Re: Period vs Modern instruments?

Ken Moore wrote:

> In article <[EMAIL PROTECTED]>, Jerry Kohl
> <[EMAIL PROTECTED]> writes
> >Whether you have only the odd or even partials, or both, is immaterial, Matt.
> >Either the overtones lie along a harmonic series, or they do not, and the more
> >conicity in the bore, the further the deviation becomes.
>
> Theory and my direct experience both contradict you.  Matt has the facts
> of the matter right,

<riffle, riffle, riffle> <check Benade> <check Helmholtz>

Yep, you're right, I'm wrong. The deformation is mainly on the fundamental, not the
partials, and has nothing to do with the conicity as such. I'll go back to my
woodwinds. (Still, the upper partials on my reverse-conical bore instruments aren't
where they "ought to be", but there must be a different explanation than the bore
shape.)

> though I don't use his nomenclature for the
> behaviour of a close parallel tube: the way I think of it, in closed
> parallel tubes (e.g. clarinet) the second overtone has (or is close to,
> in practical cases) three times the frequency of the first.

(I take it you mean the fundamental, rather than the first overtone.)

>  Note (as
> Matt has already pointed out in an earlier post) that the configuration
> of nodes and antinodes in the pipe is the same as in the second overtone
> of a conical pipe, but the different cross-sectional areas change their
> distances and the resultant frequencies.

Now I'm confused again. If the change in position of the nodes is associated with a
change in resultant frequencies, how is it that the relation to the fundamental
remains the same?

> > Horns have such a
> >gradual
> >taper that the effect is minimal, but bugles have a steeper taper and the effect
> >is correspondingly more pronounced. Valved instruments introduce a further
> >complication, in that you cannot add in a section of tubing without altering the
> >degree of taper to the bore overall. AFAIK, the added tubing is always
> >cylindrical, so the more valves you open the less conical (on average) the
> >overall
> >bore becomes.
>
> Yes, and this behaviour is detectable on the double horn in Bb and F.
> Even though none of it is actually conical, the combination of the
> parallel centre portion, the expanding sections (mouthpipe usually
> expanding in a parabolic manner, to fair into the parallel portion, bell
> expanding more and more rapidly to the mouth) and the mouthpiece
> produce* acoustic characteristics very close to that of a plain cone
> (overtones at all harmonic frequencies) for some intermediate length of
> the parallel portion, usually close to the open F horn.  The open Bb
> horn has least parallel tubing and has a compressed set of overtones and
> the B basso horn (all finger levers depressed) an expanded set.  Horn
> players don't think about this.  The Bb side is adjusted to match the
> tuning of the F side around C space, and is close for about two octaves.
> The difference is then most noticeable in the low register, where most
> players avoid the Bb horn, except for any notes which are unpredictable
> on the F.  All low notes can be sharpened or flattened easily; tuning
> comes automatically from ear and lip, with the hand helping in difficult
> cases.

Yes. I just remember from practical experience not to write low C# (and similar
notes requiring the third piston in the low register) for the trumpet, unless you
know you are dealing with a good player with an instrument fitted with correcting
slides. I had also supposed that the notorious low-register tuning problems of the
baritone horn, in comparison with the more-cylindrical euphonium, was also due to
the conical bore. Evidently, I need to brush up on my acoustical theory.

--
Jerry Kohl <[EMAIL PROTECTED]>
"Légpárnás hajóm tele van angolnákkal."