2. amps-preamps
  3. 175407-20253

Let me end the Premp/Amplifier sound debate ...

I'm old enough to remember Julian Hersch from Audio magazine and his very unscientific view that all amplifiers sounded the same once they met a certain threshold.  Now the site Audio Science Review pushes the same.

I call these views unscientific as some one with a little bit of an engineering background as well as data science and epidemiology.  I find both of these approaches limited, both in technology used and applied and by stretching the claims for measurements beyond their intention, design and proof of meaning.

Without getting too much into that, I have a very pragmatic point of view.  Listen to the following three amplifier brands:

  • Pass Labs
  • Luxman
  • Ayre

If you can't hear a difference, buy the cheapest amplifier you can.  You'll be just as happy.  However, if you can, you need to evaluate the value of the pleasure of the gear next to your pocket book and buy accordingly.  I don't think the claim that some gear is pure audio jewelry, like a fancy watch which doesn't tell better time but looks pretty.  I get that, and I've heard that.  However, rather than try to use a method from Socrates to debate an issue to the exact wrong conclusion, listen for yourself.

If you wonder if capacitors sound different, build a two way and experiment for yourself.  Doing this leaves you with a very very different perspective than those who haven't. You'll also, in both cases, learn about yourself.  Are you someone who can't hear a difference?  Are you some one who can? What if you are some one who can hear a difference and doesn't care?  That's fine.  Be true to yourself, but I find very little on earth less worthwhile than having arguments about measurements vs. sound quality and value. 

To your own self and your own ears be true.  And if that leads you to a crystal radio and piezo ear piece so be it.  In my own system, and with my own speakers I've reached these conclusions for myself and I have very little concern for those who want to argue against my experiences and choices. 

 

erik_squires
photomax
169 posts
 

Pool size and sample variation play a role here.

If you had happened upon Amir’s site in the early days after he had measured just two amps (or DACs) the different measurements would be very noticeable when presented on a graph graphic. After eight or so component tests that graph would have an obvious curve to it.

But, take a look at that graph now (after dozens and dozens of tests) and what do you see: that graph has flattened out. If he continues and eventually tests thousands of boxes that curve will continue to flatten to the point that it will look like a straight line. 
 

One camp could then say “they still all sound alike”. And the other camp could say “they all measure alike”. 
 

Does this all matter? Perhaps only when doing small sample size comparisons, like direct A:B tests at home, which is really the ony practical way of evaluating purchase options…
 

 

holmz's avatar
holmz
2,328 posts
 

This, on the OP’s leading post, says a lot:

Be true to yourself, but I find very little on earth less worthwhile than having arguments about measurements vs. sound quality and value. 

It is not like measurements are not largely correlated with preferences.
And it is not like engineers aren’t using measurements in the process of design and quality control.

They measure the living $hit out things, and they know which measurements to be doing.
If they were not, and if people did not care, then we would all be running Class-B amps. But people do not usually enjoy crossover distortion, so we have Class-A, tubes, and highly biased class-AB… as well as Class-D.

It does not matter how many measurements we do, people do not enjoy crossover distortion. And that number of people is linear with the pool size of people chosen.

ieales's avatar
ieales
1,201 posts
 

Maybe I am simple fellow… but how can the sound (SPL) be the same, if the current (and voltage) are not the same?

There’s much more to sound than SPL.

Mostly, the measurements quoted in HiFi are THD and IM @ a power level.

Occasionally, a square wave or distortion spectra.

ALL into a resistor, not a dynamic loudspeaker load.

This series of frequencies into an 8Ω load resistor gives an idea of the Phase Shift in a tube amplifier output transformer @ 10W RMS. The ear is extremely sensitive to phase, but hardly anyone mentions it. Ideally all lines should look like 200Hz & 2kHz as 45° lines. Nobody publishes anything other simple meaningless measurements that the untrained can lap up.

20Hz.jpg (566×477) (ielogical.com)

200Hz.jpg (566×477) (ielogical.com)

2kHz.jpg (566×477) (ielogical.com)

20kHz.jpg (566×477) (ielogical.com)

200kHz.jpg (566×477) (ielogical.com)

A solid state amp would do much better.

atmasphere's avatar
atmasphere
11,640 posts
 

This series of frequencies into an 8Ω load resistor gives an idea of the Phase Shift in a tube amplifier output transformer @ 10W RMS. The ear is extremely sensitive to phase, but hardly anyone mentions it.

The ear is only sensitive to phase when it covers a spectrum of frequencies. It cannot tell phase of a single frequency.

FWIW our OTLs have 0 degrees of phase shift at 20Hz to 20KHz. Phase shift at 200KHz isn't a concern. So a tube amp can do much better too 😉

Your answer does not appear to address the question posed.

ieales's avatar
ieales
1,201 posts
 

Music is a sequence of fundamentals rich in harmonics. The ear brain can definitely tell when the harmonics are shifted.

OTL - Output TransformerLESS - is off topic. The images are for "tube amplifier output transformer". Let’s take it as written that atmasphere makes fine amps.

The question was about current and voltage. The current and voltage cannot be the same if the harmonics are temporally shifted relative to the fundamental.

More to discover