martin manning wrote: ↑Sat Aug 20, 2022 1:14 am
Here's a series of 15 notes, actually 15 copies of the same note, where some of them have been inverted. Can you hear any difference?
no, honestly, I don't hear any nuance
to play devil's advocate: BY PLAYING and not just by LISTENING, will I be able to "feel" a difference (the note that seems to "come out" faster, ... ...) ???
But there, no it goes in the direction that the polarity will not act!!!???
romberg wrote: ↑Fri Aug 19, 2022 6:14 pm ... if (and this is a big IF) a speaker is very non-linear and is not matched as far as the pressure response in the push versus pull direction ...
The guitar speakers in use today, as far as I know, are almost all more or less non-linear because they were intentionally designed that way by their designers, since most guitarists prefer the sonic characteristics of non-linear speakers. Below is a link to an article with an interview on this subject with Celestion's Ian White. Here is a brief excerpt from what Ian White said:
... Designing guitar speakers is, in many ways, much more challenging than pro PA or hi-fi, because guitar speakers are so non-linear,” he says. "Hi-fi speakers are designed for linear operation mainly within what's called their 'pistonic band', the region where the speaker is moving in and out in linear fashion. Above that band, the speaker goes into 'break-up' — instead of the whole thing acting coherently like a pump or piston, little bits of the cone are all doing their own thing — but then you'd typically move that part of the signal over to, say, a mid-range driver or tweeter. With guitar speakers, there's almost no pistonic band. Within their usable frequency range, it's almost all break-up. ...”
From that article: "Imagine I had a load of different panels made from wood, glass, polystyrene and so on, he says. If I got you to close your eyes and then hit each one in turn to make it resonate, you'd be able to hear immediately which was which. That's because the different break-up pattern of each material gives a unique coloration to its sound."
I tried a little experiment: I held a piece of foam core board in front of my face and tapped it from the front and from the back with my finger. It rings for a short time, and the edges flutter, so there is a complex system of nodes and antinodes in the panel. The resulting sound is the same either way as far as I can tell, and of course this is with the considerable difference in the mechanics of my arm and hand in tapping from the front vs. the back that might affect the input signal. Even if there are a whole bunch of different vibratory modes happening in a guitar speaker cone, I'm still not convinced that the polarity of the first impulse will make any audible difference.
martin manning wrote: ↑Sat Aug 20, 2022 1:14 am
Here's a series of 15 notes, actually 15 copies of the same note, where some of them have been inverted. Can you hear any difference?
I once built a speaker cable that inverts so that I could employ a swap of speaker polarity in the event that I struggle to find the right sound. While I have tried it at home to make sure it works and on occasion used it because it was accessible, I have never actually used it to address an acoustic shortcoming in a practical situation—It never seems to cross my mind until it’s too late to bother.
I think the only thing that would convince skeptics (myself included) would be to setup some sort of test that measured *something* on test equipment of some sort. Something more precise and measurable that "I can hear a difference". How 'bout:
Feed a regular signal of some sort into a guitar amplifier.
Adjust the guitar amp to any volume and setting you think might maximize this polarity effect. I think waves with just 1/2 clipped may be the best bet. Maybe at high volumes and using a lower frequency test signal.
Sick a "good" microphone in front of the speaker. Yes. This test will also be measuring the mic's response. But they are probably less colored than a guitar speaker. One could always go back and check the mics linearity over the frequencies and SPLs later.
Record the output and save the waveform into a scope, DAW, etc.
Change the polarity between the guitar amp and speaker since this is the main thing we want to test. Touch nothing else.
Record the output of the inverted waveform into the same scope, DAW, etc.
Observe some significant difference in the waveform other than the polarity being reversed. One could look for such a difference by flipping either one again and comparing the two.
It does not sound to hard to do. And I might try setting this up. But I'm not confident that I would be able to produce a significant result. But it would be kinda cool to be wrong .
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