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

Learsfool - jitter is a form of modulation. It creates in frequency domain sidebands of very low amplitude - still quite audible since not harmonically related to fundamental. This amplitude (order of <-70dB) is proportional to level of fundamental frequency. With many frequencies (music) it becomes many sidebands - hash (noise). This noise is proportional to level of the signal and is zero with no signal - therefore is detectable only as a lack of clarity. Everything affected by noise (clarity and imaging) will be affected by jitter.

By reading this thread and some internet articles I realize that complexity of instruments' sound is something that I will never understand. One article even mentioned that bassoon at low and high notes sounds like two different instruments. In addition to complex harmonics (first five harmonics stronger than fundamental) it has pipe resonances that are getting sharper going up, resulting in "11th resonance hitting 12th harmonic". Incredible complexity - and there is still effect of the hall and technique of the player. One article mentioned interaction between instruments and gave example of two people whistling two frequencies 204Hz and 214Hz. Bystander will hear just one frequency 209Hz (average) with loudness modulated at 10Hz (difference). Orchestra has perhaps many interactions like that but produces nice harmonics. I should read on theory of music to understand it better.

What is particularly interesting to me is your discussion of different amplitudes of the harmonics having such a big effect. I am starting to come around, but it would be good to find some info on that in particular. That would certainly seem to be one of the biggest differences between live and recorded sound, then, and probably a much bigger difference than I have thought.

For a bit more background, I'd recommend that you do a bit of reading on the theory and history of electronic synthesizers and speech synthesis. In electronic music composition, this timbral relationship between the fundamental and its harmonics is commonly referred to as "formant", the change of parameters across the duration of a note is called "envelope", and the periodic change within a note is called "modulation". Approximate, crude parallels to acoustic instruments are that formant = timbre, envelope = articulation, and modulation = vibrato.

It is of course possible for analog electronics to generate their own harmonics - this is how analog synthesizers work. I've personally implemented patches on early synthesizers (ARP and Buchla) that can deliver pretty convincing flute, bell, and string sounds. Ironically, it's not so much the timbre/formant that's hard to emulate, rather it's the envelope.

Even earlier, the acoustic principles of building formants are very structured in a thousand or so years of the art of building and tuning pipe organs. Emulation of orchestral instruments became a very common goal - this style of organ-building probably reached its zenith in the very early years of the 20th century with builders such as Willis in the U.K. and E.M. Skinner in the States.

An interesting side note on timbre - I have found it a commonly-held view in vocal and woodwind pedagogy that poor tone production produces a set of overtones that are in fact not in tune with the fundamental, rather they tend to be flat. Although I have not seen any measured evidence to back this up, I tend to agree with it - as the perception of intonation problems as it relates to tone production cannot be corrected simply by raising the pitch. That is, some singers always sound flat, no matter what pitch they're singing.

all of the discussion regarding harmonics is useful and instructive, but does not address the question of whether warmth is a form of coloration. unfortunately, no one has definitively spoken on this subject.

the purpose of the thread , i believe, is the elicitation of suggestions to achieve warmth.

as i have said, without an understanding of what warmth is, the question cannot be answered.

i have proposed an (empirical) concept of warmth as deflections in spl, both positive and nagative, which are audible. as such such a concept would connote that warmth is coloration.

let me give an example.

several posters have mentioned instruments such as the violin and flute, in their discussion of harmonics.

suppose one considers the harpsichord.

if the sound of a harpsichord seems to emphasize the wood body and to some degree, obscures the articulation of the strings, i would say the impression of the sound of the harpsichord would include warmth, as one of the adjectives used. of course, the performer might be responsible for this effect, but that is another question.

i believe the warmth region comprises frequencies below 100, so it would seem that a peak in the region below 100hz (??? how many db) would produce warmth that the poster may be seeking.

all of the discussion regarding harmonics is useful and instructive, but does not address the question of whether warmth is a form of coloration. unfortunately, no one has definitively spoken on this subject.

Well, er, if "warmth" is imparted upon the timbres of instruments to a degree not present on the recording, then yes. Otherwise, no.

To "add warmth" at the studio or FOH console, I would usually first reach for a band of EQ in the 1500-2000 Hz range, moderate-to-wide Q, and cut a couple of dB. Another technique that works in the studio is to cut the upper bass (200Hz-ish centered) area in the side chain of a compressor -- this makes it a function of envelope as well as timbre, and can add "bloom" to drums and vocals.

Does that help?

Hi guys - great posts. @Kijanki - thanks for the jitter discussion. And yes, timbres of instruments are extremely complex. It makes for fascinating reading; the book I mentioned before is a great place to start - non-musicians would have no problem with any of the terminology, from what I remember of it.

@Kirkus - thanks for the great post! I had a girlfriend in college who was doing alot of composing in the electronic music studio, and was actually quite frustrated by the bewildering array of options. It was a very overwhelming experience for her. To be honest, I'm really not very enthusiastic about any form of electronic music - while I appreciate it, I just don't care for the timbres. But you are probably right that that would be a good source of info.

About your last paragraph on poor tone production affecting tuning - what you say is basically correct, and it does go for brass instruments as well. An unfocused sound will also not necessarily be flat - the pitch actually fluctuates quite a bit, and can be sharp just as well as flat, which is a very interesting phenomena. Uncentered might be a better description of what I mean specifically here - the pitch is wandering out of the player's control, and it doesn't just move in only one direction when this happens. Pitch tends to raise, for instance, particularly when the player is straining. Overall, though, the timbre of a very unfocused sound will be dull (which is why it often sounds flat even when it may actually be sharp in pitch), weaker, and often airy in the case of wind instruments. There will also be lots of "fuzz" on the edge of the sound. Some jazz musicians cultivate this type of sound for expressive purposes, and bend the pitch quite a bit. This is where the old tuning joke "close enough for jazz" originates. Another example would be of a brass player with alot of "edge" to the sound - they may sound very loud up close, but "edge" will not carry out into the hall very well on it's own - there must be a good core to the sound.

As Mr. Tennis brings up, though, how all this relates to what audiophiles call "warmth" is another question. Even if "warmth" is called a "coloration", I think Bryon is right in asking is this a bad thing? In the case of an orchestral recording, equipment that makes the sound "warmer" is almost certainly also making it more lifelike, or as Bryon would put it, faithful to the original event. I for one don't care how a piece of equipment measures, or if it is "neutral." For me, equipment that is usually described as "warm" almost always sounds better than equipment specifically described as "neutral." And then there is the recording and how (and where) it was done. To me, these are still huge factors in the perception of "warmth," despite my education I have here received on electronics, and my realization that they do manipulate harmonics quite a bit more than I understood.