An Interesting Dulcimer Experiment

Just share stories or offer advice

Postby Thud » Thu Dec 18, 2008 6:50 pm

Would you have had similar results if your bridge wasn't located at the tail piece, but 4 or 5 inches into the body of the dulcimer? As I understand it, the soundboard plays more of a role in sound production then than when the bridge is on the tail piece.

We were having this conversation on another thread, where I was learning the art of bridges. If it's farther out on the soundboard, the dulcimer has a mellower sound with more resonance. If it's closer to the end where there's less soundbox under it, the notes are cleaner/brighter.
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Postby mrchips » Thu Dec 18, 2008 7:24 pm

While a Hd is far from a MD the physics behind using a soundboard/soundbox to "amplify" the energy of strings to thim is the same. The difference is in how you can couple the 2 together with as little mass as possible without having either implode the second you touch it. :lol: :lol:

This tends to support something mulling around the back of the brain. Might try some experments to confirm it over the winter..
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Postby harpmaker » Thu Dec 18, 2008 8:46 pm

A couple of other thoughts;

Because the dulcimer is being played flat on a table, it makes me wonder as to how much the back is actually acting as a sound board.

Again, I would be interested in hearing this after the paper has been removed, as I suspect the phyiscal barrier of the paper does have an affect on the sound, creating a chamber if you will in which the vibrations resonate.

Curious also as to how the voice would be without the cross braces directly under the top.....if they are attached to the fretboard that has to have a damping factor.

Another interesting experiment would be to do the same but without a back, and also with deeper sides. The deeper sides IMO would have a major effect on the sound
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Postby rtroughear » Thu Dec 18, 2008 9:56 pm

Folks

I'm a long way from home, and am just packing up to go. I'll try and address your comments in due course, but just briefly:

Harp: The top is just ordinary newspaper stuck on with office glue. The instrument is isolated from the bench by 1" soft felt pads. I have made extensive sound, video and photographic recordngs of the whole process, and done considerable analysis of the sound. There is not a lot of difference in loudness from full top, to no top, to paper top. In fact, my preference as to sound quality was for manila folder cardboard top - that's a bit of a worry. Further study regarding braces is planned.

Mike1952 - it was never a wonderful instrument; that's why I didn't mind chopping it up. The point is that the sound with, and without, the top is not outrageously different. But you are right, there is something missing, which I'll have to elaborate on later.

Martin: I think we have collectively fallen into the trap of assuming more mountain dulcimer parallels with the guitar than there really are, myself included. Maybe it's time for a rethink.

Paul C: Sit your wife down and give her a strong cup of tea - the world will probably be the same tomorrow.


This test is part of a wider study of the instrument, which will take up the better part of the next year, and which may, or may not, yield sensible information. Or I might just get tired of it and go back to the way I've been doing things - hit and miss.

But don't stop doing what you are doing on the strength of this. This is not the full story, it's just a clue. Many people are clearly making fine instruments, even if the detailed mechanisms are not fully known. Violins and guitars have been studied for 200 and 100 years, and serious headway in understanding is only just now being made. It would be arrogant to think a real understanding of the mountain dulcimer will come in a flash.

I'll post more when I get home. Meanwhile I've put a couple of pictures on Photobucket

http://i202.photobucket.com/albums/aa91 ... ullTop.jpg

http://i202.photobucket.com/albums/aa91 ... _NoTop.jpg

http://s202.photobucket.com/albums/aa91 ... llSand.jpg

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Postby harpmaker » Thu Dec 18, 2008 10:40 pm

I think we have collectively fallen into the trap of assuming more mountain dulcimer parallels with the guitar than there really are, myself included. Maybe it's time for a rethink.


You won't get an argument from me on this....I've been saying it for years. :lol:

It looks like your study set up is quite intensive, and very interesting. I don't want to sound critical, but are you using some sort of electronic recording of decibels levels etc, in order to avoid any confirmational bias?

One suggestion I would make is to do any tests with the instrument suspended over a non reflective (or at least a minimumly reflective) surface.

