bass tuning

[Richard Brekne]

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"John M. Formsma" wrote:

> To Richard Moody and Newton Hunt:
>
> Thanks very much for your input on tuning the bass.  I look forward to
> putting these tips to work...maybe tomorrow.
>
> Best wishes,
>
> John Formsma

In late on this one, and I couldnt resist trying my hand. Be advised this
is the first time I have ever tried to advise someone on tuneing the bass.
My betters out there will please be kind enough to jump all over me where
I fail in this attempt. (Just dont hit me too hard.. I bleed easy.. grin)

The Bass.. yea..I would argue that there is no such thing as the pure
octave. Any time you use a test interval for an octave you are doing
nothing more then double checking one particular pair of coincidents in
that octave. If, in any given octave, one pair of coincedents is beatless,
then all those coincidents with a greater ratio will be narrow, and all
those with a lesser ratio will be wide (dissregarding Para-inharmonicity).
For example if you tune an octave as a 6:3 octave testing with the m3
above the lower note M6 below the upper note, then the 4:2 partials and
the 2:1 partials will be a tad wide. Likewise in this example the 8:4,
10:5 and 12:6 will be narrow (the higher the ratio the more narrow).

I like to think of the bass in terms of establishing a nice slope, or
curve where all these beat (within the octaves themselves) steadily slower
as I take decending octaves. The tests for each of these octave types help
to establish that curve. In the end, if you play succesive octaves in a
decending fashion, you should be able to pick out several of these (nearly
simultaneously) and confirm the nice easing of the beat rate in each of
these.

As you no doubt have noticed, sometimes it seems like the test you have
been using suddenly disapears, or gets lost in the maze of partials. If
you listen closely you will notice in such instances that some other
partial is actually louder at this point. (most often a higher partial).
This is natural and it generally is interperted as a transition point,
where one moves from using one octave type to another. Example: You have
been tuning octaves (decending) with the 4:2 type from the middle, and
down about C2 you cant "find" the 4:2 coincidents anymore, but you can
hear really well the 6:3. This is just dandy. Go up a few notes and listen
to how the 6:3 behaves in those octaves. Establish, as you decend, that
the beating of the 6:3 gets slower and get a feel for its general beat
rate. Then continue through the point where you got stuck using the 6:3.
Move on to the 8:4 when you need to based on the same criteria.

How high a partial ratio you end up with at the very lowest part of the
piano is dependent on how much inharmonicity the piano has. You just have
to get a feel for judgeing this, and to some degree its a matter of
personal taste. This is the essence of the stretch.

I mentioned a qualifier above about Para inharmonicity. I kinda like to
think of this as unexpected inharmonicity as it has no predictability
factor. As far as I have been able to decern from my querries on the
matter, most inharmonicity functions pretty closely to the older
inharmonicity coefficient view. Inharmonicity which diverges significantly
from this view, and especially in the negative is still unexplained as to
the nature of its causes, and there is no way of forseeing what
frequencies in affected partials will result, hence "unexpected
inharmonicity"

This causes a big problem in this curve I like to try and establish.
Sometimes a particular partial is significantly "off" from where it should
be in relation to the other partial in a string. Two things two remember
here. First, this is most evident in the lowest partial pair ratios. ie
the 2:1, 4,2 and 6:3. Second, it almost never effects more then one
partial at a time for any given string. So when you run into that
occasional octave where no matter what you do something sounds bad, use
the higher partial relationships, check them with neighboring octaves to
make sure the beat rate is right relative to them (ie a bit slower as you
decend), and try as best you can to balance that with the need to get that
"off sounding" partial as ok as you can.

I've found that thinking along these lines makes it much easier to use the
kind of advice Bill, Newton and Richard Moody describe so well. It gives
me a kind of perspective as to what I am trying to accomplish..
holistically if you will.

A book that substantiates this and explains this kind of approach very
very well is Rick Baldassins' "On Pitch" which I must thank Jim Coleman
telling me about.

Ok boys..<grin> tear me up..

Richard Brekne

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