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Thru-the-top soundpost

Don Noon

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I saw this trick mentioned in another thread on a small viola, and it seemed interesting. This is where you cut a hole under the trebel foot of the bridge, and have it rest on the extra-long soundpost which does not contact the top. I had a pretty poor fiddle that seemed like a good candidate to try it on... Chinese thing that I used for varnish testing; high-density top. The signature modes were in just the right places, but there was some strong stuff around 1000 Hz and very weak "bridge hill", so it sounded ugly.

After conversion, I find the sound much more interesting. It is definitely much less violin-sounding. Unfortunately I didn't keep a spectral data file of the original impact spectrum, but this is generally what happened:

A0 -10Hz +3.0dB

B1- -9Hz +2.7dB

B1+ -7Hz +1.3dB

Additionally, the range up to 2500 Hz appears to be a dB or two stronger, and above that it drops off to be a dB or two weaker.

So the net effect is a stronger and deeper bottom end, a little more midrange power, and less brightness. Sounds like a viola. I might eventually put viola strings on it, but I don't have any right now.

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So the net effect is a stronger and deeper bottom end, a little more midrange power, and less brightness. Sounds like a viola. I might eventually put viola strings on it, but I don't have any right now.

So it is definitely a legitimate instrument. The Welsh Crwth has a long treble bridge leg going straight through to the back. The Euyghur* which I illustrated has a region for the post isolated from much of the top. Maybe one should try making such an instrument as a formal experiment.

*Spellings differ, I don't know where to find it in Wikipedia etc. You recall the political flap when three men called Euyghurs were in Guantanamo. The region is Western China in the .....stan areas. I have also seen a photo of a Pakastani street musician playing one of these instruments. It sounds like a soft violin.

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hello all

i suppose you could say the idea isn't new. it does come up once in a while for discussion.

this mod overcomes the spagetti C string on small violas.

works very well as a 5 string hot rod without having to re-design or build a bigger body.

works amazing well as a baritone violin.

for any fiddlers, jazzers and non-conformists out there, this is the best way to open up a new tonal palette for cheap. its like slapping on a hexacore for the first time.

for classical violinists, 5 strings is the most fun in a few hundred years. but you can't play in the nose bleed positions sul G. (which unfortunately kills the performance of 3/4 of the bleeding-heart violin concertos out there ) classical violists can scream away on the Bowen concerto. the quinton isn't exactly a new idea.

doesn't sound like a violin or a viola really... but very nice and pleasing because it no longer hurts to listen.

doesn't do very well with young or inexperienced musicians because the bridge will shift during tuning and start to buzz against the top.

can be "cured" with a lesson on careful tuning/set up. a hard foam ring can be glued into the hole to reduce the problem

until the next time teacher or luthier gets his or her hands on it for an adjustment.

works best with small thick tops. not so good with thin tops or bigger violas. i want to build this into a 1/16th sized double bass, maybe put in a bass reflex port too. it might do wonders for a Suzuki bass program somewhere. (if it works... home depot here i come!)

but don't take my word for it, i'm no body! try it for yourselves folks, most of us own at least a few vso's don't we?

working on a 6 string with this set up.. will post when ready.



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As the proud owner of one of the few violas that Stradivari made while in Romania in the 1960's, when the back came un-glued, I decided to do some carving, and ultimately did the Hole in the Heart. It worked very well on a 15.5". It changes the possible mode shapes.

the top is no longer locked by the sound post. So it may permit some different low frequency modes. It is true that the bridge can do alarming things when the string tension becomes unbalanced. And the set-up person can not play with the sound post position, but for a beat up student instrument with no intrinsic value, it can be educational to try some things. I have used my hole in the heart on a couple gigs with no adverse results.

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I saw this trick mentioned in another thread on a small viola, and it seemed interesting. This is where you cut a hole under the trebel foot of the bridge, and have it rest on the extra-long soundpost which does not contact the top.

Have you tried inserting a thin wedge between the soundpost and the top? It has been written many times that the function of the soundpost is to produce a node on the top, looks like this would be an easy way to test the idea on a functioning violin.

