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General debate thread about audio measurements

amirm

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You don't have to do DBT experiments to enjoy the sound or like a particular device.
The discussion is never about enjoying a device. People enjoy listening to their phones far more than people enjoy listening to high-end audio.

The discussion is enjoying additional fidelity. That additional fidelity as with the Matrix, is not there in reality. It can be demonstrated anytime you are willing.
 

garbulky

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The discussion is never about enjoying a device. People enjoy listening to their phones far more than people enjoy listening to high-end audio.

The discussion is enjoying additional fidelity. That additional fidelity as with the Matrix, is not there in reality. It can be demonstrated anytime you are willing.
It's already been demonstrated to me... I fail even sighted level matched AB tests. I highly doubt I'll do any better on blind AB tests
 

trl

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It’s all about the type of distortions we like more (https://www.electronics-tutorials.ws/amplifier/amp_4.html) and their level, about the level of 2nd and 3rd harmonics, the level of odd and even harmonics, channel imbalance (yes, 0.5dB of channel imbalance may “improve” the soundstage because simply changes the song).

Analog/TI engineers wrote some real facts here http://www.ti.com/lit/ds/symlink/opa604.pdf:
“[...] Op amp distortion can be considered an internal error source which can be referred to the input.” - again, it’s about the type and level of distortions we like most.

“[...]
The sound quality of an op amp is often the crucial selection criteria—even when a data sheet claims exceptional distortion performance. By its nature, sound quality is subjective. Furthermore, results of listening tests can vary depending on application and circuit configuration. Even experienced listeners in controlled tests often reach different conclusions.
Many audio experts believe that the sound quality of a high performance FET op amp is superior to that of bipolar op amps. A possible reason for this is that bipolar designs generate greater odd-order harmonics than FETs. To the human ear, odd-order harmonics have long been identified as sounding more unpleas- ant than even-order harmonics. FETs, like vacuum tubes, have a square-law I-V transfer function which is more linear than the exponential transfer function of a bipolar transistor. As a direct result of this square-law characteristic, FETs produce predominantly even-or- der harmonics”
- so, of course tubes will produce a more lovely sound, same applies for the FET-input opamps.

It’s clear that we love added harmonics, sometimes phase shift too, this is happening on the Opera stage, in rock concerts...because it’s normal for the sound to bounce from the wall’s caves and to please our ears more than the neutral sound of an isolated studio.

Now what would be better: to feed our ears & brains with distortions and added harmonics or to listen to the clinical sound of a studio recording (read it: good sounding vs. perfect measuring equipment)? :)
 

Sal1950

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Now what would be better: to feed our ears & brains with distortions and added harmonics or to listen to the clinical sound of a studio recording (read it: good sounding vs. perfect measuring equipment)?
That's up to you.
Do you want to listen to a SOTA High Fidelity rig, or to something along the lines of a 1930 triode tube amp? Come by and I'll let you check out the glorious tone of my 1925 Atwater Kent.
 

trl

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No, thank you, I preffer to keep out of “drugs” and stick to the clinical sound of...Objective2 perhaps.

Tubes sound, full of harmonics, is like living inside a Matrix and getting out of the there needs help from AA (Audiophilus Anonymus). :)

However, if I’ll ever stick to a tube amp, then I’ll pick some from Garage1217...kinda picky and subjective oppinion perhaps.
 

Cosmik

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Could we put to bed the idea that it is possible to create harmonic distortion? If I play three tones simultaneously and add second harmonic distortion, what should I get? Presumably three pairs of tones - is the fantasy. But in order to do this, I would need to separate the three tones, individually synthesise the harmonics, then add them all back together again.

What would it mean to add second harmonic distortion to a violin section playing twenty different notes, or all the same note but ever-so-slightly different? While the trombones are sliding up and down at the same time?

The reality is that it is only possible to generate harmonic distortion for a single tone, and this is done using a 'bent transfer function'. The same bent transfer function on two tones, or twenty tones, produces garbage.

With DSP it might in some circumstance be possible to analyse the signal and split it into its components - but a valve isn't doing this.

In the recording studio, the producers have access to individual feeds and so 'harmonic distortion' might be more viable - on a solo voice, for example. The consumer can only do the same trick by choosing simple recordings - which explains much of the audiophile canon perhaps?
 

pkane

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Could we put to bed the idea that it is possible to create harmonic distortion?
I'm a bit confused by this. Harmonic distortion is produced by a non-linear transfer function. It's an effect and not the cause. It is possible to simulate various non-linear transfer functions, symmetric or asymmetric, in DSP. This can then be applied to any complex piece of sound or music you'd like, not just simple sine waves. If you do feed it a single tone, you'll see even and/or odd and higher order harmonics being added in an FFT plot. The result will be much more complex when used on a complex waveform. I don't see anything strange or impossible here. Are you saying this can't be done?
 

