OOO without scallopping and live back

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JurgenV
Myrtle
Posts: 74
Joined: Mon Dec 10, 2018 6:58 am
Location: Bavaria, Germany

OOO without scallopping and live back

Post by JurgenV » Sat Aug 31, 2019 6:09 am

Hi again,

I finally started with my two experimental builds. One will be a falcate braced OOO and the other one a x-braced OOO where I aim for the frequency response of a guitar I built earlier. Here I will change from the original scalloped bracing to straight braces as they are used for the J45 in the books so that I have more control over the system.
Thicknessing for both tops already done according to the calculations using the frequencies determined by tapping the plates. Falcate bracing already laminated and the other braces are in preparation. But I still have one problem:

For the falcate OOO everything so far is clear concerning design questions but for the x-brace I still can´t decide if I should use the original (non-live) lattice braced back or if I should go for a live back. At the moment I tend to take the live back because tuning to a specific frequency seems to be easier. Did anyone here experiment how a live back changes the tonal properties of an otherwise standard x-bracing?

Any comments or feedback would be appreciated.

Juergen

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Trevor Gore
Blackwood
Posts: 1605
Joined: Mon Jun 20, 2011 8:11 pm

Re: OOO without scallopping and live back

Post by Trevor Gore » Tue Sep 03, 2019 2:05 pm

A live back will make your guitar sound about 1/2 a size larger, (i.e. a 00 will move toward a 000). This is because the coupling reduces both the main air and main top resonant frequencies and so the guitar sounds stronger in the bass than it otherwise would. The T(1,1)3 peak also helps reduce the amplitude of the T(1,1)2 peak, which can be useful in helping to avoid wolf tones.

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