Un-coupled top frequency

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AKEric
Sassafras
Posts: 41
Joined: Fri Sep 28, 2018 1:29 pm

Un-coupled top frequency

Post by AKEric » Tue Apr 26, 2022 4:58 am

Hello,

I'm determining the monopole mobility of a just finished steel string. I need to find the UN-coupled tops main frequency. The strings are off, and the sound hole is plugged with a cut off sour cream container. When I tap it into the analyzer with no saddle or bridge pins I get 188hz. With a finished saddle and pins installed I get 178hz.

It doesn't make a huge difference when I plug it into my monopole spread sheet, but which one would be the more accurate one?

Thanks for any help,

Eric

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Trevor Gore
Blackwood
Posts: 1562
Joined: Mon Jun 20, 2011 8:11 pm

Re: Un-coupled top frequency

Post by Trevor Gore » Tue Apr 26, 2022 8:25 am

AKEric wrote:
Tue Apr 26, 2022 4:58 am
Hello,

I'm determining the monopole mobility of a just finished steel string. I need to find the UN-coupled tops main frequency. The strings are off, and the sound hole is plugged with a cut off sour cream container. When I tap it into the analyzer with no saddle or bridge pins I get 188hz. With a finished saddle and pins installed I get 178hz.

It doesn't make a huge difference when I plug it into my monopole spread sheet, but which one would be the more accurate one?

Thanks for any help,

Eric
The one with the pins and saddle, and also the strings (not necessarily tensioned). These all add mass and so change the uncoupled frequency. The pins also seal the bridge pin holes, which makes a difference, too. Effectively, you're looking for the monopole mobility with the guitar as close to playing condition as you can reasonably get it, then keep that condition standard so you can compare between guitars.

AKEric
Sassafras
Posts: 41
Joined: Fri Sep 28, 2018 1:29 pm

Re: Un-coupled top frequency

Post by AKEric » Wed Apr 27, 2022 2:11 am

Thanks so much Trevor. This makes a lot of sense. It seems like doing the plate deflection test with the strings on would be a good idea for the same reason.

Eric

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