John Curl's Blowtorch preamplifier part II - Page 2943 - diyAudio
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Old 17th November 2012, 06:10 PM   #29421
RNMarsh is offline RNMarsh  United States
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Default gross distortion in loudspeakers -

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Originally Posted by RNMarsh View Post
This paper is excellent in bridging the gap between objective testing and listing/hearing loudspeakers ---->

The conclusion I have a hard time with... to use the knowledge to sort of hide and cover up the poor driver performance. I guess if you have taken the dynamic driver technology as far as you can and its still pretty bad, you can use this approach.

Thx- RNMarsh
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Old 17th November 2012, 06:20 PM   #29422
gpapag is online now gpapag  Greece
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Originally Posted by RNMarsh View Post
Need multi-tone stimulous.

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Czerwinski Et. Al. [Cze 01] investigated how the number and energy of intermodulation
products changes in relation to harmonic products for different number of initial
tones and orders of nonlinearity.

The dominance of intermodulation products is striking, a fifth order nonlinearity for example with 20 initial tones produces close to half a million IM-products but only 40 harmonics of the initial tones. Some conclusions that are drawn in [Cze 01] are:
An n:th order nonlinearity needs at least n input tones to reveal all possible intermodulation
combinations of the input signals.
• The number and energy of the intermodulation products vastly exceeds that of
the harmonic products when multiple input tones are present. The disproportion
grows rapidly with the order of nonlinearity.
• High-order nonlinearity generates very low levels of harmonic distortion of this
order, compared to the levels of IM-products and lower order harmonics.
Quote above from (p. 6-7):
http://publications.lib.chalmers.se/...ext/126969.pdf


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Originally Posted by RNMarsh View Post
The conclusion I have a hard time with... to use the knowledge to sort of hide and cover up the poor driver performance. I guess if you have taken the dynamic driver technology as far as you can and its still pretty bad, you can use this approach.
We may have a hard time with that but this is I think proper “engineering” (that is, if relevant target specifications can be set through such a research and drivers can be thus easily fabricated, with a low price tag).

George
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Old 17th November 2012, 07:02 PM   #29423
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Originally Posted by RNMarsh View Post
Because this is an electronics forum
Speakers are electronic parts...
It was an image as loudspeakers characteristics, as well as electronic characteristics (impedance mostly) can change the behavior of any wiring.

If you have to deal with capacitive long wires loads, as an example, what did-you do ? Try to change the building for shorter wires, or change the output stage for it can drive such loads ?

...There is a lot to do to improve electronic designs for better noise, better bandwidth/phase, less distortion, less EMI problems, less output impedance etc... things we can measure as imperfect than to play with magical stuff that nobody can measure or justify by numbers or theory and even blind tests.
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Last edited by Esperado; 17th November 2012 at 07:06 PM.
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Old 17th November 2012, 07:15 PM   #29424
RNMarsh is offline RNMarsh  United States
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Originally Posted by gpapag View Post
We may have a hard time with that but this is I think proper “engineering” (that is, if relevant target specifications can be set through such a research and drivers can be thus easily fabricated, with a low price tag).

George
Makes sense to me. I was just lamenting the fact that what we have to deal with - dynamic driver - is so messed up to begin with and we still cant seem to make it significantly better than what we have now. This cure proposed is fine and maybe it will require all their better systems to have such and amp included in a speaker. but it aint cheaper. Nor widely available. yet. Does JBL have a sellable, working product using these concepets?
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Old 17th November 2012, 08:24 PM   #29425
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This is just personal experience folks, this is the climate that I operate in. That is why we could take on the WORLD with the CTC Blowtorch, and usually, if not always, WON!
JC, you prepared to put up Blowtorch against unspecified competition in an ABC Blind Listening Test?

This isn't speakers so won't cost $50k to arrange properly. You set up Blowtorch with your choice of ancillaries and have a person of your choice personally verify the 'switching' arrangements don't degrade the clarity & definition. You choose the Listening Panel and they choose their own music. Everyone tested individually and can take up to a day to rate the 3 devices. They can choose to have instant switching or extended sessions. Some people may be asked to repeat their test. (This is a good sign and usually indicates they may be true golden pinnae)

I suggest John Atkinson as one of your panel but everyone can remain anonymous to protect the guilty. Results to be posted in several forums and perhaps in Stereophile.

The Dynamic Duo, L & V are retired and I'm sure can be persuaded to supervise.

Forfeit to be decided, may be $1k donation or a case of wine to a charity of the winner's choice. Someone has to bankroll my side but my charity is the Benevolent Society for Deaf Speaker Designers and if I win, I'll be happy with a single bottle of Burgundy or Sauternes and the rest can go to your charity. Young wine will do.
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Christophe, lets see if he really has courage
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Old 17th November 2012, 08:35 PM   #29426
gpapag is online now gpapag  Greece
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Originally Posted by Esperado View Post

...There is a lot to do to improve electronic designs for better noise, better bandwidth/phase, less distortion, less EMI problems, less output impedance etc... things we can measure as imperfect than to play with magical stuff that nobody can measure or justify by numbers or theory and even blind tests.
+



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Originally Posted by RNMarsh View Post
but it aint cheaper. Nor widely available. yet.
You may be right that things don’t go forward fast enough in this field. Leo Beranek had pointed out that too.
Although perception masking effects and critical bands were known as far back as your ancient Kellog’s design, although hard facts were verified and firm algorithms established before 1970, we still face today the label “this site is under construction”.
As usual, the revolutionary wave will come through the mass gadget market and will hit the white elephants with a delay.
The research going on now aims toward how existing theoretical knowledge can be cheaply (mass manufacturing)embedded into small size products with low power demands.
The elephants will serve later as repackagers of “delux” oversized versions of the same (save some fancy names and appropriate de-mything).
The technological products will be cheap nevertheless and widely available (or just because of this. Remember, video card, sound card…)

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Does JBL have a sellable, working product using these concepts?
I don’t know if fragments of all this have entered the large driver’s manufacturing world.
But I don’t think that JBL is the leader on this promising field (don’t be fooled by the presentation).
I remember a link by Mr. Curl on a current JBL compression driver some days ago. I smiled as I had just read a Bell’s 1928 article http://www.alcatel-lucent.com/bstj/v...stj7-1-140.pdf , as well as Beranek’s remarks over the construction. (see attachment)

George
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File Type: jpg air chamber distortion.jpg (320.3 KB, 128 views)
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Old 17th November 2012, 08:38 PM   #29427
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No double blind-tests for me, thanks.
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Old 17th November 2012, 08:39 PM   #29428
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Originally Posted by john curl View Post
Dick Sequerra referred me to early books on crystal alignment, found by X-ray studies. Got any ideas?
No idea, please define the meaning of direction for an AC signal and please what did Dick Heyser say????
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Old 17th November 2012, 08:43 PM   #29429
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Everyone, this is where the answer ends: I can ONLY make what other people and I find works better than some other approach. A 'double-blind' ABX test will not show any difference. If you believe in double-blind test results, there is no more to say.
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Old 17th November 2012, 08:44 PM   #29430
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Dick Heyser told me more than I have put here, 40 years ago, but it is none of your business as to exactly what.
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