dB levels question?

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chrisbaer
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dB levels question?

Post by chrisbaer » Tue Apr 30, 2019 2:07 am

So, the frequency analysis of viewtopic.php?f=33&t=8478 this guitar looks like this:
BO 1 Final.png
Do the Books discuss varying dB levels in regard to the various T1, T2, T3s? If so, could someone point me to which section? I'm curious why my T1 is so low (and it's consistent across multiple tappings) in this build and what effect that might have on the sound?

Regarding the T1, 2, 3 frequencies, I think I made the top way too tight in this build. I believe I left the braces too long (too close to the sides) and perhaps didn't thin the edges of the top as much as I could have. Even with a heavier bridge than I'd normally use on a Gore/Gilet build, the T1 is still 100+. I think I'll add some side weights to lower the T2 to give more space from the T3. I carved out the back brace based on initial tap testing, but it lowered far more than anticipated when the guitar was finished and strung up. I always seem to be low in the T3, even before carving out the brace. Any suggestions on how to tighten that up?

Thanks as always! Any help is greatly appreciated!!

Chris

chrisbaer
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Re: dB levels question?

Post by chrisbaer » Tue Apr 30, 2019 2:51 am

Lordy, I've had a brain fart here and was thinking of the T1 as the top instead of the T2. Sigh.

So, perhaps the reason for the T2 being a tad lower than my target is the heavier bridge.

Please disregard. :oops:

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Trevor Gore
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Re: dB levels question?

Post by Trevor Gore » Tue Apr 30, 2019 8:40 am

chrisbaer wrote:
Tue Apr 30, 2019 2:07 am
Do the Books discuss varying dB levels in regard to the various T1, T2, T3s?
All I say is that the dB level is uncalibrated. That is due to the uncontrolled tap strength and the recording environment (mic response, mic position, signal strength, room reflections, etc. etc.). To get calibrated dB levels you need a lot more kit, far beyond what your typical guitar maker would want to invest in. Much of the useful information is in the resonant frequencies, which change very little with tap procedure. Having said all that, you can get quite repeatable results as I show in Fig. AI 1-1.

Adding side mass to bring the T(1,1)2 down to 170Hz should give you a close to "text book" result.

chrisbaer
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Re: dB levels question?

Post by chrisbaer » Wed May 01, 2019 2:09 am

[/quote]
Adding side mass to bring the T(1,1)2 down to 170Hz should give you a close to "text book" result.
[/quote]

Great! I thought as much. Thanks!

Chris

chrisbaer
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Re: dB levels question?

Post by chrisbaer » Wed May 01, 2019 3:52 am

I added 230g (115g on each side) and this is the new spectrum analysis:
BO 1 Final 230g.png
I'm going to call that good!!

Thanks all!

Chris

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Trevor Gore
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Re: dB levels question?

Post by Trevor Gore » Wed May 01, 2019 9:03 am

Well done, Chris! The numbers look good, but how does it sound?

chrisbaer
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Re: dB levels question?

Post by chrisbaer » Wed May 01, 2019 10:05 am

It sounds great, Trevor! I think the extra weight opened up the low end just a little bit, which I thought was a little lacking. The volume is great and the whole instrument has a 'choral' quality to it. If you let a chord (or even just a single note with a little vibrato on it) ring, there is just a whole different level of complexity from other guitars I've owned in the past.

I'm hoping to meet up with a friend of mine later this month who's a world-class guitarist and get some really good recordings. I'll post clips when that happens.

Thanks again!

Chris

chrisbaer
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Re: dB levels question?

Post by chrisbaer » Sat Jun 01, 2019 3:17 am

I was finally able to visit a guitarist friend and get some sound clips. It's pretty amazing to listen to a good guitarist play your instruments!
Anyway, here are a few sound clips. They were recorded with a handheld Tascam DR-40x (which I just got... I'm super happy with the quality of the recording!). They were pretty loud on my system, so if anyone listens, turn the volume down to start.

https://drive.google.com/file/d/1l5zeOl ... sp=sharing
https://drive.google.com/file/d/1Vd8eF- ... sp=sharing
https://drive.google.com/file/d/1QhYEsj ... sp=sharing

He loved the tone, but suggested a less wide fretboard and slightly lower action. I'm starting my next build, so I'll try shrinking the neck down a bit.

Dave M
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Location: Somerset UK

Re: dB levels question?

Post by Dave M » Sun Jun 02, 2019 3:48 am

Great sounding guitar - and great playing. As you say hearing one of your instruments played properly by someone is a great feeling.
------------------
Dave

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