Originally posted by guitarbanjoman
...but going back to my original idea... the location of the “bridge” between the two vibrating heads might be an interesting subject for experimentation...
The existing location of the “top” bridge ie the existing bridge that we all have on our banjo heads is about a third of the diameter of the head away from the tailpiece.
This location is determined by at least two things I can think of right now...
- strumming would probably less comfortable if the bridge were in the center of the head
- the banjo neck would probably have to be longer if the bridge were in the center.
But the “inner” bridge, or possibly multiple bridges, could be anyplace we want it to be...
My hypothesis is that putting the “inner” bridge in the very center of the circle would accentuate the longer wave, more bass-y and/or midrange-y tones.
While placing the inner bridge directly underneath the upper bridge would transmit the most powerful vibrations to the lower membrane.
What would happen if there were several small “sound-post” type bridges at different locations between the two membranes? I’m not smart enough to figure that out, maybe you are!
This is similar to the concept of a violin soundpost.
It's basically a way of doubling the sound board because in a violin, the back plate isn't a resonator as much as in a guitar.
It's literally a secondary soundboard because the sound post transmits all the residual vibrations the front plate wouldn't have been able to absorb.
Difference though with a banjo is that you'd create a sealed vacuum as well as producing a secondary sound board.
This is why bass drums are sealed. Sealed vacuum being pressurized upon a strike creates really loud bass tones.
Same as when you smack a bag of potato chips. The pressure crashing up against the walls of the back creates this bassy thump.
This would be obscured slightly by a sound post as you would also get string vibration on the second vellum. I think you'd wind up with a muddy sound because of this.
They way to solved this is to put two holes on either side of the bridge on the top vellum (Like F-Holes)
You can reinforce the holes of that vellum with some metal rings, that way you don't loose pressure on those parts of the vellum as uneven head tension would cause other issues.
Another likely safer way to do this is to use a 10" top head, and then install a 12" head on a banjo resonator of the banjo.
Than install your sound post from the bridge to the resonator's drum head. The trick will be tensioning the head on the resonator, but you could use a tensioning system like that on the Fire Fly banjo.
Edited by - ProperNoun on 02/10/2019 04:50:59
I saw a bho member selling a twin head some years ago. They didn't like it, too heavy and muffling
But in the world of drums, I've seen it in snares, and hedwitschak offers Bodhrans with a 'twin skin' lamination - bodhranmaker.eu/en/fireball
I also think it'd be fascinating to make a heavy central 'dot' on a banjo head like exists in tablas, made of?iron filings and rice powder?. That dot gives them the capability of being highly tonal drums instead of, say, bongos.
'Gibson years' 1 hr