Better Way to Measure Bass Sustain?

[lat]

Comparing sustain on different basses seems to be a somewhat subjective exercise. The method I have heard espoused is to pluck a string and time how long you can hear it. So, you are never going to pluck the string the exact same way any two times, and you may not hear the end of the audible portion of the vibration consistently. This may be close enough for most purposes, but I have been wondering about using a more consistent, repeatable process that would aid in a more objective comparison between instruments.

Sustain is just a form of decay, not too dissimilar to radioactive decay, I think. Radioactive decay is measured in half-life. Could this also be applied to the decay of sustain? Pluck a string, and, using an oscilloscope, record when the amplitude of the tone generated is half of what was initially plucked. This time would be the half-life of the instrument's sustain. Do that for each string and you might have a specification that could be objectively compared between instruments.

Now, I'm not an engineer, so I could very well be missing something, but I would like to hear what others think about this.

And no, I have not been drinking more whiskey than is considered helpful...

EDIT:
I really only care about having enough sustain to carry through maybe a couple of bars at the most. My reason for bringing up this question was centered around the fact that discussions about sustain didn't have a way to objectively compare basses. Using the methodology that is applied to radioactive decay seemed like it might be a possibility. It is more idle curiosity than anything else.

 

[lz4005]

You still wouldn't eliminate the randomness of how hard you pluck.

There are two ways to do that: Either repeat the test 30 or 40 times and average the results, or build a mechanical device that will pluck the strings with the exact same amount of force every time.

That said, measuring sustain as a length of time is ultimately pointless. It's an envelope. There's an initial attack, then a functional plateau, then a decay to zero. Without quantifying all that, saying bass #1 sustains for 10 seconds and bass #2 sustains for 12 is meaningless.

And even then, every note sustains differently. Are you going to compile a matrix of all the data for every fret position? Oh, and string construction/gauge makes a difference. So better test it with multiple types....

Or practice and play more. Make it sound good and forget about measuring things.

 

[lat]

I don't think it would matter how hard you pluck, since you are just measuring how long it takes for the amplitude to reduce by half. If the decay is linear, it shouldn't matter what the initial amplitude is... All this is subject to correction by those who know more about the engineering associated with vibrational decay...

 

[mdogs]

As much as it pains me to say this, the amount of sustain a bass has, or more correctly, knowing the amount of sustain a bass has is pretty much a pointless exercise taken on only by people who could benefit far more from additional practicing then pursuing meaningless data. What do you know, that didn't actually pain me at all.

 

[lat]

A moment of silence, for the death of intellectual curiosity.

 

[tpaul]

If it's that difficult to measure, why does it matter?

Not trying to be flippant here. I just question whether anyone would ever notice the difference between the sustain of two basses, when said sustain is so alike that the difference can only be determined by measuring its half-life.

And there are so many other variables...

Also, I'm biased against the whole question, because I think sustain is vastly overrated.

 

[bassbenj]

I don't think it wouldn't matter how hard your pluck, since you are just measuring how long it takes for the amplitude to reduce by half. If the decay is linear, it shouldn't matter what the initial amplitude is... All this is subject to correction by those who know more about the engineering associated with vibrational decay...

This is more or less correct. How hard you pluck makes no difference (unless you system is non-linear like say with a compressor) because you are trying to measure the time for the decay of the pluck from full value to some lesser one (not necessarily half). But nothing is ever as simple as you like. Usually if you were to watch the bass signal on a display you'd get some wave that would slowly get smaller and smaller without changing it's shape. The time to fall to some selected fraction would be the sustain. However, when you pluck a string it vibrates not only a one fundamental frequency but also at a number of higher frequency harmonics. And it can turn out that these harmonics do not decay at the same rate as the fundamental bass note. This effect is common on a "dead spot". Often what you hear is fundamental note that very quickly dies away with the weird high harmonics lingering on. That means the harmonics do not all have the same "sustain". When this happens if you were watching the output wave you might see it changing shape as it decays away. From an engineering point of view this sort of thing would make it difficult to make a precise measurement of an instrument's "sustain". So as usual, when trying to judge instruments there is engineering but there is also "art" and both need be considered to come to an understanding.

 

[lat]

This is more or less correct. How hard you pluck makes no difference (unless you system is non-linear like say with a compressor) because you are trying to measure the time for the decay of the pluck from full value to some lesser one (not necessarily half). But nothing is ever as simple as you like. Usually if you were to watch the bass signal on a display you'd get some wave that would slowly get smaller and smaller without changing it's shape. The time to fall to some selected fraction would be the sustain. However, when you pluck a string it vibrates not only a one fundamental frequency but also a a number of higher frequency harmonics. And it can turn out that these harmonics do not decay at the same rate as the fundamental bass note. This effect is common on a "dead spot". Often what you hear is fundamental note that very quickly dies away with the weird high harmonics lingering on. That means the harmonics do not all have the same "sustain". When this happens if you were watching the output wave you might see it changing shape as it decays away. From an engineering point of view this sort of thing would make it difficult to make a precise measurement of an instrument's "sustain". So as usual, when trying to judge instruments there is engineering but there is also "art" and both need be considered to come to an understanding.

Awesome. Thanks for the great insights ben! Figured there were other forces at play, with such a complex system as bass resonance.

 

[JRA]

how is this 'sustain' measurement useful in practical terms?

what if your instrument has the longest sustain ever measured? --- and then you join a bebop quartet.

 

[5StringBlues]

You could go and have a bite and .........


you'd still be hearing that.

 

[InternetAlias]

A moment of silence, for the death of intellectual curiosity.

