Re: Ampico Crescendo
By Craig Brougher
The timing of early "Stoddard" Ampicos on the slow crescendo was 11 seconds and fast crescendo about 2 sec. The timing of the later model Ampicos was 9 sec--slow crescendo, and 1.5 to 2 sec. fast cresc.
The slow crescendo timing wasn't that critical, since the _average_ slow crescendo was used for mechanical, rather than musical compensation. For example, the average 1" to 1.25" slow crescendo hole barely even budges the gauge. A 2.3" slow crescendo at a tempo 70 lasts 1.42 seconds, and in that time, raises the pressure about 1" when the intensity is playing at 20".
Here's a slick little formula for calculating the time it takes to watch a hole cross the trackerbar: t = 50 h / T. Where t = time in seconds, 50 is a real bona-fide number, h = hole in inches, and T is the tempo, like 60, 70, 80, etc. Now we can go out there and amaze everybody.
Regarding test rolls, I don't have an Ampico A test roll anymore. Something happened to it. I do have what they called a 25 note repetition tester. That is a roll that helps you even up the intensity between the bass and treble to get them exactly even, if I recall. I admit though, I don't use it anymore, but it might be a handy crutch for someone starting out.
The Ampico B test roll is by far the best tester ever designed. It is designed to test the Model"B" to its limit. It also has a crescendo test which is determined by the 1922 roll coding standard set by Ampico, and should be a perfect test for anyone who wishes to know both the ideal rate of crescendo as well as the optimum timing according to the roll coding methods used in the 20's. Whoever wants to study crescendos will need this roll.
Stoddard's rolls were not that useful, and assuming that his crescendos were represented accurately on those test rolls may be a bit of a stretch. He wasn't one to reveal anything of engineering value to anybody. If you remember, he even rigged up a gadget with spark coils and batteries to power lights and a spark gap that was operating innocuously on a table, looking very official, when the bankers came to visit. When asked, he just said it was an experimental device used in testing the reproducing mechanisms. So to expect Charles to provide you the answers for $1.25 about all the mysteries of the Ampico is unlikely.
Craig B.
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(Message sent Thu 6 Jun 1996, 13:13:59 GMT, from time zone GMT.) |
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