Dynamics expander

[Matias]

Hi I was wondering, crazy idea. Is some kind of DSP for expanding dynamics? Not that heavily clipped material can be saved, but considering a good musical source, I am thinking of a DSP plugin that attenuates lower amplitude signals (say 90% of the amplitude band, from 0 to full scale) by an X amount of dB, and from up there a curve gradually leaves the full signal go through without attenuation at full scale. The idea is that this would compensate the typical loss of dynamics in the amplification chain (from source to amp to speakers)?

 

Or better yet if the system could be measured by the owner with a microphone (close miking) and create a custom "expansion curve" by system?

 

Too crazy idea?

[rayooo]

There have been I recall some various analog type dynamic range expanders over the years. I recall in one case there being a threshold setting were signals above had the gain turned up, signals below were reduced. The basic concept worked..but there were as many artifacts created as improvements made from what I could tell.

 

It does seem though with all the DSP capabilities these days, a digital file could be pre-processed with much better results than in the past. seems like a reasonable idea to me, who knows? maybe?

[firedog]

There are some tools for digital sweetening, I think I saw it discussed over at the What's Best forum a long time ago.

 

The Paul McCartney album "Memory Almost Full" is volume compressed to the point of being unlistenable IMO. I'm a McCartney fan, so poking around the Net one day I found an illegal download of it with what was called "reverse volume compression".

 

It sounds much better than the original, and is actually the version I listen to now - not the original. I don't know what the guy who made it did to it, but I think it was a form of what is called "expanding". This doesn't reverse the VC (I don't think anything can) but it softens the most annoying aspects of it.

 

If anyone actually knows something about this topic, pleas chime in.

[dc2bluelight]

Hi I was wondering, crazy idea. Is some kind of DSP for expanding dynamics? Not that heavily clipped material can be saved, but considering a good musical source, I am thinking of a DSP plugin that attenuates lower amplitude signals (say 90% of the amplitude band, from 0 to full scale) by an X amount of dB, and from up there a curve gradually leaves the full signal go through without attenuation at full scale. The idea is that this would compensate the typical loss of dynamics in the amplification chain (from source to amp to speakers)?

 

Or better yet if the system could be measured by the owner with a microphone (close miking) and create a custom "expansion curve" by system?

 

Too crazy idea?

 

Ditto to others, there have been many analog attempts over the years. But you have to understand the problem they were trying to address. It's an attempt at un-doing the dynamics processing applied in the recording/mastering process, and/or dynamic noise reduction. The best ones employed multiple bands of processing, which provided more expansion with less artifact. In fact, a single wide band expander is pretty useless. In the pro audio world, Dolby made a device that utilized their standard Cat.22 Dolby "A" type noise reduction cards, designed to normally function in an encode/decode noise reduction system, as a four band dynamic expander to be used as a single-ended noise reduction tool. Worked pretty well too.

 

Dynamics expanders all suffer from the same issue. They are trying to un-do dynamic compression without actually knowing what exactly was done that has to be un-done. There were and are no standards, and in any multitrack production, one track may be highly compressed while another pretty much goes barefoot. Once mixed, you simply can't deal with them separately ever again. Expanders, at best, worked only when tweaked manually, and only on certain songs or pieces of songs.

 

Just doing it with a DSP doesn't solve any of that.

 

One problem with your question, though, "The idea is that this would compensate the typical loss of dynamics in the amplification chain (from source to amp to speakers)?" Um...that's not where loss of dynamics occurs. If an amplifier changes something enough to produce a change in dynamics, it is producing horrendous levels of distortion. Not a very popular thing to do, so they don't.

[HIFI]

I still have a DBX 3BX Dynamic Range Expander from the early eighties that I use with rock music vinyl only when I am in my 1980 moods. For what ever reason it hurts the sound performance of my cd versions of Clash, Ramones, UKSubs, Tom Petty . . . I assume these same recordings are so deeply compressed on red book cd there is not enough dynamic range difference to do any real processing.

 

Please don't hate me for owning and operating a 3BX. There is a place/time for dynamic range processing.

[dc2bluelight]

What? No Phase Linear 4000? Auto-Correlator? Peak Unlimiter? Hmm?

 

Actually, the 3bx was one of the good ones.

 

All you need now is a subharmonic synthesizer, and you are ready to rumble.

[Matias]

Thanks for the replies!

[dpstjp2]

Not quite what you're looking for, but the Meridian 518 does allow some interesting manipulation and resolution enhancement of audio.

[Matias]

Does anybody know if B&M use this concept in their speaker's DSP?

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