Re: Re: [Harp-L] Comb material



What you would be building is a pipe organ. The pipes will not much affect pitch but will greatly affect the response of the reeds and the sound. The length of pipe is inversely proportional to the pitch frequency. I think that it is approximately a quarter wave length for an open-ended pipe but I'm not certain.. The formula for wavelength is L = c / f Where L is wavelength in feet, c = velocity of sound, ( see http://en.wikipedia.org/wiki/Speed_of_sound) about 1125 feet/sec, and f = pitch in herz. (cycles / sec.) After you calculate the approximate length of each pipe, you will need a way to vary the effective length of the pipe to fine-tune it to the pitch of its reed. I think that some organ pipes have a sleeve that clamps on at the tip that can be moved up and down to change the effective length. First you will tune the reed to the correct pitch and then tune the pipe for maximum response.

The problem with pipes in a harmonica is that they have to be big to be resonant! What you are going to wind up with is something that looks a lot like pan-pipes. You will be substituting reeds in the bottom ends for the whistle effect of blowing over the tops of the pipes. Now that I think of it, you might consider installing harmonica reeds in a set of pan-pipes. It might save you a lot of time and effort making pipes.

What you are contemplating is a reed pipe organ. Like any picture you have seen of a pipe organ, each pitch has a different length pipe.There is a lot of information available on the internet about pipe organs. You might start by looking at http://www.lawrencephelps.com/Documents/Articles/Beginner/pipeorgans101.html

The material of which the pipes are made does not affect the sound. For experimentation, I would look for cardboard tubes that are used for cores in rolled goods such as fabric, carpets, paper, etc. Schedule 40 (thin & cheap) PVC pipe or steel electrical conduit from the hardware store are other possibilities.

I suspect that puttong resonant pipes is well-covered ground and what you need to do first is look at what others have tried...andmostly failed...to do. I would guess that Google would help you uncoveer a lot of that History. Pat Missin can also suggest sources of information

I am NOT a pipe-organ expert. The above comments are intended ONLY to aim you in the right direction to get the information that you need.

Good luck. Please let us know how your investigation and experiments turn out.

Vern
Visit my harmonica website www.Hands-Free-Chromatic.7p.com

----- Original Message ----- From: "Rick Dempster" <rick.dempster@xxxxxxxxxxx>
To: "Vern Smith" <jevern@xxxxxxx>; <harp-l@xxxxxxxxxx>; "Jeff roulier" <jroulier@xxxxxxxxxxxx>
Sent: Monday, April 23, 2007 10:38 PM
Subject: Re: Re: [Harp-L] Comb material



Thanks for that Vern;
                                 What about the 'reed-in-a-pipe', as
seen in the reed-organ or street/barrel-organ, as well as in the 'Asian
mouth organ'. How does the pipe effect the pitch of the reed?
                                 I am thinking of attaching a
harmonica reed to a thin pipe (on it's exterior circumference) and
playing around with it.
                                According to Pat Missin's site and
another linked to it, there were/are instruments like this, but the
range of a free reed in a variable length (ie with finger holes) pipe is
limited to an octave, and the further from ther fundamental pitch, the
weaker the tone.
                               This is why, it would seem, free reed
instruments make use of multiple reeds and/or pipes.
                               I imagine the reed in a sax, clarinet
etc (a 'fixed' reed?) can be supported by the players mouth making tone
production a negotiable proposition.
                               I can't help thinking of the endemic
tuning problems of fretted instruments compared to the piano, which has
a string for each note.

RD

"Vern Smith" <jevern@xxxxxxx> 23/04/2007 17:46:22 >>>

----- Original Message ----- From: "Rick Dempster" <rick.dempster@xxxxxxxxxxx>
To: <harp-l@xxxxxxxxxx>; "Jeff roulier" <jroulier@xxxxxxxxxxxx>
Sent: Sunday, April 22, 2007 10:52 PM
Subject: Re: Re: [Harp-L] Comb material



        I am still unclear myself about the differences or
relationship between the harmonica and fixed reed instruments, such
as
clarinet, sax etc., which must bear similarities to other non-reed
instruments such as trumpet, flute tenor horn, trombone etc. etc.

       Any info on these subjects would be much appreciated by
Yours's truly,
RD


Harmonica and accordian are free-reed instruments. The reed swings
freely
and doesn't touch anything. There are no resonant tubes in the
harmonica or
accordian.

Woodwinds:
In Clarinet and sax the reed slaps the mouthpiece every cycle.
Oboe and bassoon are double reed instruments in which each reed slaps
another reed coming in the opposite direction sort of like clapping
hands..
The flute is essentially a whistle.
All the woodwinds have a resonant tube whose effective length is
changed by
opening holes to the outside.  Although these instruments (except
flutes)
have flared bells, most of the sound emanates from the first open
hole.

Brass:
In trumpets, trombones, tubas, etc., the player's lips act as double
reeds,
one slapping the other as they come together in a sort of Bronx
cheer..
In brass instruments, the length of the resonant tube is changed by
(dis)connecting extra lengths of tubing of various lengths by means of

valves.
The player selects various resonant registers by varying the muscular
tension in his lips.

Materials make a substantial difference in tone in stringed
instruments,
drums, and bells, but not in harmonicas or wind instruments..

Vern






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