able to tune the compressor to grab the bass and the peak detector to grab the bass drum.

The other thing that I like about this design is the simplicity of controls. Each section is almost like a one knob squeezer. So even though it has a lot of knobs there aren't many knobs to turn in each section.

 

[JohnRoberts]

Using your definition of invention I think this qualifies. It will realize a novel and useful result using known means. A better mousetrap is still a mousetrap. This is not DIY. This will only happen with a production run. They will sell.

I have been wrong enough times to not trust my judgement about how well a brand new product will sell...  Good luck. 

I had to run 250 at a pop of my drum tuner to get effective production pricing on circuit board assembly.

JR

PS: One of my tasks working in product management was projecting sales for production scheduling. Even seeing a long term sales history it was hard to get it right every month.  One time I had a serious advertising campaign scheduled so upped my sales projection for the few SKUs I expected to get a bump from the ads... (Peavey rarely ever advertised individual products with any frequency, so this time was different.) The puke actually managing the factory schedule ignored my advice (I guess he had heard overly optimistic forecasts before from enthusiastic product managers). Of course I remained in chronic backorder on those SKUs and was constantly getting beat up by the dealers and reps when they couldn't get enough product to meet demand (arghhh).  It became academic later when a new marketing empty suit gutted my successful ad campaign....that ad campaign could have been even more successful if we built enough inventory to satisfy demand.   (you can lead a horse to water but can't make them drink).

 

[Gold]

I have been wrong enough times to not trust my judgement about how well a brand new product will sell...  Good luck. 

This is something I would use and is meant for mastering engineers. I know the potential customers and the market. That's why I'm confident it will sell handfuls of units a year. Year after year. This isn't mass market. I have no idea how most products will sell.

 

[alexc]

take the Finalizer as an example. It has a three band compressor with a limiter in each section. First the thresholds are tied together in that there is only a ceiling threshold adjustment for the limiter. Second there is no ratio choice for the limiter.

I don't think that's accurate - I use a Finalizer Plus hardware unit and the 'compressor' section with 3 bands definitely has thresholds, ratios and levels for each band, as well as selection of the two break frequencies for defining the 3 band-widths.

..

However, this is interesting 

 

[Gold]

I don't think that's accurate - I use a Finalizer Plus hardware unit and the 'compressor' section with 3 bands definitely has thresholds, ratios and levels for each band, as well as selection of the two break frequencies for defining the 3 band-widths.

Yes that's correct. The compressor sections also have attack and release. The limiter in each section doesn't. You can only set the ceiling (threshold) on the limiter. I don't remember being able to change the ratio of the limiter. If you try to set the limiter ceiling low enough to act like a peak detecting compressor the compressor section will be working overtime.