In a message dated 12/30/2000 9:40:15 AM,
hugo.haesaert@... writes:
>Check out :
>
>http://www.windworld.com/emi/
>
>Experimental Musical Instruments homepage .
Hi Hugo,
Great to hear from you again! This is absolutely perfect -- they even sell
those oddball PUs I was thinking about! I should say "great minds think
alike" -- not mine, however. Mr. "Beetlebaum" had suggested I look at the
Bart Hopkin book "Musical Instrument Design." Hopkin was the guy behind EMI
Quarterly and the EMI website. I actually had a copy of this book on my
bookshelf (I got it from Paul recently in one of his auctions). I've spent a
brief time looking at it since yesterday, and can highly recommend it for
anyone with even a passing interest in these types of issues. It even has a
short chapter devoted to resonators and radiators, as well as a short
appendix devoted to amplification using different types of PUs.
Anyway, in the chapter "Chordophones" there is a section on Electromagnetism
as a way to get strings vibrating. Specifically:
"You can reverse the process [of using a PU to generate an AC electrical
current from a moving string] by sending a heavily amplified alternating
current pattern to a pickup, speaker driver, or other device which will serve
as an electromagnet. When the electromagnet is held close to a steel string,
it will drive the string. If the frequency of the signal sent to the
electromagnet doesn't approximate any of the string's natural frequencies,
the string doesn't respond much, but if there is a match, the string shows a
generous resonance response, with gradually increasing amplitude."
It goes on to mention that using this technique for each string of the piano
was how Stephen Scott and Alex Stahl did their "bowed piano" recordings in
the 80s (I really liked these, BTW). Hopkin also says:
"Another [way] is to use a pickup in the conventional manner to pick up a
string's frequency, and send it to an amplifier, and then back to another
electromagnet held near the string, to perpetuate the sound. This is the idea
behind the electric guitarist's sustain-enhancing device called the E--Bow."
Sorry for the length of this thread to those not interested in these ideas,
but I can tell at least a few people are as interested as I am (if not more
so).
JB