Sound post or Under-brace ?

Bob
@bob
11 months ago
129 posts

Ken Hulme:

Ditto on the cross brace -- make it 1/4" x 3/8" with the long side running from the top toward the back.  Place it right under the last bit of fretboard touching the top.  Sound posts are problematic in dulcimers; we mostly do not want the top and back coupled together, but rather want them to each vibrate on their own...

Hi Ken H,

I think I am going to go with the brace that will go right under the last bit of fret board touching the top, right down to the tail piece. This would support the section where a complete fret board would go. Probably add a support right behind the sound holes as well. I hope it's not excessive.

Bob
@bob
11 months ago
129 posts

John Gribble:

On flat top guitars there is a bridge plate, a piece of wood somewhat larger than the bridge glued to the inside beneath the bridge. But this is more to prevent twisting, since the strings are attached to the bridge. On archtop guitars where the strings attack to a tailpiece, there isn't any special bracing under the bridge. But the arch itself is very strong because of the shape. How do you plan to attach the strings? What sort of bridge do you plan to use?

A nice looking instrument, by the way.

Hi John,

I am going to use a tail-piece to attach the strings. (Something akin to a Viola da gamba). The bridge will be attached to a foot which should give some support against a top collapse, and will be unglued o the top. Thanks for your compliment as well :)

Ken Longfield
@ken-longfield
11 months ago
527 posts

I agree with Bob in that you don't need bracing or a sound post. I disagree with Joe and KenH regarding sound posts. Both C. N. Prichard and James Edward Thomas used sound posts. Prichard used one, a square piece of wood about 3/8" x 3/8 inch under the middle of the fretboard. Thomas used two sound posts about the size of a 1/4 inch dowel at the third and tenth frets. When Kevin Messenger built his first Prichard reproduction he did  not know that Prichard used one. Including one on his second build, he noticed a significant increase in the volume (loudness) of the instrument. All of my Prichard and Thomas reproductions use the appropriate sound posts which do not diminish the sound of the dulcimer.

Ken

"The dulcimer sings a sweet song."

robert schuler
@robert-schuler
11 months ago
251 posts

Bob, with a 3/16" top, narrow body and low string break angle you don't need bracing or sound post. They will only serve to dampen the tone...  Robert.

Ken Hulme
@ken-hulme
11 months ago
1,530 posts

Ditto on the cross brace -- make it 1/4" x 3/8" with the long side running from the top toward the back.  Place it right under the last bit of fretboard touching the top.  Sound posts are problematic in dulcimers; we mostly do not want the top and back coupled together, but rather want them to each vibrate on their own...


updated by @ken-hulme: 11/27/16 08:47:38AM
joe sanguinette
@joe-sanguinette
11 months ago
95 posts

i think a cross brace behind the sound holes would be a good idea.  i'm not a fan of soundposts

John Gribble
@john-gribble
11 months ago
72 posts

On flat top guitars there is a bridge plate, a piece of wood somewhat larger than the bridge glued to the inside beneath the bridge. But this is more to prevent twisting, since the strings are attached to the bridge. On archtop guitars where the strings attack to a tailpiece, there isn't any special bracing under the bridge. But the arch itself is very strong because of the shape. How do you plan to attach the strings? What sort of bridge do you plan to use?

A nice looking instrument, by the way.

Bob
@bob
11 months ago
129 posts

So, the 'concept dulcimer' I am building is coming along now, and I have a question...

As you can see by the attached photo (hopefully), the fret-board doesn't extend the length of the top, so there will be need for support under the bridge (the dulcimer top is 3/16" maple, the rest is 1/8" cherry).

One thought is to install a Sound Post inside the body (under the tenor side of the bridge, giving support from the bottom plate).

Another thought is to glue a solid brace inside the top plate (beneath where the lower fret-board would have been).

The aim is to keep the top from collapsing from the tension from the strings on the floating bridge.

Your suggestions would be greatly appreciated!

 

 

Dulcimer  6.jpg
Dulcimer 6.jpg  •  617KB


updated by @bob: 11/28/16 01:55:30PM