Cosmik

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I'm a bit confused by this. Harmonic distortion is produced by a non-linear transfer function. It's an effect and not the cause. It is possible to simulate various non-linear transfer functions, symmetric or asymmetric, in DSP. This can then be applied to any complex piece of sound or music you'd like, not just simple sine waves. If you do feed it a single tone, you'll see even and/or odd and higher order harmonics being added in an FFT plot. The result will be much more complex when used on a complex waveform. I don't see anything strange or impossible here. Are you saying this can't be done?
I am saying that a nonlinear transfer function generates intermodulation distortion when applied to complex signals - not harmonic distortion. For sure, you can have any transfer function you want using DSP, but it won't be 'harmonic' when applied to a complex signal.
Intermodulation (IM) or intermodulation distortion (IMD) is the amplitude modulation of signals containing two or more different frequencies, caused by nonlinearities or time variance in a system. The intermodulation between frequency components will form additional components at frequencies that are not just at harmonic frequencies (integer multiples) of either, like harmonic distortion, but also at the sum and difference frequencies of the original frequencies and at sums and differences of multiples of those frequencies.
 
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pkane

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I am saying that a nonlinear transfer function generates intermodulation distortion when applied to complex signals - not harmonic distortion. For sure, you can have any transfer function you want using DSP, but it won't be meaningful when applied to a complex signal.
Can you please explain why a physical device with a non-linear transfer function does not produce the same intermodulation effects? And if I can simulate the same transfer function as some physical device in DSP, why would this not be meaningful?
 

Cosmik

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Can you please explain why a physical device with a non-linear transfer function does not produce the same intermodulation effects? And if I can simulate the same transfer function as some physical device in DSP, why would this not be meaningful?
A physical device would be identical to the DSP and vice versa. But neither DSP nor the physical device would be generating harmonic distortion when applied to a complex signal.

The idea that a valve "generates second harmonic distortion" is only true for very simple, single tones. Put real music into it and you get garbage. As I said in my previous comment, if you choose your recordings carefully, then maybe the distortion might add some 'edge' to simple music. But put in a symphony orchestra and you are reminded of the character of those old valve radios with paper speakers or 78 records.
 

pkane

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A physical device would be identical to the DSP and vice versa. But neither DSP nor the physical device would be generating harmonic distortion when applied to a complex signal.

The idea that a valve "generates second harmonic distortion" is only true for very simple, single tones. Put real music into it and you get garbage. As I said in my previous comment, if you choose your recordings carefully, then maybe the distortion might add some 'edge' to simple music. But put in a symphony orchestra and you are reminded of the character of those old valve radios with paper speakers or 78 records.
Got it, and fully agree. I've been thinking about a generalized DSP distortion toolbox, something that would let me mix and apply various types and levels of distortion. An adjustable non-linear transfer function was one of the main components planned :)
 

Cosmik

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Got it, and fully agree. I've been thinking about a generalized DSP distortion toolbox, something that would let me mix and apply various types and levels of distortion. An adjustable non-linear transfer function was one of the main components planned :)
Well, best of luck with it, but personally I think you should be putting your efforts into eliminating distortion! :)
 

andreasmaaan

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Got it, and fully agree. I've been thinking about a generalized DSP distortion toolbox, something that would let me mix and apply various types and levels of distortion. An adjustable non-linear transfer function was one of the main components planned :)
@pkane I'm very interested in what you're doing, as controlled distortion is something that is impossible with all the consumer DSPs I'm aware of, and what you're doing is something I've been meaning to try for some time but have never got around too (big learning curve for me in terms of maths and programming).

Would you be so kind as to share with me whatever you come up with? :)
 

pkane

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@pkane I'm very interested in what you're doing, as controlled distortion is something that is impossible with all the consumer DSPs I'm aware of, and what you're doing is something I've been meaning to try for some time but have never got around too (big learning curve for me in terms of maths and programming).

Would you be so kind as to share with me whatever you come up with? :)
Of course. At the moment it's just in the planning stages -- too many audio projects started and not completed as is :)
 

amirm

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I think the point that harmonic distortion is not just the clear effect we see in sine waves was worth mentioning. With any real music we will have a spray of such distortions for every fundamental frequency. In my listening tests I find that this spray will then hide low level detail. The effect is not what people describe in tonal response changing.

I find the effect mostly when bass notes come in. Due to their high amplitude and ample bandwidth for harmonic distortion to materialize, it is easier to hear the loss of detail that way.

Now this is not solid, controlled listening test results. :) But it is what I observe at modest levels of THD.
 

RayDunzl

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With any real music we will have a spray of such distortions for every fundamental frequency.
I can measure harmonic distortion coming from the speakers.

The relative levels are quite dependent on the level of the fundamental, and the harmonics rise more rapidly than the fundamental as the volume level is increased.

Do electronics increase their distortion proportionally more rapidly than the fundamental (at normal rising signal levels), or is there a more fixed relationship?

Is there even enough electrical harmonic distortion to matter?
 
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amirm

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Is there even enough harmonic distortion there to matter?
WIth headphone amplifiers, yes. I can easily push them to single digital THD numbers by just turning up the volume.
 

RayDunzl

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I can easily push them
Is that at "normal" or "too loud" levels?

(I realize things go wrong when you run out of steam)
 
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