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


Many audiophiles set out to assemble a system that sounds “warm.” I have heard several systems that could be described that way. Some of them sounded wonderful. Others, less so. That got me wondering: What is this thing called “warmth”?

It seems to me that the term “warm” can refer to a surprising number of different system characteristics. Here are a few:

1. Harmonic content, esp. added low order harmonics
2. Frequency response, esp. elevated lower midrange/upper bass
3. Transient response, esp. underdamped (high Q) drivers for midrange or LF
4. Cabinet resonance, esp. some materials and shapes
5. Room resonance, esp. some materials and dimensions

IME, any of these characteristics (and others I haven’t included) can result in a system that might be described as “warm.”

Personally, I have not set out to assemble a system that sounds warm, but I can see the appeal in it. As my system changes over time, I sometimes consider experimenting more with various kinds of “warmth.” With that in mind…

Do you think some kinds of warmth are better than others?

Thanks for your thoughts.

Bryon
bryoncunningham
... For a given volume, fundamental frequency, and envelope I can't envision anything other than differences in harmonic structure that could account for differences in timbre, tone, or the basic character of the note.
Just to be sure it's clear, I should add with respect to this statement that I am referring to the directly heard sound produced by the instrument, apart from hall effects and apart from artifacts of the recording and playback processes.

Best regards,
-- Al
Hi Al - you wrote: "If you are saying that any note produced by any instrument will naturally and invariably contain frequency components of non-zero amplitude at ALL harmonic multiples of the fundamental (lowest) frequency component of the note (and I don't know whether or not that is true), then yes, that would mean in a literal sense that the system cannot INTRODUCE a harmonic that isn't already there."

Yes, this is exactly what I am saying. All of the harmonic overtones of a sounded frequency are always present in the timbre, so electronic distortion cannot introduce or create new harmonics, it can only distort those already present.

About your last statement: " For a given volume, fundamental frequency, and envelope I can't envision anything other than differences in harmonic structure that could account for differences in timbre, tone, or the basic character of the note." This is a strange statement. The basic difference in timbre between a flute and a violin, to use your example, is that one is made of metal and one is made of wood, not to mention the fact that their sounds are created in a completely different manner as well. This is obviously the largest factor in the difference in timbre. Without going into the science of it, waves produced by a string behave very differently from waves produced by a tube. A tube with one end closed behaves differently than one open at both ends, and conical and cylindrical tubes behave differently as well. Side holes in the tubes have their effects as well, of course. Not to mention different types of wood or metal alloys used in the instrument's construction, which have very great effect on the timbre.

Another important thing to point out is that although some of these various timbres are more acoustically complex than others, the overtone series for all of them is always the same - it doesn't matter what instrument is creating it.

As a side note, the flute happens to be one of the purest instrumental timbres, and the oboe is one of the most complex. This is the reason that the oboe gives the A to tune the orchestra - it's complex tone is more easily audible.

Last, another word on the audibility of these harmonics. Sometimes, it is possible for the brain to concentrate on an overtone of the tone sounded, if this frequency has already been sounded, so that the ear is aware of it. For instance, if a piano sounds A440Hz, and then the A an octave below (220Hz), it will be easier to attempt to hear the A440 overtone within the sounded A220Hz tone. This takes some training, of course, especially if one wants to try to hear more difficult overtones. There are some people who have claimed to be able to hear as many as 27 different overtones, but the vast majority of researches seriously doubt this claim - 5 or 6 at most, and that for a very highly trained ear indeed. Those types of experiments are fascinating.

Best regards to you as well, Learsfool
"I am unaware of any naturally occuring 'harmonics' in an electrical signal. Only distortion of what ever type."

Harmonic distortion measurement is done by feeding pure fundamental with no overtones (sinewave) and subtracting the same fundamental from the output. Whatever remains are harmonics introduced by electronics that weren't in the original (source) signal. You can call it naturally occuring harmonics (introduced by electronics). Enhancing means adding system produced harmonics to instrument harmonics. System can also introduce harmonics by intermodulation or transient intermodulation. It is also possible for system to introduce frequencies that are not harmonically related to fundamental frequency as it happens often with A/D or D/A conversion with jittery clock.

Instrument might have all overtones but they don't have to be harmonic overtones. Many instruments (like percussion) produce inharmonic overtones. System will alter the sound by adding it's own harmonics.
Learsfool,
The basic difference in timbre between a flute and a violin, to use your example, is that one is made of metal and one is made of wood, not to mention the fact that their sounds are created in a completely different manner as well. This is obviously the largest factor in the difference in timbre. Without going into the science of it, waves produced by a string behave very differently from waves produced by a tube. A tube with one end closed behaves differently than one open at both ends, and conical and cylindrical tubes behave differently as well. Side holes in the tubes have their effects as well, of course. Not to mention different types of wood or metal alloys used in the instrument's construction, which have very great effect on the timbre.
I think that in order for our understandings to converge, what is needed is a description of the differences in spectra that RESULT from the differences you are describing. Although I'm not sure that any of us can provide that without further research. I may try to do some research on that if I get a chance tonight or tomorrow.

If a violin and a flute were to play notes having the same fundamental frequency, the same volume, and the same duration, and if their respective notes as captured by a microphone were fed into a spectrum analyzer (a device which shows the frequency components of a signal, and the amplitudes of each of those components), what would the differences be between the two spectra, that account for their very different sounds? That is the key question, as I see it.
Electronic distortion cannot introduce or create new harmonics, it can only distort those already present.
Although it may not have been your intention, this statement would seem to imply that a distortion component at a given frequency would not be added by the system were it not for the presence in the original sound of a harmonic at that same frequency. Which is not the case, as I and Kijanki (whose post I am in full agreement with) indicated.
Although some of these various timbres are more acoustically complex than others, the overtone series for all of them is always the same - it doesn't matter what instrument is creating it.
Their frequencies are always the same, for a given fundamental frequency. But the amplitudes of each overtone in the series will be very different for different instruments.
The flute happens to be one of the purest instrumental timbres.
Yes, which I think corresponds to its notes having less harmonic content than in the case of most other instruments. I.e., its notes come closer to being a pure sine wave than those produced by other instruments (although of course they are still considerably different than a pure sine wave). Which I think is a basic reason that a flute, when not well recorded and reproduced, can often tend to be "hard" sounding.
Another word on the audibility of these harmonics....
To clarify, I certainly do not assert that individual harmonics are readily perceivable. What I believe is that differences in harmonic structure (the amplitudes of the harmonics, relative to the amplitudes of other harmonics and to the amplitude of the fundamental) are the primary determinant of timbre and tone. Therefore when we perceive differences in timbre and tone, we are perceiving the EFFECTS of differing harmonic structures.

Best regards,
-- Al
Following up on my previous post, I found this excellent writeup:

http://www.phys.unsw.edu.au/jw/sound.spectrum.html

It appears that I was partly right, but not seeing the whole picture. Some excerpts from the writeup:
If you change a sound without changing its loudness or its pitch then you are, by definition, changing its timbre. (Timbre has a negative definition - it is the sum of all the qualities that are different in two different sounds which have the same pitch and the same loudness.) One of the things that determines the timbre is the relative size of the different spectral components....
Let's look between the harmonics. In both of the examples shown above, the spectrum is a continuous, non-zero line, so there is acoustic power at virtually all frequencies. In the case of the flute, this is the breathy or windy sound that is an important part of the characteristic sound of the instrument. In these examples, this broad band component in the spectrum is much weaker than the harmonic components. We shall concentrate below on the harmonic components, but the broad band components are important, too....
Introductory physics text books sometimes give the impression that the spectrum is the dominant contribution to the timbre of an instrument, and that certain spectra are characteristic of particular instruments. With the exception of the closed pipes mentioned above, this is very misleading. Some very general or vague comments can be made about the spectra of different instruments, but it is not possible to look at a harmonic spectrum and say what instrument it comes from. Further, it is quite possible for similar spectra to be produced by instruments that don't sound very similar. For instance, if one were to take a note played by a violin and filter it so that its spectrum were identical to a given spectrum for a trumpet playing the same note, the filtered violin note would still sound like a violin, not like a trumpet.

Here are some general statements about spectra:

* bowed strings and winds have harmonic spectra
* plucked strings have almost harmonic spectra
* tuned percusion have approximately harmonic spectra
* untuned percusion have nonharmonic spectra
* the low register of the clarinet has mainly odd harmonics
* bowed strings have harmonics that decrease relatively slowly with frequency
* brass instruments often have spectra whose harmonics have amplitudes that increase with frequency and then decrease.

To say anything that is much more specific than that is misleading.
The rest of the writeup is quite interesting as well, and even provides a good deal of additional specific discussion concerning the flute.

Best regards,
-- Al
Hi guys - Kijanki, you make a very good point about jitter (and explains yet another reason why digital has never sounded as good as analog for me), and the intermodulation distortions. I guess I thought that jitter had more to do with timing, but I suppose that it would indeed produce harmonic distortion as well.

Al, I do understand now much more where you are coming from, thanks very much! I will have to read up on these types of electronic distortions some more. When I took a graduate level acoustics course, it was geared (as was the very fine textbook which has always been my main reference ever since) to performing musicians and live acoustics, not recordings and electronic equipment. In fact, I am not sure that purely electronic distortions were discussed at all, I will have to look that up. I have never been one to judge audio equipment by the specs, anyway, so these types of things have never held much interest for me. This discussion has certainly got me curious, though!

I will have to check out the article you linked when I have some more time to give it serious attention. Just reading over your quotes from it, it seems like very good info. The text I mentioned goes into great detail about all of those issues mentioned. If you care to look it up, it is entitled The Musician's Guide to Acoustics, by Murray Campbell and Clive Greated, and was published by Schirmer. I do see, getting it out, that the last couple of chapters discuss electronics briefly (I think mostly from the perspective of electronic instruments rather than audio equipment, though), but the book is basically about acoustic instruments and how they behave, and how the room affects them. So my knowledge of acoustics is much more in that line, things that affect live performance rather than recording playback.

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. Thanks so much for sharing your knowledge - between you and Atmasphere in particular, I have received quite an education on this site.
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.
The definition of warmth in audio as defined by the person who introduced the word to the lexicon of audiophiles is in this thread; see J. Gordon Holt. I suggest the following: it has been used for decades. If the definition is clear, then there is little reason to tinker with it. If we need new words to describe something similar, let's find new words, and not confuse them with existing terminology. If the existing definition doesn't agree with ones interpertation, too bad, find a new word for what your trying to convey, no reason to muddy the waters with more confusion. If the definition is unclear, that's something else.
02-21-11: Almarg
…the system can certainly, as I see it, CREATE a harmonic, as a distortion product of the fundamental frequency of the note, irrespective of the existence of that harmonic in the original signal.
02-22-11: Kijanki
Harmonic distortion measurement is done by feeding pure fundamental with no overtones (sinewave) and subtracting the same fundamental from the output. Whatever remains are harmonics introduced by electronics that weren't in the original (source) signal.

The comments above are what I had in mind when, on 2/12, I wrote:
If the warmth is on the recording, and you hear it at the listening position, then the playback system is accurate with respect to warmth. Hence it is not an ADDITION. If, however, warmth is not on the recording, but you still hear it at the listening position, then the playback system is not accurate with respect to warmth. In this case, warmth is an ADDITION to the signal introduced by the playback system.

It is probably safe to say that all equipment is additive, but some equipment is more additive than others, at least with respect to the addition of harmonic content. The evidence for this can be seen in the the kind of measurements that routinely appear in Stereophile, such as Amp A and Amp B. As you can see from the graphs, Amp B adds harmonics of considerably greatly amplitude than Amp A. Hence, with respect to harmonic content, some equipment is more additive than others.

Amp A – the one with less added harmonics – is the Pass XA30.5, which is what I currently own. Amp B – the one with more added harmonics – is the PrimaLuna DiaLogue 7. The upshot of all this is that, in light of my desire for additional warmth, maybe I chose the wrong amp.

Moving on to…

The issue of whether instrument timbre is reducible to harmonic content. I am completely out of my depth here, so will remain agnostic. Having said that, IF instrument timbre is EVEN PARTIALLY reducible to harmonic content, then it reveals a flaw in the “additive approach” to playback.

Here is how I characterized the “additive approach” in a previous post…
02-12-11: Bryoncunningham
I have recently come to believe that some "additions" to the signal introduced by the playback system, while inaccuracies relative to the recording, may nevertheless be MORE accurate relative to the live event. That is because, both deliberately and accidentally, the recording process often REMOVES characteristics like warmth from the recording. Hence the ADDITION of warmth by the playback system actually makes the sound at the listening position closer to the sound of the live event.

And here is the flaw in this approach…

What is ADDED during playback will not be identical to what was SUBTRACTED during the recording process.

The reason is because, while the harmonic contents of live events are almost infinitely VARIABLE, the harmonic “additions” of playback equipment are largely CONSTANT, being persistent artifacts of a circuit's more or less fixed parameters.

Does this mean that I am retreating from my newly acquired view about the value of the additive approach to playback? No. I am merely recognizing a limit to the additive approach, namely that it cannot replace EXACTLY what is missing from the recording. Hopefully it can replace an approximation of what is missing. And that will have to be good enough.

Bryon
the fact that a word is defined does not rule out the possible arbitrary nature of the word. i am not saying holt's definition is not valid, but like any word in the english language, the duration of its usage and acceptance in communication is afctor in its utility.

by the way, what is the source of gordon holt's definition. does anyone have a reference for the definition.

perhaps if enough people accept the definition and when mentioning the word accept gordon holt's definition , it should be sufficient.

only a few people have cited holt's definition, so it seems that his definition may not be definitive.

for example, is the originator of this thread eliciting suggestions as to attain what holt defines as warmth ?
02-23-11: Mrtennis
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.

This is a valid observation, Mrtennis, but I have found this discussion informative and interesting, in spite of our failure to arrive at a single definition of "warmth."

I think the reason why a single definition of warmth is elusive is because "warmth," as a metaphorical description of sound, is not a unitary category. It is a disjunctive category, i.e., a category of the structure X or Y or Z etc.. Disjunctive categories can be unwieldy and frustrating, but they are useful under certain circumstances.

Judging from the discussion on this thread, "warmth" seems like it can refer to harmonic content, frequency response, time domain behavior, ambient cues in the recording, listening room acoustics, and probably other things I've left out. In my view, what unites all of these diverse characteristics under the common category of "warmth" is the listener's subjective experience of each of them as "warm."

This heterogeneous definition of warmth leaves something to be desired in terms of conceptual Law and Order, which I normally find very appealing. But I suspect that, in this case, a heterogeneous definition is as good as we're going to to get.

What seems to follow from the the apparent fact that there are different KINDS of warmth is the likelihood that there are different WAYS OF ACHIEVING warmth, which is something I have learned from reading this thread.

Bryon
Hi Bryon,
... The issue of whether instrument timbre is reducible to harmonic content. I am completely out of my depth here, so will remain agnostic.
Let me make sure it's clear that implicit in my previous post (the one with the lengthy quotes from the "What Is A Sound Spectrum?" writeup) is that I now recognize that timbre is only partially reducible to harmonic content, and other factors also affect timbre significantly. An example of those other factors is the low level broadband component of the flute spectrum that the article discussed. I still suspect, though, that for most instruments harmonic content is typically the most significant determinant of timbre.
IF instrument timbre is EVEN PARTIALLY reducible to harmonic content, then it reveals a flaw in the “additive approach” to playback.... What is ADDED during playback will not be identical to what was SUBTRACTED during the recording process. The reason is because, while the harmonic contents of live events are almost infinitely VARIABLE, the harmonic “additions” of playback equipment are largely CONSTANT, being persistent artifacts of a circuit's more or less fixed parameters.
I'm not sure that the variable/constant distinction is particularly meaningful, even within the limited context of harmonic distortion. The harmonic components resulting from distortion in the electronics will continuously vary as a function of the varying spectral components of the music, and to some extent with the overall signal level. Harmonic distortion introduced by the speakers will vary with signal level as well as with frequency, and will often overshadow the distortion components introduced by the electronics. Throw in intermodulation distortion, transient intermodulation distortion, the complexity of the music, the complexity of the sounds of the instruments themselves, hall and room effects, the vagaries of the recording process, etc., etc., and the “approximation” you spoke of would seem to be all that can be hoped for, regardless of the approach that is chosen.
The upshot of all this is that, in light of my desire for additional warmth, maybe I chose the wrong amp.
On the other hand, as was said earlier, with your speakers an amp having a high output impedance (such as the Prima Luna and probably most other tube amps) will de-emphasize lower frequencies relative to upper mid and high frequencies. Obviously, that would be in the wrong direction with respect to adding warmth.

So I'm not sure where that leaves us, but those are some thoughts.

Best regards,
-- Al
I'm not sure that the variable/constant distinction is particularly meaningful, even within the limited context of harmonic distortion. The harmonic components resulting from distortion in the electronics will continuously vary as a function of the varying spectral components of the music, and to some extent with the overall signal level.

I agree with this, Al, insofar as I recognize that the harmonic content introduced by equipment varies as a function of the spectral content and level of the input signal. So perhaps "variable vs. constant" is not quite the right distinction.

The distinction I was trying to capture is between the harmonic content of the live event vs. the harmonic content of the reproduced event. To the extent that the recording process diminishes the harmonic content of the recording, the additive approach to playback may do something to replace what is missing. But it cannot, so far as I am aware, replace the EXACT missing harmonic content, since the harmonics introduced by equipment are, in essence, artifacts.

The fact that equipment-induced harmonic artifacts vary as a function of the spectral content and level of the input signal does make them "variable," perhaps even as variable as the harmonics of the live event. Nevertheless, equipment-induced harmonic artifacts are not SIMULACRA of the harmonics of the live event. That is the flaw in the additive approach to playback that I was trying to point out.

Bryon
Looking back on this thread, I have another thought...

There has been a lot of discussion about how increasing warmth in a system might involve ADDING something to the signal, like low order harmonics. It occurs to me that increasing warmth might also involve SUBTRACTING something from the signal.

Maybe the most obvious example of how subtracting something from the signal might increase warmth is subtracting treble, which amounts to the same thing as adding midrange/bass. A less obvious example is contained in Al's second post on 2/6, namely subtracting destructive acoustical effects like comb filtering. One final example that I have personally experienced is subtracting (or at least reducing) jitter in digital playback, which to my ears increases the perception of "warmth."

Bryon
“and how do you get it”… I just went to “warm” by changing the footers under my CDP from Stillpoints to HRS Nimbus Couplers. I really liked what the Stillpoints did, but at times my system sounded a little “thin”. Without losing any of the good that the Stillpoints brought, the HRS Nimbus Couplers added what can best described as “weight”.
Some times, it could be as easy as swapping the source I/c. Not to alter freq response but take that electronic tinze/noise surrounding the notes. I have three sets of cables at each source, same corresponding brand for each level of sound i desire- neutral, slightly warm and warmer. You will be surprised how 'listenable' most music would become... true changing cables every once in a while is a chore and one set of cables is always your primary choice. It is no different than some folks trying different tonearms, cart, diif DAC sampling, diff sources...

One characteristic that warmer sound gets you is the image size ( overall- fundamental and harmonics and air) of instruments become life size which I personally consider primary requisite.
In 1970, a girl who I shared a house with, had a Fisher tube receiver and a pair of KLH bookshelf speakers that were given to her by a friend. Thats the first time I experienced "warmth" which totally had me captivated. Warmth is a full, rounded, refined relaxed sound that has a silky thickness and velvet texture to the music. A more of a full body to the sound where the upper frequencies seem to bend down more and blend and integrate into the mid-bands. From that era, several factor's come into play. Tubes at the time that were made by Sylvania, Zenith, RCA, and GE, were better built then the best tubes of today. Back then they had double glass envelopes, heavier filaments, and the technical artists who made those tubes are non-existent today. They were like composer's. In fact, the hardware machines are still in existence collecting dust at those companie's, but their is no one around today that has the technical ability to revive the technique and skill to make those tubes. A lost Art. The tubes from that time would last for ten years or more, as compared to tubes today that are good for 4K to 6K hours. Another fact is at the time, speakers had a lower sensitivity of 83 to 86 db's. Speaker's today with sensitivity between 90 and 96 db's, have a more aggressive open top end. Speakers with much lower sensitivity have a more relaxed character. Back then most amplification in homes was between 25 to 40 watts. Also, tweeters back then were more simple and basic, and it wasn't until the late seventie's when Phase Technology in Florida invented and built the worlds first ferrous oxide fluid filled tweeter which improved the dynamic range. For the most part, it was the tube designs from fifty years ago that gave us that warm, rich, full velvety sound. If those type of tubes
came back on the market, we would return to the full analog glory that has been lost.
its very simple. try attenuating the frequencies between 3 and 5 k by say 3db and increasing the spl by 3db between say 90 and 200 (i may be a little off here) and , voila! warmth.