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Old 23rd November 2012, 07:46 PM   #29741
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Quote:
Originally Posted by john curl View Post
Well, its friday and I promised an exam. However, I am pretty darn sure that most of you are completely unprepared for one, as I would have expected.

You see, very few people are REALLY interested in doing or even understanding exotic measurements like the Hirata test, they just like to pick and poke at the very idea that the test might give some interesting results. ... loadsa important guru pontificating ..
JC, I think the 'very few people' you mention are probably all here and waiting with bated breath for your results. I for one am always interested in tests that have some correlation to good sound.

Please don't keep us in suspense. How did Blowtorch do? Did anyone turn up with a simple 5532 amp for you to test?

Which of the Hirata tests does your box do?

Can someone tell me if this is the relevant Quan paper? New Techniques for Evaluating Audio Amplifiers via Measuring for Induced Wow and Flutter and Differential Phase Distortions

Some gurus have been telling us ad nauseum that these tests are really important. At least one Golden Pinnae device has failed Quan. Are there Golden Pinnae devices that fail Hirata too?

Last edited by kgrlee; 23rd November 2012 at 07:52 PM.
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Old 23rd November 2012, 07:53 PM   #29742
bcarso is offline bcarso  United States
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Originally Posted by kgrlee View Post
Relevant perhaps, but an earlier one than he gave at the most recent AES convention (btw I have seen neither one --- I asked a client who was there in San Francisco to see if he could snag a preprint, but I doubt that he was able to).
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Old 23rd November 2012, 08:10 PM   #29743
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Originally Posted by john curl View Post
Scott, you have to try to UNDERSTAND what the Hirata test measures, before you can say anything about it.
Not particularly difficult to understand, but isn't this some kind of archeolgy trying to find out why bad 40yr. old designs sounded bad. Those Crown amps were basicly engineered at the uA741 level. Engineers just didn't understand at the time (at least some audio engineers didn't).
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Old 23rd November 2012, 08:15 PM   #29744
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Originally Posted by john curl View Post
and actually believing what I hear as a reasonably accurate determination of what sounds good and what does not.
Unless you believe you are the center of the world (as-it seems) and the model for the build of each living creature, how can-you pretend what you 'actually' hear have anything in common with what hear a young woman with more than one or two octaves up in the trebles comparing to you ?
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Last edited by Esperado; 23rd November 2012 at 08:19 PM.
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Old 23rd November 2012, 08:22 PM   #29745
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I am continually amazed that I can hear any small differences in audio at all. Of course, I am often commanded by SY to do double-blind ABX tests in any case, just to make sure that I can't hear any differences, then I can be sure that I don't know anything at all about anything audio.

Last edited by john curl; 23rd November 2012 at 08:26 PM.
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Old 23rd November 2012, 08:23 PM   #29746
RNMarsh is offline RNMarsh  United States
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Default Rs - THD results-

Here's the data on an Rs in the feedback loop --> 1985 -->
first is the raw thd of the driver in a rear loaded horn enclosure (big)-5-6% at 45Hz;
next is the same driver in the same box with the horn cut out and converted to a bass-reflez design 2.5-5%;
The last one is same except with the motional feedback resistor (Rs). 1.6% minimum. Enjoy -- RNMarsh
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File Type: jpg SPKR-THD Rs.jpg (545.5 KB, 130 views)

Last edited by RNMarsh; 23rd November 2012 at 08:27 PM.
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Old 23rd November 2012, 08:45 PM   #29747
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Originally Posted by kgrlee View Post
Looks interesting. I believe in modulation measurements to reveal something we might miss in highly averaged methods (HD, IMD etc.) that are sensitive only to steady periodic phenomena.
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Old 23rd November 2012, 08:46 PM   #29748
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Quote:
Originally Posted by kgrlee View Post
JC, I think the 'very few people' you mention are probably all here and waiting with bated breath for your results. I for one am always interested in tests that have some correlation to good sound.

Please don't keep us in suspense. How did Blowtorch do? Did anyone turn up with a simple 5532 amp for you to test?
My apologies gentlemen. JC is in Berkeley,CA, not Canoga Pk.

Brad, I hope you didn't get 5,000 people waving 5532 preamps knocking on your door and demanding to see the Messiah.

JC, its likely Quan will present another paper at next AES, San Francisco. As you are on good terms with him, why not offer Blowtorch for him to test?

It won't affect future sales whichever way it goes so a safe bet.
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Old 23rd November 2012, 08:55 PM   #29749
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Originally Posted by john curl View Post
I am continually amazed that I can hear any small differences in audio at all. Of course, I am often commanded by SY to do double-blind ABX tests in any case, just to make sure that I can't hear any differences, then I can be sure that I don't know anything at all about anything audio.
JC, don't make statements like this, even in jest! Us faithful who grovel at your feet would all commit seppuku if there was the slightest hint that this could be true.

Please ignore the disbelievers and just concentrate on doing the Hirata and Quan tests on Blowtorch.
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Old 23rd November 2012, 08:56 PM   #29750
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CTC Blowtorch preamps are not sold anymore, after Bob Crump has passed away.
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