How do I build an electro magnet strong enough to vibrate piano strings?

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SUMMARY

This discussion focuses on building an electro magnet capable of vibrating piano strings without striking them, similar to the function of an E-bow for guitars. The conversation highlights the potential use of a loudspeaker or tactile transducer mounted to the piano's soundboard to achieve this effect. It references existing technologies, such as the "sustainer" used in guitars, and suggests that a tactile transducer could effectively excite piano strings. The discussion emphasizes the importance of utilizing established technologies rather than reinventing them.

PREREQUISITES
  • Understanding of electro magnets and their applications in musical instruments.
  • Familiarity with loudspeakers and their vibration principles.
  • Knowledge of tactile transducers and their use in sound production.
  • Basic concepts of sound vibration and resonance in musical contexts.
NEXT STEPS
  • Research the construction and operation of Hammond organs for insights on string excitation.
  • Explore the design and functionality of tactile transducers for musical applications.
  • Investigate existing patents related to devices that excite piano strings.
  • Learn about the "sustainer" circuit technology used in electric guitars.
USEFUL FOR

Musicians, instrument builders, and audio engineers interested in innovative ways to sustain piano sounds and enhance musical performance through technology.

no.juan
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I would like to build an electro magnet capable of causing piano strings to vibrate without the strings being struck first. As long as the hammers are up, the strings would vibrate on their own accord.
An E-bow, used by guitarist for the same purpose, will (sort of) work on a limited range on the piano - but on only one note at a time. I would like to build something that can be hung inside the piano, close to the strings, that covers a wide range of notes. Hopefully I would be able to silently depress the keys, lifting hammers on those keys only, and thus creating an infinitely sustained piano sound, but without the attack the hammer gives. Thanks!
 
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A normal loudspeaker will do this, especially if 'hard mounted' to the piano frame.
 
Hi - thanks for writing. Please excuse my ignorance, as I know nothing of physics. Would a speaker create this effect w/o producing any noise itself? Is there something inherent about a loud speaker that, if attached to the bottom of the piano sound board, would cause the strings to vibrate enough to produce sound themselves?
 
Sound is vibration. The speaker will vibrate, pushing a column of air that will also vibrate. Connecting it to the sound board will just force the strings to vibrate too.
 
@OP: have you studied the construction of Hammond organs? There is no sense in re-inventing the wheel when there is very old and well-tested technology that can already do what you want.
 
I made this in 1981, showed it to Fernandes and tom sholz, and was told it had zero marketability.

A few years later, fernandes comes out with "the sustainer'.

30 years later, many big name guitarists have at least one "sustaining axe" in their collection.

I came up with this one day when I pushed down the tremolo bar (way down) on a kramer beretta guitar in a room lit by only one flourescent light and saw the string and speaker cone vibrating in synch. while wondering how I can get feel of standing in front of a cranked 4x12 cabinet while using a headphone amp.

Maniac music makes a sustainiac like the sustainer but they have an older model that is a tactile transducer that mounted to the headstock of the guitar.

I believe a tactile transducer attached to the soundboard of a piano could get you what you want to excite the strings but I'm not sure a mic. would be best for being the source of the signal you send to the transducer.
 
There are many patents of devices that excite piano strings to vibrate but none that will cause feedback the way a "sustainer" circuit can.
 

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