MIMF

Hello All,

My name is Matt and I am an amateur builder. I have made a few acoustic guitars which you can check out at my site:

http://www.customguitarbuilding.com

The latest guitar I made has plenty of warm bass resonance and volume due to forward shifted, scalloped bracing, and is very light overall because I used Spanish Cedar for the neck. However, it lacks the sustain of my cheapy smaller bodied Vintage V300. That guitar is much heavier and smaller though. You can see and hear the guitar here:

https://www.youtube.com/watch?v=KCcO...&nohtml5=False

I wonder if there is a trade off between having an extremely responsive top where the energy quickly dissipates and the sustain.

Just want those plucked notes to last longer on the next build without losing volume and warmth.

Any thoughts appreciated

Matt

Hi Matt,
A responsive top is the main objective in the quest for volume, tone and projection.

But you are on the right track regarding energy dissipation. The answers can be found in construction of the back and sides, particularly the sides. Dense rigid linings will help a lot. I use 3 X 2.5 mm laminated oak or ash for my top linings. Maple will work just as well. You can also improve the lower bout foundation by using maple for the lower transverse bar. This should tie firmly into the linings for maximum rigidity. Back linings can be 2 X 2.5 mm laminated from the same wood as the top linings.

You may get still more sustain by doubling up on the sides. When I do that I use 2 X 2 mm laminated sides. Usually both inner and outer are of the same wood.

Going to the back, you can make it a little heavier, say 2.5 mm and use denser wood for the brac es such as mahogany. Some also use a pair of longitudinal braces, one on either side of centre.

Matt Hammond wrote:I wonder if there is a trade off between having an extremely responsive top where the energy quickly dissipates and the sustain.

In this interview, Matthias Dammann explained the relation between volume and sustain as a psychoacoustical phenomenon:

Sustain is another phenomenon, which is connected to the psychology of hearing. The ear does not hear the actual tone duration. It hears the sound volume ratio of the transient to the decaying sound. An instrument is loud only after the transient oscillation. The decay is - even in the loudest guitar - always quiet. The ear perceives the at the beginning strong, then decaying curve of the sound volume and gets the impression that the sound is short and percussive. If one checks this however with measuring techniques, one can see that in a loud instrument, the sound is just as long, as in a quiet instrument, to which one attributes very much sustain. But the ear “feels” subjectively. A loud instrument is therefore felt more percussive with less sustain. The percussive element is for me an essential characteristic of the guitar sound.

Wow, thanks for the info..very interesting...

Michael Lazar wrote:Hi Matt,
A responsive top is the main objective in the quest for volume, tone and projection.

But you are on the right track regarding energy dissipation. The answers can be found in construction of the back and sides, particularly the sides. Dense rigid linings will help a lot. I use 3 X 2.5 mm laminated oak or ash for my top linings. Maple will work just as well. You can also improve the lower bout foundation by using maple for the lower transverse bar. This should tie firmly into the linings for maximum rigidity. Back linings can be 2 X 2.5 mm laminated from the same wood as the top linings.

You may get still more sustain by doubling up on the sides. When I do that I use 2 X 2 mm laminated sides. Usually both inner and outer are of the same wood.

Going to the back, you can make it a little heavier, say 2.5 mm and use denser wood for the brac es such as mahogany. Some also use a pair of longitudinal braces, one on either side of centre.

Right ok....all very interesting

Markus Schmid wrote:

Matt Hammond wrote:I wonder if there is a trade off between having an extremely responsive top where the energy quickly dissipates and the sustain.

In this interview, Matthias Dammann explained the relation between volume and sustain as a psychoacoustical phenomenon:

Sustain is another phenomenon, which is connected to the psychology of hearing. The ear does not hear the actual tone duration. It hears the sound volume ratio of the transient to the decaying sound. An instrument is loud only after the transient oscillation. The decay is - even in the loudest guitar - always quiet. The ear perceives the at the beginning strong, then decaying curve of the sound volume and gets the impression that the sound is short and percussive. If one checks this however with measuring techniques, one can see that in a loud instrument, the sound is just as long, as in a quiet instrument, to which one attributes very much sustain. But the ear “feels” subjectively. A loud instrument is therefore felt more percussive with less sustain. The percussive element is for me an essential characteristic of the guitar sound.

