Violin Forum/Message Board

[John Cadd]

While I have been dabbling with my new guitar I was having trouble with too much sympathetic resonance in some pieces.
This ,I discovered was due to the air resonance not quite matching the top and back resonances.
I did a little test to alter the internal air resonance by partially blanking off the soundhole.By reducing this hole the air resonance is lowered.I found an overlap of approx 2.5 cms cured the problem and even better made the guitar much nicer all round for tone (richer and fruitier).
As a separate exercise.-------
If I drop a piece of foam rubber inside the guitar the resonance frequency will go in the opposite direction.
This second exercise is less likely as the guitar top would have been made too thin and in all probability would have collapsed.
The violin, being a delicate creature,will not like too much brutal treatment but a few small pieces of foam rubber will suffice .Just use some cone shapes in the circular holes.It will be very educational.I know for a fact that some makers don`t tune the backs and bellies so there could be some interesting results .
A more permanent "fix" would be a piece of black paper inside a hole (not too visible).

[Dave Chandler]

What if you think the problem is the other way around -- that you need larger openings? How would you check?

I do like your idea of closing off an area to see how it affect the sound. Worth trying.
_________________
Dave in the Blue Ridge
Southern Violin Association

"Success is the ability to go from one failure to the next with no loss of enthusiasm" Winston Churchill

"I took the road less travelled, and now I don't know where I am." Marco Polo

[John Cadd]

I would hate to try to open out a violin soundhole but some instruments by Guarneri look as if he did that himself when they were already made.The air volume is not too difficult to control although if the sides move before gluing you have a more complicated situation
That would mean if the SIDES get ;

closer the resonance will be a bit high.--Needing smaller hole(s)

further away resonance will be a bit low.---Needing bigger hole(s).
This shows up more if you look up guitar sites.It`s an awkward thing to adjust in a violin.

[John Cadd]

Sorry I left out half your question.Blanking off part of the hole reduces air resonance.To do the opposite start with a piece of foam rubber inside the body.(very squashable)If you find this makes a better sound you could glue in some balsa wood in positions that would not interfere with the acoustics internally (not necessarily one single piece and not all in one place).I shall get into a lot of trouble saying all this.
The violin police will be shooting me down in flames or losing my message completely.How about layers of balsa glued to the bottom block?Also see what noise it makes if you fill the violin with Helium.