dark & thick sound = poor projection

Construction and repair of Classical Guitar and related instruments
Dave M
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Re: dark & thick sound = poor projection

Post by Dave M » Mon Mar 05, 2018 9:08 pm

This interesting discussion suggests to me that I should reevaluate my last classical build with which I was very disappointed. It seems when I am playing it to be rather low volume (for whatever that term may mean!) particularly in the trebles. Perhaps to a listener at some distance it my actually be better than I think.

These properties as described above make the evaluation of a given instrument much more complicated than at first thought.
Dave

chiral3
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Re: dark & thick sound = poor projection

Post by chiral3 » Mon Mar 05, 2018 9:19 pm

The other thing that hasn't been mentioned here is how much a player "plays into" the guitar. Earlier Vesa stated correctly that it's about the higher harmonic intensity, which will have less dispersion. I have some thick top, 9-fan guitars that myself and others have built that really get loud and somewhat beam when played into. Beaming really has nothing, technically, to do with directionality, and more to do with dispersion. These are guitars that no matter how hard I play into them they never break up. Clear trebles with great separation. The fundamentals aren't as strong though.
"Life is under no obligation to give us what we expect" - Margaret Mitchell

astro64
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Re: dark & thick sound = poor projection

Post by astro64 » Mon Mar 05, 2018 9:49 pm

chiral3 wrote:
Mon Mar 05, 2018 9:19 pm
The other thing that hasn't been mentioned here is how much a player "plays into" the guitar. Earlier Vesa stated correctly that it's about the higher harmonic intensity, which will have less dispersion. I have some thick top, 9-fan guitars that myself and others have built that really get loud and somewhat beam when played into. Beaming really has nothing, technically, to do with directionality, and more to do with dispersion. These are guitars that no matter how hard I play into them they never break up. Clear trebles with great separation. The fundamentals aren't as strong though.
So this already gets very confusing then. Someone earlier mentions that it is the "fundamental" that carries, not the higher harmonics. Also, in my understanding of "beaming", it is very much the same as directionality. We must have a different understanding of the term "beam". For a radiating surface, the "beam" specifies both the direction and angular width of the emitted signal (isn't the width here the "dispersion" of the signal?). Lastly, a guitar may not break up even when played hard, but did you meant that these instruments actually get louder when played hard or do they just not break up (i.e. don't turn into a more percussive sound) but also don't get much louder?

chiral3
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Re: dark & thick sound = poor projection

Post by chiral3 » Mon Mar 05, 2018 10:33 pm

Astro64, good points. I meant to separate hearing louder, father away from beaming and directionality (via dispersion). The fundamental will, to your point, dominate near field, but it's the intensity (as in dBs) of the higher harmonics that matter farther out. I've noticed that the stiff tops, or tops with higher effective mass, have a quality that you can play into them and you get a disproportionate output. I have paper printouts of spectrums somewhere in my shop but, when I was playing around with these Fleta/Hauser variations, I noticed this behavior. A good example of a powerful player that exploits this (besides me :D ) is Jorge Cabellero. He plays a guitar with a thick top with, I believe, 9 fans and a diagonal cross strut.


Maybe one other way to say it is that there's more beaming as the wavelength gets smaller relative to the radiative size of the source. You could turn this on its head and say it's because there's less dispersion.
"Life is under no obligation to give us what we expect" - Margaret Mitchell

chiral3
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Re: dark & thick sound = poor projection

Post by chiral3 » Mon Mar 05, 2018 10:46 pm

By the way, one thing that I've always theorized plays into the subjective perception of everything we are talking about are the equal-loudness contours. Obviously a builder isn't building a transducer with a flat response, but humans are more sensitive to certain parts of the spectrum. I brought this up a few years ago on the forum and I don't recall it getting much discussion. I guess it's something we don't think about too much.

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astro64
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Re: dark & thick sound = poor projection

Post by astro64 » Tue Mar 06, 2018 4:55 am

Ok, chiral3, I think we agree.

