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Wow!

Thanks for reminding me, Jay.

I use Cladni patterns to 'tune' my tops. Some years ago I was looking at a top, and the patterns were more asymmetric than usual. Then I remembered that I had not put the patch on the X. When I did the symmetry improved, and the pitches went up.

I will have to try and replicate that deflection test if I remember next tiem. That is quite an impressive difference.

I think I remember this topic coming up in the past on this or another forum and one of the old Martin guys (John Arnold maybe?) was suggesting that the weaker cloth patch might actually have something to do with the Martin tone. I thought the idea was a bit crazy but perhaps there is something to it.

Are you thinking of doing it with a cloth patch the next time? That would be very interesting.

I remember reading that same point somewhere too about the flex in the x-brace joint possibly contributing to the Martin sound. If that is so and one wanted to get that effect without the risk of x-brace splitting, then the approach used by Jay Lichty and Michaeldc (fellow OLF member) of reducing the x-brace height at the joint and capping it with a wood cap would be a way to introduce some flex there and at the same time greatly reduce the chance of x-brace splitting from the lap joint in the way mentioned in some of the posts above.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

Oh yes I seem to remember some discussions about the techniques they use. I'd have to think about it. I like the spruce cross cap for it's structural purposes. I suppose one could use a thinner spruce cap to get the same results maybe?.

I have started experimenting with epoxy and CF tow for this purpose.
I laminate several layers 60~70 mm in length over the X joint instead of using cloth.
Pete.

I 'tune' the top using the Chladni method before assembling it to the guitar by shaving the braces. The nice thing about a wood patch is that if I decide to lower the height of the X crossing it's easy to shave it off, and replace it later on. I would not want to do that with an epoxy/CF patch.