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MMD > Archives > November 1998 > 1998.11.06 > 10Prev  Next

Tempo Acceleration On Rolls
By Craig Brougher

Since we have been discussing tempo acceleration of the music on rolls,
I wanted to measure an Ampico roll and an 88-note roll of about the
same length, and see if the steps-per-beat of the perforator at the
beginning and end of the roll was changed.  I first had to choose
rolls that traditionally have no tempo change-ups or rubato.  Naturally,
I went to the stride music in blues.

In the Ampico roll, "Cryin' For the Carolines," Tempo 80, very steady
"blues meter", the music portion of the roll is 30.53 feet long (first
note to last pedal perf.)  At a tempo of 80, on my piano it takes 229
seconds (3 min 49 sec) to play that distance.

At the first measure, the first beat is 1.3" long.  At the end of the
roll, the same beat is 1.7" long.  The reason this is such a great roll
to test is because the tempo is so perfectly even, without any rubato
or phrasing that would upset the meter.

That is a step change of 30% in 30 feet.  Tempo-wise, I can detect no
acceleration at all.  It seems to be perfect, but I don't claim to have
Robbie's ear for that.  However, it proves that even very short pop
Ampico rolls are fully tempo-compensated.

An equal length 88-note roll, QRS "Taint Nobody's Bizness If I Do"
takes 3 min, 20 seconds at a tempo of 85, or 28.33 feet of music.
That's a good roll to do this on, too, because the meter is perfectly
unvarying (ideally).  The distance between beats at the beginning is
2.4" and at the end, is still 2.4."  That means the 88-note roll is
not compensated.

I think that Robbie may be getting reproducing rolls confused with 88-
note rolls, as to which ones "bug" him.  I see, at least from this very
cursory ten minute exercise, that reproducing rolls are fully compen-
sated, while 88-note rolls are not.  So I don't think he will have any
problem with reproducing rolls unless there is something wrong with his
Ampico roll drive system.

One last note about the Ampico B is the large take-up spool, having
roughly twice the circumference as a Standard take-up spool, will
create less change in music tempo than a small spool will, since the
acceleration is due to the percent change of the circumference of the
take-up spool.  That should cut the usual acceleration by half.

Craig Brougher

 [ "Cryin' For the Carolines", p.b. Victor Arden, Ampico 212601, was
 [ released in 1930.  An Ampico pop roll from the mid-1920s or before
 [ is more likely to have no compensation.  -- Robbie

(Message sent Sat 7 Nov 1998, 00:27:20 GMT, from time zone GMT-0600.)

Key Words in Subject:  Acceleration, Rolls, Tempo

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