MOTM

----- Original Message -----
From: <elhardt@...>
I was asking about vibrating a string mostly out of curiousity for other
things I had in mind. But what I would really want to do now is remove the
lowest sounding string on something like a violin and put a device on the
bridge in  its place that will vibrate the bridge which in turn puts the
whole violin body  into motion. I would probably just use a sawtooth wave
and would control the pitch from a synthesizer.

--LH--
The whole problem with this as I see it is the notion that the pitch could
be altered by changing the frequency of the device inducing the string to
vibrate.  The string has a natural frequency at which it will resonate
(along with many associated harmonics).  The only way to change that
frequency is to adjust the tension of the string or adjust the length (by
fretting).

Assuming that one used a variable frequency and was successful at getting a
string to vibrate, I  would think that only amplitude, and not frequency
would vary.  As the frequency of the modulating signal approached the
resonate frequency of the string, vibration would be at maximum amplitude.
As frequency increase or decreased from that point, the sting would simply
become less responsive to the inducing device.

That's how I see it.  And, I would think that only low frequencies could be
induced to begin with.  And, then, it seems an electro-mechanical induction
might produce the best response from the string.  So, metal would work (like
it does with the guitar e-bow thing).  But, I would think non-metallic
strings would be very resistance to significant induced vibration.  Perhaps
acoustically induced.  But, I am guessing the amplitude of the signal needed
to induce the string to vibrate would mask the actual sound of the vibrating
string.

However, I have seen all strings of a piano set into simultaneous vibration
by musicians mixing drinking and equipment moving.  As my memory serves me
(and it seems a bit cloudy on the event), I think each string vibrated at
its own tuned frequency.

Well, that's my $.02 on the subject.  I do know a "little bit" about low
frequency induction issues.  Say, around 60 Hz.
<snicker>

Larry (the power) Stooge