[sdiy] Reverb opinions, please

[phillip m gallo]

I also built an acoustic delay using PVC tubing, i was spurred on by an
article in Audio Amateur about an DIY "time cube".   The Audio Amateur
design used an old magnetic ear piece of the type used with the old
transistor radios. 

Instead of that form of driver, i used an old ElectroVoice compression
driver which have two 3/4"  apertures, one in "front" and one in "back"
(and thus 180deg out of phase).   I put a long length of 3/4" PVC tubing
on one end, and a shorter tube on the other (forget the length but they
where cut assuming the velocity of sound at sea level).   I then used
electret mic's for recovery.   Since i was using a compression or "horn"
driver i attenuated the low end so that even at the low power levels
required i wouldn't pop the diaphragm.  

As noted if you coil the tubing you get mechanical coupling which often
could be exploited to good effect.  The coils didn't need to be
separated by much distance to attenuate what seemed to be mechanical vs.
acoustic coupling.    I made a makeshift box to filled with fiberglass
which fixed the coiled tube in isolation.   Delays where precious back
then so it found quite a bit of use.   Even used it in a live PA
situation but utility was limited by the feedback that resulted from the
very loud "hard rock" PA.

Tore it down to make a "poor mans" vocoder (talk box) and still have the
tubing and compression driver in the garage.

regards,
p


-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl] On Behalf Of harrybissell
Sent: Friday, May 21, 2004 9:18 AM
To: Dave Magnuson
Cc: TIm Daugard; synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] Reverb opinions, please


Congrats... you just invented the Cooper "Time Cube" (iirc)... ;^P

I tried a garden hose... the worst part is that if you coil the hose,
and the loops touch each other... the mechanical conduction of the sound
can 'short
circuit' the airborne sound... mine did !   I'd go with a straight tube
if
possible...

H^) harry

Dave Magnuson wrote:

> At 08:12 AM 5/21/04 -0500, TIm Daugard wrote:
>
> >Also in my parts pile is 40 ft of PVC pipe, a speaker and a few
> microphones. I'm
> >going to try an acoustic delay line, when I get around to it. Theory 
> >says
> that
> >maybe the bass will be attenuated less than the treble.
>
> As a kid, I remember yelling down the hose for the pool vacuum.  It 
> was about 1-1/2" diameter and 50+ feet long, with a ribbed or 
> corrugated texture to it.  Sounded really cool, and I imagine it would

> make a great acoustic effect.
>
> I can picture placing the coil of tube in a sealed wooden box with XLR

> mic and 1/4" speaker connection.  There would obviously be some bleed 
> of the "dry" signal if the mic and speaker were close together... but 
> I hardly ever use my delays at 100% wet signal anyways.  Plus if you 
> cranked up the driver volume (or the mic gain) you could push it into 
> feedback.
>
> Dave (Wonder if dad would notice if I stole his pool hose) Magnuson
>
> Resonant Frequency:
> resfreq at hoohahrecords.com 
> http://www.hoohahrecords.com/resfreq/index.html