Seeking "breath" and "chime"

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dshaker
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Location: Palo Alto, California

Seeking "breath" and "chime"

Post by dshaker » Thu Sep 04, 2014 6:02 am

I took my first falcate-braced guitar to a gathering of musicians last week and most of the folks were very nice, but no one got any greedy looks in their eyes, though that's what I would have really liked.

One particularly good guitarist and guitar seller - someone whom would be interested in selling my guitars if they were particularly seductive - he said he thought the sound was lacking "sparkle". I assume that this comment, translated into the Gore standard terminology, would be "needs more 'breath' and 'chime'", where
breath = a band around 8400 hz
chime = a band around 4000 hz

I need to confirm this for myself with a recording, a quiet room, a good set of headphones, and audio editing software, but if I concur with this fellow, the next questions will be:

Is there any modification I can do to the completed guitar to enhance those frequencies?
How should I modify future builds to enhance those frequencies?

I expect there are answers in The Books, but 30 minutes of searching didn't reveal them
to me. Maybe its time for a re-read...
-Doug Shaker

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Trevor Gore
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Re: Seeking "breath" and "chime"

Post by Trevor Gore » Sat Sep 06, 2014 10:18 am

Hi Doug,

Can you please post some more details of what you built, e.g. guitar size, bridge mass, monopole mobility and main resonance frequencies?

dshaker
Myrtle
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Joined: Sat Aug 31, 2013 6:38 am
Location: Palo Alto, California

Re: Seeking "breath" and "chime"

Post by dshaker » Tue Sep 09, 2014 4:52 am

Trevor-

I'll need to measure the monopole mobility. It may be the weekend before I get to it, but I'll get there.

The shape is a classical guitar shape, taken from someone or other's measurements of Segovia's Hauser,
though the strings are steel strings. The bridge mass is 26 grams.

Do you have a preferred condition for the main resonance measurement? Strings on or off? Soundhole plugged or open?

Thanks,

Doug Shaker
-Doug Shaker

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Trevor Gore
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Re: Seeking "breath" and "chime"

Post by Trevor Gore » Tue Sep 09, 2014 9:08 am

dshaker wrote: Do you have a preferred condition for the main resonance measurement? Strings on or off? Soundhole plugged or open?
For straight-forward resonance measurement, the guitar should be in the condition you play it in: strings on, tuned, sound hole not plugged. The procedure for monopole mobility measurement is somewhat different and is in the book (P1-90).

dshaker
Myrtle
Posts: 77
Joined: Sat Aug 31, 2013 6:38 am
Location: Palo Alto, California

Re: Seeking "breath" and "chime"

Post by dshaker » Tue Sep 09, 2014 2:05 pm

I just reread the procedure for measuring the monopole mobility and I appear to have been overthinking it. Is the following correct for measuring the stiffness, K:

1. Put the guitar on its back.
2. Put approximately 1 kg on the soundboard, near the bridge.
3. Measure how far the soundboard sinks under this load. You will need to use a method of measurement accurate to 0.1 mm, at least. Accurate to 0.01 mm would be better.
4. Divide the weight, in grams, by the deflection, in millimeters. The result is the stiffness K.

Is this correct?
-Doug Shaker

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Trevor Gore
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Re: Seeking "breath" and "chime"

Post by Trevor Gore » Tue Sep 09, 2014 4:28 pm

dshaker wrote:Is this correct?
Nearly.

You'll need to convert the mass you use as a weight (say 1 kg) to newtons (force), by multiplying by the gravitational constant g (= 9.81 metres per second squared). So 1kg weight = 9.81 newtons force. Here's a pic of the rig I use:

viewtopic.php?f=1&t=4358#p51461 (second pic down).

There are a few more pics in this thread:

viewtopic.php?f=33&t=5464#p62894.

You'll definitely need a dial gauge or similar, but you probably have one for measuring thickness, anyway.

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