Electric valves (re digest 960103)
By Robbie Rhodes
Mike and David, thanks for correcting me about book music cardboard. One of our subscribers plans to check on available North American cardboard, just in case there is a new product which would be equivalent to the good German material.
The question of spring stability still bothers me, and I need input from an expert. I _do_ know that the front compression springs on my heavy Chevrolet sedan must be replaced every six years, when the front license plate scrapes the curb!
I haven't seen return springs in the horseshoe chest magnet valves, nor in the Concertola valve. Were different styles produced, perhaps for organ use?
The Stahnke electric valve only looks like a solenoid: the inner steel core is fixed. The only moving part is a tiny disk with a "long" compression spring to assure fast return.
You say that a typical MIDI-operated valve has a low duty-cycle. I disagree! The soft pedal channel, and the lowest intensity channels in a DuoArt, can remain "on" continuously for several minutes. The temperature of the valve assembly rises until it stabilizes at a much higher temperature, as limited (typically) by convection airflow. At high temperatures the coil current is reduced, which affects the turn-on time. This is not a _big_ problem, but it must be considered in system design. ALL these little problems must be considered, and weighed to decide which is the best overall valve design to purchase or construct. That's why I plan to test as many different designs as I can find, and I'll publish a report right here.
You stated "to date no one has been able to demonstrate that the Reisner valve has any perceived inadequacies." Well, the old horseshoe style valve is _noisy_ : it clicks, loudly enough to be annoying if it's not shrouded in a sound-muffling box.
On the other hand, I concede that different folks have different "perceived inadequacies". Few buyers of QRS and PlayRite music rolls notice the sloppy timing in the rolls which are carelessly copied -- and re-copied -- from old 1920s originals. Because of inconsistent and random response in the reader and perforator, the slots in the roll don't match the original. Chords which are supposed to strike "squarely" instead "ripple" across the keys. Maybe this inadequacy goes unperceived, but _I_ notice it, and I consider the degradation objectionable.
When I questioned the practice, John Malone (PlayRite) answered offhandedly, "Oh, that's all right, because we tell the customers it was hand-played!"
Baloney! If the chords in the original roll or disk file are "square", I want them reproduced that way. That will reassure me that the critical timing of the expression channels is correct, too.
-- Robbie Rhodes
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(Message sent Fri 5 Jan 1996, 17:01:38 GMT, from time zone GMT-0800.) |
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