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Topic: Adding a Transducer to a piano's Soundboard

Does anyone here have experience adding a transducer (or several) to a piano's soundboard?  It seems like this might be the purest way to have Pianoteq working in a "Player" capacity, similar to that of a Yamaha TransAcoustic or a Kawai hybrid.  I am contemplating such a project.

Here are some 'teaser videos':

https://www.youtube.com/watch?v=NTfl7o5xbyI   - an audio speaker made of spruce, as a type of alternative musical speaker

https://www.youtube.com/watch?v=TXmY9Oi2DXA   - David Pogue's review of the Yamaha U1 TransAcoustic

https://www.parts-express.com/resources … e-exciters  -  A parts company's page with videos on using transducers/exciters

http://www.denismusique.com/en/yamaha-u … lent-ta-pe  An interesting page showing how Yamaha doesn't stick stick transducers on the soundboard (as I was considering doing... hmm..?)

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Re: Adding a Transducer to a piano's Soundboard

Cool.  With cream on top.

The spruce speakers are interesting (and would also probably get me evicted, alas - somehow I think all that resonance would go down badly with everyone else !).

I'm not sure if Pianoteq sound models actually would work on this idea.  Wouldn't they need an actual transducer model in the sound system (instead of mics) to get the required output ?  Which incidentally might be an interesting idea for the next version.

OK, given the choice of spruce speaker or hybrid piano I'm going to vote for ... that woman's voice.  I could listen to that for hours and not notice a single word or much else.  :-)

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Re: Adding a Transducer to a piano's Soundboard

Cool, I'm glad you posted!

I've been experimenting with a set of transducers. I'm a complete neophyte, so I've been learning from scratch. My first impulse was to use an actual piano soundboard but I'm realizing that a soundboard for a digital pianos should have a different design.


WEIGHT
We can use a very light/thin soundboards, like the ones we see on violins, guitars, drum heads and flat panel speakers. We don't need to support the weight of a piano frame and strings.


MATERIALS
The main principle seems to be a high strength-to-weight ratio - as light as possible and as strong as possible. High-quality tonewood is the traditional material , but I've gotten decent results with 3x3 aluminum sheets, foam board panels, drum heads, guitars and cajons.

Someone pointed out to me that 'wood is also carbon fiber', which I thought was funny. So I'm curious to see if a DIY carbon fiber board will work.

In high-quality tonewood, the fiber is lined up in parallel and also tightly packed together. The problem with most commercially available carbon fiber plate is that the fiber is woven together at 90 degree angles, but I think laying carbon fibers more like the grain of high-quality tonewood will work. My summer project will be to turn some unidirectional carbon fiber into a soundboard. A side note, Phoenix Piano carbon fiber soundboards also use unidirectional fiber carbon as opposed to woven carbon fiber.


SHAPE
The shape of traditional soundboards seems to be mostly functional with only a small nod to acoustics. For example, piano soundboards get their shape mostly from the piano frame while guitar & violin soundboards are shaped to be easy to hold.

But I was stumped for figuring out a shape because I know nothing about soundboard design. I decided a plain old circle would work the best (see videos below). You can see that the sound waves on a circular plate sound waves are clear and closer to traditional speaker design. I figure a 4-foot circle to start to get decent treble/bass response and if it works, build a 6-foot one. (there's also a question -  orient horizontally like a grand piano or vertically like an upright).



Circular Chladni plate
https://www.youtube.com/watch?v=CGiiSlMFFlI

Rectangular Chladni plate
https://www.youtube.com/watch?v=1yaqUI4b974

Last edited by Groove On (16-04-2018 09:24)

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Re: Adding a Transducer to a piano's Soundboard

Very interesting, especially about the theoretical driver design.  Circular is likely the most elegant, and most speaker manufacturers do this.  I wonder if Magnepans and Quad ESLs and other planar manufacturers have difficulties at the corners with materials and edge attachment. 

I will follow your progress with the creation of the best driver, while I am most interested in learning how to best drive the 'speaker' that I have - mainly my upright piano's soundboard.

What can you add about driver size, power demands, attachments, etc.?

- David