The effect of mass on a guitar's sound

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a_arnold

Posts: 558
Joined: Jul. 30 2006

The effect of mass on a guitar's sound

They say that the best singers are overweight because they can project their voices better. The sound vibrations can't vibrate the rest of their body because of it's mass, and therefore the vibrations are focused in the vocal chords, giving clarity and strength to their sound.

I was struck by a comment someone made on this forum about the effect of heavy machine tuners on the sound of a guitar, and it got me thinking.

I have a negra and a blanca, both made to the same plans by the same luthier, both using a spruce top. The Brazilian rosewood is heavier (I can feel the difference when holding both), and the negra seems to have much more sustain and maybe a little more volume.

And one of Torres' innovations in his later years was to sand the top thinner near the edges so it could vibrate more independently of the rest of the guitar and accelerate more responsively to string vibration -- so the top is dampened less by interaction with the rest of the guitar -- like Pavarotti's vocal chords vibrating independently of his rather stolid, immobile body.

Heavy rosewood, machine heads (and, presumably, steel neck reinforcement, when used) -- not to mention how tightly the guitarist holds the body of the guitar, all affect the effective mass of the instrument, preventing the body of the guitar from moving and absorbing vibration from the top. The less the body moves, the more the vibrational energy has to be dissipated by the top. Ergo, more projection.

So the question: Does the extremely light construction in blancas diminish their sustain? Is this why flamenco guitars have more "punch" than classicals and less sustain? And why my lighter blanca has less sustain than the negra?

Huber's book on "The Development of the Modern Guitar" says that many luthiers maintain that the back/side wood is immaterial to sound, and that the only reason that flamencos traditionally had cypress back and sides was economic -- gypsies were an underclass. Same with pegs. They're cheaper. But now I'm beginning to question that.

Comments?

REPORT THIS POST AS INAPPROPRIATE | Date Apr. 11 2007 3:02:53

Ramón

Posts: 440
Joined: Feb. 23 2005
From: La Jolla, Ca

RE: The effect of mass on a guitar's... (in reply to a_arnold)

Not having THAT much experience to say 'is or isn't', it just seems to vary so much from guitar to guitar. I think that may be the hardest goal for builders; Consistency - given that wood seems so inconsistent.

I had the privilege of playing a 1957 (maybe a '67..?) Archangel 'blanca' flamenco. It was THE LOUDEST, most explosive guitar I have ever heard - even more so than a double-top Ruck, brazilian-wood classical I'd heard play!

Astounded doesn't begin to describe my reaction. I'd asked; "Is this thing plugged in"???? I was blown away.

And it was as light as a feather......

REPORT THIS POST AS INAPPROPRIATE | Date Apr. 11 2007 3:27:18

avimuno

Posts: 598
Joined: Feb. 9 2007
From: Paris, France

RE: The effect of mass on a guitar's... (in reply to a_arnold)

I would tend to agree with you ramon. I have the same experince. I think that the building method and touch of the luthier combined with the dissimilarities in tone woods from guitar to guitar does create very unique instruments. I would tend to think that categorizing tone in terms of rosewood or cypress is only part of the answer of the tone of the guitar. The above mentioned factors are as important. All these incidently make every hand-built guitar unique.
a_arnold, your theory is very interresting though. Although Carreras is also an amazing tenor with a very very powerful voice in a package about 1/3 the size of Pavarotti.

REPORT THIS POST AS INAPPROPRIATE | Date Apr. 11 2007 6:50:55

Per Hallgren

Posts: 241
Joined: Jul. 1 2006
From: Sweden

RE: The effect of mass on a guitar's... (in reply to a_arnold)

Yes, of course mass is important in a vibrating system, difference of speed of sound in different materials also, and stiffness, and...

Building a good guitar is about getting a good balance between all the parts. It is maybe a clichée but that is the SIMPLE truth. An experienced luthier is working with a lot more details in the guitar than the novice and if he manage to build a great guitar it is because he has managed to get all the different parameters, all the small details, to work as a team and not as individuals sometimes working against the team.

REPORT THIS POST AS INAPPROPRIATE | Date Apr. 11 2007 7:12:32

Anders Eliasson

Posts: 5780
Joined: Oct. 18 2006

RE: The effect of mass on a guitar's... (in reply to a_arnold)

quote:

So the question: Does the extremely light construction in blancas diminish their sustain? Is this why flamenco guitars have more "punch" than classicals and less sustain? And why my lighter blanca has less sustain than the negra?

Yes

And cypress is now used because of sound and pegs because of sound and looks.

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Blog: http://news-from-the-workshop.blogspot.com/

REPORT THIS POST AS INAPPROPRIATE | Date Apr. 11 2007 8:39:22

a_arnold

Posts: 558
Joined: Jul. 30 2006

RE: The effect of mass on a guitar's... (in reply to a_arnold)

You're all absolutely right (except I have to say I think Carreras couldn't match the Pavarotti punch. Just listen to the "3 Tenors" PBS show. Granted, Carreras was recovering from an illness at the time, but still...).

Yes, there is a lot more to luthiery than the mass of the guitar, and absolutely it is a balancing act that only experience can achieve. And there will inevitably be miraculous exceptions like Ramon's Archangel blanca.

I know there can't be a simple path to the ultimate guitar (if there even is such a thing). And I know there are other factors. It's just that I have this blanca and negra pair by the same experienced maker (Castillo), and I can feel an obvious difference in mass, I KNOW the mass difference doesn't reside in the soundboard, rather in the back and sides, and I can hear a clear difference in the sustain. Insofar as possible, all other variables are eliminated here. When my wife, who knows nothing about guitars, heard it for the first time from the other room (not knowing I had even received it) she yelled "What happened to your guitar?!?" It's that obvious.
I'm really just asking about the effect of mass.
Maybe the answer is to take Mike Kasha's experimental method. Take a very light guitar and clamp the body (without hampering the top's vibration) so it can't move at all, thus simulating infinite mass, and compare the volume clamped and unclamped. . . someone may have already tried this. I don't know.
Tony Arnold

REPORT THIS POST AS INAPPROPRIATE | Date Apr. 12 2007 13:35:58