Alan Carruth
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Re: dark & thick sound = poor projection

Post by Alan Carruth » Tue Mar 06, 2018 5:30 pm

'Beaming' is, I think, a function of the way the top (in particular) works at higher frequencies. In the low range the lower bout of the top pretty much works like a loud speaker cone, moving in and out as a unit: a 'monopole'. This starts to break up somewhere above the pitch of the open G string (usually) when the top 'cross dipole' mode gets going. The bridge is rocking from left to right around the center line. Half of the top area will be in phase with the monopole (which is still working, even if it's not at as high an amplitude) and half out of phase, so the sound starts to be projected in a different direction. This shifts suddenly as you actually pass the dipole resonant pitch, and the motion of the dipole goes from being in phase with the string to out of phase, while the monopole motion stays the same. This shows up quite clearly if you measure the sound output of the guitar in different directions as you go up in frequency.

As you go higher in pitch the top breaks up into more and more smaller areas, each of which is out of phase with it's neighbors. What you hear coming off the top is a sort of sum of the sound coming off all the different areas, and it adds up differently depending on which direction you are looking at. You can, of course, think of the sound hole as just another top area. The top with the hole is a 'phased array'. Close up a lot of the sound simply cancels out, but as you go farther away one or another direction predominates, and the sound is 'beamed' out.

I remember one Classical 'shoot out' at a GAL convention that was held in a class room at the college. Folks in the back of the room said that one guitar was a 'cannon'. I was near the front of the audience and thought it was nothing special. The player said he could barely hear it, and Dana Bourgeois, who was running the test and stood off the player's right elbow, said he could not hear it at all.

FWIW, I have noticed that it's often the 'better' guitars that do this, although seldom to such a degree. In a hall that is properly set up for music (the classroom was, of course, designed for speech) there is enough mixing to give all of the audience a good sound. As I mentioned before, a well made and 'balanced' top can still project well at high frequencies, even if it was designed and built to accentuate the lows. It's hard to do that, though: usually it seems to be the thicker tops ,or, at least, those that are very stiff for the weight, that do it.

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geoff-bristol
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Re: dark & thick sound = poor projection

Post by geoff-bristol » Wed Mar 07, 2018 1:42 am

Dave M wrote:
Mon Mar 05, 2018 9:08 pm
This interesting discussion suggests to me that I should reevaluate my last classical build with which I was very disappointed. It seems when I am playing it to be rather low volume (for whatever that term may mean!) particularly in the trebles. Perhaps to a listener at some distance it my actually be better than I think.

These properties as described above make the evaluation of a given instrument much more complicated than at first thought.
Have you tried different places to play it ? I was amazed at my small kitchen. If I play properly I sit and face the back door - thats how I always sit there. However - if I just turn around and face the other way, it like playing a different instrument !

Also - give it time to open up. If its little overbuilt that not a bad thing - but everything that might 'settle' in take so much longer - maybe months rather than a week or so strung to pitch ?

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fast eddie
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Re: dark & thick sound = poor projection

Post by fast eddie » Sat Mar 31, 2018 5:12 am

Alan Carruth just gave the best explanation (above) of the physics of guitar acoustics that I have found thus far. Thanks very much. I am able to follow it because my last job was research in Underwater Acoustics. Many of these concepts translate to guitar acoustics.
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vincentx
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Re: dark & thick sound = poor projection

Post by vincentx » Sat Mar 31, 2018 9:01 am

Had the same experience. But I don't think dark & thick is the problem. Projection and loudness don't mean the same thing. And the guitars with powerful fundamental tone projects way better than these with lots of overtones.
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Stephen Faulk
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Re: dark & thick sound = poor projection

Post by Stephen Faulk » Sat Mar 31, 2018 10:18 am

I was with a partner who was a soprano for a long time. She explained all this to me in terms of singers. She said listen to Bidu Sayao, even on a recording you can hear the difference between loudness and projection. Then listen to so and so modern singer trained to be loud and dark...it becomes wooly and loose the farther you sit from them.

Her teacher was alive at the time, an older woman in her 80's who had sung at La Scala and was trained in Italy in the 1940's. I talked to her on several occasions about sound and projection, Iearned a lot from those two singers. She told me the stories of working, being trained by a horny old Italian man who chased her young self around the piano, but evidently at the time he knew more about bel canto than anyone alive. She was fond of saying "Fat does not resonate, it's your skull." She also said he never caught me.

Sopranos are difficult and tricky, but if you manage to build a guitar like with a voice Bidu Sayao, you've got something. After having spent time with those two generous and wise bel canto ladies I've never gone back to talking about guitar sound as abstract, it always about the human voice. Dark and wooly is ok, but high partial support like a resonating skull is better.
Patience at the bending iron pays in rounded dividends!

