Better Way to Measure Bass Sustain?

#21
FWIW, I’m an engineer, although not a sound engineer.

Half life is simply a mathematical term used to describe any kind of decay, so yes it could be used to describe the characteristics of a string’s vibration.

But is it useful as a practical objective comparison between two instruments? Meh. Not even remotely, in my opinion.

One issue you’d encounter is terminology. Technically, there are four phases in an envelope: attack, decay, sustain and release. On a plucked string instrument, there is an abrupt attack phase, a somewhat equally abrupt decay, followed by what is basically merged sustain and release phases.

I disagree that this wave would remain a constant shape regardless of the initial energy put into it, particularly across the full range of an instrument. There are far too many variables at play.

I would be interested in seeing the curves for various strings, at various points in their lives, but simply to satisfy my own curiosity.
 
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#22
From a purely academic standpoint, if I were to test this, I might do something like fire up my DAW pull out the basses I'd want to test.

My methodology would be as follows:

1. Set bass A so that it has a set max registered volume level for hard hits - usually I have this at around -6dB.

2. Record a handful of notes from across the fretboard - maybe open, 6th fret, and 12th fret for each string, providing 12 samples. I'd hit each note hard, and then let it ring out until it's fully decayed to around -54dB or something around there.

3. For each sample, I'd then measure the amount of time between some post-attack level and some sufficient decay level. I'm thinking from -24dB and -48dB should work well as I'm looking at my meter and a sample decay.

4. Pull out bass B, reset the max level for -6dB on hard hits, and continue on the steps until you have a set of samples for bass B, and measure accordingly.

I'm not sure an average for each bass would be meaningful, given potential variance from note to note, but you could definitely compare each note individually (Bass A open E to Bass B open E). Given that I'd be doing this in a DAW, I'd be able to measure the decay from proposed -24dB to -48 dB to a sufficiently small fraction of a second if desired.

Like many posters, I'm typically more concerned with how a bass/string combination decays rather than duration, but from an academic standpoint I think the process above is how I'd personally go about it if I wanted to test such a thing. :)
 
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#24
This is helpful in knowing how long you can hold a note while gesturing to the crowd with your picking hand or, blowing fire or, spitting up blood. Bass basics people.

636057464044226398-gene.jpg
 
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#25
lat said:
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.
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The following method uses voltage to displace a string, which would eliminate the need for plucking: http://users.spa.aalto.fi/mak/PUB/SMAC03_Measurement.pdf

Also: please don't do this. Find a better way to spend your time.
 
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#26
Measuring the decay is actually a common way of measuring the qualities of speakers. See here, page 1 bottom. It's called 3D spectrogram (I believe). I guess it would be an integral part of many DAWs.

The example in my link, you can see how long does it take for the speaker to fall silent on different frequencies. Quicker to fall silent means cleaner, unbiased sounding (IMO). The reason for measuring is so that you can compare the speakers you want to use, without giving in to myths.

Back to the topic:
I can easily imagine this method to be applied on bass, to answer many questions: What does the tone knob really do? What is the real difference between rounds and flats? If I turn down the volume, does it change the sound? Is it true that my new pickguard doesnt affect the sound at all, even if it's tort? Does it make sense to buy a box A just because the manufacturer says it can play frequencies above 12kHz, while box B goes only to 10kHz?

I have never measured sustain, but I tend to measure many things that are creatively affecting something. The other option is to trust somebody else. My father, electrician, says 'when you can't measure, you believe'. Right?
 
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#27
InternetAlias said:
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.
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oh-crap.jpg


You failed to mention how the vicinity of Flux Capacitors can impair the duration.
 
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#28
I built a P Bass using A Schecter imbuya body (imbuya is the densest of the South American walnuts), a heavy 80s Fender maple neck, a ridiculously heavy Ken Smith bridge, and a Seymour Duncan quarter pounder. The bass weighed in at about 17 pounds. I couldn't even handle two sets with that anchor, sold it to a big dude who looked like a linebacker. Before he put it in the case, I hit the A string. I bet it's still ringing.
 