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I haven't experimented any further with this, other than doing it and checking the response spectrum. Clearly the mode shapes will change, as there is no direct coupling of the back and top thru the soundpost. The change in mode frequencies can not happen without a change in mode shape... barring other changes like regraduation. At the moment, I have some soft foam filling the gap between the soundpost and the edge of the hole, to help keep the post centered. It might be adding some stiffness and damping, but I don't expect it to be much.

With this little diversion, and messing around with Stuart's CF creation, I haven't been getting much done on #5 and #6 lately; I want to get back to work on those before playing around with more experimental things.

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This is a principle used in the Chrotta: http://www.klangwerkstatt-musiktherapie.de...nte/chrotta.htm

Interesting to see the results of the changes as Don showed. A musician friend of mine has a violin that originally was designed with the bridge foot resting on the soundpost. I have also investigated a violin design with such a soundpost, but it was attached to a bar system inside the instrument intended to take up much of the string tension and helping the instrument act like a monopole. Some results were shown in this article (my first): http://www.akutek.info/Papers/AB_Deflection_modes.pdf

Here is a clever method of measuring the radiation efficiency on a naormal violin and a later version of such special violin. www.nvo.com/winmls/nss-folder/musicalacfiles/ICA_ArticleMorset.doc

According to Knut Güettler, the system worked better for the viola design of his.

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violin revoked,

interesting, its sounds like a good idea for an electric violin, they tend to be shrill. Have you done any 5 string electrics?

hello saintjohnbarleycorn

i use my instruments primarily as acoustic rigs, but yes, i remember setting up 2 5-string acoustic/electrics. both were given away and i used these pick-ups glued to the inside of the back: http://windworld.com/products-page/electro...re/piezo-films/ it helps with the shrill quality with most metal/hard piezo pick-ups . i've used schattens from stewmac (link here) in the past, but i wanted something a little more mellow. unfortunately, i chose the 6 inch films and they were too hot and acted more like microphones sometimes. still, a jazzer violinist friend of mine didn't object and used it on a gig the day i gave it to him... brave soul...

presently, i'm still coupling the soundpost to a modified bridge with a steel pin made from a large sewing needle. i hope to make purpose built bridges next time and embed a piezo pick-up right into the bridge. I have spoken to LR Baggs a while back and they told me they do custom installs, but i really want to figure it out for myself :) a pre-amp or EQ will help with the shrill.

a purpose built bridge will also help a little with the nagging premonition of a bridge snapping in half at a gig. the baritone violin vibrates quite violently. we'll see if it holds together for another year.

the overtones from these mods light up my harmonic tree in a very different and strange way. i don't think of them as violas but some sort of musical instrument that requires playing techniques related to the viola family.


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I intend to build a violinish object that will have a very tall bridge resting on a cedar/fir back through an oval sound hole with a stop tail piece on a cedar/fir top. I don't know if anyone previously has experimented with this configuration but I thought I'd try it... I might even incorporate a concave top.



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  • 7 years later...

I have a cheap, factory made violin. I am not a luthier, but I still started modifying it, because a luthier charges more than the instrument is worth - this being said, a handmade instrument should always be fixed at a luthier but this is just a cheap instrument. The varnish was furniture varnish and it made it sound nasal. I took the varnish off and changed the shape of the bridge and it does sound better but I would like it to be darker and more mellow in tone. Could this idea be applied to such an instrument, and if so, should I open the instrument despite having no clamps to close it back on? Is it any way I could do this adjustment without having to open the violin? Thank you.




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My super cheep viola ($70 in 1963,  but hey that included a case!  -  was coming unglued, so, as long as it was open, why not carve a little.  After reassembling, about 100% better.  Then later I heard about 'Hole in the Heart'.  Drilled a hole and cut a chopstick as an extension - About 100% improvement.  


So you have a VSO.  Are you willing to value it at $0.00  and trust yourself to do something.  Whatever happens - you will learn things about yourself and violins!

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  • 4 years later...

The Hutchins Upright Viola works around the playability issue of the Bigger Violas by reorienting the instrument to be played Vertically like a Cello, which means the sound will project towards the walls, but still the Hole in the Heart technique might help improve the sound of those low notes even more.

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