Unless you're actually skilled with designing and performing a study, and know how and which parameters to lock, and also know what the actual purpose/use case/value of the test is, what you refer to as "intellectual curiosity" here is pretty much a waste of time, because you want to do something that's roughly scientific... But you gain nothing from being only halfway there.

We're talking about a highly non-linear system with a ton of variables, and you want to test only one of them, with very little regard for, or knowledge about, the others.

Also, no, saying that decay is linear would be an oversimplification. It absolutely does matter how hard you pluck, hell, you could pluck so hard that the string hits the frets, at which point quite a lot of low frequency amplitude will be converted into high frequency amplitude (and heat). In fact, that's how slap works.

 

[GretschWretch]

From a purely utilitarian perspective, as long as the note sustains as much as you need it to when you need it to, anything beyond that is superfluous and likely irrelevant, so the comparison between basses likely is a road to nowhere. I have notes on basses that do not sustain as long as I would like; but they sustain long enough for the application, so I live with it.

 

[lat]

how is this 'sustain' measurement useful in practical terms?

what if your instrument has the longest sustain ever measured? --- and then you join a bebop quartet.

Not really sure of the practical application, but maybe comparing strings on a bass? If one string has markedly less sustain, then it could be used for problem determination? Or, comparing sustains for basses of the same model, to the same end? Dunno...
I really only care about having enough sustain to carry through maybe a couple of bars at the most. My reason for bringing up this question was centered around the fact that discussions about sustain didn't have a way to objectively compare basses. Using the methodology that is applied to radioactive decay seemed like it might be a possibility. It was more idle curiosity than anything else. Not saying this about you, JRA, but I really don't understand the hate on for someone that is just curious about understanding an aspect of measuring how a bass resonates. I guess I should have stuck to discussing which pickguards affect tone... lol

 

[lat]

Unless you're actually skilled with designing and performing a study, and know how and which parameters to lock, and also know what the actual purpose/use case/value of the test is, what you refer to as "intellectual curiosity" here is pretty much a waste of time, because you want to do something that's roughly scientific... But you gain nothing from being only halfway there.

We're talking about a highly non-linear system with a ton of variables, and you want to test only one of them, with very little regard for, or knowledge about, the others.

Also, no, saying that decay is linear would be an oversimplification. It absolutely does matter how hard you pluck, hell, you could pluck so hard that the string hits the frets, at which point quite a lot of low frequency amplitude will be converted into high frequency amplitude (and heat). In fact, that's how slap works.

... and that was the point of the whole shaging thread, to find out if using the half-life methodology had any merit. Thanks for proving my point.

 

[Thumpin6string]

Not sure the point of measuring sustain, but sustain can be good or bad depending on the situation. Having long sustain gives you more options. The graphite neck on my 6 string will hold a note or sustain almost indefinitely no matter how hard or lightly you pluck. It comes in handy sometimes.

 

[Pilgrim]

As much as it pains me to say this, the amount of sustain a bass has, or more correctly, knowing the amount of sustain a bass has is pretty much a pointless exercise taken on only by people who could benefit far more from additional practicing then pursing meaningless data. What do you know, that didn't actually pain me at all.

This is the conclusion I have come to. I have never owned a bass that couldn't hold a note as long as I needed, unless I had a mute on the strings...in which case, I obviously would not be interested in "sustain." If I really, really needed very long sustain, I'd just turn the amp up and pluck more lightly so the note would audibly ring longer.

 

[darwin-bass]

You may be on to something. Half life should help to work around the inconsistency of plucking force.

I do doubt the usefulness of measuring sustain however. While academically interesting it is low on the list of attributes that really affect bass performance.

 

[2F/2F]

Now, I'm not an engineer, so I could very well be missing something...

Yep. You are missing that nobody needs to know, on a technical level, how long his or her bass sustains. The sustain of any bass is something that, as a player, you learn the attributes of, and learn how to control, without needing to tally, count, measure, or whatever.

 

[AlexanderB]

Comparing sustain on different basses seems to be a somewhat subjective exercise. The method I have heard espoused is to pluck a string and time how long you can hear it. So, you are never going to pluck the string the exact same way any two times, and you may not hear the end of the audible portion of the vibration consistently. This may be close enough for most purposes, but I have been wondering about using a more consistent, repeatable process that would aid in a more objective comparison between instruments.

Sustain is just a form of decay, not too dissimilar to radioactive decay, I think. Radioactive decay is measured in half-life. Could this also be applied to the decay of sustain? Pluck a string, and, using an oscilloscope, record when the amplitude of the tone generated is half of what was initially plucked. This time would be the half-life of the instrument's sustain. Do that for each string and you might have a specification that could be objectively compared between instruments.

Now, I'm not an engineer, so I could very well be missing something, but I would like to hear what others think about this.

And no, I have not been drinking more whiskey than is considered helpful...

It is sometimes depressing to see all the very vocal technophobes on the forum striking down on people wanting to expand their knowledge and view on things!
(Funnily, I think it is more or less the same crowd that are so quick to elevate some people working in the business, like agedhorse, to the skies, and blindly parroting what they say, regardless of it is applicable in a certain context or not!)

Anyhow, I have successfully done measurements like this, using the input my DAT recorder. It has a fast, easy to read fluorescent display, with high resolution and "peak hold".

Decide on a certain reduction, like -20 dB, pluck and count. Try different spots and different eq to emphasize spread in the frequence spectrum if you like.
Once the initial transient is passed, the decay ratio is rather even and flat, at least on better instruments.

Have fun!

 

[john m]

Yep. You are missing that nobody needs to know, on a technical level, how long his or her bass sustains. The sustain of any bass is something that, as a player, you learn the attributes of, and learn how to control, without needing to tally, count, measure, or whatever.

Bingo