From: au462@cleveland.Freenet.Edu (Robert Drake)
Newsgroups: rec.music.folk
Subject: Re: Plucked instrument construction
Date: 30 Aug 92 02:26:19 GMT
Article-I.D.: usenet.1992Aug30.022619.2481
Organization: Case Western Reserve University, Cleveland, Ohio, (USA)



in an earlier artical,  garry@ithaca.uucp (Garry Wiegand) asks 
for advice towards buiding his own autoharps.  i trained as a
violin-maker, and have since been involved in mostly "weird"
homebuilt instruments, but:

>I've got millions of questions. See if any of these grab you.

>1) I notice that (hammer) dulcimers are commonly double-strung, and
>cymbaloms are triple- or quadruple-strung, with the strings sounding
> in unison. Would an increase in volume be the primary purpose of this
> multi-stringing?

partly volume, but more tone.  those pairs (or triples or more) are never
*perfectly* in tune anyway, and when they sound, each string changes
tension during the course of its vibrations, shifting in frequency & timber
as it does so.  the INTERACTION between these modulating single vibrating
bodies is what produces the characteristic tones, and the complexity of the
interaction is why synthesised instruments fail to duplicate the acoustic
sound.

>2) Would I be correct in assuming that longer strings in a plucked
>instrument would tend to produce a sweeter tone?
&
>3) I've observed on my psaltery and on a harp that the closer the pluck
> is to the midpoint of the string, the "much better" the sound. If this
>is generally true, how do guitars get away with being plucked so far
> away from the midpoint? (I'm thinking that excessive ringing of
> autoharps comes from some of the strings being plucked on the ends.)

"sweeter" and "much better" are kind of subjective terms.  a longer string
(tuned to the same note) will generally have more mass than a shorter one,
this changes the tone yes, but sweet in the ear of the beholder.  plucking a 
sting in the middle will tend to emphasize the 2nd harmonic (the "note"
one octave above the fundamental--similar to damping a string in the 
center and releaseing the damping finger immediate after plucking)--
second harmonics are pleasing in that they are percieved as close to 
consonant, but more simplistic than some other harmonic components...
guitar players will vary their tone by playing at differnt points between
the bridge & the midpoint; actually averaging around 1/4 of the way up
the string, producing similarly low-order harmonics

>4) I have been figuring out the basic size/length/tension/breaking-
>point/stretchiness/sound-quality curves of steel strings the hard way.
>Bang Twangggg! Is there anything written which might help me? I need
>more than the Physics 101 treatment. (A computer program would be
>great.)

try plotting a graph w/ the guage/note relationship for a variety of guitar 
sets (which will hold the length ratio constant) to get general emperical
data without sacraficing stings.  there was a series of articals in Experimental
Musical Instruments (PO Box 784, Nicasio CA 94946--an excellent 
source of informantion) that explained the variety of factors in fairly
technical but easily understood terms...  remember that in the autoharp,
as the hammer dulcimer, string length rather than guage is the primary
tuning factor.

>5) The violin has a small soundbox and a wonderful tone. The ukelele
>has a small soundbox and a tone, ah, unique to itself. The classic
> autoharp is on the ukelele end of the spectrum. What are the elements
> of soundbox/top design that cause the differences in sound quality?

it would take several books to cover this one.  a uke (as well as the guitar
and most other plecturm strings) has stings anchored in the center of the
face of the instrument--the string is pulling UP on the (wood)membrane;
the membrane tries to resist being pulled while still being flexible enuf to 
vibrate.  when the string vibrates, it pulls on and then relaxes it's pull on
the top, which vibrates, but it's always bsically acting in opposition to the 
string  itself. the best that can be made is a standoff/compromise. 

in a violin, the sting, passing over the bridge, presses DOWN on the
instrument's face; this downward force is distributed over the entire top
by the curve of the wood and the bass-bar that runs under one foot of the 
bridge, and (via the soundpost under the other bridge foot) to the back of
the instrument.  when the string vibrates, the bridge rocks back and forth,
causing the front and back to alternatly--AND IN UNISON--compress and
release the air inside the box.  plus a bunch of other stuff...

the short answer is--ukes and guitars are basically at war with themsleves, 
wherease violins are complex systems of balanced forces.  the sound-producing
mechanisms are *completely* and intrinsiclly different. (did you ever see a 
200 yr old guitar?  A violin isn't really in mature voice until it's at least 
150 yrs old..)


