Saturday, March 13th, 2010
A Worn Out Vose & Sons Baby Grand Piano and an Outdated Roland Keyboard Gets New Life
I’m excited about the latest project in progress at New Covenant these days… it concerns the making of a hybrid piano from a vintage 1930’s era Vose & Sons 5′-8″ baby grand that needed a new pin block and complete rebuilding.
A Yamaha CGP-1000 Want-a-be
The idea came to gut this old piano case and fit it with an electronic keyboard. I might have first got the idea from a Michael W. Smith concert. Michael sits at what first appears to be grand piano. If you look closer at one of his videos, he’s actually playing an electronic keyboard in a light duty grand case that’s sold commercially. I began taking out the worn key action of my personal acoustic baby grand and noticed the high quality, one piece, solid spruce soundboard. I remember back about 20 years ago, I visited the home of a piano builder and was astonished at a pair of home made speakers he had made. He had taken a couple of pieces of solid spruce with a medium quality speaker mounted on the soundboard to enable the soundboard to actually vibrate the sound into the room. These were very clean sounding and efficient speakers. I began to wonder if there wouldn’t be a way to use the Vose & Sons soundboard as it’s speaker system. This would seem to be a way to have a very natural sounding piano without the head aches of worn out wooden parts. There would be no scheduled instrument tuning… if only we could vibrate the sound board with a synthesized piano wave from a keyboard… with strings, hammers, and harp missing.
There are a couple of hybrid piano manufacturers at the time of this writing who are doing this very thing. Kiawa’s model CA91 uses a transducer driven soundboard “for creating the warm acoustic sound” and six speakers to support the characteristics of the other non-piano sounds. I began to research and found that there were patents that described the process of using a transducers mounted on soundboards. These are tactile transducers and are much like the magnet and coil of a speaker. Rather than being attached to a cone, these are mounted to a soundboard.
I started with some very inexpensive, plastic encased tactile transducers, rated at 10-20 watts each RMS (continous). I ordered 4 pairs, connected them to the sound board. Wired them in series and parallel to wind up with 8 ohms load and turned on the power. The low frequencies were missing. These particular transducer sets were designed for 5db roll off of lower frequencies with a capacitor wired in… but I knew I was on to something. It was good to hear and feel the vibration of the sound board… the sound was amazingly good.
Full Range Sound
Called the engineer with a leading manufacturer of tactile transducers and found that my application was not new. This engineer told me that he had put together a display using there transducers mounted to very inexpensive string instruments, such as violins, cello, etc. and had amazed a crowd using these devices as the speakers. I settled on a full range tactile transducer, connected it to the soundboard and was amazed with the realism. The bass was back… I had a full range piano sound that you could feel, coming from the inside of the piano case.
The old Roland RD300 electronic keyboard was upgraded to a key weighted Yamaha CP33. The fan noisy Crown amp borrowed from our church sound guy was upgraded to a quiet, 150 watt RMS home theater type stereo amp. I found that I really liked the stereo image from the CP33 so I kept the original plastic mount transducers to carry the right channel. The sustain pedal is operated from the original acoustic brass pedal mounted in the lyre which in turn operates a SPDT micro switch connected to the pedal action and electrically plugged into the keyboard.
The piano feels and sounds believable to me as a pianist. We often have folks come up on the platform after church and are somewhat amazed when told it’s not a real piano they have been listening to. That’s a great compliment.
If you are interested in more information on this project, contact me by email firstname.lastname@example.org. Thanks for reading.
Dwayne Crouse – April, 2010
Tags: homemade Yamaha CPG-1000