Damman's guitars are very loud. They are also known for lack of sustain and a tone that is described in terms like "nasal", "artificial", "disorienting", "off putting" and so forth. Guitars like Damman"s (Double Top) and/or Smallman"s (ultra thin top/balsa carbon fibre lattice) produce a broader range of upper harmonics than a traditionally built guitar. Upper harmonics are progressively sharp in relation to the fundamental note. In a normal guitar, the brain processes this somewhat dissonant mixture and translates it into a pleasing or "rich" tone. When the mix of upper harmonics becomes too strong, the brain processes and translates as a sound that is less pleasing as described above.

I completely disagree with Damman's idea that sustain is a psychoacoustic phenomenon and that the ear does not hear the tone duration in loud instruments in the same way as quieter ones. I've heard both loud and quiet guitars, some with long sustain and some not.

Build a guitar with moderate impedance and moderate damping...string energy slowly bleeds into the structure and a long sustain is accomplished. Boom.

That said, extended sustain should not be the goal for every guitar, just as max volume is likely not a requirement for every instrument (more likely, greater dynamic range is a more useful metric). The more likely requirements are for 'good' or 'acceptable' sustain and volume, as well as other acoustic characteristics, with emphasis being more the case of 'a little extra <fill in blank> without losing <fill in blank>'. I've had feather-light guitars in the shop (I have four guitars by other custom builders in the shop as I write, as well as a couple vintage Gibbies and Martins) with thin, speaker-like sides and thin, active back that sustain forever and have quite a bark...and ones that are more glue than wood (e.g., thick, laminated backs and sides with oversized linings) that make a Les Paul look light, and show the same level of sustain and volume.

Multiple paths to a single end state, but not all builders can follow each of those divergent paths to an acceptable solution.

Just to throw in a wildcard here, recent medical journal reports show a link between the brain's audio processing capability and jet fuel/fume exposure. My wife is convinced that all career pilot are def due to jet noise and selective hearing, but now it looks like I hear things, but process them less effectively than those without decades of exposure to the sound of freedom. At least that's what I'm sticking with while continuing to ignore her requests to answer the phone, take out the trash, let the dog in, etc.

"Just to throw in a wildcard here, recent medical journal reports show a link between the brain's audio processing capability and jet fuel/fume exposure. My wife is convinced that all career pilot are def due to jet noise and selective hearing, but now it looks like I hear things, but process them less effectively than those without decades of exposure to the sound of freedom. At least that's what I'm sticking with while continuing to ignore her requests to answer the phone, take out the trash, let the dog in, etc."


Lacquer thinner can be substituted in a pinch.

We apparently are what we absorb!

For what it’s worth, I see the volume – sustain balance as a zero sum game…

You pluck the string and you get yourself a finite amount of energy. That energy can be used for whatever you want, but you only get a set amount of it. It takes energy to move the mass of wood, to move the air, to make the noise, and louder means more air moved and so more energy spent per second moving it. Moving less air means less loud but your energy budget can move the air longer before its all spent.

Assume the pluck is an inheritance you got from a long lost uncle. You can spend it all on one big splash [Volume], or you can gradually spend it over a period of time [Sustain]. But once spent, it’s gone.

Todd,
Could you provide a link to the study connecting kerosene fumes and audio processing? I'd really like to read that.
It's also been shown that, with hearing loss, if the neuro pathways don't receive input for an extended period of time ( as in hearing loss not addressed for an extended time) the atrophy of the pathways processing those frequencies can cause the loss of processing those frequencies to be permanent, even if the input is re-established.
So my scientific explanation to my wife involves the Stones' Steel Wheels concert 30 years ago.

