[Dixielandjazz] Re: Columbia's echo

David Palmquist davidpalmquist at dccnet.com
Thu Sep 25 21:16:48 PDT 2003

Thanks, Andy.  I think that must be exactly what I'm talking about.

At 07:32 25-09-03, Andy.Ling at Quantel.Com wrote:
>Dave Palmquist asks:-
> >
>Sometime in the late 1960's, a high school friend who was taking
>electronics showed me a gadget used to create reverberation.  It was
>mechanical rather than electronic,
>Is anyone familiar with this gadget, and if so, can they explain the
>technology?  It seems obvious to me that I haven't got a clue what I'm
>talking about.
> >
>I assume what you are talking about is a spring delay line.
>The way these work is to take the input signal and then using
>something like a small loudspeaker make one end of the spring
>vibrate. Then at the other end of the spring you have something
>like a microphone to pick up the vibrations and convert them back
>into a signal that can be mixed with the original.
>(NOTE for the techies out there I know it's not a speaker
>and microphone, but the analogy works to simplify things)
>The delay is determined by how long the vibrations take
>to travel down the spring, which, in part, is determined
>by how long the spring is.
>The reverb is achieved simply by mixing the original and
>delayed signals. The delayed signal acts just like an echo.
>The reason vibrations and springs are used is that vibrations
>take a lot longer to travel down a spring than the electrical
>signal takes to travel down a similar length of wire.
>Interesting effects could be achieved by hitting the box
>containing the spring and making it vibrate. This would
>add to the vibrations caused by the original signal.
>We used to have a PA with a spring delay line for the reverb
>and if someone kicked it it produced some very odd sounds.
>Andy Ling
>Dixielandjazz mailing list
>Dixielandjazz at ml.islandnet.com

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