What is Warmth?

Raul, I disagree a bit about warmth in live classical concert. People described various concert halls' characteristic and warmth is certainly one word that keeps cropping up. I have not heard all that many great halls around the world but I would say for example that Vienna State Opera House certainly sounds warmer Grosse Festspielhaus in Salzburg which is warmer than Metropolitan Opera House. The old Orchestra Hall (before renovation10-15 years ago) was quite a bit drier, cooler in tone than Carnegie Hall and so on. Fazioli piano is crystal clear, cooler in tone than Grotrian which is more woody, darker/warmer tone. Warmth is a coloration for sure but I am not sure if it is neccessarily an abberation. What should be use as a standard in neutrality?

Hi Raul, it is difficult to define such a subjective term. I agree with you about the location of recording microphone and actual listening position in a concert hall and all that. On the other hand, I am not sure about the difference between warm sounding stero equipment and instrument/hall. Let see if I get this right. Most people tends to imply that roll off high frequency and the bump in mid upper bass seems to give rise to what we hear as warmth in stereo equipment. Now, acoustically dry concert hall, as I understand it is a hall the have very small reverberation time, say 2-3 ms where as the acoustically more pleasing tone hall, those that seems to be richer, denser tonal color, usually has longer reverberation time, around 4-6 ms (I read about this somewhere a long time ago, not sure if I remember the number correctly). However, richer, denser tone does not neccessarily means warmer sound. Depending on where you sit in the audience, there is definitely going to be some roll off of high frequency in comparison to close mike position. Sitting at 10-30-50m away from the stage, one would expect certain decline or roll off of high frequency, more so than low frequency by various instruments to exist. I think that's why real symphonic concert seems to sound less bright and duller than what I hear on recording and that's why orchestra nowaday tries to compensate for that by raising the frequency on the note to give that extra brightness. Whether the roll off characteristic of each hall give rise to warmer sound in some concert halls over the other, I am not sure.

When talking about different made of the same instruments, warmth is definitely a term that I often hear people using to describe the different in sound, French vs German tone, brands of pianos, various wood used in instruments. However, I have not heard anyone specifically say that it is the characterisitic high frequency roll off of mid/upper bass bump that give rise to the warmth quality in each instrument or not. Personally I play piano and own a Grotrian grand piano. I have also played quite a bit on Steinway, Fazioli, Yamaha, Ibach, vintage Erard and Pleyel and I what perceived as warmth tone when compare each instrument is definitely quite valid.

PS when talking about roll off high and mid/upper bass bump, I tend to think of some ported speakers or some tube equipments. However, a warm sounding class A solid state amplifier generally tends to measure pretty flat from 20Hz to 20,000Hz, does it not? May be I am missing something here.

Atmasphere, thanks for a really good explaination, electrical wise. Not to knitpick since I am learning a lot here but definition that GH gave for warm/dark is really more about imbalance between high frequency and low frequency. If I understand you correctly, it is not that warm audio equipment have tilted frequency response per se but more that distortion from 2nd harmonic is more pronounced at the bottom end giving illusion to more lower frequency and less at the top, is that correct?

Talks of harmonic as distortion is a bit surprising. I suppose, from instrument point of view, it is the harmonics that give rise to richer,fuller, denser, usually more pleasing tone. I suppose wrong kind of harmonics would do exactly the opposite. In fact certain piano maker such as Bosendorfer intentionally added a 4th string to certain range of notes and is not struck by piano's hammers at all to increase sympathetic vibration and presumbably increase overtone and harmonics. I suppose audio equipment is not supposed to add its own signature of harmonics and just play whatever signals that is passed through only.
I am curious if you might have an example of equipments that you would consider to be one that is able to tame most of the harmonics created by audio equipment itself. Certainequipment that tends to emphasize clarity and detail that comes with cold, analytical tendency probably has its own set of distortion as well. What would be your closest ideal to neutrality? I am not picking on you but just would like to get some idea of a reference. Thanks for your comment.