Hi,
This assertion is based on what exactly?
Looking at John's site it seems he mostly tests at 90dB/1m (or as he writes it 96dB/0.5m).
For the SM75-150S this means it is tested at 0.5 Watt while it is rated at 75 Watt. Try as I might (not that hard admittedly), I cannot find a 75 Watt Tube Amp tested at 0.5W for HD readily.
What I do have are measiurements of a 100 Watt rated tube amplifier including measurements (THD only sadly) at 1 Watt, so it is probably fair:
SoundStage! Measurements - Convergent Audio Technology JL2 Signature Mk 2 Stereo Amplifier (8/2007)
Red line is 1 Watt into 8 Ohm
FFT at 10Watt into 8Ohm.
Eyeballing I see around 0.25% H2 and between 0.03% and 0.1% H3 at a level that is around 22dB below rated power for the ATC Driver. This is pretty good, but easily beaten by most tube amplifiers, excluding SE with Zero NFB types, as shown above, where the amplifiers distortion is around 20dB lower than the "low distortion" driver.
Ciao T
This assertion is based on what exactly?
Looking at John's site it seems he mostly tests at 90dB/1m (or as he writes it 96dB/0.5m).
For the SM75-150S this means it is tested at 0.5 Watt while it is rated at 75 Watt. Try as I might (not that hard admittedly), I cannot find a 75 Watt Tube Amp tested at 0.5W for HD readily.
What I do have are measiurements of a 100 Watt rated tube amplifier including measurements (THD only sadly) at 1 Watt, so it is probably fair:
SoundStage! Measurements - Convergent Audio Technology JL2 Signature Mk 2 Stereo Amplifier (8/2007)
Red line is 1 Watt into 8 Ohm
FFT at 10Watt into 8Ohm.
Eyeballing I see around 0.25% H2 and between 0.03% and 0.1% H3 at a level that is around 22dB below rated power for the ATC Driver. This is pretty good, but easily beaten by most tube amplifiers, excluding SE with Zero NFB types, as shown above, where the amplifiers distortion is around 20dB lower than the "low distortion" driver.
Ciao T
John,
Yowser.
Seems Quad have lowered their speakers HD a lot since the ESL-63's. Good stuff. Maybe I'll break down and get a pair.
How do they do at 111dB/1m?
Ciao T
It's a Quad electrostatic
John Atkinson
Editor, Stereophile
Yowser.
Seems Quad have lowered their speakers HD a lot since the ESL-63's. Good stuff. Maybe I'll break down and get a pair.
How do they do at 111dB/1m?
Ciao T
Hi,
As individual harmonics are not given and I do not have the raw data, your guess is as good as mine.
Quite horrorshow# I guess...
Then again, most tube tube amps also do rather well in that metric, even SE Zero NFB ones...
Ciao T
# Horrorshow is Nadsat (a teen slang invented in "A Clockwork Orange") for "good" and is derived cockney style from the russian word for good, Karashow..
As individual harmonics are not given and I do not have the raw data, your guess is as good as mine.
Quite horrorshow# I guess...
Then again, most tube tube amps also do rather well in that metric, even SE Zero NFB ones...
Ciao T
# Horrorshow is Nadsat (a teen slang invented in "A Clockwork Orange") for "good" and is derived cockney style from the russian word for good, Karashow..
It's a Quad electrostatic
John Atkinson
Editor, Stereophile
Funny that.
2905 is the only loudspeaker I've heard that betters ATCs in midrange performance.
Yes, and as we all know, one will be hard pressed to find many tube amps out there performing significantly worse than the CAT you mention...
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Last I read Earl uses (mostly/only?) SS gear, I assume he is happy with their metric. Gobs of GNF passed in some cases.
Let me quote Earl exactly, "The Pioneer chip amps are superb."
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My colleague, could have told you 40 years ago, that DISTORTION itself is not key factor in how an amplifier sounds. Negative feedback is often a necessary 'evil' that the vast majority of us use to make 'successful' amps. Charles Hansen is an exception to this, finding, for HIS ears, global feedback is something to avoid and he offers products that have relatively high distortion, but are well made. With these components, he has edged me out, on more than one occasion, in listening comparisons. Why this is so, is the point of WHY GC, BK and I went to visit Richard Heyser, 40 years ago. Why do amplifiers often have listening quality limitations, even when they measure well with conventional measurements, and are stable, etc.? Especially when loudspeakers often measure so bad, and we knew this, because Richard Heyser was the loudspeaker reviewer for 'Audio', I worked for the Grateful Dead and other companies, and measured loudspeakers with my own wave analyzer, and GC designed a PA loudspeaker system with BK, back then. We KNEW then what many of you are just finding out, about loudspeaker distortion. Yet our listening experience told us that the electronics was just as important to get 'right' whatever that is, as extremely low distortion speakers by horn loading or other means. (more later)
I don't much care what one person says is their favorite amplifier, or speaker for that matter. Even a pro in the field can be extremely limited in breadth of experience of what is really out there, and what really works, just like some country boy might be in love with his Daddy's pickup truck, and can't appreciate a Porsche, Mercedes, BMW, etc., because for HIS uses, the pickup truck does just about everything 'right'.
