Re: Digest 980425

I have been waiting to respond to the ongoing discussion about "build-up"
in roll speed, but now that Robbie has done all the work of posting his
formulae, my post can be easy.

In 1984, Robbie assisted the Chicago Chapter of AMICA in producing NEW
Ampico rolls.  Robbie's part was to take the data from the Stahnke
recording piano and format it for use on the Tonnesen perforator.

Part of the task that Robbie performed was to create a program that
continuously compensated for roll build up based on the use of an Ampico B
take-up spool.  The project was to produce two jumbo rolls.  After
crunching all the numbers, we found that the longest roll would be about
210 feet (the physical limit of the take-up spool) if the initial tempo was
"65".  Given the correct starting speed, this huge roll plays exactly at
the correct tempo, start to finish.

Since the project also offered the music of each jumbo roll on five large
size Ampico A rolls, the beginning tempo of each  A roll was determined
from speed build-up on the jumbo roll.  Odd tempos like 76.892 were merely
rounded off to the nearest five, tempo 75 in this case.

By planning for build-up on the jumbo roll, the production of the other
rolls was a cakewalk.  Had the process been to piece together several rolls
to make the jumbo roll, the 100% tempo accuracy would have been lost.

Bruce Clark has commented about the production of Jumbo rolls under Harold
Powell's  ownership of Klavier rolls in California.  I visited with Harold
and found that no masters exist for jumbo rolls.  The factory did indeed
use individual masters compiled to produce the Jumbo rolls.

When Powell produced jumbo rolls, he did not always copy existing old
jumbos as Clark suggests.  When the masters were usable, Powell produced
his jumbos by sequentially loading individual masters in the perforator.

I have about thirty of the Powell recut Jumbos and there is a mix of both
kinds of production.  Those rolls produced using factory masters are
clearly identified by noting the chain bridging with perfectly round
perforations.  Copied rolls will have elongated chain bridging in the note
field.  There are some jumbos, both factory and Powell, where the program
order gets mixed up, further proof that the jumbos were complied, sometimes
erroneously.

Bob Taylor