02-10-11: Learsfool
...you can have a system that measures very well in the frequency response that still sounds very cold (or doesn't resolve timbre correctly) - I have heard many of them in dealer's showrooms - so that is why I do not equate "warmth" with frequency response. Harmonic structure does come much closer to my conception.
Learsfool - I agree that a system that measures well in frequency response can nevertheless fail to sound warm. In other words, balanced frequency response isn't a
sufficient condition for the perception of warmth. But that doesn't mean that balanced frequency response isn't a
necessary condition for the perception of warmth.
I suspect that, to be perceived as warm, a system must have a balanced frequency response, within some range. (BTW, I don't think "balanced" is necessarily the same thing as flat.) I think that bright systems, or systems with very little bass, are less often perceived as warm. And I think that systems with elevated upper bass and/or lower midrange are more often perceived as warm. In addition, Al pointed out how anomalies in frequency response, like those created by comb filtering, might conceivably diminish the perception of warmth.
Taken together, these considerations seem to suggest that there is a link between frequency response and the perception of warmth, even though, as you point out, some systems that measure well in frequency response nevertheless fail to sound warm.
This is not just about semantics or logic. It's about HOW TO GET warmth in your system, when you don't have it. If warmth is both a matter of frequency response and harmonic content, then manipulating one of those variables could presumably contribute to the perception of warmth.
RE: The use of frequency response to increase warmth. I think efforts to balance frequency response are a good idea, whether it's done with tone controls, eq, or room treatments. I use all three, but would still like some additional warmth. One way to get it, in light of the observations above, might be to elevate the upper bass and/or lower midrange of my system. But I'm not a big fan of this idea. I tend to experience systems with elevated upper bass/lower midrange as uneven, slow, thick, or unresolving.
RE: The use of harmonic content to increase warmth. I think this is a much better idea. The obvious way to add harmonic content is to add tubes, as several posters have pointed out. Unfortunately, in my case, that would mean changing both my amp and my speakers, since my speakers aren't very tube friendly. That could get expensive, but I'm considering it.
Bryon