What "THD" is considered "HiFi"? - diyAudio
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Old 4th April 2010, 06:08 PM   #1
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Default What "THD" is considered "HiFi"?

Hey guys, I have been looking up data sheets for various chips I have. I was wondering what THD is considered "HiFi". Is 0.02 high fidelity? If not what would you consider the cut-off between hi-fi and mid-fi?
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Old 4th April 2010, 06:46 PM   #2
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Difficult question

There is no doubting the fact that Passlabs offerings are "hi end" & therefore Hifi & yet the amps will happily produce up to & possibly more than 0.1% distortion at a fair drive level. You see it's not so much about the level of the distortion but more about the type of distortion. If it's even harmonic then it actually sounds musical rather than degrading the sound, this is more through design though.

Any chip amp will be a class B or AB design & these tend to produce odd order harmonics which isn't so musical. 0.02% isn't bad at all though, a properly laid out PCB will probably result in a decent sounding amplifier. Compared to what's on offer at the local electrical retailers these days with there plastic midi systems with lots of lights & fireworks i think i'd rather go with what you are looking at
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Old 4th April 2010, 07:23 PM   #3
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I'm listening to a Class-D "chipamp" with 0.1% THD+N @ 1W.

Sounds "Hi-Fi" to me.
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Old 4th April 2010, 07:32 PM   #4
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There's no reason to have more than about .005% THD in an inexpensive modern design, but to be seriously high end the amp has to run very hot and produce no less than 0.25%.

CH
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Old 4th April 2010, 07:50 PM   #5
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There are only two "correct" answers to this question, imo:

- ZERO distortion
- A value of "distortion" that is usually below 1.0% AND also has a harmonic series that is not "objectionable" to the ear.

So, the second answer is the only practical one in the real world.

There has been much discussion of this issue here on DIYaudio and elsewhere. But recent research (Dr. Geddes), and some older research (D.E.L Shorter) both point to the same conclusion. That is, the ratios of harmonic spectra are more significant than any absolute number.

The problem with many chips and chipamps is that they often have objectionable ratios of harmonic distortion spectra.

Thus it can be shown in double blind tests that amps that have high and very low distortion can be grouped together by listeners, while other amps with either high or low distortion can be disliked by listeners - the difference being the spectra of distortion.

Of course, if you have a speaker that creates "nasties" on its own, the effect of the amp may be less evident or impossible to discern.

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Old 4th April 2010, 07:55 PM   #6
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I can't listen to any more than 0.00329%, especially above about 115.2 dB.
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Old 4th April 2010, 08:32 PM   #7
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ok, post factious responses...

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Old 4th April 2010, 08:46 PM   #8
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Surely everyone got the joke. Back when I dreamt of someday becoming an electronics repair tech I met an audio salesman that eventually had to tell me flat out that plain old distortion specs don't mean a whole lot. Of course I couldn't believe it. I had already seen tons of big box store grade receivers rated at <.01% back when A/V specific shops were much more common. At that point I thought that anything audiophile grade had to have less distortion than that. Eventually I fixed that salesman's Accuphase P-300, which was rated at .03%, and it just blew away (Edit: BLEW AWAY) everything I had ever heard at the time. His lack of respect for numbers and insistence about how they tend to leave large parts of the picture undescribed probably had something to do with me never earning an EE degree.

Last edited by Andrew Eckhardt; 4th April 2010 at 08:55 PM.
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Old 4th April 2010, 08:56 PM   #9
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I got the tongue-in-cheek, but without an "emoticon" there are non-native english speaking people here who are not familiar with this sort of thing being intended as humor... fwiw.

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Old 4th April 2010, 09:08 PM   #10
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I've had that playing music the ear cannot hear 1% or less. And I believe pure tones the human ear can hear as low as .3%.

however I listen to music and not pure tones
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