Amica Ampico Article Review, Part 4
By Craig Brougher
Amica Ampico Article: Fourth installment commenting on technical errors.
So far, we have quoted Jeffrey Morgan to show that :
1. He was unaware that the Ampico B system compensated for stack
transients.
2. He didn't really understand the purpose of the stack equalizer
pneumatics.
3. He felt that a particularly overcomplicated, "cumbersome and slow" (his
words) design was extremely ingenious.
4. He thought that the first intensity set point of the Crescendo
pneumatic was somehow fed back to it from the stack.
5. He totally mischaracterizes the purpose and use of crescendos and
believes that since the Model A crescendos are independent of the
intensities while the Model B amplifies the intensities and is
therefore "dependent on the intensities" that proves the Model B is
incompatible with Model A rolls.
6. He believes that binary coding on the roll controls the crescendos
I might add one clarification to his first point--"the Model B crescendo system does not initiate corrective action for stack transients as do most earlier Ampico crescendo systems."
I take that to mean the expression system as a whole, and not the crescendo system only. Because in neither piano does the crescendo have to take corrective action for stack transients at all. That is why each piano's crescendo is powered directly by the pump.
And if he is referring to the action of the amplifier through the Model A crescendo, then he has a double problem, because he is either admitting that when the Modify Switch is set to Normal or Medium, (both are the same) and the amplifier switched out of the circuit, by his own criteria, it becomes a direct-to the-pump-spill crescendo, just like the Model B. So either way, it is wrong. And if he believes that the crescendo is required to also correct for stack transients, he would be inventing another system altogether which would not even play on an Ampico. So even supposing that he meant the expression regulation system when he said "crescendo system" is giving him the benefit of the doubt. Otherwise, he would be wrong about both the Model A and B.
Now to the next points: (can you believe this?)
7. "The Model B crescendo does not operate in the same four modes as
previously described... though at faster speeds. It also employs the
same binary language using two trackerbar ports." p 71, para 4.
ANS: We have already covered the fallacy of thinking that this is a binary code-controlled device. We have explained that the Ampico Crescendo is actually an analog ramping device, not a binary controller. See Inspector's Instruction Book, 1919, pp 4-6.
The fact that the B Crescendo moves at twice the speed of the Model A is calculated, since the precondition given Dr. Hickman was that the new piano had to be fully compatible with the 1921-22 standard dictating roll coding format. Any extra capability could not compromise its ability to play at least as well, and usually better, the older Model A rolls. It succeeds wonderfully. Any Model B that does not meet this test is either not set up right, or has deficiencies in its restoration -- usually valves and ball bleeds.
The reason that the Model B crescendo collapses twice as fast as the Model A is because its effect by percentage of its closure is only half as much! Now does it make sense? And you know, this isn't an opinion. It is provable. I have measured it and know what I'm talking about. Granted, there is an exponential function involved, so it isn't a perfectly linear relationship, but more than adequate. It fully approximates the Model A, if that was ever the criteria anyway.
Knowing Dr. Hickman, he was thorough and had a very mathematical mind. He would have simply calculated it from the ideal roll coding technique, whereas Charles Stoddard was a seat-of-the-pants inventor. He would not have calculated anything, probably. He would have built a testing apparatus to test the response and get what he wanted that way.
The purpose of telling us that the Model B does not do the same things a Model A does is to cast aspersions on its design and to call it incompatible. This is not true. The criteria was not to analogize the Model A, but to build a better player which would be designed around the roll coding format. Everybody at Ampico agreed, including the eternal skeptic, Angelico Valerio who was frankly amazed.
8. "In the second amplification position, the crescendo capability is
nullified." p 71, para 6.
ANS: Here is the most ridiculous, embarrassing statement in the entire article. Jeffrey just wrote without thinking, I would hope. This is exactly the same thing as saying, "When the Model A crescendo is fully closed, its crescendo capability is nullified." Neither statement makes any sense whatever, because in the fully ON position, both are fully ON. There is no more crescendo to be had, so the crescendo is "nullified." Wwell, that's apparently acceptable for the Ampico "A", but inexcusable for the Model B.
And where, perchance, are the technical committee advisors on this one? Apparently they didn't know any better, themselves. "That's real technical, complicated stuff there. Only a engunear could figger it out. That's jest over mah haid."
Craig B.
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(Message sent Sat 25 May 1996, 02:51:25 GMT, from time zone GMT.) |
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