Sustain

[Dan Phillips]

Sustain, Volume, Loudness are they all the same?

[Michael Lewis]

No, but it also depends on how you define your terms. Sustain is how long a tone rings. Loudness and volume can be the same thing or not depending on your definition of each term. To most of us regular folks they are the same thing but to an audiophile they can be different. Often the qualities that benefit sustain detract from loudness or volume, and vice versa.

[Waddy Thomson]

And, don't confuse loudness with projection. They may be very different. Some guitars are not particularly loud, but cut through and project to the back of a room.

[Alan Carruth]

There are actually two ways to get long sustain, that I call 'Les Paul' and 'banjo' sustain. In 'Les Paul' sustain, the bridge and top are relatively heavy, and it takes a long time for the sound energy to get out of the string and into the top where you can hear it. The sound may not ever get very much above the threshold of perception, so even though it can go on for a while, you might not hear it. With 'banjo' sustain the bridge and top are light, and turn the string energy into sound effectively. The level rises above the threshold of perception quickly, and takes a while to die back to that level again. The 'banjo' type will be louder, of course, and the two systems give a much different timbre. For one thing, 'Les Paul' type guitars tend to lack power in the. higher frequencies. 'Banjo' type guitars tend to have more of that, and the rapid attack seems also to contribute to a perception of 'brightness'.

I like to distinguish 'loudness' from 'volume' (or 'power) by saying that loudness is a perception, whereas power is an objective measurement. Our perceptions of loudness are shaped buy all sorts of things, such as the spectrum of the sound, the envelope (rise and fall time), and so on. All else equal, doubling the power in a sound is usually only a barely noticeable increase in loudness, whereas adding in as little as 1% of the original power in a higher harmonic can make the sound seem much louder. Loudness and power are very hard to relate to one another: one author spends an entire chapter in his book on acoustics talking about the various systems for doing so, and admits in the end that none of them are all that good.

'Projection' seems to have a lot to do with the spectral content of the sound. Our hearing is much more sensitive to sounds around 3000 Hz than it is to those much lower or higher in pitch, so adding in harmonics in that range usually helps the sound to 'carry' further for a given power. Again, there's probably more to it than that. I've seen guitars that had plenty of output in that range, but that did not project all that well; usually they seem to have a 'flatter' response in that range than the ones that do project. That makes sense, since variations in the spectrum from one note to the next give your ear some change to latch on to. Our senses tend to be set up to detect changes and ignore stuff that doesn't vary much, since the stuff that doesn't vary tends to be neither dangerous nor edible.

As usual, it's all more complicated than it 'should' be...

Alan Carruth / Luthier

[Chuck Tweedy]

How about:

As usual, it's all more complicated than we would hope it to be...

Really, it should be that way so that we don't get run over by that car (modern day equivalent to getting eaten I guess)

[Chuck Morrison]

I can't say that I ever thought of banjos as having sustain worth mentioning when compared to guitars. Lots of penetration (lots of high harmonics) and initial ramp up for certain but usually a fast decay, not to nothing, but much lower than the initial peak.

However, I know a fellow who bends my ear quite a bit about the different tones, sustain, volume etc of his various banjos. His detailed descriptions include the type of head, hoop tensioning, type, shape, weight of bridges, necks and other bridge details... All of which I've tried to remain ignorant about all these years (and until now succeeded).

So in spite of all this evidence to the contrary, banjo sustain still seems like an oxymoron.

[Dan Phillips]

Thanks all for the good replies. I agree with Chuck Morrison - sustain on a banjo seems to be an oxymoron ( unless Jens Kruger is playing it). Now the guestion becomes to get great sustain from a pinapple shaped Weissenborn, if I am willing to give up some volume, loudness, power, projection, etc. - what do I do? My idea is to provide some very stiff internal bracing between the nut and an endpiece that is not directly connected to either the top or back. I am a novice so please correct me.

[Michael Lewis]

I think to help sustain you would want to make the structure stiff so it doesn't absorb the energy of the strings so quickly. The strings are the engine, they have the energy while they vibrate, and as long as the energy is not dissipated they will continue to vibrate.

Selection of materials can be rather important in this regard, so select materials with low internal damping. Woods that ring like cast iron or glass would be a good choice. Black locust and osage orange should work.

Don't give everything away just to maximize on sustain, you want some tone to go with the whole thing, don't you?

[Alan Carruth]

OK, gimme a break, willya? I was not talking about sustain on banjos per se, I was talking about sustain on guitars with really light tops, which are sort of like banjos in that respect. Would you have preferred 'Flamenco sustain'? ;o)

Alan Carruth / Luthier

[Brad Heinzen]

Alan, I was with you there. It seems like the question is what do you want to give up to get sustain - tone, volume, etc. Personally, I don't want to get sustain at the expense of tone. I'd rather give up a little sustain and a little volume to get something that sounds good. Realistically, most people don't play in concert halls, and I wish they didn't all want a guitar that's built for that.

[Dan Phillips]

Of coarse, tone is what is most important. If sustain is more complicated than it should be - tone is extreemely more complicated than it should be!

Most guitars have very thin tops and backs and a lot of bracing - would thicher tops and backs with less bracing sound as good?