I recently reviewed my knowledge of the Ampico crescendo and
intensity systems, and whether the so-called "First Intensity" is
properly termed one of the Ampico's series of intensities or is simply
a starting calibration point, analogous to Duo-Art's "Zero degree".
In the process of that review, I found a glaring omission on the part
of the Ampico Studios, one that I had never noticed, and have never
heard anyone else mention.

First things first: Whether or not the Ampico "baseline power
set-point" (how's that for a politically correct term?!) can or
should be called an "intensity", with or without adjectives (1st,
2nd, etc.) is, in my opinion, a distinction without a difference.
(See https://en.wikipedia.org/wiki/Distinction_without_a_difference )

In my opinion, a compelling case can be made that Ampico's so-called
"1st Intensity" _is,_ indeed, an intensity, at least for the Ampico "B"
mechanism.  The baseline power set-point (BPSP) is perhaps a concept
that we rebuilders have come to understand to mean the minimum power
(usually measured as inches of water column vacuum) in the stack which
will reliably cause individual notes to sound with uniform, minimum
"loudness" throughout the compass of the keyboard.

As a practical matter, this is impossible to achieve for a given BPSP
because human hearing, for adults, seems to be at its most sensitive
around 3000 Hz, becoming less sensitive as you go both higher and lower
on the keyboard.  Heavier hammers in the bass end or the piano may
partially compensate for this "roll-off", but not so much going the
other way, since the hammers typically get smaller and lighter.

But, so what if Duo-Art called the BPSP the "Zero degree" ("The Duo-Art
Reproducing Piano 1925 Service Manual", p. 4), Ampico called it the 1st
Intensity, and Welte, well Welte doesn't seem to call it anything, but
at least tells you how to set it ("Instructions for Testing and
Regulating the Original Welte-Built Welte-Mignon Reperforming
Instrument, Upright, Grand and Console" [undated], p. 25).

But what's in a name (said Shakespeare), surely an "intensity", by
any other name, would sound the same.  Okay, maybe that's stretching
the analogy a bit too far, but you get the picture.  Were these terms
a hedge against patent infringement actions?  Perhaps, I don't have
a clue, but I don't read this interpretation into the Barden-Hickman
interview.  I submit this is indeed a semantic distinction without
a difference.

Next, I refreshed my understanding of the concept of dB (decibels)
as related to sound and hearing.  One assertion that "A 3 dB
difference, which is defined on a log10-based scale, is the smallest
loudness difference the human ear can differentiate" is incorrect.

First of all, we need to be clear about to what the "dB" is referring.
dB by itself is meaningless unless you know (usually from the context,
if not stated) to what property it is referenced.  In the audio arena,
the "loudness" of sound is typically measured in units of dB SPL (SPL
standing for Sound Pressure Level).  In humans, this value ranges from
2 x 10-5 Pascal or 0 dB (SPL) (defined as the threshold of hearing to
approximately 200 Pascals or 140 dB (SPL) (defined as the threshold of
pain).  A Pascal is a scientific unit of force.

In this context, essentially all references I checked (a good one
can be found at http://physics.bu.edu/~duffy/py105/Sound.html ) specify
that the smallest change that can be differentiated by the human ear is
plus or minus 1 dB (SPL).  Ordinarily, a change of 3 dB (unreferenced)
represents a doubling (+3 dB) or halving (-3 dB) of a quantity, say,
the power (in watts) that is producing a sound.

For example, let's say you have an audio system that is producing a
musical tone with the expenditure of 10 watts.  If you double the power
(+3 dBW, to 20 watts) it will sound "louder" but _not_ twice as loud.
The physiological acoustic properties of the human ear would need for
the power to increase to 100 watts (+10 dBW) in order that the sound
be perceived as "twice as loud".

Now, where is my "compelling case" for declaring the Ampico ("B")
1st Intensity to be a true intensity?  Well, just have a look at that
well-referenced Figure 10, Intensity Scales, from p. 20 of the 1929
Service Manual.  {Insert figure 10 graphic reference here.}

Look at the three curves as they cross the so-called "1st Intensity"
ordinate.  These are not the lowest points on the curves!  There
are lesser, easily measurable values resulting from use of the
"Sub-Intensity" (tracker bar 0T open).  The BPSP (baseline power
set-point) does not _have to_ be adjusted to be 5.6" WC with _no_
tracker bar holes open, although it typically is, by instruction and
test roll usage.

You _could_ also work backwards and set your BPSP, with 0T open, at
something less than 5.6", using the adjustment screws (Figure #3, item
"E").  Curiously, that figure does not identify (on the drawing itself)
the purpose of that item, although the wording on the next page (p. 9)
clearly says, "The opening E can also be adjusted to even up the No. 1
intensity pressures, Bass and Treble" (emphasis added).

If the contention is that an "intensity" can only be considered as
No. 1 so as long as there is a lesser value that may be considered
the "set-point", then I submit that the "Sub" intensity fulfills that
purpose handily.  If you accept the leap of convention that the
Sub-intensity constitutes the BPSP, it hardly makes sense to treat the
"A" mechanism differently, just because it doesn't have a Sub-intensity
mechanism, so we might as well define its no-tracker-bar-holes-open
setting as "1st Intensity" also.  Ladies and gentlemen of the jury,
I rest my case.

Now for the great "Missing Intensity Mystery".  For this I ask you
to refer to a slightly modified version of the Intensity Scales,
Fig.  10, p.20.  {Insert modified figure 10 graphic reference here.}
Specifically note the bottom line captioned "Tracker Holes Open For
Above Settings." Conspicuous by its absence is the combination of holes
2 and 4!  This is a valid combination and should produce a power level
somewhere between 4 and 6, but where is it?  Not there!

So I pixel edited a scan of the chart, cutting it vertically and
separating the two parts, adding in a new ordinate between 4 and 6
representing the combination 2 & 4.  This obviously distorted the
three power curves which I re-approximated in red, but look what this
does to the number of "intensity" settings!  The "B" now has not 6, not
7, not 8, but 9 -- count 'em! -- _nine_ values from Sub to 2nd
Amplification.

Who knew?  Has this discrepancy never been noticed before?  I scoured
the MMD Archives but could find no entry to suggest it has been.
(References to the contrary appreciated.)  There may only be a very
small difference between the power created by #6 alone and #2 & 4
together, but I'll bet it's still measurable.  Unfortunately, I don't
currently have an operable "B" mechanism in the shop to confirm this
theory.

John Grant

 [ 1929 Ampico Service Manual, Figure 10, P. 20 (Unmodified)
 [ http://www.mmdigest.com/Attachments/15/09/23/150923_081354_Ampico%20B%20Fig%2010%20-%20P%2020%20-%20Unmodified.JPG 

 [ 1929 Ampico Service Manual, Figure 10, P. 20 (Adjusted for "Missing Intensity")
 [ http://www.mmdigest.com/Attachments/15/09/23/150923_081354_Ampico%20B%20Manual%20Pg%2020%20(Adjusted).JPG