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From: Pat Missin
Date: Fri, 30 Aug 1996 23:47:12 +0100
Subject: Plastic vs wood bodies

... and finally, the post you've all been waiting for. The definitive,
objective, scientific answer to the ultimate question of life, the harmonica
and and everything:

Is there a tonal difference between wooden bodied harps and plastic bodied
harps?

Yes. Well - at least, sort of - but...

We compared our brand-new, improved harp, with Brand X..., but seriously, folks:
I took a fairly standard 270 type chromatic (for the record a '40s vintage
Chromonika II - a German-market model with short slot reeds and steel
coverplates), made a spectrogram (basically a graphic representation of the
frequencies present) of the harp's sound, then replaced the body with a
polyurathane comb made by Vern Smith. The spectrograms were made of the
sound produced by hole 1 blow and hole 1 draw, using an improvised air
supply (made from a vacuum cleaner). Because of the noise made by this less
than perfect arrangement, I gated the sound, but any faults in the first
spectrograms were duplicated in the second and so should cancel each other
out. To give a better picture of what actually happens when you play, I also
repeated the process whilst blowing the harp normally. I tried to keep the
sound as consistent as possible (using VU meter and oscilloscope), but there
will be some differences - hence the artificially blown harp. Was there a
difference?

Well, yes - but the most noticeable difference was in the overall volume of
the harp, being a little louder on the plastic body. This could be due to
the fact that the slide assembly and mouthpiece seem to be more airtight on
the plastic body, although perhaps it was more airtight all round (although
the plates had previuosly been gasketed onto the wooden comb, so it should
have been pretty darened airtight before!). Interestingly, the difference
was more marked on the blow note than on the draw. Tonally, there was not
much difference that could not be accounted for by better compression - the
plastic body was slightly brighter (again more noticeable on the blow notes
than on the draw). I don't know that these differences would be noticeable
to the ear - I recorded a short piece a few times both before and after,
then played them to some non-harp playing friends of mine (musicians and
non-musicians). Nobody seemed to be able to hear any difference reliably,
although I realise this is a less than scientific approach (it could well be
that any tonal differences between the two harps were masked by my cheap
cassette deck!).

So does the plastic make the difference? Well, it's difficult to say
definitely one way or the other. There was a difference, but it could well
have been within the range allowed for by "experimental error". The issue of
compression comes into play here, too. It also has to be mentioned that the
plastic comb is not exactly the same shape internally, as the woodem comb.
In order to make the comparison better, it would have been nice to have a
plastic comb EXACTLY the same size and shape as the original. My own
experiments across the last few years have shown that the shape of the reed
chamber seems to have an effect on the sound (I have had more success in
altering the tone of the harp by changing its shape, rather than by altering
its material; I have discovered several ways to un-improve the harmonica!).
Following my own common-sense (?!), as well as the studies of Douglas Tate,
Richard MacKenzie and others, I decided that the ideal harp would have the
smallest possible amount of air in the reed chamber. Less air to move in
order to start the reed moving = easier to play harp! At least that's what I
figured. Well, I have a couple of metal bodied harps with minimal space in
the chambers, but I'm not entirely sure I prefer them to my regular Lee
Oskars. On the other hand, I have some Lee Oskar reeds on an M&M plastic
body with wood covers - its reed chambers are larger than a standard Oskar
and whilst it may (I'm not sure) take more wind to play, it also *seems* to
have as "bigger" sound. I guess it could be like guitar strings - the
lighter ones are easier to play, but the heavier ones give you a bigger
sound. (Having said that, it has to be noted that B.B. King uses *really*
skinny strings, but still gets a full sound!) Blackie Shackner makes some
similar comments in this quarter's "Harmonica Happenings". Any one out there
with any opinions on this? Future work (when I get the time) will involve
setting up a set of Marine Band plates on several combs of the same shape,
but different material; and several combs of the same material, but
different shapes. Anything of note will be posted here first - stay tuned!

Conclusions, well I guess altering *anything* about the harp will make
*some* difference, but I'm still convinced that the biggest difference you
can make, is to connect your harp to a different mouth!

Any comments, questions and criticisms welcome.

Pat Missin - pa~lobalnet.co.uk

"...my music's a lot better than it sounds!" (with apologies to Mark Twain)
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