[sdiy] reverb - the catch?

[Eric Brombaugh]

JH. wrote:
> I just read the patent.
> 
> It's truly brilliant, but there is a catch:
> 
> As far as I understand it, you cannot do this with your standard Accutronics 
> tanks;
> you have to roll your own spring: something designed to pass ultrasonic 
> signals.
> 
> (If you can do this - and they even give the formula of the material, the 
> dimensions, and the temperature of the oven in the patent! - you'll have 
> something that probably is far better, and certainly a lot easier to achieve 
> than what I originally intended to do.)

True dat.

I spoke with him about this yesterday - he was pretty tickled that folks 
on the list were reading through his old work, done a few years before I 
was born. He mentioned winding the coil springs on a lathe using a 
threaded rod as a mandrel, annealing them, etc. He was using 
piezoelectric transducers - probably because the carrier frequency was 
too high to drive through normal voice-coil style transducers you see on 
audio frequency systems.

Eric