>6) Why are banjos so loud? (Hmm, I would guess it's the membrance top.
>I'm curious - are there other stringed instruments in the world with
> sounding surfaces made from materials other than wood?)

africa (where the banjo originated), india, and china all have stringed
instruments with membranophone sounding boards

>7) People have told me that sound energy is transferred from strings to
>soundbox primarily through the air, and other people have told me that
>it's through the bridges. Who's closer to right? (It's of interest
>because the standard autoharp has heavy nearly-immobile bridges.)

in an autoharp (as in the lap dulcimer) the bridges are so anchored and
immobile that most of the energy transfers thru the air.  that's the
basic reason for the volume problem you're addressing.  in the hammered
dulcimer (as in the guitar, uke, banjo etc) the bridge is sitting in the 
middle of the main resonating surface--since it is freer to vibrate, 
most of the energy transfers there.  the problem with both the autoharp
and hammer dulcimer is that (because of the number of strings) the
amount of force is so great that you can't afford to anchor them to a nice
delicate/flimsy piece of wood--the thing would just fold up as soon as you
tuned.  the advances in hammered dulcimer construction(see below) have 
mostly been in bracing schemes under the bridge(s) that allow for enuf 
structural support and still allow for efficient energy transfer to the face
 of the instrument.  it would be an interesting trick to combine a bridge 
scheme that somehow sat in the middle of the face of an instrument with 
the damper bars of an autoharp, without winding up with a very un-
wieldly instrument...

>8) The zither is close to an autoharp, and perhaps zithers are better
>made - I'm not sure because I've not ever had the chance to see or hear
> a good zither. Are there people, perhaps in Europe, who are building
>good zithers? Where can I listen to one? (I'll be passing through
> Cleveland and Boston soon, if that's a help.)

about the same as far as i've heard.

>9) I've been told that the state of the art of hammer-dulcimer-building
> has improved a lot over the last twenty years of interest in the
> instrument. Does anyone know of a good background book, or of a good
>dulcimer builder who might enjoy contracting to build some experiments
> or who might give instruction?

folks seem to be pretty secretive in my experience.  get a goose-neck 
penlight and dental mirror, examine instruments you see that sound
good.

>10) Is there a class or a teacher in general anywhere that could get me
> off to a good start? (The instruction would probably need to be
>non-instrument-specific.) (I know there are amateur autoharp-builders
>out there who could tell me good things; I have not gotten in touch
> with any of them yet.)

elkins college in elkins west virginia offers lots of folk-music courses, 
usually during the summer.  some instrument building, but i'm not sure
about aoutoharps specifially

>11) I've invested about 1500 hours learning to play, so far. I have
> great respect for instrument-building as, I suspect, an equally-
> or more-challenging art. What sort of investment should I expect to
>make to learn to build well?  (I do have an expert-woodworker friend to
> learn some of it from.) Any advice to someone thinking of taking the
> plunge?

take yr time, think things thru, take yr time, don't take shortcuts...



as fr the "secret of Strad" that the ensuing thread on this topic has
run towards:  someone discovers the "secret" about evert 30 years or
so--varnish is a favorite, as is wood (by the by, most of the trees
comparbable to the ones the Cremona makers prefered are now almost
impossible to get not--EXTINCT due to acid rain)... the upshot is, 
everyone would like to find an easy answer, some majik wand to wave
over their half-assed workmanship and have it turn into something
sublime.  THOSE GUYS WERE MASTER CRAFTSMEN!  you cd get good at some-
thing, too, if you spent 40 years mastering your craft.  but our age
(& economy) doesn't reward or afford that kind of patience & attention.
i've been known to preface that with something about "ya know what's
wrong with this society...", but that's too easy an answer, too...
enuf

yrs
luigi
Newsgroups: rec.music.folk