It's amazing what a possum board will do for a dulcimer... ;)

But again, I don't want to come across as being critical. I think what you are doing is very interesting and I look forward to hearing your results.
Last edited by harpmaker on Fri Dec 19, 2008 12:56 am, edited 1 time in total.
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Postby mrchips » Thu Dec 18, 2008 11:37 pm

Personaly I WILL be very interseted in the results of the study on that MD.. While I dont think the full results will cause many, if any makers go to paper tops, it will give some sort of qualifed information on them.

The acoustical properties of lets just say mainline insterments are farly well know but just try to find the equivlent on dulcimers.. There are many things in common with all stringed insterments and at the same time things unuiqe to each..
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interesting experiment?

Postby hammerman » Fri Dec 19, 2008 12:40 am

I'm not quite sure what this thread is all about inasmuch as I've not downloaded the stuff, but it seems like it has to do with paper tops on mtn dulcimers. If you take the back off a speaker, what do you see vibrating there? Isn't it a cone of stiff paper/cardboard?
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Postby mike1952 » Fri Dec 19, 2008 5:20 am

it would have been interesting to compare wood vs paper.
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Postby mrchips » Fri Dec 19, 2008 6:15 am

Hammerman all you need to do is look at the youtube thing to get the drift of whats going on. VERRY intersting.

In 99.999% of the cases you are right about speakers but I know of and have worked with one type of speaker that does not have a speaker cone, no magnets or wire inside it.. Havent seen one in many years as so far theyre too complex and expensive to replacete the standard cone/magnet/wire speakers. Funny thing about speakers, other than a better understanding of how they work and many years of refinements on them they havent changed much since the very first one was concived.

There are some develpments in the world of nanotechnology that could well result in a speaker being nothing more than a thin sheet of some kind of materal in a frame or just a thin sheet of something hanging on a wall. It probally wont happen in my lifetime though. :lol:

Anyways, back to the thread topic. This looks like its going to realy shake up a lot of oppions on how a MD really works. :lol: :lol: :lol:

Glad to see ya back to making those great hammers and may run into you ove in Irving Texas this year.
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Postby mike1952 » Fri Dec 19, 2008 6:39 am

" There are some develpments in the world of nanotechnology that could well result in a speaker being nothing more than a thin sheet of some kind of materal in a frame or just a thin sheet of something hanging on a wall. It probally wont happen in my lifetime though. "

You mean something like Magneplanar? They are a very thin sheet of something impregnated with wire. They were invented 1969 and are known as one of the best loudspeakers around. You could own the top of the line pair for $10K. I once owned the next one down but they are just too big.
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Postby mrchips » Fri Dec 19, 2008 9:45 am

naw actually based on carbon fibers react to voltage . heady stuff if you look it up.

the ones I was refering to are the electrostatic ones that use a higly chared layer of air ascting as what is the cone in normal speakers. The power suplys for those can be leathel.. The one I was messin with dont fry bugs if they happen to get into that charged field. It litterly expodes one. :lol:
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Postby Ken Bloom » Fri Dec 19, 2008 12:04 pm

All of this bears out what I have been saying for years. There are two analogies that are used for building dulcimers, the guitar approach and the zither approach. In the guitar approach, the bridge sits in the middle of the soundboard (which here is the top) and the whole system functions very much like a guitar.
The zither approach is very different. This is the more common way of building dulcimers. The back is the major soundboard, just like in the modern concert zither. The top is so stiff and full of holes that it can't do a whole lot more than contain the airspace. The back is a nice large plate that can vibrate and is the major air-moving component. The modern concert zither is the same. The top can move but it's area is reduced by two soundholes. The pinblock is glued to the top but not the back. The fingerboard is glued to the top with substantial bracing under it that does not touch the back. The quality of the spruce for the top is of a lesser grade than for the back. I could go on but it's almost Christmas.
The point is that we have two instruments that have a common ancestor that developed along very different lines but still share the same basic physics when it comes to sound production.

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