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Old 01-29-2009, 05:32 AM
taylorcc taylorcc is offline
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Default Archtop break angle

Is loudness a function of break angle?

On a flat top guitar as the saddle is lowered the string break angle decreases and loudness tends to diminish, or so the conventional wisdom goes.

On archtops with tailpieces the break angle is very very low. So, do archtops with tailpieces have less loudness than flattops? Why or why not? Discuss
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  #2  
Old 01-29-2009, 06:06 AM
Bruce E Bruce E is offline
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Originally Posted by taylorcc View Post
Is loudness a function of break angle?

On a flat top guitar as the saddle is lowered the string break angle decreases and loudness tends to diminish, or so the conventional wisdom goes.
Not entirely. The saddle is a lever arm which moves the top. When the saddle is lowered the length of the lever arm is shortened.

Quote:
On archtops with tailpieces the break angle is very very low. So, do archtops with tailpieces have less loudness than flattops? Why or why not? Discuss
The heighth of the bridge on an archtop is usually quite a bit more than those on flat tops. It is the lever arm that does the real work in exciting the top. The break angle of the strings establishes a quiescent force, or bias point around which the strings excite the sounding board, and there doesn't seem to be a direct relationship of break angle to loudness. There only needs to be "enough." I've read that Gibson has determined an optimum break angle for flat tops, but I don't recall how much it is.

Interesting discussion. I am eager to read other opinions.
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Old 01-29-2009, 08:49 AM
Howard Emerson Howard Emerson is offline
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Originally Posted by taylorcc View Post
Is loudness a function of break angle?

On a flat top guitar as the saddle is lowered the string break angle decreases and loudness tends to diminish, or so the conventional wisdom goes.

On archtops with tailpieces the break angle is very very low. So, do archtops with tailpieces have less loudness than flattops? Why or why not? Discuss
Actually a GOOD acoustic archtop is always louder than a good flat-top. Why do you think they were used to replace the banjo in orchestras back in the 1920's?

Carved archtops are built on the same principle as violins, with the top being compressed by the strings/bridge pushing down on it. What they lack in sustain, like violins, they make up for by being loud and being able to cut through other instruments.

Of course then there are archtops, like my 1927 Gibson L-5, which I use for bottleneck, because it also has quite a bit of sustain, but that's a different story.

HE
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Old 01-29-2009, 11:13 AM
Howard Klepper Howard Klepper is offline
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Originally Posted by taylorcc View Post
Is loudness a function of break angle?

On a flat top guitar as the saddle is lowered the string break angle decreases and loudness tends to diminish, or so the conventional wisdom goes.

On archtops with tailpieces the break angle is very very low. So, do archtops with tailpieces have less loudness than flattops? Why or why not? Discuss
Neither of the two assumptions is always true. The answer to the archtop vs. flattop question is no.

Loudness (as opposed to volume) is a subjective impression, influenced heavily by frequency and transients. Break angle (once sufficient to get good vibration transfer and hold the strings in place) affects overtone series far more than it does volume. That may be heard as a change in loudness, since, other things being equal, trebles make a louder impression for a given volume than does bass. Put another way, your guitar may be moving more air than that banjo in the next room
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Last edited by Howard Klepper; 01-29-2009 at 11:18 AM.
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Old 01-29-2009, 11:25 AM
Howard Emerson Howard Emerson is offline
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Neither of the two assumptions is always true. The answer to the archtop vs. flattop question is no.

Loudness (as opposed to volume) is a subjective impression, influenced heavily by frequency and transients. Break angle (once sufficient to get good vibration transfer and hold the strings in place) affects overtone series far more than it does volume. That may be heard as a change in loudness, since, other things being equal, trebles make a louder impression for a given volume than does bass. Put another way, your guitar may be moving more air than that banjo in the next room

Ah, yes, Howard, but that banjo will make a louder bang when tossed into an empty trash can............

HE
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Old 01-29-2009, 12:12 PM
guitar_stringer guitar_stringer is offline
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Originally Posted by Bruce E View Post
Not entirely. The saddle is a lever arm which moves the top. When the saddle is lowered the length of the lever arm is shortened.



The heighth of the bridge on an archtop is usually quite a bit more than those on flat tops. It is the lever arm that does the real work in exciting the top. The break angle of the strings establishes a quiescent force, or bias point around which the strings excite the sounding board, and there doesn't seem to be a direct relationship of break angle to loudness. There only needs to be "enough." I've read that Gibson has determined an optimum break angle for flat tops, but I don't recall how much it is.

Interesting discussion. I am eager to read other opinions.
This is in-accurate.

An archtop guitar with a tailpiece, relies solely on downforce acting on the bridge, to excite the top. No lever arm exists in this state. The only fulcrum (lever arm) applications exist on fixed type bridges (flat tops or dome tops), where the string break angle imparts a torque (levered) moment on the bridge.
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  #7  
Old 01-29-2009, 05:39 PM
Bruce E Bruce E is offline
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Originally Posted by guitar_stringer View Post
This is in-accurate.

An archtop guitar with a tailpiece, relies solely on downforce acting on the bridge, to excite the top. No lever arm exists in this state. The only fulcrum (lever arm) applications exist on fixed type bridges (flat tops or dome tops), where the string break angle imparts a torque (levered) moment on the bridge.
OK, I agree I didn't explain myself as clearly as I meant to. The bridge of the archtop works more in an up-down pumping motion than a bridge on a flat top. I agree. But are you implying that the bridge of an archtop has no rocking motion (torque) whatsoever? I'm having a hard time with that concept. Please elaborate.
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  #8  
Old 01-29-2009, 06:26 PM
Howard Emerson Howard Emerson is offline
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OK, I agree I didn't explain myself as clearly as I meant to. The bridge of the archtop works more in an up-down pumping motion than a bridge on a flat top. I agree. But are you implying that the bridge of an archtop has no rocking motion (torque) whatsoever? I'm having a hard time with that concept. Please elaborate.
The bridge is not connected to the top by anything other than friction, and therefore there is no pulling of the top by the 'rocking motion', however little, that is created while tuning, or bending a string, for instance.

HE
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  #9  
Old 02-02-2009, 06:43 AM
taylorcc taylorcc is offline
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After I posted the question about break angle it occurred to me that guitars with pinless bridges have a rather low break angle with no effect on loudness or volume.

So far I've learned from this thread that:

- for archtops with tailpieces the bridge / saddle is high so there is sufficient break angle and down force to get the top moving.

- there is a correlation between break angle and loudness / volume but it's not linear. Rather low break angles can be sufficient to get a guitar top moving.

Thanks for the replies so far.
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2009 CA Cargo Raw, 2006 Collings OM-1 SS light build, 2004 Taylor 714ce, 2000 Taylor 310K, 1991 Martin HD-28, 1971 Martin 0-18, 1967 Guild F-30

2006 Ovation Legend 6756LX 12 string, 2004 Taylor 354ce 12 string, 1976 Guild G312-NT 12 string (dreadnaught shape)

1966 Martin T-15 tiple, Mele koa ukulele
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