phildefer
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Post by phildefer on Oct 23, 2020 16:02:04 GMT -5
I have two stratocasters mexican, and I want to compare their sound with some analysis tool when you use the same pickup in both guitars. In both guitars, the pickup frequency response are identical, but one have guitar has clearly more bass bass (when I play the low E string) and more sustain than the other. How to characterize such difference ?
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Post by antigua on Oct 23, 2020 21:08:29 GMT -5
I have two stratocasters mexican, and I want to compare their sound with some analysis tool when you use the same pickup in both guitars. In both guitars, the pickup frequency response are identical, but one have guitar has clearly more bass bass (when I play the low E string) and more sustain than the other. How to characterize such difference ?
If you're using the same pickup, and the guitars sound different, then I suppose that excludes the pickup has being the cause of the difference. Do you want to analyze the difference of the guitars, and not the pickups? Do the guitars sound different when strummed? One thing to look at is whether or not they have floating or decked tremolo's, that can make a difference difference.
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phildefer
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Post by phildefer on Oct 24, 2020 2:29:09 GMT -5
yes I want to analyze the sound difference between both guitars, ideally I imagine that we could a spectral signature for each guitar or something like that.But how to proceed ? Playing one note through a sound card, recording the sound and then computing the spectra but the note strumming will be different for each recording, so it is an issue. Or directly using the Velleman oscilloscope with the spectrum analyzer option ? I will check also the tremoloes if it could be the root cause of the difference.
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Post by antigua on Oct 24, 2020 2:58:04 GMT -5
yes I want to analyze the sound difference between both guitars, ideally I imagine that we could a spectral signature for each guitar or something like that.But how to proceed ? Playing one note through a sound card, recording the sound and then computing the spectra but the note strumming will be different for each recording, so it is an issue. Or directly using the Velleman oscilloscope with the spectrum analyzer option ? I will check also the tremoloes if it could be the root cause of the difference. This sort of thing has been done by many people, so there's not really any well established method. Plucking the strings by hand doesn't work so well, because it's really hard to detect subtle differences when your strumming hand is inputting very big differences. I did something similar here guitarnuts2.proboards.com/thread/7998/tonal-effect-pickup-height , I used an electromagnet to vibrate the strings like an eBow would, but that turned out to know work great because it produces hardly any higher harmonics, and the difference between two guitars' sound might be revealed in the higher harmonic content. Suppose you find a way to vibrate the guitars uniformly, or pluck the strings very uniformly, you could capture audio sample of the two guitars, and then do a spectral analysis of the wave forms, and the spectral analysis will show varying amplitudes of all the specific harmonics. It's nearly impossible to strum the strings, manually or mechanically is a very consistent way, such that you could attribute differences to the guitars, and not your own hands. Even how you hold the guitars, or set them on your table or work bench will also affect how they sound, that sort of a testing is a lot of work. That's why I'd sooner look for shortcuts, such as knocking on the guitars with your knuckles, and listening for a difference. If they have very different resonances, or if they sound very different unplugged, it's possible that they're physically different enough to affect what is received by the guitar pickups, too. I can't think of a reason one would have a lot more bass than the other, maybe check the pickup height's very carefully and make sure that was the same in both cases.
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phildefer
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Post by phildefer on Oct 24, 2020 4:21:46 GMT -5
Many thanks for your advices, will review the different possibilities and try.
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phildefer
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Post by phildefer on Oct 25, 2020 3:19:02 GMT -5
Finally, I checked the Vibrator differences and indeed the tuning of Vibrato makes a difference on bass presence and sustain. So it was the root cause of sound differences between both guitar. Anyway will try to check how to measure this.
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Post by antigua on Oct 25, 2020 13:38:30 GMT -5
Finally, I checked the Vibrator differences and indeed the tuning of Vibrato makes a difference on bass presence and sustain. So it was the root cause of sound differences between both guitar. Anyway will try to check how to measure this. I've noticed this also, that a Strat with a floating trem seems to have less sustain and less low end. I'm not clear on the physics of it, but the sustain of the strings relies on a stiff support structure, and of course the floating trem is a less stiff structure. I don't know why the bass would decrease to a greater extent than the treble, but it could be because the floating trem unit vibrates sympathetically with the lower frequencies, causing a more rapid decay, but not as much for the higher frequencies. There are a lot of players who deck the trems of Strat because they don't intent to use the trem arm, but some say that if it's decked, it won't sound like a "Strat", and I agree with the latter, I think the floating trem is part of what makes a Strat sound distinct from other guitars with similar pickup configurations. The same is true of Jazzmasters and Jaguars, which have imperfect vibrato mechanisms that give the guitar a particular decay characteristic.
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phildefer
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Post by phildefer on Oct 25, 2020 16:52:26 GMT -5
One of the strat had its trem decked and the low end and sustain were less important than the other strat with undeck trem. And the decked trem strat indeed sounded less strat than the other. This is what I also noticed.
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timtam
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Post by timtam on Nov 4, 2020 4:55:41 GMT -5
There are many potential sources of such variation. From resonant modal frequencies of the neck, to micro-interactions between the strings and frets (dependent on setup), to specific absorbances between two same-generation bent steel strat saddles, etc, etc (many examples in Zollner ch7 below). That's before you even get to the electronics. In your case you would have the same pickup, but then there's the pots - extremes of typical pot tolerances are probably enough to load pickups differently. The resonant modal frequencies of the neck tend to be associated more with lower frequency string vibration losses. In fact, what the existing evidence suggests is that there is really no such thing as "two identical guitars".
While all of the above have been demonstrated to produce tonal differences, there is not yet a standard suite of tests that one can do to isolate the sources of tonal differences. One could measure admittance (conductance) at the bridge, nut, and every fret, as has been commonly done by guitar scientists. Unfortunately the equipment to do that is not that easily accessible. A simpler approach would be to measure sustain of every note, such as the so-called "T30", the time for the amplitude to drop by 30 dB after a standardized picking motion (ie motorized/mechanized picking and fretting). Ideally that would include software to separate the fundamental and the overtones (harmonics), as they decay differently and are thus responsible for tonal differences from the time the note is struck. Changes in the frequency response of new strings in their first hour of use have also been described, so that would have to be tightly controlled.
One possible way to begin would be to just measure one T30 value for every fretted note on the neck. Then replace components on the "test bed guitar" one at a time (keeping previous changes), and look at incremental changes in T30: for change in pickup, electronics, bridge/trem, neck, body. That would give you a series of T30 versus frequency plots, one for each component change (similar to the series from top to bottom in the right column below from Zollner, in that case for different guitars from full acoustic via (semi)hollow bodies through to a strat - clear differences in frequency-dependent T30 can be seen.
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