Quote from: Arnold B. Krueger on 2014-11-27 12:19:58

Because of  my professional experience with computers particularly mainframe computers going back to 1965 I have long been intimately familiar with SMPS. I've also built thousands of PCs and every one had a SMPS.

  Please forgive me Arny for being blunt but that is like the gas station attendant saying he is intimately familiar with the engine in your car because he has put gas in thousands of cars .

All you need there is a screwdriver to bolt a power supply to a PC case.  And plugging in its cable into the motherboard.

That gives you no understanding of how PC switchmode power supplies work.

My kids in elementary school were building their PCs and I am pretty sure they, nor their friends had any idea how they worked.

Quote from: amirm on 2014-11-27 15:44:57

Quote from: Arnold B. Krueger on 2014-11-27 12:19:58

Because of  my professional experience with computers particularly mainframe computers going back to 1965 I have long been intimately familiar with SMPS. I've also built thousands of PCs and every one had a SMPS.

  Please forgive me Arny for being blunt but that is like the gas station attendant saying he is intimately familiar with the engine in your car because he has put gas in thousands of cars .

For opener's Amir your unfounded, unwarranted, egregious personal insults skip over most of just the fraction of my response that you quoted out of context.

Bottom line Amir while it is true that a smart high school kid can sometimes successfully build a PC without help, you have shown above how you lack even those basic skills.

Quote from: Arnold B. Krueger on 2014-11-27 16:06:32

Quote from: amirm on 2014-11-27 15:44:57

Quote from: Arnold B. Krueger on 2014-11-27 12:19:58

Because of  my professional experience with computers particularly mainframe computers going back to 1965 I have long been intimately familiar with SMPS. I've also built thousands of PCs and every one had a SMPS.

  Please forgive me Arny for being blunt but that is like the gas station attendant saying he is intimately familiar with the engine in your car because he has put gas in thousands of cars .

For opener's Amir your unfounded, unwarranted, egregious personal insults skip over most of just the fraction of my response that you quoted out of context.

Arny, I didn't ask you to reply or provide your resume.  You did both so I commented on them.

so let's see.....

Amir trumpets an old obscure article by Arny (his personal bete noir) & Co that seems to be comparing two amps, at least one of which had 'problems'.....

He admits he's never heard of or read a rather more widely read article, in Stereo Review (then a mass market newsstand magazine popular with audio fans), from 1991 by E. Brad Meyer, describing load conditions under which two amps will sound different.....

All the while, across multiple websites and threads therein he makes of habit of putting people down* in the guise of 'educating' them from his expert** POV...

And then complains here that posts critical of him have the intent of 'putting me down under the cover of giving me advice'....

Is this guy a piece of work, or what?

Quote from: krabapple on 2014-11-27 17:16:41

so let's see.....

Yes, let's....

Quote

Amir trumpets an old obscure article by Arny (his personal bete noir) & Co that seems to be comparing two amps, at least one of which had 'problems'.....

Wow, how far we have come.  This is a forum that prides itself on requirement for providing double blind evidence of audibility. Now posting about such evidence is a sin!  Why?  Because it has a positive outcome.

The support for forum TOS #8 seems to have stemmed from the expectation that all double blind tests of such would result in negative  outcome.  I can't rationalize commentary like Steven's any other way.

That aside, that test is obscure because until I bought a copy and quoted it online, no one in any of these forums had seen or read it.  Even AES papers claiming to be rounding up amplifier tests did not reference this work where positive identification occurred. 

Hopefully with threads like this we increase its visibility and take it out of obscurity status.

Quote

He admits he's never heard of or read a rather more widely read article, in Stereo Review (then a mass market newsstand magazine popular with audio fans), from 1991 by E. Brad Meyer, describing load conditions under which two amps will sound different.....

Come again?  You made a reference to that article.  I asked you to quote what you think is relevant to this thread.  You turn that into me not having the article?  What does that have to do with you putting it forward as  evidence?

As it turns out, I do have the article . Let me quote a relevant section from it:

1% of the time is not 1% distortion.  If it is 100% distortion 1% of the time, you'll hear it

False claim. Calling a few comments about my experiences with SMPS a resume just shows how desperate some people can become to distract attention from their egregious false claims such as:

http://www.madronadigital.com/Library/Mark...3Amplifier.html

Reinventing the Audio Power Amplifier: Mark Levinson No 53
By Amir Majidimehr

"While this provides improved efficiency it aggravates a weakness of switching amplifiers which is their very high sensitivity (compared to linear amplifiers) to power supply voltage variations and noise which unfortunately get worse with switching supplies. "

Amir, instead of sticking your nose where it doesn't belong, why don't you concede the point or provide believable evidence that switchmode power supplies always makes amplifiers perform audibly worse which is your basic claim, above.

