an attempt at a simple co-opted high power ebow: will it work?

[jerisburningissue]

a brief background of the project:
a SINGLE string at high tension (92lbs) with a pickup
(more details at the end if you're curious)

the attempt:
rather than creating new circuitry, my thought was to split the output of the pickup already being used and route it to one of those small 9v powered mini guitar amps - remove the cone and perm. magnet from the speaker and place the voice coil close to the string and voila, high power, adjustable, already made.

concerns:
since voice coils are meant to push and pull against a polarized permanent magnet, when reacting with unpolarized steel, will it simply PULL and pull? and therefore oscillate at twice the input frequency? (i say oscillate loosely, it would be more like bumps with no smooth transition at 0V, just flipping everything below axis of a sin wave to positive ^^^^^^^)

questions:
is this true?
does it matter?
is there a simple fix or is it easier to start from scratch with the amp circuit rather than co-opt an existing one?

more project details explaining the need for high power:
the instrument is a single string that needs to be able to slide 3 octaves (C3-C6). the thinnest piano string (⌀0.075cm, ϱ7.85) at a scale of half wavelength would need to be at a tension of 92lbs (full wavelength would be 366lbs) which puts C6 at 16.39cm from the bridge, and therefore the output coil would be ideally placed at around 8.195cm from the bridge. given the high tension and close proximity the bridge, a conventional ebow's attack is too long for consistent sliding.  doing a 1/4 wavelength scale would bring it closer to guitar tensions but then both the ebow and pickup would need to fit in the 8.19cm between the bridge and C6, which is not possible.

[PRR]

Welcome.

oscillate at twice the input frequency?

Yes.

[jerisburningissue]

Thanks and thanks.
So I suppose a fix would be to put a diode or rectifier before the coil.
anyone have thoughts one which is better?

[amptramp]

Page 52 of the following magazine:

https://www.worldradiohistory.com/Archive-Radio-Electronics/60s/1968/Radio-Electronics-1968-05.pdf

has an article on vibrating wire filters and oscillators where a horseshoe magnet straddles a guitar string and causes vibration due to current running through the guitar string.  The magnet can be moved (a slider would be ideal) to where it can emphasize certain harmonics and null out others.  Their circuit design is rather touchy about gain but can be replaced by an op-amp based circuit with better gain control. 

[jerisburningissue]

wow - super cool! thanks!

[toneman]

Page 52 of the following magazine:

https://www.worldradiohistory.com/Archive-Radio-Electronics/60s/1968/Radio-Electronics-1968-05.pdf

has an article on vibrating wire filters and oscillators where a horseshoe magnet straddles a guitar string and causes vibration due to current running through the guitar string.  The magnet can be moved (a slider would be ideal) to where it can emphasize certain harmonics and null out others.  Their circuit design is rather touchy about gain but can be replaced by an op-amp based circuit with better gain control. 

Hey, there's also a good article about OPAMPS (Operational Amplifiers)!!!