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?
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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).
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).
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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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.
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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
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
Attachments
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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.
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.
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.
John, I guess the world's divided into 2 sets of people: those who've rationalised that certain types of variations can't make a difference and therefore will never hear it happen, and those who can just hear that it is so and are happy to keep experimenting, because that gives them the best results ...
Frank
Thanks for this Mr. Marsh. I can confirm the distortion reduction works for small 8" & 6" speakers too.
A bonus is the speaker will be much less boomy in your reflex example with the feedback.
Really? Can you point out some posts where he commands you to be sure you can't hear any differences? And how would that make you sure that you know nothing about audio?
References, please.
Not only, fas42. There is a third way.
Order of magnitude.
Let-me give an example. You are in charge of the aerodynamic performance of a formula one. What do you prefer ? Spending time on testing the air penetration of different paintings and varnishes, or optimize the bodywork in wind tunnel?
I will give-you an other example: What is the interest of testing different wires and printed board materials around a µ741 ?
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It is obvious that THD had been reduced by negative output resistance. Draw the graph of THD versus excursion on the same frequency and you will get similar results with horn, port, closed box, closed box driven by an amp with negative resistance.
The initial point was, driver with bigger cone can introduce less distortions on the same low frequencies generating the same SPL. It is also obvious and does not require any proof, IMHO. Bigger cone in equal conditions will require less power and less excursion for the same SPL. That means less distortions.
An externally hosted image should be here but it was not working when we last tested it.
Pardon, I attached the wrong picture. This pictures are better. They are about Alpine R-Type 12" drivers I use in woofers and in subwoofer at home. As you may see, they designed for "compensation" of distortions. But such compensation means multiplication of 2 polynoms, that increases the order of the resulted curve, also you may see some quite significant 2'nd order component that increase intermodulation. Distortions on the same excursion are less than older speakers had, but they increase more abruptly, and are of higher order. i.e. more audible as distortions.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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