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A Worn Out Vose & Sons Baby Grand Piano and an Outdated Roland Keyboard Gets New Life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
Michael W. Smith in concert
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.
The Technology
Sound board with inexpensive transducers mounted along bridge
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.
1985 Roland RD300 cut down to fit
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.
Upgrades
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 admin@www.ncftitusville.org. Thanks for reading.
Dwayne Crouse – April, 2010
Tags: homemade Yamaha CPG-1000