Conservative Octaves

[Jim]

Dear Steve:

It is good to see someone else go thru the same process I am going thru.
Your explanations were very good.

Jim Coleman, Sr.


On Thu, 24 Oct 1996, Stephen F Schell wrote:

> Hello List!
>
> I have been reading the mail for the past month or so, and have enjoyed
> it a great deal. I thought I'd weigh in on the octave stretching
> discussion.
>
> My general strategy is to widen octaves as much as possible throughout
> the piano; the limit being the point where the single octave becomes too
> noisy, usually at the 2:1 level. This, for me, is between 1/4 and 1/2 bps
> (except the high treble and low bass), depending on the piano and how it
> is voiced. The idea is to battle the tendency for the scale's
> inharmonicity to seriously mistune the partial coincidences, which can
> do much to strengthen the tone  if they are in close enough agreement.
>
>
> Reinforcement of the piano's sound from coincident partials is a powerful
> phenomenon. One can demonstrate this by "ghosting", i.e. playing a note
> briefly while silently depressing another note containing partials
> coincident to the note being played. The partial(s) excited this way
> will sing out, often loudly. It's no wonder people often refer to the
> sustain pedal as the "loud" or "swell" pedal.
>
> Look at it from the perspective of a note on the piano, say C6. It's
> first partial coincides in frequency, more or less, with the second
> partial of C5, the third partial of F4, the fourth partial of C4, and so
> on. The higher the inharmonicity of the scale, and the more
> conservatively one expands octaves, the more these coincidences will
> disagree, becoming progressively sharper to C6 down the scale. Even with
> an aggressive stretching tactic, the inharmonicity wins eventually; the
> 16th partial of C2 may coincide with the first partial of C6 on paper,
> but is often 40 cents or more sharp on a real piano. This is okay,
> though; such a high partial may not be able to generate much sound
> anyway. What is important is to maximize the agreement of those partials
> which can contribute significantly. For my money, those are the octave
> (2:1), twelfth (3:1), double octave (4:1), and triple octave (8:1). At
> least those are the ones I have learned to pay attention to.
>
> So how does one achieve a tuning where these coincidences can sing in
> harmony? By expanding the octaves the maximum acceptable amount
> throughout the piano. I generally like to set double octaves (at 4:1
> level) about 1/2 bps wide throughout, except for the upper treble. I aim
> for a pure twelfths all the way up, which usually results in a double
> octave which becomes pure by about C7, then progressively but gently
> narrow in the top octave. Triple octaves often remain pure to C7 or
> higher, then likewise turn narrow. This seems to provide the top few
> notes with maximum reinforcement; the octave is wide maybe 4bps, the
> twelfth is pure, the double octave is narrow maybe 3bps.
>
> I find that the pure twelfths approach seems to squeeze the most from a
> piano's treble. Compared to the pure double octave tuning I did for
> years, the sixth octave is expanded more, which really helps those
> pianos tending to weakness in this area.
> Sometimes, though, a compromise is necessary on a few notes around F6,
> where a pure twelfth overstretches the double octave. In the top octave,
> 2:1s beat wide only a few bps, instead of the gritty buzz that can
> develop in them with pure double octaves.
>
> Carl Lieberman taught me a great tuning test years ago. He likes to use
> both hands to play four neighboring positions of the same note ( i.e.
> A3, A4, A5, A6) simultaneously, let them sing for a moment, listening
> for whatever develops in the mix of sound. There are a great many
> partial coincidences shared among those four notes. What is desired is
> an overall solid sound, with a minimum of grumbling disagreement. This
> test is useful anywhere on the piano. Curiously, an aggressive
> stretching tactic will generally yield the smoothest and most powerful
> sound with this test.
>
> Does anyone around here hand out tickets for being verbose? Hope not.
>
> Steve Schell
> stfrsc@juno.com
>
>
>
>