Fishman Aura DI

[pwnuts]

I've recently become more and more obsessed with this pedal, largely due to its ability to take piezo inputs and make them sound more natural, excellent in a stage setting. Looking so far I've found no schematics, sadly, and I've assumed that the effects were run simply by microcontrollers, but does anyone have an idea of how exactly this pedal works?
Thanks!

[GFR]

I guess it's something like this:

http://www.sidus.eng.br/vh/violaohibridoi.php

[overflow]

Definitely digital.  I'm only going off how I would approach the design... but my guess is captured impulse response of a large selection of acoustic guitars.  If you apply an impulse (quick high energy 'shot' of noise) and record the response that the instrument makes (in a  anechoic room, with some very nice microphones), you can convolve that signal with a more 'dead' signal coming off a piezo.  Because the computation is fairly complicated, it probably gets simplified and/or compressed into an easier to implement equation, then applied.  Really just a very specific kind of reverb and EQ.

It's fairly simple in theory, but difficult in practice...

I've tried to capture the impulse response of my cello using a measurement microphone and a digital noise signal called a 'maximum length sequence' once.  You then do some math on the recording to extract the response of the instrument.  Suffice to say, the result wasn't exactly ideal, but with some more work potentially usable...  The idea was to then use that response to create an equation to apply to an electric cello with no resonating body to make it sound a little more realistic.  Haven't touched that project in some time though.

This is the same stuff people use for convolution reverbs.  Sampling acoustic spaces, then applying them to recorded signals.

[potul]

I guess the process would be something similar to this:

http://www.diystompboxes.com/smfforum/index.php?topic=91062.0

Looks interesting.

[G. Hoffman]

I haven't tried one in a long time, but when they first came out everyone in my shop who tried one thought they sounded better in bypass.



Gabriel