[sdiy] Re: About this LC filter formula questions

[John L Marshall]

Harry,

I was considering using ultasonic transducers. It seems that 8kHz of flat
bandpass could be obtained. Just hetrodyne up at the sending end and
hetrodyne down at the receiving end. There should be a lot less outside
acoustic interference (except for the bats). Quarter inch copper pipe in a
coil with sponge separators between turns could function as a waveguide.

Take care,
John
------------------------------------------------------------------
Pacific Northwest Synthesizer Meeting
August 9, 2003
www.sound-photo.com
------------------------------------------------------------------

----- Original Message ----- 
From: "harrybissell" <harrybissell at prodigy.net>
To: "Ken Stone" <sasami at hotkey.net.au>
Cc: "Glen" <mclilith at charter.net>; <synth-diy at dropmix.xs4all.nl>
Sent: Saturday, May 31, 2003 7:02 PM
Subject: Re: [sdiy] Re: About this LC filter formula questions


> The biggest problem is keeping the main audio path in the hose... not
through the
> walls of the hose. I had a lot of trouble with the coils of hose touching
each
> other...
> forming a sneak path.  It was big and it was sensitive to external noise
as well...
>
> not too practical.  Easy to see why the idea is abandoned.  My hose was
3/8" ID
> (garden hose)... I used a compression driver and a dynamic microphone
(electrets
> were not 'invented' yet :^)
>
> BTW I heartily recommend the BBD as a better DIY vehicle for delay,
compared with
> the coiled hose method...   H^)
>
> I was thinking of a 4" PVC sewer pipe buried the length of my property...
with a
> small
> electric train moving a microphone into various positions....   :^P
>
> H^) harry
>
> Ken Stone wrote:
>
> > There is a half built one in my workshop at the moment. For a workable
echo,
> > you need 20 metres of hose. I ahve 40, with multiple taps using
electrets
> > set in T-pieces. To top it off, there is also a set of reeds being
excited
> > by the same speaker, which should produce some interesting "resonant
responses"
> >
> > This method has been around for ages. Shcober Organs tried it before
> > settling on tape loops. The Time Cube is a commercial example, and
numerous
> > experimentors have built their own.
> >
> > Ken
> >
> > >
> > >Here's a freaky idea:
> > >
> > >Build a "tube echo" with a large length of flexible plastic pipe, which
has
> > >been rolled into a coil. Connect one end to a small box which contains
a
> > >speaker. At several points along the pipe, drill a small hole and
insert an
> > >electret microphone into the hole. Connect preamps (probably with some
EQ)
> > >to each microphone. Then use your scanning circuitry to sweep back and
> > >forth among the various microphone signals. In other words, do the
whole
> > >delay line with sound instead of an electrical transmission line
simulation.
> > >
> > >How's that for an unusual vibrato-chorus design?
> > >
> > >One thing's for certain, it's sure to have an "analog" character to it.
> > >
> > >
> > >later,
> > >Glen Berry
> > >
> > _______________________________________________________________________
> > Ken Stone   sasami at hotkey.net.au
> > Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
> > Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>
>