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In Reply to: RE: Recent and future amplifier measurements posted by fstein on November 10, 2015 at 15:37:13
This also indicates that the lowering of cholesterol is not a GOOD surrogate for the clinical outcome as there is a poor correlation apparently.
The data generated by Stereophile actually tells a lot but the interpretation needs to be understood in the context of psychoacoustics and not absolute numbers.
Follow Ups:
JA and SP are not allowed to do power cube test on amplifiers (most of his friends would stop talking to him for sure) toobies would fail miserably , red cards and penalties would be the order of the day ...Anyway,
SP maybe getting ready to do something very Unique, its all skunk works at the moment, rumor has it to be some kind of amplfier comparison test , is a fuzzy wuzzy noise on the ac line Top of the podium class-D in the same league as their class-A SS or Tooby counterpart? will JA and SP survive? such comparisons are not for the weak of knee or the vicodin crowd, Absolute Shytusty may never forgive him , again ..!
You are in our prayers John .
Go Rossi ......
Edits: 11/11/15
> JA and SP are not allowed to do power cube test on amplifiers (most of his
> friends would stop talking to him for sure) toobies would fail miserably ,
> red cards and penalties would be the order of the day ...
I have actually been thinking about power cube tests for a long time. But
like all things that might be important but are never urgent, it remains
on my To-Do list. In the meanwhile, you can infer what a power cube
measurements would look like from my current tests of an amplifier.
John Atkinson
Editor, Stereophile
If you could infer the results from existing tests, why bother with power cubes at all? I think experience shows you can't draw such an inference. Unless old test data were replaced by retesting using a new method, it would invalidate the old data. There would be no valid way to compare the old tests with the equipment tested by the new method. If the new data showed that amplifiers that tested well in the past test poorly in the new test, that would cast a shadow over all previous reports. What a can of worms that would open up. Of course the power cube test still doesn't address the question of what happens as a result of reverse EMF. The power cube remains a passive load even if it adds reactive loading to resistive loading. It's closer to real world but not quite there.
> If you could infer the results from existing tests, why bother with power
> cubes at all?
Because 1) it's more complete a measurement set and 2) the resulting graph
is much easier for the reader to grasp than trying to visually integrate
several separate graphs.
John Atkinson
Editor, Stereophile
Peter is not using his anymore John, maybe he will donate it to SP ..... :)
Go Rossi ......
> Peter is not using his anymore John, maybe he will donate it to SP... :)Peter Aczel once described me as "Highly intelligent, extremely competent..."
forget the rest of what he wrote :-)> Go Rossi ......
Alexander Rossi? Watched him compete in Austin 3 weeks ago. Impressive drive
in an uncompetitive car.
John Atkinson
Editor, Stereophile
Edits: 11/12/15
Yep Alex Rossi is a fantastic young driver, following him from His Karting days was disappointed to hear he is not with Haas's attempt next year , maybe he has a better ride in the works ...
As to the other Rossi , he was done in by the Tres Damas .... :)
Go Rossi ......
Edits: 11/12/15
Wifey and I went to COTA last year and to Montreal in June, but scheduling didn't allow us to go to Austin this year.
We're planning a trip to Silverstone next summer.
Oh, you mean the other F1.
"You won't come back from Fletcher-Munson curve"-Jan and Dean
this flavor . :)
Montreal ....
Great atmosphere , Silverstone will be an eye opener if first time , fanatics Galore .....
Go Rossi ......
A PowerCube testing scenario would be cool.
However, everything would be hunky-dory until a PowerCube test revealed some extremely poor measurements of a golden-eared favored amplifier. Then any subsequent Powercube results would be labeled irrelevant. :)
Everything is a double-edged sword.
Dave.
provide insight to an amp's ability to drive a range of loads which certainly can be important with many speakers. Since I've been using full range electrostats since the 70s, I have needed to use amplifiers capable of driving challenging loads for optimum results. What's to disagree about here?
On the other hand, it is a quantitative measure as opposed to being a qualitative one. Peter Aczel thought the power cube response of the Behringer A500 was quite good. Which speaks nothing about its overall sound quality.
At least, it sounds uniformly poor across a wide range of speakers. :)
I'm well aware of the Powercube objectives.
You say quantitative, I say qualitative.
Regardless, once again you've created a straw man with the Behringer example. I was talking about the case where amplifier-X (that you've subjectively evaluated and think sounds great) comes up well short when enduring a Powercube measurement scenario. Another straw man, admittedly...but it seems this is the only thing you can understand.
So, I assume your conclusion (based on your quantitative comment) is that Powercube measurements are valid but with qualifiers? I would not disagree with that.
I see a lot of complaining in this thread about amplifier testing being invalid without complex loads. The question quickly becomes what complex load would be appropriate? Pick a speaker system at random and use it for a "baseline" complex load? Since various speaker system impedance loads vary all over the place, that doesn't help much.
And of course, it won't help much if a tester wants to explore the maximum power capabilities of the AUT. (Destroyed speakers.)
The Powercube at least makes an effort in this (complex testing) direction. I think it would be a worthwhile addition to JA's amplifier testing scheme. More objective data is always good. Whether it's ultimately deemed irrelevant and/or misinterpreted by audiophile agendas is sort of beside the point.
Cheers,
Dave.
Regardless, once again you've created a straw man with the Behringer example.
Evidently, you missed the point illustrated. While the A500 may be able to drive a quantifiably wide range of speakers, its sound quality nevertheless remains poor. Got it this time?
So, I assume your conclusion (based on your quantitative comment) is that Powercube measurements are valid but with qualifiers?
They tell you what they tell you. Nothing more. The ability to drive speakers with odd phase angles and reactive components is most certainly ONE consideration for selecting an amplifier.
The question quickly becomes what complex load would be appropriate?
Very good question since there is such a wide range of variations. I have no particular preference.
I think it would be a worthwhile addition to JA's amplifier testing scheme.
As do I. It would help narrow down the field for those who choose speakers with demanding loads. I am of that number.
The Threshold Stasis I used for over thirty years driving electrostats fared very well. Nelson specifically designed them to drive the Dayton-Wright. Similarly, I have also experienced very good success with the current VTLs (as have other Sound Lab users) for more than a decade.
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