“e” vowel vs. “a” vowel.
I wish I had better clips but this is what I have on hand. before you crucify me for the low quality of recording and playing, these clips are 12 years old.
I find the distinction between the two sounds is unintuitively most present when playing big power chords (as opposed to single note melodies) since that gives you way more harmonic content with a distorted amp. that’s not to say the vowel character isn’t noticeable otherwise, just that for me it’s easier to elicit with low power chords.
“a” example:
“e” example:
Of course “e” vs “a” is a rather hyperbolic way of describing it. the “e” example does not literally sound like an “e”. To me both actually sound like “ahhs.” But the second does sound slightly more “pinched off” than the first example. Why is that?
One explanation comes from how we actually hear vowels. You could probably guess that the difference of vowels is because of different harmonic content which is produced by the vocal system. It is a fact that the fundamental pitch of the voice does not affect the vowel’s character. to wit you can use a vocoder to sound out a sentence using only one fundamental frequency (one “note”) and have it be perfectly intelligible.
so what makes a vowel sound like a vowel? it turns out it’s the resonances in the vocal tract which change the peaks and valleys in the frequency content of the harmonics produced by your vocal chords. it also turns out that really the first (lowest) two resonances (called “formants” in phonetics or voice processing lingo) are what matter the most in distinguishing vowels. check out this table which lists the bottom two resonance frequencies for different vowel sounds averaged over some population: Formant - Wikipedia
in addition, the first formant tells us a little about how “open” or “closed” sounding the vowel is, with lower sounding “closed” (i.e. pinched off) and higher sounding “open.”
we can see that the “eee” sound (IPA symbol: i) has a resonance at around 240 Hz and another around 2400 Hz, while the “ahh” sound (IPA symbol: a) has of its two bottom resonances around 850 Hz and 1610 Hz.
my claim is that on something like vintage marshall, we all know there’s that characteristic upper midrange peak at around 2 kHz. Drive the amp harder and this peak becomes even more pronounced. Somebody with more knowledge could explain why these behaviors exist. Regardless, I think this can in part make the character of the notes take on a slight “eee” character as that peak becomes more prominent, especially when you’re presented with a bunch of low frequency content and that upper peak, but not much in between. unlike voice, the “source” signal of your guitar into an amp is not well approximated by a pulse train so there are other factors which affect the character of the “vowel” heard than some characterization of the amp’s frequency response in the linear regime. but in short, a low resonance peak and a high resonance peak without much energy between those peaks is going to sound like an “eee” where two more closely spaced peaks in the middle are going to sound more like “ahhs.”
as to why fryette’s amps have more tendency towards the open “ah” sound I can only guess. my guess would be that something about the design accentuates a midrange peak which is at a lower frequency than the 2 kHz+ we see in other amps, and combine that with probably more frequency content in the 600-1000 Hz region as well. perhaps additionally something about how when the power section and transformer are overdriven, the resonances don’t get overly peaky as well. I’d welcome any additional thoughts people have about this.