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#32
2F/2F said:
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.
Click to expand...

Thanks for telling me what I need to know... My life now has direction.

lol
 
#34
JRA said:
how is this 'sustain' measurement useful in practical terms?
:D
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Knowing what an instrument will and won't do is helpful. But...it's a combination that you're measuring, not just the instrument. Right now, I have an E string on one of my basses that's a bit dead - not bad, but the rest of the set is so alive I don't want to change strings. Last weekend, I was playing the open A rather than the A on the E string because...it'd sustain long enough there to do what I needed artistically, in a certain part of a certain song, while the A on the E string wouldn't. If I change strings, the sustain time on the E will improve, but the bass hasn't changed. As has been noted above, if you're in a loud environment, sometimes you can also get infinite sustain from positive feedback - that's another consideration in this.

Anyway, sustain, (once you're past the attack transient of the note) is a pretty linear thing, and in acoustics we measure things like that all the time. Reverb in a room is measured as RT60 - the time when the reverb tail drops to 60 dB down from its initial value. Sometimes, when you're in a noisy environment, you'll measure the time to 30dB down and double that value, as the signal at 60 dB down would be buried in noise. You could measure string sustain the same way. Half life would also kinda work, but as you're looking for only a 6 dB drop (half the amplitude is 6 dB down), the measurement uncertainty isn't as good looking at that small of a drop - the transient part of the vibration takes too much of that time, so the measurement won't be as meaningful or consistent as if you wait for more decay.
 
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#35
micguy said:
Knowing what an instrument will and won't do is helpful. But...it's a combination that you're measuring, not just the instrument. Right now, I have an E string on one of my basses that's a bit dead - not bad, but the rest of the set is so alive I don't want to change strings. Last weekend, I was playing the open A rather than the A on the E string because...it'd sustain long enough there to do what I needed artistically, in a certain part of a certain song, while the A on the E string wouldn't. If I change strings, the sustain time on the E will improve, but the bass hasn't changed. As has been noted above, if you're in a loud environment, sometimes you can also get infinite sustain from positive feedback - that's another consideration in this. Anyway, sustain, (once you're past the attack transient of the note) is a pretty linear thing, and in acoustics we measure things like that all the time. Reverb in a room is measured as RT60 - the time when the reverb tail drops to 60 dB down from its initial value. Sometimes, when you're in a noisy environment, you'll measure the time to 30dB down and double that value, as the signal at 60 dB down would be buried in noise. You could measure string sustain the same way. Half life would also kinda work, but as you're looking for only a 6 dB drop (half the amplitude is 6 dB down), the measurement uncertainty isn't as good looking at that small of a drop - the transient part of the vibration takes too much of that time, so the measurement won't be as meaningful or consistent as if you wait for more decay.
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yeah, i get it, thanks.

my post aside: i think it's a hoot that so many value sustain while playing on P's with fat/heavy strings which are older than their children and who brag about "thump"....

does sustain sit in the mix? :D
 
#36
JRA said:
yeah, i get it, thanks.

my post aside: i think it's a hoot that so many value sustain while playing on P's with fat/heavy strings which are older than their children and who brag about "thump"....

does sustain sit in the mix? :D
Click to expand...

I play in churches. Sustain is a valuable part of what I do. A P bass with 10 year old flats would never work for what I do. Ooops, did I say that out loud?
 
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#39
Sometimes the issue of sustain isn't even whether "your bass" has enough sustain, but whether a particular note you need to sustain decays way too quickly or slowly. There's something to be said about the difference in sustain when it comes to notes further up the neck, because it's a whole different ball game compared to, say, open strings.

One one hand, we'd prefer uniformity so that we know what to expect when we pluck a note. At the same time, having different sustain (on say, 5th fret of the E string and open A) provides opportunities to get different timbres/levels of sustain.

No right answer, just what you need.
 
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