6:3 bass octaves---why?

[Richard Brekne]

Well, to begin with, you dont just choose 6:3's in the bass. On some uprights
8:4's become quite useable, and on large grands 10:4's and 12:6's come into play.

But there are several things what come into the picture in this puzzle. One is
that these partials become quite dominant in the sound envelope you get when
playing an octave. Another has to do with the way inharmonicity in piano strings
and scales behaves. By the time you are around the C3-C4 octave the 2:1 and 4:2's
are going to get just a bit wide, and the 6:3 is going to pretty much catch up
with them,  So you have 3 octave types very close to beatless in this range and
you want to try and find a happy medium where you get the most pleasing affect...
and that turns out (by popular consensus) to be zooming in on the 6:3 octave
types, and holding them near beatless, a bit on the wide side (0.5 bps max for
me).

Now if you have a Tunelab, try taking your next Yamaha U1 and from C3-C4
downwards and tune perfect 12:6's the whole way down. Just zero the phase display
for the 6th partial of each reference note, and tune the octave below to that.
This is way to low for such a piano, but as an extreme example its instructive.
Then do the same useing 10:5's and 8:4's

As far as making the 12th the determinant for the bass, remember you have 12th
types just like you have octave types. Relavant types for tuning the bass are
9:3's 6:2's and 3:1's. For most uprights you can come up with a perfectly
comfortable tuining by moving from a pure 3:1 in the top bass to a slightly
narrow (circa 3bps) 9:3 in the lowest notes.

The point is, no one interval type is in the end THEE determinant. Inharmonicity,
and what kind of stretch effects you want to create with that are.

Cheers

RicB

Tvak@aol.com wrote:

> OK.  I can tune a 6:3 octave in the bass.  But why?  Musically speaking, why
> a 6:3 octave?  Why would we choose to make sure that THOSE two partials are
> in tune?  Why wouldn't the single or double octave be more important in
> musical terms?
>
> Musically speaking, why wouldn't the 2:1 octave rule throughout?  I could
> even see the musical rationale for a 4:2 octave in the bass, making sure that
> the the double octave is clean, but why make the octave + 5th be the
> determining factor in that area of the piano?
>
> When I think about this as a musician, it doesn't add up to me.
>
> I do it.  But I don't know why...
>
> Straighten me out,
>
> Tom S
> _______________________________________________
> pianotech list info: https://www.moypiano.com/resources/#archives




--
Richard Brekne
RPT, N.P.T.F.
UiB, Bergen, Norway
mailto:rbrekne@broadpark.no
http://home.broadpark.no/~rbrekne/ricmain.html