Bob Cordell Interview: BJT vs. MOSFET - Page 52 - diyAudio
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Old 7th January 2007, 04:24 PM   #511
ingrast is offline ingrast  Uruguay
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Quote:
Originally posted by Nelson Pass


If by this you mean "objectively measures better" versus
"sounds more like being there", then you are right - it is
important to make the distinction.


Sorry, and with due respect.

This line of argument never fails to mistify me - understanding it is not marketing in disguise - which of course I asume is not the case.

It is simply not acceptable to admit the existence of "unknown" or "unmeasurable" effects placing audio more or less at par with paranormal phenomena or alien abductions.

Neither will I push a naive approach whereby if an amplifier measures better than certain objective limits, then it "must be all right" no matter what others say. This is neither conductive to improvements for that matter.

But what I won't buy is, given a measurement setup including all the signal chain up to the speakers and listening environtment, and in that setup one verifies the acoustic presure fields match accurately the soruce within reasonable tolerances as to what the ear can discriminate, that then someone else may come with a different setup which in principle is less objectively accurate yet is defended as more "close to reality".

This is not black magic, this is not quantum weirdness, this fairly well understood macroscopic physics. If subjective appreciation does not match objective measurement, then something is wrong and can be found, either in the listener or in the complete test setup.

Rodolfo
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Old 7th January 2007, 04:50 PM   #512
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Rodolfo, if your customers are deaf and they still need " juice sound ", is hardly persuade them, that is better to listen " objectively measured better "... It is probably dilema, in front are standing every designers sooner or later...Try to think, which version he select...
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Old 7th January 2007, 08:33 PM   #513
ingrast is offline ingrast  Uruguay
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Quote:
Originally posted by Upupa Epops
Rodolfo, if your customers are deaf and they still need " juice sound ", is hardly persuade them, that is better to listen " objectively measured better "... It is probably dilema, in front are standing every designers sooner or later...Try to think, which version he select...

That's why I placed the caveat in the second line - I asume we are at least in this forum and thread - doing away with unconfessed marketing strategies.

Of course I understand marketing considerations and the constraint of being succesfull in business may dictate departures from what could be acknowledged unremitting adherence to accuracy.

Rodolfo
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Old 8th January 2007, 01:10 AM   #514
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Quote:
Originally posted by suzyj


If this can be done in a way that ensures the listeners aren't aware of what they're listening to, then it's valid.

Otherwise, I fear that all people will hear are their own prejudices.

Regards,

Suzy
I'm sure that's *all* they'll hear. I mean, not even the sound of a truck driving by outside can get through ... prejudices.
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Old 8th January 2007, 12:24 PM   #515
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Quote:
Originally posted by ingrast
at par with alien abductions.
I've been waiting so long for that to happen i decided to become one myself. If you happen to bump into something green or blueish, preferable on the "Eve" side, hand out some directions.

The discussion on measurement before tasting the pudding in contrast to hearing and verifying with numbers seems like an endless clash between two opposing elements.

Funny thing, the whole MOSFET era started with both technical arguments on how much easier it is to drive MOSFETs, AND with the rationale that they sound better because of their softclipping nature and the "tube"-like blah blah.
Seems to me like the parties on both side of the fence were wrong.
Sounds like it isn't that favorable to skip the drivers on MOSFET output stages and without an additional EC circuit a class AB MOSFET output stage can not compete with BJTs, according to the statements of both the ones with ears and tools.

MOSFET power amps have come from all over the place.
Haflers from the US, Perreaux from Australia, Musical Fidelity from GB, Scylla and Sphinx from where i live, AVM and Neumann from Germany, to name just a few.
Thomas Hohne, the guy who set up the Neumann MOSFET amplifier brand in Germany also markets the Aaron label. Long time ago Mr Hohne personally tried to persuade me to buy one of his class AB Neumann amps.
Peculiar thing, the MJ15003/4 output stage Aaron amps of the same guy "sounded" far more acceptable than the Neumann horror.
Same goes for every other class AB MOSFET name i mentioned above, in any circuit topology. Even a Conrad Johnson Evo2000 tube/MOSFET hybrid is not everyone's flavor.
Which is not the case for high bias amps like the big MF and Perreaux type numbers, the full class A opamp input MOSFET amplifier of AVM and a full bias tube input Sphinx Project 16.
Let's not forget to mention Mr P's products.
Both Mr Curl, Mr Cordell, AND Nelson Pass seem to have their facts more straight that many others, imho.

Mr Ras must be one heck of a designer.
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Old 8th January 2007, 01:17 PM   #516
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ASAP you will see measurements of my MOSFET " baby ", Jacco... I hope, that you will be satisfied...
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Old 8th January 2007, 01:40 PM   #517
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Pavel,

competition accelerates, polarising does not.
Science works both ways : to observe and analyse, in either sequence.
I adore numbers, but to taste an apple you'll have to bite it.
I'm convinced there will be a lot more coming out from your sleeve.
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Old 8th January 2007, 02:32 PM   #518
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I'm not Mikeks, Jacco, so my verbal support will be not ideal. But I hope that you will be understand...
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Old 8th January 2007, 03:21 PM   #519
ingrast is offline ingrast  Uruguay
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Quote:
Originally posted by jacco vermeulen
......
The discussion on measurement before tasting the pudding in contrast to hearing and verifying with numbers seems like an endless clash between two opposing elements.
.......

These should not be opposing elements. That they look so can be attributed to at least a couple of facts.

Manufacturers need strategies to focus on in order to make themselves visible, and a common strategy is to pull away "sonics" features from hard objective data.

Audio is a particularly fertile ground for this, given the infinite ability of human beings for self-deception, which leads to the second fact.
I confess to find my amplifiers better than every other one, for I "know" they are designed with the strategy I consider best, and measure very well. Of course the same must happen with other designers and their cherished works, no matter how different in design and performance they could be.

One can rationalize on particular design strategies based on known facts like gm vs. current or clipping behavior, and it is OK as guides for implementation, but the proof is in the pudding and as Bob has often quoted, the devil is in the details.

The bottom line is that given equal listening setups, including speakers and environment, a system that succeeds in reproducing accurately a sound field as originaly aquired, cannot be judged inferior to other whose objective prformance measured this way falls below.
If that happens, it should not be attributed to "unknown" or as yet "unmeasurable" factors, something is wrong with the listener or the setup or both, and it can be traced and explained.

Rodolfo
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Old 8th January 2007, 04:01 PM   #520
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Hi, Ingrast,

Why do you think so many people likes tube amps?
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