What is “warmth” and how do you get it?

FWIW, I think that when we attend many concert halls, especially large ones with many patrons, we are often exposed to "warmth". The same instruments can sound quite different; without an audience, in different rooms or even in different seats. Depending on your perspective "warmth" can be either natural or a by-product of a typical live listening experience.

Hi guys - Hifibri wrote in his last post "By changing overtones you change the shape of the wave and the resulting sound." As I have tried to explain, the actual overtones do NOT change.

Al, you are probably correct about the amplitude of them changing, I would need to get out my acoustics books to make sure. However, since these overtones we are speaking of are not audible to the vast majority of even highly trained ears, changes in their amplitude then would not be audible either, and they would be very minute in any case (though some would argue that this does not mean the brain wouldn't perceive the change somehow). The actual amplitude of the total sound of course has a far greater effect on the waveform. You bring up a very interesting question, though. How a musician's subtle changes in timbre affect the waveform is something I would need to look up (certainly these changes obviously effect the waveform somehow) - but I am not sure that my books go into that much detail. What I can say is that there is no way a musician can deliberately change the volume of a specific overtone in his sound, so even if you are completely correct, there is unfortunately no practical application of this for actual live performance.

Regardless of what the answers to these questions are, things like what Al terms "hall effects" have a MUCH greater effect on the perception of "warmth" (Unsound is perfectly correct in his last post), and the recording itself has an even greater effect. The design of the audio equipment also has much to do with it - for instance, to bring up Onhwy61's point, many designers of digital processors routinely omit all harmonics above the range of human hearing, claiming what the ear can't hear it won't miss. Many of us beg to differ, and it has been proven that the brain can detect frequencies above what the ear can hear. LOL, am I now getting dangerously close to arguing against my point? This is a fascinating discussion, indeed.

02-13-11: Almarg
...realistic reproduction of timbre, which as I see it correlates with accurate reproduction of the RELATIVE amplitudes of the harmonics and the fundamental of each note, as well as proper time domain performance and ambience reproduction, I envision as being the keys to the PROPER reproduction of warmth.

RE: Harmonics. I agree with you completely that the relative amplitudes of harmonics are a significant factor in the perception of warmth.

RE: Time domain behavior. Earlier on the thread, Newbee said something similar - that warmth is partly a matter of a system's ability to portray the decay of notes. I suspect you mean something similar. Do you think that tubes are inherently better at this?

RE: Ambience. As I mentioned in a previous post, it never really occurred to me that ambience was a significant factor in the perception of warmth. That is probably because I have a number of studio recordings with no "hall effects" that nevertheless sound warm to me.

Having said that, it seems plausible that the indirect sound from a recording space might contribute to the perception of warmth, whether from the kind of "frequency contouring" you alluded to or from other effects. But that also seems to imply that, under some circumstances, flawed recording spaces might diminish the perception of warmth. In other words, some hall effects might sound warm, while other hall effects might sound cool. Do you think that's true?

I should add that if the indirect sound from recording spaces can affect the perception of warmth, for better or worse, then it seems to follow that the indirect sound from listening spaces might also affect the perception of warmth, for better or worse. Hence there might be ways to increase the warmth of a system through acoustical treatments in the listening room, which is an interesting idea to me.

Bryon

"...While other hall effects might sound cool". Yes, but I would think that's more likely in small, highly reverberant halls, and not as likely to happen in typical concert venues.

RE: Time domain behavior. Earlier on the thread, Newbee said something similar - that warmth is partly a matter of a system's ability to portray the decay of notes. I suspect you mean something similar. Do you think that tubes are inherently better at this?

I would not go so far as to say that tubes are inherently better with respect to time domain performance. Their main advantages, as I see it, relate to harmonic balance, and also to increased dimensionality and better imaging (although as I indicated earlier, I can't explain technically why that would be so).

However, tube designs lend themselves more readily to minimal use of feedback. As Atmasphere has frequently pointed out, feedback, at least if not done judiciously, can create or enhance objectionable distortion components. It can also affect the quality with which the leading edge of rapidly changing transients are reproduced. Our hearing mechanisms give particular emphasis to those leading edges, as a result of the Haas Effect and the Precedence Effect. Although as was stated in Newbee's excellent post, that is most applicable to instruments whose notes have fast risetimes. His comments about decay times I also think are very true.

It seems plausible that the indirect sound from a recording space might contribute to the perception of warmth.... But that also seems to imply that, under some circumstances, flawed recording spaces might diminish the perception of warmth. In other words, some hall effects might sound warm, while other hall effects might sound cool. Do you think that's true?

I would doubt it, at least assuming the hall is at least semi-decent. I can't remember ever being in a hall in which the instruments sounded "cool," in the way that they can on some recordings.

In a hall, I just about invariably sense a sort of "aura" surrounding each note (more so or less so depending on the instrument and the music, of course), that contributes to a sense of richness/body/warmth, and which I believe is a result of the summing together of delayed sound and directly heard sound.

... Hence there might be ways to increase the warmth of a system through acoustical treatments in the listening room, which is an interesting idea to me.

Room acoustics and treatments are not one of my areas of expertise, but my instinct, with respect to situations where physical and aesthetic considerations are not too limiting, would be that it should often be possible to find a compromise that would enable "cold" recordings to be warmed up somewhat, without significantly degrading reproduction of good recordings. But only to a limited extent, given the disparities in delay times between listening rooms and halls.

Best regards,
-- Al