I've been researching the characteristics of "A" rolls -- without having
any around to actually study.  However, Durrell Armstrong told me that
the Supertone and Challenge rolls that Capitol made used the same
perforator, adjusted between 9 and 6 to the inch depending on the target.
This means that the paper advance was the same on both.

What I see is 21 rows/inch, 12 rows/quarter on the rolls marked between
70 and 80, and 8 rows/quarter on those that are marked 60.  I've been
given to understand that "A" rolls operate at 60-65 feet/min.

Something doesn't click here.  If the roll goes at 60, and the
rows/quarter are 12 (for most fox-trots) that would have the music going
r-e-a-l s-l-o-w, good for gut-bucket blues, but terrible for fox-trots.

So my guess is that up-tempo pieces on "A" rolls are cut 8 to the
quarter, and blues are 12 to the quarter.

If so, then swing notes are allocated in sequences of 5 row/3 row pairs:

   -----|---|-----|---|-----|---  etc.

This leaves triplets, which I hear (and sometimes see on other double-time
88 note rolls as 3-3-2 combination:

   ---|---|--|---|---|--|---|---|--  etc.

Which at normal fox-trot tempo are heard as triplets.

Also, on the Challenge/Supertone rolls,  the bulk of the tune notes are 2
rows, "accented" notes are 3 rows.  Legato sequential notes
(A,A#,B,C,C#,D etc.) butt up with the end of one just before the beginning
of the other i.e. no pulling back.  So it seems to me to have been a
subtle mannerism when to pull back the notes.  I know Bob Berkman at QRS
told me that the reason they do it is to prevent warping when the
tracking mechanism kicks in.

I'd appreciate any comments, confirmation etc. about the "A" rolls.

Cheers,

George Bogatko
http://www.intac.com/~gbogatko

 [ My notes on 88-note rolls produced by Capitol indicate that they
 [ always used about 20.24 rows per inch, and 12, 10, and 8 rows per
 [ beat.  When you get a supply of "A" rolls to analyze, watch for
 [ changes in the perf advance distance (rows per inch) between songs,
 [ so that the paper speed can be independent while the music changes
 [ its "metronome" speed.  -- Robbie