SteveL123
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Re: dark & thick sound = poor projection

Post by SteveL123 » Sat Mar 31, 2018 2:30 pm

Stephen Faulk wrote:
Sat Mar 31, 2018 10:18 am
I was with a partner who was a soprano for a long time. She explained all this to me in terms of singers. She said listen to Bidu Sayao, even on a recording you can hear the difference between loudness and projection. Then listen to so and so modern singer trained to be loud and dark...it becomes wooly and loose the farther you sit from them.

Her teacher was alive at the time, an older woman in her 80's who had sung at La Scala and was trained in Italy in the 1940's. I talked to her on several occasions about sound and projection, Iearned a lot from those two singers. She told me the stories of working, being trained by a horny old Italian man who chased her young self around the piano, but evidently at the time he knew more about bel canto than anyone alive. She was fond of saying "Fat does not resonate, it's your skull." She also said he never caught me.

Sopranos are difficult and tricky, but if you manage to build a guitar like with a voice Bidu Sayao, you've got something. After having spent time with those two generous and wise bel canto ladies I've never gone back to talking about guitar sound as abstract, it always about the human voice. Dark and wooly is ok, but high partial support like a resonating skull is better.
Had to search for "bel canto" in google, where "other people also asked what is castrato".
I wouldn't want my guitar with good sound and projection to be called a castrato. :wink:

Alan Carruth
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Re: dark & thick sound = poor projection

Post by Alan Carruth » Sat Mar 31, 2018 11:07 pm

Stephen:
Thank you.

Some time back the amateur chorus I sang with performed Elgar's 'Gerontius'. Mezzo Victoria Livengood was the Guardian Angel. Her first solo entrance in that role was the line 'Hail, man and brother, hail!". I was behind her in the chorus, and the hair on my neck stood up. She had a tag line: "Alleluia, and praise to His name!" that she sang from time to time. When Gerontius' soul went before the throne of God to be finally judged among the elect, she sang it out full voice. If she'd sung it twice I'd have had to sit down. That's the sound I want in my guitars.

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Re: dark & thick sound = poor projection

Post by Stephen Faulk » Sat Mar 31, 2018 11:50 pm

Alan,
I hear the way you hear, I want the bass to have a resonant nature that you hear in the richness given by upper range resonance distributed through the bass. The problem is not making basses in classical-flamenco-nylon guitars, it's making treble sing. But the problem is where to stop featuring enough high partial to give the whole guitar beautiful color and support. Too much overtone is annoying, it gets in the way. It's not natural, and we want a natural guitar that speaks without being forced, but when pushed will not break up at a reasonable hard push.

Another observation about high partial being present is that I've worked with flamenco performers a lot and many of them prefer guitars that are flatter in high partial profile. They almost want guitars that have very little high partial support that is noticeable, they want it subdued. The reason is that they work with microphones and often guitars that are a little on the high partial hot side, which sound good when played by the right player unamplified, can be difficult to manage on stage in different venues with different sound techs and systems. So often whether they under stand this consciously of are hearing it they pick guitars that are natural sounding to flamenco, but are what I call 'backed off' the full potential of blooming out out with high partial support. You have to underplay the high partial in a way that gives the guitar a rich natural voice, more like Ben Webster, or Dexter Gordon playing tenor sax, and still let it have the power.

So as mentioned above one effective way to get the high partials underplayed is to mess with the cross dipole, make it softer, make it more open and loose. But too loose and you get a breathy underpowered guitar. That's why super good flamenco guitars are elusive, the backing off has to be just right. That said, many flamenco players can work with guitars that are slightly more over tone present. Back to the singer, flamenco guitars to me reflect the voice of a natural flamenco singer, a person who allows that part of the voice to have that Ben Webster color.
Patience at the bending iron pays in rounded dividends!

Alan Carruth
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Re: dark & thick sound = poor projection

Post by Alan Carruth » Sun Apr 01, 2018 7:44 pm

The cross dipole helps in several ways, but there is more to it than that, for sure. I pay a lot of attention to the spectrum between, say, 600-1000 Hz, the lower part of the 'resonance continuum', where it seems as though the number of peaks and the peak-to-dip ratio matters in the timbre. There's an old study by Mathews and Kohut on this. If I can find it I'll post a pointer.

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