The best judges of amp quality are usually experienced reviewers who have tried a wide variety of amps, and a good majority of experienced listeners, who have nothing to gain or lose was to which amp they prefer sonically. This has been MY experience, in any case.
The best judges of amp quality are usually experienced reviewers who have tried a wide variety of amps, and a good majority of experienced listeners, who have nothing to gain or lose was to which amp they prefer sonically. This has been MY experience, in any case.
This was the ESL-2805. Manufactured in China but to a higher standard than my memories of the ESL-63. Even so, the EL-63 was a "0.1% speaker" back in the early 1980s.
I didn't try that, I think that is when the magic blue smoke escapes
The specification list the maximum output as 2N/m^2 on axis at 2m. (I'll let someone else convert that to dB spl.) The spex also list the THD at 100dB/1m as 1% 50-100Hz, 0.5% 100-1000Hz, 0.15% >1kHz .
John Atkinson
Editor, Stereophile
regarding some of the other punting I like to engage in, the old and tied metric of what is possible and what is not, regarding gating energies and molecular structures. When we avoid the dogma, advance can and does happen. the trick comes in finding the edges of the dogma in the self --and peeling it away:
LED's efficiency exceeds 100%
For the first time, researchers have demonstrated that an LED can emit more optical power than the electrical power it consumes. Although scientifically intriguing, the results won’t immediately result in ultra-efficient commercial LEDs since the demonstration works only for LEDs with very low input power that produce very small amounts of light.
In their experiments, the researchers reduced the LED’s input power to just 30 picowatts and measured an output of 69 picowatts of light - an efficiency of 230%. The physical mechanisms worked the same as with any LED: when excited by the applied voltage, electrons and holes have a certain probability of generating photons. The researchers didn’t try to increase this probability, as some previous research has focused on, but instead took advantage of small amounts of excess heat to emit more power than consumed. This heat arises from vibrations in the device’s atomic lattice, which occur due to entropy.
The researchers, Parthiban Santhanam and coauthors from MIT, have published their study in a recent issue of Physical Review Letters.
LED's efficiency exceeds 100%
~~~~~~~~~~~~~~
And while you weren't looking, it quietly sneaks onto the world stage.
However, the mechanics of such are illustrated for the nth time. Pounding that into the heads of the dogmatically recalcitrant is and has always been the issue at hand.
It's everywhere, it underlies and underscores everything. All one has to do is take a fresh look. The literature that supports it ---is thousands of years deep and a thousand tomes wide.
LED's efficiency exceeds 100%
For the first time, researchers have demonstrated that an LED can emit more optical power than the electrical power it consumes. Although scientifically intriguing, the results won’t immediately result in ultra-efficient commercial LEDs since the demonstration works only for LEDs with very low input power that produce very small amounts of light.
In their experiments, the researchers reduced the LED’s input power to just 30 picowatts and measured an output of 69 picowatts of light - an efficiency of 230%. The physical mechanisms worked the same as with any LED: when excited by the applied voltage, electrons and holes have a certain probability of generating photons. The researchers didn’t try to increase this probability, as some previous research has focused on, but instead took advantage of small amounts of excess heat to emit more power than consumed. This heat arises from vibrations in the device’s atomic lattice, which occur due to entropy.
The researchers, Parthiban Santhanam and coauthors from MIT, have published their study in a recent issue of Physical Review Letters.
LED's efficiency exceeds 100%
~~~~~~~~~~~~~~
And while you weren't looking, it quietly sneaks onto the world stage.
However, the mechanics of such are illustrated for the nth time. Pounding that into the heads of the dogmatically recalcitrant is and has always been the issue at hand.
It's everywhere, it underlies and underscores everything. All one has to do is take a fresh look. The literature that supports it ---is thousands of years deep and a thousand tomes wide.
You may want to listen to the speakers prior to purchasing it, for HD may not be the whole story about how speakers sound.
Given the tenuous grasp on physics of some here, someone has to be boring and burst some balloons so it might as well be me! Otherwise we will be flooded out with perpetual motion, audio data files with non-physical memory of their history, amplifier performance changes not mediated via the output terminals etc. etc.
STILL, it is an interesting measurement. Of course, you can't get something for NOTHING, but IF you get better performance than you would normally predict, it can be both interesting and useful to discuss it. Those whose minds are so 'full' that you can't even 'wonder' just a little are rather limited, in my estimation.
Not so fast!!
It would violate the second law of thermodynamics. Things don't automatically flow from a state of high entropy (less organization, e.g. longer wavelength) to a lower state (more organization, e.g. shorter wavelength). In the case of a LED at 135 degrees (as compared to the same LED at room temperature), you might expect an increased output of photons in the far infrared. Not an increase of photons @ a (much higher) visible frequency.
vac
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