If you could provide reliable evidence that SMPS are as bad as you say with swichmode power amps, people around here who recommend and use them with switchmode power amps could be put back on the road to audio nirvana.

Oh how quaint.  Amir 'found' the E. Brad Meyer article that he must have 'forgotten' before, when he evinced no clue as to its existence.  An article by the guy he  says isn't really authoritative enough to write articles like Meyer & Moran 2007.

Well, that's nice.  He's reviewed it carefully and pulled one line from it and now he accepts EBM's authority, which he interprets as saying: only having >>1% 'ordinary harmonic distortion' makes amp differences audible.  Arny & Co's amps didn't have that, therefore amps sound different because of.... magic reasons, I guess.

Everyone here is on to him, as I expected they would be.

Where is the double blind test to demonstrate that?

Warm up your highlighter, Amir!  There may be pop quizzes on the material!

Quote from: krabapple on 2014-11-27 21:19:14

Warm up your highlighter, Amir!  There may be pop quizzes on the material!

Steven, I am going to ask you directly and specifically: do you have the Meyer article that you asked me about?

Pop quiz!  Please identify the *page number* where each snippet occurs:

1. "...tube amplifiers (and solid-state amps designed deliberately to behave like tube amps) will tend to behave differently...."

2. "...to this day, no one has been able to do it, except under special conditions...."

3." ...looks like we should buy the transistor amplifier because its response is flatter...."

4. "...amplifiers cost thousands off dollars, and people buy them....."

5. "...an upward tilt below 500Hz that gave the tube amplifier a warmer overall tone..."
You will not be graded on a curve.

But I do so enjoy providing educational resources to the needy such as Amir. 

-References-

PS. Amir can read these for extra class credit:
the well-known, long and considered, but ultimately inconclusive, essay by Rod Elliot
http://sound.westhost.com/amp-sound.htm

and Roger Russell's amusing and also well-known  (to those in the trenches) 'Audio Distortions' page, which includes an anecdote about hjis own ABX of amplifers
http://www.roger-russell.com/truth/truth.htm

Warm up your highlighter, Amir!  There may be pop quizzes on the material!

The discussion here is about class D amplifiers.  Contrary to popular myth, class D does not mean "Digital."  The letter D was just the next one in the alphabet.  So you working with mainframe computers gives you no familiarity whatsoever with the design of class D amplifiers.

the usual self-aggrandizing blather

Horrors of horrors.  Meyer agrees with the subjective reviewers as to which amplifier sounded better!

Same to you Ammar and the rest of the membership in US.

In comparison testing I have done, switching amplifiers using the classic class D configuration always sport incredible low frequency control and power. They beat out linear class AB amplifiers almost regardless of price.

What they give up though is high frequency fidelity which I find somewhat harsh. The distortion is highly non-linear and challenging to spot but it is there. The Mark Levinson No 53 is the first switching amplifier I have heard which does not have this compromise. Its bass is amazingly authoritative: tight and powerful. Yet the rest of the response is absolutely neutral and pleasant.

If that doesn't upset folks here, this one for sure would:


Here is the caption for above:

Close up of Nordost SPM bi-wire speaker cable with WBT solderless locking banana plugs and the Legacy Whisper binding posts. The SPMs are in a protective custom semi-rigid vinyl/nylon mesh tubing.

Looks like he has not read those references on his web site. 
Story of my life on this forum it seems.

The beauty part of providing you links to educational resource you've lacked, Amir, is that it provides them to others here, too, who are free to visit or revisit them at whim to put your incorrigible quote-mining into context.

We're onto you here, you know.  This isn't your WTF forum, or even AVSF.

Quote from: krabapple on 2014-11-28 06:35:05

The beauty part of providing you links to educational resource you've lacked, Amir, is that it provides them to others here, too, who are free to visit or revisit them at whim to put your incorrigible quote-mining into context.

Steven, would you kindly indicate in that list which one of those papers/articles you have read?

Quote

We're onto you here, you know.  This isn't your WTF forum, or even AVSF.

Ah, you smart ones .

Quote from: amirm on 2014-11-27 22:35:32

Horrors of horrors.  Meyer agrees with the subjective reviewers as to which amplifier sounded better!

But until he starts doing proper DBT preference testing, his comments have no better intellectual support than theirs. It is all GIGO.