This should get you there.

http://www.ncbi.nlm.nih.gov/pubmed/24588226

I flew one of those aircraft with 130dB in the cockpit (forward transmission is about 3 feet above and slightly aft of flight crew...it's the high pitched whir heard from heavy lift tandems), so even the ANR systems we got during the last years of my flying career did nothing for the bone conduction-induced damage. Add to that the 30 years of exposure to Jet A and JP-4/5, and my potential disability percentage is looking more like my marginal tax rate every day.

Randy Roberts wrote:
"For what it’s worth, I see the volume – sustain balance as a zero sum game…"

It is if the efficiency remains the same. That's how many of the current crop of 'loud' guitars get their added power: they do things to extract more energy from the string, and turn it into sound. The problem with this approach is that the guitar is already (believe it or not) one of the more efficient musical instruments. Anything you do to increase that also tends to make problems, such as 'wolf' notes. Also, the styandard repertoire is built on the sound of the thing as it is, and altering the efficiency tends to alter the timbre in ways that can be unsuitable.

Several years ago somebody brought a Smallman by the shop. It had his CF and balsa lattice bracing on the redwood top that was about .6 or .8 mm thick. The top sat on a heavy and rigid plywood rim, and the back was a bent arch of BRW about 5 mm thick. All of the weight in the rim and the back served to keep the sound in the top, if you will, and since that's the most effective sound radiator on the instrument, it increases the efficiency. The result was certainly loud, but it had the timbre of a wooden resophonic guitar: only slightly less raucous than a metal cone. That sort of tone does smooth out some in a large space, and the concert players really like those guitars. It was not at all pleasant in a small room. From what I've heard this is a common issue with the 'loud' boxes in general.

I completely agree with Al.. Our guitar society has brought in 4 to 5 internationally known guitarists every year for the past 20 years and I've heard every one of their guitars both in the concert hall and the smaller room we use for master classes. Included in these were all of the GFA winners over the past 20 years many of whom played Smallmans. Dammans or similarly made clones.

The guitars I enjoyed the most were very traditional instruments played by folks like Pavel Steidl, Carlos Barbosa Lima and Roland Dyens. That being said, volume is where the money is in the world Lutherie and if you need to make a living at it volume at the expense of tonal quality is where you may have to go.

" That being said, volume is where the money is in the world Lutherie and if you need to make a living at it volume at the expense of tonal quality is where you may have to go."

It seems ironic that a loud but tonally challenged instrument is preferred in some circles over one that has good tone, but requires amplification when played in a large hall. Very few classicals can be "plugged in".

It makes perfect sense from the player's standpoint. If you're trying to make a living as a Classical guitarist you can either play lots of rooms under 200 seats, or fewer larger ones that seat more than 1000. The small room scenario puts you on the road most of the time. Classical audiences don't like the idea of amplification, with some justification IMO. Loud guitars do sound a bit less nasty in larger rooms, and certainly better than one that is being pushed beyond it's limits.

It does seem to me that many of the modern 'loud' boxes have a timbre that makes me think of small guitars, and wonder if part of the solution would be to just make them bigger. I've made a couple of Classicals on my version of the the 12-fret 000 platform, which is an inch wider than almost any fan braced Classical. The X bracing allows you to get away with it, and the top can end up as light as a fan braced top but with larger area to make more sound. I showed one to Sharon Isbin, who liked it very well, and never even noticed the wider lower bout. I've also made a couple of successful arch top Classicals, with 16" wide lower bouts, and they sound good, although, perhaps, still a bit on the 'small' side. Maybe I'll make a 17" one (L-5 size) some time. Again, with the added vibrating area they do put out more sound. It's tricky to get the balance right, but then, that's true of all Classicals.

I have to wonder, though, if the 'loud' boxes are having what I consider a deleterious effect on the playing style. I went to a Classical guitar festival a couple of years ago at a Conservatory, and all the kids seemed to be trying to see who could play the most notes the loudest. All the subtleties of tone that are what endeared the Classical guitar to me were just gone. Some other folks have commented on that as well in other places. I hope that's not the way the instrument is going.