[sdiy] Midiverb reverse engineer project?

[Richie Burnett]

As far as I know it's all in the reverb algorithms.  Some of the later 
Midiverb used the general purpose micro (that handles MIDI and the UI) to 
poke new coefficient values into the DSP part on the fly to do modulation 
effects like flange and chorus, and also to add a bit of movement to break 
up the metallic ringing in long reverb tails.  Keith Barr has been quite 
open about the design and algorithms of the Midiverb in various online 
forums.

As I understand it, the FV-1 is Keith's result of distilling down the bare 
essentials of what makes a good reverb, and then designing a "DSP" chip 
optimised for this task.  For instance it has hardware sine/cosine LFO's, 
and can implement things like linear interpolation and allpass filters using 
just a pair of special instructions tailored to chorus/reverb generation.

-Richie,


-----Original Message----- 
From: Tom Wiltshire
Sent: Tuesday, October 18, 2016 2:02 PM
To: Mikko Helin
Cc: Synth-Diy
Subject: Re: [sdiy] Midiverb reverse engineer project?


On 18 Oct 2016, at 11:56, Mikko Helin <maohelin at gmail.com> wrote:

> You don't need to reverse engineer the hardware, the sound is in the
> algorithms I guess.

Is that right? Did any of the early units do anything special on the analog 
side? Compander or tone filters or anything? I don't know anything about the 
Alesis reverb units, and I never owned one.

Aside from that sort of pre/post processing, I agree - you should be able to 
take a recent basic DSP and recreate it exactly. Doing it on an FV-1 would 
be a nice touch, since Keith Barr designed that chip.

Tom


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