There are few innovations in acoustic guitar that seem to come out of nowhere and are things that you never would have thought of. And actually deliver what they set out to do. The Yamaha TransAcoustic Guitar is a prime example of such an innovation.
If someone told you that they could get reverb and chorus sounds out of an acoustic guitar without using any external electronic effects, you would not believe it. But the engineers at Yamaha have done this by really thinking outside the box– by treating the acoustic guitar body as a loudspeaker. There’s already an acoustic amp present — it’s the guitar itself. To create the extra sound effects, the TransAcoustic senses the acoustic signal using a conventional piezo system connected to the top and sends it to an electronic circuit inside the guitar which drives an actuator connected to the guitar back. The effects electronics are similar to the effects boxes we all know and love from the THR series (which most likely some added DSP processing to account for the natural acoustic amplification rather than a conventional speaker). The key innovation is using the actual guitar body as the amplifier by having the actuator drive the guitar back.
The top on any guitar is the soundboard of the instrument which is what vibrates and creates the sound. The Yamaha engineers recognized that you can use this soundboard as one large loudspeaker, and have used this technique in the TransAcoustic Piano technology.
For the TransAcoustic guitar, it’s been stated that the electronics are from the THR amps division, and the TransAcoustic technology is from their piano division. However, the guitar is unlike a piano in that it has an enclosed space with both top and back. Attaching an actuator to the top might dampen the natural vibrations due to the weight and size. This would have an adverse effect on the natural guitar sound. But since you only want to enhance the signal as a background voice (like chorus and reverb), the logical choice would be to drive the back instead. This is exactly what the TransAcoustic guitar does. It does use two 1.5V batteries to drive the electronics and actuator, but this is a small price to pay for getting luxurious chorus and reverb sounds in an acoustic guitar with no amplifier!
This is brilliant for those that want the great and natural sound of an acoustic, supplemented with chorus and reverb effects — but without using an amp, or the coloration of the amp. It’s the natural guitar sound through the soundhole.
This is an amazing example of innovative thinking using technology to achieve unparalleled results which are both desirable and usable.
Check out some videos on the Yamaha TransAcoustic: