In a previous post i explained why all harmonics (set apart the powers of 2) are notes out of tune, and if the music is tonal, that is based on the musical modes used in the classical music things get even worse.
In this case the amplifier harmonics even if they were right with respect to the musical notes would produce notes that are out of the played mode..
The bolded below are the notes in a major scale, the amps harmonics will be all present that s why i also bolded them.
1.0000000
1.0594630
1.1224620 H9 1.125
1.1892071 H19 1.1875
1.2599210 H5 1.25
1.3348398 H11 1.375
1.4142135 H11 1.375
1.4983070 H3 1.5
1.5874010 H17 1.0625
1.6817928 H13 1.625
1.7817974 H7 1.75
1.8877486 H15 1.875
2.0000000 H2 2.00
So imagine a piece of music using only the white keys on a piano, that s C major scale, and that there s a second pianist in the background playing the piece with a piano out of tune.
What i find amazing is that such observations are completely left out in any debate about the so called "musicality" of amps, as if the point wasnt exactly music reproduction but mere ego boosting.
So i have a question for the proponents of high THD amps, do you think that music sound better if we add a content that is not related to the musical frequencies other than by being out of tune systematicaly..?.
In this case the amplifier harmonics even if they were right with respect to the musical notes would produce notes that are out of the played mode..
The bolded below are the notes in a major scale, the amps harmonics will be all present that s why i also bolded them.
1.0000000
1.0594630
1.1224620 H9 1.125
1.1892071 H19 1.1875
1.2599210 H5 1.25
1.3348398 H11 1.375
1.4142135 H11 1.375
1.4983070 H3 1.5
1.5874010 H17 1.0625
1.6817928 H13 1.625
1.7817974 H7 1.75
1.8877486 H15 1.875
2.0000000 H2 2.00
So imagine a piece of music using only the white keys on a piano, that s C major scale, and that there s a second pianist in the background playing the piece with a piano out of tune.
What i find amazing is that such observations are completely left out in any debate about the so called "musicality" of amps, as if the point wasnt exactly music reproduction but mere ego boosting.
So i have a question for the proponents of high THD amps, do you think that music sound better if we add a content that is not related to the musical frequencies other than by being out of tune systematicaly..?.
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I've made such observations, at least about issues arising from the disparities between the overtone series and the nearby notes based on equal temperament, I believe somewhere in here.
Equal temperament is a marvelous invention in many ways, and most of us have gotten quite conditioned to it, such that among the just intonation intervals the major thirds now sound quite flat.
What also can occur is that when players play with really precise just intonation there can occur a fusion for sustained notes that sounds more like a single instrument.
But again, at the end of the day we listen to music and not usually to amplifiers. I like mine free from distortions and with a flat frequency response, but I wouldn't run screaming from a room populated with glowing power triodes.
Another thing: the correspondence between perceived pitch and log frequency is only rather good over a restricted range. I had thought that by now this and related would have been studied in sufficient detail that it would be a fairly settled subject. Then I bought a recent book: Plack et al. eds, Pitch.
The audibility of distortion
And the fifth harmonic is harsh too.
The pristine zero distortion sound is often called "dry" or "clinical", (putdowns which I dont like) but remember Peter Walker of Quad fame said an amp should be a straight wire with gain. Very low distortion has always been my goal, but I am increasingly curious to build two SETs to make a comparison.
And the fifth harmonic is harsh too.
The pristine zero distortion sound is often called "dry" or "clinical", (putdowns which I dont like) but remember Peter Walker of Quad fame said an amp should be a straight wire with gain. Very low distortion has always been my goal, but I am increasingly curious to build two SETs to make a comparison.
seems rather misplaced - musical instrument harmonics are harmonics, +/- tiny amounts of correction for the resonator's precise properties
at small levels relative to anything else naturally occurring in a given human hear critical bandwidth we pretty much don't hear below 1% added or subtracted components - critical band masking is a strong feature well established, exploited by lossy perceptual codecs
but IMD products are sum and differences of every frequency component going into a distortion mechanism of the form n*fa +/- m*fb where n,m vary over every integer combination that adds up to the order of the nonlinearity
I expect that IMD difference products are particularly troublesome, more readily heard
at small levels relative to anything else naturally occurring in a given human hear critical bandwidth we pretty much don't hear below 1% added or subtracted components - critical band masking is a strong feature well established, exploited by lossy perceptual codecs
but IMD products are sum and differences of every frequency component going into a distortion mechanism of the form n*fa +/- m*fb where n,m vary over every integer combination that adds up to the order of the nonlinearity
I expect that IMD difference products are particularly troublesome, more readily heard
Natural scales will change nothing, the amps harmonics will be out of tune, notice that i used a single fundamental but there s no music wich is single note, if a chord comprising three notes is played each note will have its out of tune harmonics generated by the amp, oriental scales that use one or two notes that are tuned at about 2^(1/24) ratio certainly wont accomodate well with amps harmonics.
Distorsion is not a problem if it was willfully added in the original signal, thing is that the final result must not be modded, SET amps are all good if they are used as part and sound signature of the musical apparatus to get a given sound, but using them for reproduction is like getting back to the studio and remixing the initial recording.
The tympanies inertia is such that the perceived frequency is out of tune at some point, i m pianist and I know that the two last octaves of a piano must be tuned accordingly for the notes to sound right, but this change nothing to the thing, unmusical harmonics will be shifted accordingly, although the higher range is not the problem given the ear sensitivity at those frequencies as well as the energy distribution of musical contents.
You are right that there s a whole area that is minored, i guess that some basic music theory is necessary for whom pretend to deal with the notion of musicality of a sound system, and here we are on something that is not subjective and wich is measurable.
IMD can be worse at equal amplitude since it s potentialy even more out of tune that THD but there s still a lot of it in any music, now if i take your formulae and apply it to a musical signal i notice that the first order sums are not related to musical frequencies, but the first order products are perfectly pitched by the virtue of the musical signals being related by a geometrical progression, you guessed that second order products originating from a sum will be out of tune while those who originate from....well i guess that you have no trouble concluding without any more explanations.
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Getting back to what the microphones picked up is what I would like to do,
but can't because, like street drugs, the product has been stepped on
before it gets to the customer.
Listen to a sampling of what's out there these days and tell me that it isn't
usually true - between special effects and the miracle of compression
people who are usually not the artist are modifying the signal, and typically
the artist does not control it.
So it's hard to fault the paying customer who wants to goose the illusion
a little bit with a tube unit or magical singing bowls (or a glass of wine).
😎
A glass of whine can be quite good, for both the whine and the perception...😉
As you rightly point it, it s like the tools that would have allowed for a much better sound quality are used for the opposite purpose in broad commercial productions, that s said i dont think that you re a fan of thoses mixtures, and that you know where to find the good records, there s editors like Denon (do they still release records?), or ECM in Europe that put the emphasis in high sound quality.
Taking into account Wahab's posts, we could consider how HD and IMD difference products might might appear in acoustic regime. There, they might be AM.
In which case, from a perceptual point of view as time domain phenomena, as beats, (roughness), which fuse perceptually as indistinguishable at a rate of about 20 Hz, which we can perceive at least to rate of 150 Hz, and possibly twice that, but to which we are more sensitive with increasing SPL, unlike harmonic distortion which is masked by increasing SPL.
You might find these papers interesting:
http://musicalgorithms.ewu.edu/learnmoresra/files/vassilakis2007smc.pdf
http://www.cell.com/current-biology/abstract/S0960-9822(15)00737-X
Online measuring gadget:
SRA 2.0 © 2008 - Spectral and Roughness Analysis of Sound Signals
Generally speaking in Western music when roughness is used as a musical device the sound might be described as "darker" although depending on degree and context, perhaps "warmer". Eg:
https://www.youtube.com/watch?v=fGlnRahtqM0
My personal take away is that we should put all distortion from amps and speakers down in the weeds and eq in the sound qualities we might find desirable.
If you are talking stereo replay where we have many cues within the stereo soundfield - Absolutely without question.
If you are talking something like a mono source, for example electric guitar into guitar amp, much harder, possibly not, although I am still surprised what some people can hear.
Lot's of incredible sounding gear have an almost complete absence of H2.
Of note, I was watching a video of Bascom H King about his latest design, a hybrid tube / SS amp that has almost complete absence of even order harmonics but by all accounts sounds great.
For everything that we do know about great sounding audio gear, there still seems to be a lot we don't know.
T
On re-reading the above I see that you're describing a two terminal square-law device with finite impedance and not an "op-amp" idealized device like Putzeys, etc. or the conventional feedback block diagram. This is easy to believe even without invoking the dread F-word because the shape of the curve changes. It's a clear explanation of the case of local degeneration and so very useful for thickies like me.
Could you comment on the difference between two series'd non-interacting stages, each with error signal injected and each with some "local" feedback around its own error injection point, and an additional "global" feedback around both stages in these two situations:
1) lots of "local" feedback and less "global" feedback, and
2) less "local" feedback and lots of "global" feedback
adjusted to bring the total of local plus global feedback the same for both, and same everything else. I think I can understand it for an imaginary linear (zero injected error) situation, straight outta Black, but the non-linear real-world situation is trickier.
Thanks again very much,
Chris
The -90 or 100 dB I am referring to would be as measured on the output of a preamp so let's say dBV. The distortion will decrease as the output of the preamp goes down so that it is at -120 dBV at say 100 mV out.
I am using these figures since this would be a typical opamp based preamplifier performance.
Assume the preamplifier drives a ZERO distortion amplifier for the sake of this thought experiment.
I am using these figures since this would be a typical opamp based preamplifier performance.
Assume the preamplifier drives a ZERO distortion amplifier for the sake of this thought experiment.
In my experience ECM put the emphasis on 'odd' first. But the recordings are often spectacular. The selected signs box set has something to challenge almost anyone.
I think that for non chart type music the recording quality is getting steadily better. No proof other than really enjoying the latest releases.
JVC A-X9 is the exception in gnfb family amps, like a few another - he is playing very good as it is.
A-X9 is very bright amp and is playing extremely well with "dark speakers" especialy in current mode (with series resistor to high efficient speakers): http://www.diyaudio.com/forums/solid-state/250272-current-drive-loudspeakers-30.html#post4062040
Simple chip transconductance amps provides similar very good sound too.
Both cases would give an infinite series of re-entrant distortion. Other things being equal (and they rarely are equal) you get lowest distortion with no 'local' negative feedback and lots of 'global' negative feedback. You can sometimes get even lower distortion by careful use of local positive feedback to boost loop gain. Stability issues, local overloading (including slew rate problems or clipping) mean that a mix of 'local' and 'global' feedback gives the best results. There isn't a magic formula; at least, I am not aware of one. Given a suitable mathematical model it might be possible to come up with some numerical guidance about how to apportion the feedback.Chris Hornbeck said:
I just used the audio slang about the volume of highs reproducted by amp and speakers. Some speakers when played via the series resistor are playing "dark" with lack of highs.