It's too bad the forum software does not include quotes within a reply - it could. but be that as it may ...
It's not clear, Ron, what you mean by a "sonic 'center of gravity'", but let's look at what is in the lower midrange/upper bass portion of the frequency spectrum.
An 88 key piano covers the frequency spectrum across which orchestral instruments are scored. The 44th key is the E (~329 Hz) above middle C. So there's a middle. Almost all instruments will touch that frequency, though a small few do not; for example timpani, bass, bass saxophone, piccolo and most sets of bells don't cover that E.
Different people name portions of the frequency spectrum and the frequency ranges they assign to those names will vary. Consider Gordon Holt - he says the Upper-Bass covers 80-160Hz and the Lower Midrange runs 160-320 Hz. His top doesn't quite make it to the middle E. Robert Harley says the Upper Bass goes from 100-250Hz and the Lower Midrange runs from 250Hz to 500Hz. Harely's top goes an octave above middle-C. If we take Holt's low and Harely's high, the middle (the center of gravity?) of
that is around 196Hz - the G below middle-C.)
I understand you are talking about components but it's worth correlating with what we hear. A typical soprano can get an octave above Harley's Lower Midrange and a violin another octave above that. A string bass will play an octave below Holt's Upper-Bass. A lot of information is contained in the UB to LM frequency spectrum, but a goodly amount falls outside of it.
While I don't
quite agree with Karen's characterization, I think she was getting at the notion that modern audiophiles tends to emphasize hearing detail as a hallmark of component/system goodness and that such a component can do that to the disadvantage of midrange tonal balance. I believe there is some truth in that slight retelling of her essay.
There is audiophilery as entertainment and audiophilery as reproduction. Some people put more emphasis on one or the other. Synthesists and Naturalists. (The following is the writing on the side of the box to comply with political correctness: There is no 'right' or 'correct'. As
@marty so eloquently restated a central tenet of the Mick Jagger School of Art Appreciation (
"I'm no schoolboy but I know what I like" - lyrics) when he said:
There are only 2 kinds- wine you enjoy and wine you do not. All that other stuff (it tastes like plums, cassis, tobacco, burnt toast etc) is mostly crap."
)
Partly, the recognition that accurately revealing all information (detail?) is less than primary.
That's not speed, or slam or detail. Here's a caeser-like question: In differentiating themselves from other components, are manufacturers really differentiating themselves from the sound of live music? or ... why have audiophile's come to place such value on characteristics outside those core to music: tonality, dynamics and timing?
This is not about the Upper-Bass/Lower-Midrange. A center of gravity is the average location of the weight of an object - where weight is evenly distributed. For a preference of 'balance', rather than giving a frequency, and since many say we all hear differently, I'll simply point - I'll point at the orchestra on stage.