Here it is:

"Hi Ratpack,

Those two terms have been in common usage among some of us that participated for 20 years or more in the double-blind listening tests of loudspeakers conducted at the National Research Council in Ottawa.

If you were on the listening panel, there was a vertical rating scale for "Brightness- Dullness", with "very dull" at the bottoom and "very bright" at the top, as well as a kind of ideal mid-position. Dull signified a depressed midrange and rolled off highs, so it was "muffled" and "lacked detail".

"Very bright" verged on harshness; too much midrange and high-frequency emphasis. But you could use "bright" as a compliment as well, meaning "bright, quite detailed" or you might qualify that a bit, if you heard treble resonances that were annoying.

"Warm" was typically used to describe a speaker whose frrequency response had an audible boost in the upper bass octaves from about 80 Hz to 500 Hz. It might be about 3 dB or so, but it lent a kind or "rich" (another synonym) fuzzy resonance to male voices, double bass, cello, etc.

"Warm" was also used to describe a kind of rich, harmonic wash that characterized speakers with lots of even-order harmonic distortion in the bass octaves, and that was also applied to some tube gear, which typically adds that kind of "musical" distortion to signals. Audiophiles mistake that quality for some ethereal or mysterious trait that belongs to their particular tube device. In fact, it's just a different kind of musical distortion, but distortion nonetheless.

The opposite of "Warm" might be termed "Lean", lacking bass content or "Thin"--too little bass relative to midrange and treble.

Regards,

Alan Lofft
Axiom Resident Expert"

And, now, some are using those terms to describe pre processors and receivers that are supposed to have a very flat frequency response and very low THD!!

Go Figure!!!!!!!!!!!!