my 5 cents:
a amp has one purpose, to amplify the incoming signal. nothing else.
if it adds anything that wasnt there before, its not just a amplifier but a effect processor or equalizer.
the lower the noise, the lower the thd, the better.
but most manufacturer thd claims are just false, allways look for independend non sponsored measurements.
if a amp does what its supposed to and provides enough power to not become something else, its something i can take off my list of things to worry about.
a amp has one purpose, to amplify the incoming signal. nothing else.
if it adds anything that wasnt there before, its not just a amplifier but a effect processor or equalizer.
the lower the noise, the lower the thd, the better.
but most manufacturer thd claims are just false, allways look for independend non sponsored measurements.
if a amp does what its supposed to and provides enough power to not become something else, its something i can take off my list of things to worry about.
It’s been accepted since before WWII that THD isn’t a useful figure of merit for amplifiers. Examples abound. It is however an almost infallible way to detect whether an amplifier is operating correctly
There are sources of harmonic and other distortions many orders of magnitude greater than electronics, either pre or power amps.
Loudspeakers have harmonic and other distortions of around 1%. The only show in loudspeaker town with lower distortion are electrostatic loudspeakers with around 0.1% distortion. And if you listen to vinyl records, you can add at least another half a percent.
There are those who reckon you can tell the difference in SQ from changing a single opamp, which have around 0.0001% harmonic and intermodulation distortion or lower. This, and noise is so low that special techniques are used by chip manufacturers to measure them.
But mixing desks in recording studios have hundreds or thousands of vanilla opamps - usually NE5532 or similar, and no listener to recorded music gives this a second thought, which I find curious.
Loudspeakers have harmonic and other distortions of around 1%. The only show in loudspeaker town with lower distortion are electrostatic loudspeakers with around 0.1% distortion. And if you listen to vinyl records, you can add at least another half a percent.
There are those who reckon you can tell the difference in SQ from changing a single opamp, which have around 0.0001% harmonic and intermodulation distortion or lower. This, and noise is so low that special techniques are used by chip manufacturers to measure them.
But mixing desks in recording studios have hundreds or thousands of vanilla opamps - usually NE5532 or similar, and no listener to recorded music gives this a second thought, which I find curious.
I was not very happy with my Mother's RCA stereo bought with Top Value stamps about 1966. My dad had a 1963 Airline (Montgomery Wards) FM radio that sounded better.
I was much happier with the dynaco ST35 at the college library about 1969. Later the ST70 I bought and put new e-caps and tubes in. Those measured ~1 % HD magazine reports said. ST70 was 10% HD at max 7 W/ch before the repairs the McIntosh saleman said.
Both the dynacos were blown away by the Peavey SS amps I repaired that allegedly produce .03 to 0.1% HD. I can't really hear the .03% HD CS800s being better than the M-2600 0.1% one. My speakers have 2nd & 3rd harmonics down 25 db from signal at 5 W, the datasheet says.
I still have the ST70 , the Airline radio, and the Peavey amps. The RCA record ripper was given away.
I was much happier with the dynaco ST35 at the college library about 1969. Later the ST70 I bought and put new e-caps and tubes in. Those measured ~1 % HD magazine reports said. ST70 was 10% HD at max 7 W/ch before the repairs the McIntosh saleman said.
Both the dynacos were blown away by the Peavey SS amps I repaired that allegedly produce .03 to 0.1% HD. I can't really hear the .03% HD CS800s being better than the M-2600 0.1% one. My speakers have 2nd & 3rd harmonics down 25 db from signal at 5 W, the datasheet says.
I still have the ST70 , the Airline radio, and the Peavey amps. The RCA record ripper was given away.
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"Sounded better" is something completely different from measuring noise, harmonics or distortions. Usually you don't want your amplifier to sound, like "at all". So a good THD is IMHO a must - however our ears/brain-combination is working so well, we should probably not care too much, and other parts of the music reproduction chain have significantly more influence on the sound anyway. I see it more like a technical challenge,
The "T" in THD neglects the fundamental sonic difference between H2 and H5 (for example).
Thus it has poor correlation to human perception of "sound quality".
"And is subjective SQ useful to assess amps?" If you want to assess them regarding subjective sound quality - sure!
Thus it has poor correlation to human perception of "sound quality".
"And is subjective SQ useful to assess amps?" If you want to assess them regarding subjective sound quality - sure!
