Welcome to A.B. Bonds ; Ampico B Design
By Robbie Rhodes
Welcome, A.B. Bonds, and thanks to "BamBam" Bill Jelen for telling the world about the Automatic-Music Digest.
Have you compared the Ampico A versus B control systems? Quite a difference. In my humble (?) opinion, the Ampico B and the earlier Welte system are the only reproducing piano systems that were really _engineered_, instead of just cobbled together by tinkerers. [Yas, yas, those are strong words. What do _you_ say, Robin Pratt?!!!]
Anyhow, I can tell you of my experiences with the spool drive motor. When I brought home my Weber Ampico B in 1957 my mother yelped, "You're wiping out the television at the neighbor's homes." Well, I wiped 'em out with my ham radio, too...
So I cured the interference in two steps:
1. I installed ceramic disk capacitors (0.01 microfarad, 600 volts) on the outside of the motor end-bell, connected from each brush holder to the frame.
2. I installed a "buffer capacitor" network across the tungsten governor points, in the fashion of the old vibrator chopper used in vacuum-tube auto radios. I think the capacitor was 0.05 ufd at 600 volts, with a 22-ohm series resistor.
After these modifications I could run the piano on the same branch electric circuit with our TV receiver, with only minor interference. Mom and the neighbors were much happier!
Regarding the Ampico B unit valve with the ball-check:
In the late 1950's Wayne Stahnke interviewed Dr. Clarence Hickman, the engineer who developed the system. When asked if he had ever tried the valve with 5 feet of tubing (as in the grand piano), Dr. Hickman replied that he hadn't thought of that, and changed the subject of conversion. ...!
The professional player techs in this group can advise you better than I about repair of the Ampico B valves. Do verify that the ball check is working. If not, you can remove the little check valve and clean it in an ultrasonic tank. (See your friendly local jeweler.)
My Ampico B piano is now under restoration with technician Randy Cox, and we have made a new _Ampico A_ valve set and primary valves for the piano. I decided, with reassurance from Randy and Wayne, that the slightly lower noise of the ball valve did not offset the poor performance at low intensities.
-- Robbie Rhodes
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(Message sent Thu 14 Dec 1995, 15:23:36 GMT, from time zone GMT-0800.) |
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