Virzi on a Dakota Mandola

[DanHouse]

I built Musicmaker’s Dakota mandola kit a few years ago and am not fond of its tone… seems thin and “banjoesque”. I am considering installing a Virzi in it to change the voice. I have read the thread on a Virzi on a flattop so it’s seems feasible. Anyone else try this? …

[Charles E.]

My first thought is that it is over braced thus impacting the tone in an unfavorable way.
Did you induce an arch into the top?

[rcc56]

Yeah, it looks to me like there's enough lumber in that X brace for 2 or 3 mandolas.
If you were to re-profile it to the same shape and contour of the other braces, the instrument might wake up.

[Richard500]

Whatever else a Virzi can do, I’m sure that it adds mass to the top, and that might be the wrong direction.

[peter.coombe]

I doubt a virzi would solve the problem. With flat topped instruments you can get that "banjo" effect to the sound if the edges of the top are too thin relative to the thickness in the center. It can happen with lattice braced guitars if the edges are too thin. The bracing does look a bit hefty, but not knowing the thickness of the top is difficult to say if that is the problem. It is an unusual bracing pattern but should work if the overall stiffness is in the right ball park, but is difficult to say without having the top in my hands. Flat top mandolins and mandolas are a little tricky because they tend to fold inwards from the string pulling force and downwards pressure of the bridge. The top has much less stiffness than a carved top so the bracing does need to make up for the lack of stiffness. Hefty bracing adds mass which is not a good thing for a top. I use carbon fiber tow which allows me to keep the mass low, and it also improves the stability so they stay in tune.

The other thing I have learned from flat top mandolins and mandolas is that the back contributes to the sound, and not in a good way. So if you can shut the back up by making it more massive, the sound greatly improves. Gore and Gilet call that a "dead back" system in guitars, but the back is never completely dead, it will always make some sort of contribution to the sound, but the aim is to minimize that as much as you can. Making a dead back is also tricky because making the back thicker to increase the mass will increase it's stiffness, and too stiff relative to the top is not a good thing. The stiffness is proportional to the cube of the thickness, so stiffness will increase more than the mass which is directionally proportional to the thickness. It is a matter of getting the right balance, and you can only nail that from measurements and experience.

[Tavy]

+1 on the other opinions here (and yes I have built a flat top with a Virzi), if you haven't already done so, those braces can be trimmed so they have more of a triangular cross section (ie taper in thickness towards the top), that removes a lot of mass without compromising stiffness too much. I would also say that those braces could taper in height more towards the ends.

Again if you haven't already done so, it's a good idea to tack the back on lightly with newspaper in the joint, string her up in the white and then you can easily pop the back off, make adjustments and repeat till happy. This allows you to test out 2 or 3 different variations per build and develop a feeling for how bracing effects both tone and strength much more rapidly than you would otherwise.