Yes, already before WWII it was seen that THD as a single number without HD profile isn't a useful figure of merit with the exception of single-ended amps where HD profile is well-known. Unfortunately many even on this site mistake this to mean that measuring HD is not useful.
Well you can measure amplifiers and DACs and speakers with real music now:
The age old questions.
Hugh, yours are asked too broadly, IMO, but it may spark yet another lengthy discussion.
You asked two short questions without constraints, so ...
1) Never as a stand alone measurement, but the inverse may be true. It may provide an excellent indication of 'bad' sound quality.
2) To those that want to enjoy them subjectively or sell/market to those that want to enjoy them subjectively.
Hugh, yours are asked too broadly, IMO, but it may spark yet another lengthy discussion.
You asked two short questions without constraints, so ...
1) Never as a stand alone measurement, but the inverse may be true. It may provide an excellent indication of 'bad' sound quality.
2) To those that want to enjoy them subjectively or sell/market to those that want to enjoy them subjectively.
A unilateral THD may not be enough, and subjective assessment is biased by mood, dependent on source material, and subject to highly variable human judgment.
But Bohrok mentions harmonic profile.
What do people think about this? Does it offer more reliability prediction, and how about the multi-toned, cacophonous issue of music itself and the issue of intermodulation? Is that a big issue?
Hugh
But Bohrok mentions harmonic profile.
What do people think about this? Does it offer more reliability prediction, and how about the multi-toned, cacophonous issue of music itself and the issue of intermodulation? Is that a big issue?
Hugh
I'm a bit of a goof when it comes to these questions....
In order to get thoughtful / useful answers to these age-old questions, it will be incumbent upon you, Hugh, to specifically define what you mean by 'good'.
Edited to add - This will be just to save time... because the follow up will be that you'll also need to specifically define what you mean by "sound quality" and how it would be assessed.
In order to get thoughtful / useful answers to these age-old questions, it will be incumbent upon you, Hugh, to specifically define what you mean by 'good'.
Edited to add - This will be just to save time... because the follow up will be that you'll also need to specifically define what you mean by "sound quality" and how it would be assessed.
"Does THD accurately predict good sound quality?"
Great question, Hugh ... if I didn't know you, I'd be thinking you were a troll! 😀
But then we get answers like this:
Me - I'd prefer to listen to a tube amp - or an ss Class A amp - combined, of course, with spkrs that they can drive well ... than any Class D amp (with its vanishingly low THD).
And this:
Absof'inglootely! But "sounding good/better" is, I suggest, what is important, when you are listening to a system - not how low its "noise, harmonics or distortion" might be!
THD is certainly important - but, as Hugh mentioned:
... harmonic profile is the key to whether an amp sounds great - or not.
Great question, Hugh ... if I didn't know you, I'd be thinking you were a troll! 😀
But then we get answers like this:
Me - I'd prefer to listen to a tube amp - or an ss Class A amp - combined, of course, with spkrs that they can drive well ... than any Class D amp (with its vanishingly low THD).
And this:
Absof'inglootely! But "sounding good/better" is, I suggest, what is important, when you are listening to a system - not how low its "noise, harmonics or distortion" might be!
THD is certainly important - but, as Hugh mentioned:
... harmonic profile is the key to whether an amp sounds great - or not.
A band performes with microphones in the studio.
This is fed into a mixerboard.
Recorded onto CD.
To some CD-player.
It is true that pre- and poweramplifier are only a very little part of the chain.
There are many other parts that influence the final result.
Like the listening room and speakers.
Listening with good headphones should make less impact on the sound. But have distortion, too.
This is fed into a mixerboard.
Recorded onto CD.
To some CD-player.
It is true that pre- and poweramplifier are only a very little part of the chain.
There are many other parts that influence the final result.
Like the listening room and speakers.
Listening with good headphones should make less impact on the sound. But have distortion, too.
It is not!
Just having fun because these threads always devolve into opinions: some passionate, some based on science, some just ... because.
If you want hifi, the amplifier should not sound like anything. I think it is really that simple. The rest is lofi, and can of course sound great!
35:24:35 (inch)
90:60:90 (cm)
Do the above numbers guarantee pleasant aesthetics?
Actually no, but very likely she's a stunner, especially if she's more than 175 cm (5.75 ft) tall.
Numbers do matter, however we want to be kind.
90:60:90 (cm)
Do the above numbers guarantee pleasant aesthetics?
Actually no, but very likely she's a stunner, especially if she's more than 175 cm (5.75 ft) tall.
Numbers do matter, however we want to be kind.