Top Weight - How much is too much?

[Allen]

I've got this 0M on the go that is going to have a all Raintree (Monkeypod) body, including the top. I've got the top braced in a standard X pattern and very similar to my other 000's / 0M's. The previous guitars have had more traditional tops on them, and have come in at a between 180 and 200 grams. This one however comes in at 320 grams.

The top is at 2.5 mm and the bracing is actually been taken down more than I would have on say a spruce top. The top has a really nice strong ring to it, and has good partial overtones. If I hadn't weighed it, I would have been stoked. Now it's got me a little concerned.

I can thin the perimeter some once the box is closed up. I had planned on doing this anyway. But I'm still going to end up with a top that is probably 1/3 heavier than my conventional ones.

What's everyones thoughts on this?

[Bob Connor]

Not sure Allen, but I've just started on a series of unusual tops as well which include Sassafras, Celery Top Pine (which is actually a hardwood), Huon and Bunyah I'm thinking of throwing Myrtle into that mix as well.

I'll keep you updated as I get through them.

Jeffrey Yong would be the bloke to talk to. He does drop in here from time to time but I think I have his email if you want to get in touch with him directly.

[Hesh1956]

Yep Jeff Yong would be the one to know since he builds with Billy Pod all the time.... He is also a very nice guy and I am sure that he would be happy to help you.

This idea of ultra light-weight tops can be taken to far IMHO. Although I shoot for very light weight tops too this is with spruce, all I have ever used except for RW and WRC. When I get around to a Billy Pod guitar, I have a couple of sets, I am sure that the top weight will be much heavier than spruce because Billy Pod is much heavier than spruce.

If it were me Allen my friend I would be looking for how easily the top rings and not be to concerned about the inherent weight of the wood.

[Taffy Evans]

Hi Allen
My simple way of looking at it is: it will take more energy to move something that is heavy. I would think one will need enough energy to exite the top into moving air within the body. I'd be thinking responce and flexibility, and possible not the weight of the plate. If the weight = strength I'd think about how thin can I go with the top. Thats only what I would do, its not based on any expert knoweledge.

[Allen]

I emailed Jeffry Young and sent some pictures of the top. I bit the bullet and just glued it to the rims. The only way to know for sure is to just do it, so time will tell. I've got a bunch more sets of this wood from the same tree, so if nothing else, it'll be a learning experience. Will keep you up to date with my progress.

[Allen]

Jeff has got back to me with some advice. Says that with the heavier weight of the top, he finds using a heavy bridge (he uses ebony) and brass bridge pins works best.

[graham mcdonald]

Allan,

There are two factors to consider. One is the mass of the soundboard, the other it's stiffness. There is a set amount of energy coming from the strings which gets transferred to the soundboard. The more mass that the soundboard has means more energy gets used up in making it move, rather than being radiated as sound (the soundboard will actually get warmer, I suspect, but not so much that you will notice it). The result will probably be a quieter instrument, but maybe one with more sustain as the extra mass of the soundboard will store the string energy longer. Those instruments I have seen and heard with hardwood soundboards tend to have a more midrange sound, with neither the warmth of the bottom end nor the sparkle in the highs of the best spruce soundboards. Similar in some ways to ladder braced steel strings. Not an unpleasant sound but different.

The other factor is how stiff it is, and that will determine where the resonances lie. It is always useful to listen for and note down where the two major (and easily findable) top resonances are. Hold and 10 o'clock and tap at 4 o'clock and move the fingers around until the lowest clear note is heard. That is you first main top resonance. Then hold at the tail block position and tap in the middle. This will be around an octave higher. If you do that with every instrument and write it down in a notebook, you do build up some data, and when an instrument turns out exceptionally well (or disappointingly, as they sometimes do) you might have a clue to what you did right (or wrong)

Have a look at the UNSW acoustics site for some pics of one of Gerard Gilet's soundboards. This stuff is a very useful tool in trying to understand why stringed instruments do what they do. Looking forward to seeing the finished instrument.

cheers

graham