I would like to answer Bob Taylor's letter now about my article "Ampico
Misconceptions" (Digest 96.11.10).  Bob is a fine roll coder, and this
cannot take away from his expertise or knowledge.  However, we can all
learn and profit from someone else's viewpoints and information.

The title of Bob's rebuttal letter in Digest 96.11.12, "The Ampico B AND
Ampico A Are Not Compatible", is absolutely correct.  As a matter of fact,
it is the very reason I wrote the article to begin with.  No direct
equivalence between models is necessary, as long as both are equally
compatible with the standardized roll coding format Ampico settled on
in the early 20's.  In this we fully agree.

Bob wrote:

> Even though Craig Brougher has claimed that the Ampico B plays the
> early "A" rolls (pre 1926) in a truly compatible fashion, it is my
> opinion that this not the case.  I find that the Ampico "B" only
> achieves its maximum volume by using both full intensity setting
> (level 7) simultaneously with full crescendo travel.  Conversely, the
> Ampico "A" may achieve its maximum level of play with EITHER (not
> both) of those two volume control components at maximum.  The problem
> is that many Ampico "A" rolls lack  simultaneous coding of the
> crescendo and intensity steps when maximum playing volume is desired.
> The result is that the "B" plays these passages at only 50% of its
> maximum power, while its predecessor is at maximum effort volume.
> This is a very common event in a broad spectrum of rolls from the
> inception of the Ampico until the first "B" rolls (popular series)
> were introduced in Nov. 1927.  ("Blue River" 209161-E,  first
> released fully coded Ampico "B").

While this is _theoretically correct_ and I have no problem with the
possibility of doing it as Bob suggests, in practice the "1922 standard
format" coded roll never raised the pump pressure above the normal
setting using discrete intensity codes alone. Crescendos were ALWAYS
used. Here is why:

The intensity codes are intended to accent certain notes and chords
instantly, by momentarily increasing the stack pressure just before the
rolls plays the note or chord!  In neither the models A or B is the
stack pressure able to go higher than nominal pump pressure, unless the
pump pressure is increased.  So with crescendos or without, the highest
pressure a model A achieves is limited by the pump pressure.

Unless the higher pressure needed is _anticipated_  by the roll, and
unless the pump pressure is increased _beforehand_ with (usually) "fast"
crescendo, even the highest intensity desired will seldom rise above
nominal pump pressure.  If a higher intensity were left on for a period
of time, it is possible, in the model A, to tighten the spill valve and
raise the pump pressure.  However, this happens through _positive
feedback_ to the pump, through the amplifier directly by stack pressure,
and therefore happens relatively slowly.  As a matter of fact, you can
watch the Ampico amplifier pneumatic slowly tightening the spill spring.
It is prompt but not sudden, and must follow the intensity. It cannot
accompany the intensity for accents.

Intensity codes, as I said, are discrete pressures intended for instant
accents, while crescendos are "continuously ramping pressures."
Crescendos in the A piano raise the overall "platform" pressure, or
pump pressure which the intensities build upon.  Neither model A or
model B, in practice, can use the intensity codes in the way they were
intended and still raise pump pressures on the fly. It is physically
impossible.

Crescendos are also needed so that there is a discernible difference in
volume when the piano is switched between Brilliant and Normal mode. This
is because the mode switch only alters the action of the amplifier, so
coding with intensities alone -- without crescendos-- would sound about
the same in both Normal (Medium) position and Brilliant position, since
the pump in the model A cannot respond instantly to the intensity codes.

By the way, Larry Givens wrote a letter questioning my comment that only
one copy of the model 1A Ampico (actually the precursor of the Stoddard
Ampico) had ever been built. I rechecked my statement and found that to
be in error. I meant the "model 1", not the "model 1A". The "model 1" is
mentioned on pg. 68 of the Ampico Reproducing Piano, by Richard Howe.
It is the model I (Roman Numeral 1) that was the precursor of the model B.
I should have written:  "In the first place, you don't have to worry about
the so-called "Ampico model 1" which is actually the pre-model B. Only one
of them was ever built!"  I also could have said, "Besides that, the
Ampico never had a zero intensity!"   Many thanks to Larry Givens for
bringing this to my attention.

I think that you can see, despite the knowledge to code rolls and rebuild
pianos, that a full understanding of the Ampico has not necessarily been
required up until now and so becomes largely a cut-and-try method which,
sooner or later, will still yield satisfactory results. It's just a lot
slower that way.  Still, it would be much easier if we would take this
accrued knowledge and refine it to recreate the "Ampico standard roll
coding format".  That cannot be done however until these misconceptions
are largely cleared up.

There's nothing quite like shining a bright light on the real problem,
and it is this MMD forum that has made it all possible!  It is the
free-for-all discussion which has allowed the facts to surface here.
(And it's about time!)

Craig Brougher