John Curl's Blowtorch preamplifier part II - Page 2321 - diyAudio
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Old 19th May 2012, 08:21 PM   #23201
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Quote:
Originally Posted by hitsware View Post
>apparently Golden Ears can "listen through"
>these loudspeaker distortions of thousands
>times greater magnitude

It doesn't take "golden ears"
Distortion does not mask distortion.
If a signal is run through 10 distortion producing
stages, (audibly) the differance between no stage
and after stage 1 is near equal to between stage
9 and stage 10 .............
Actually simple harmonic distortion can cancel under some conditions. It is a useful design technique in amplifier stages.
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Old 19th May 2012, 08:36 PM   #23202
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Morinix, that is a good website for showing what we try to do with TOPOLOGY to lower inherent distortion, SO THAT we do NOT have to use so much negative feedback or even zero global negative feedback. Why do we want this? Because there is SOME distortion that may NOT be measurable by normal test equipment that the ear DOES pick up on. I am sure that these 'distortions' exist. There is too much evidence toward their existence.
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Old 19th May 2012, 09:22 PM   #23203
morinix is offline morinix  United States
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Quote:
Originally Posted by john curl View Post
Morinix, that is a good website for showing what we try to do with TOPOLOGY to lower inherent distortion, SO THAT we do NOT have to use so much negative feedback or even zero global negative feedback. Why do we want this? Because there is SOME distortion that may NOT be measurable by normal test equipment that the ear DOES pick up on. I am sure that these 'distortions' exist. There is too much evidence toward their existence.
Hi John, just curious because of the rampant stream of consciousness in this thread. Just lately I come to find this thread that started in part 1 nearly SIX AND A HALF YEARS AGO. Since I don't have the time to read every post I was just intrigued how these recent analyses related to the lamentation of the original poster not being able to find a schematic. Let me ask you this; If someone on this forum presented a correct outline of what you did on the design of the Blowtorch would you cop to it?
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Last edited by morinix; 19th May 2012 at 09:26 PM.
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Old 19th May 2012, 09:52 PM   #23204
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Maybe not. Who cares, anyway?
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Old 19th May 2012, 09:55 PM   #23205
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> Actually simple harmonic distortion can cancel under some conditions.
> It is a useful design technique in amplifier stages.

That may be for special planned instances, but in general
distortion does not mask distortion.
This is incredibly unknown !
The (say) 1% produced by an amp can be discerned with
a speaker producing (say) 10% as easily as if the speaker
produced (say) 1% (or 0% for that matter)
(by discerned I mean recognized if switched on/off)
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Old 19th May 2012, 10:18 PM   #23206
morinix is offline morinix  United States
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Quote:
Originally Posted by john curl View Post
Maybe not.
Good to know.
Quote:
Originally Posted by john curl View Post
Maybe not. Who cares, anyway?
Hmmm, well, enough posters to have this thread in the 1st grade if it was a person.
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Old 19th May 2012, 11:20 PM   #23207
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Quote:
Originally Posted by jneutron View Post
There's a company that has been testing and categorizing silicon for dc to dc conversion at 77k. Power as well as smart stuff. The purpose of conversion at 77k is to eliminate the warm to cold transition heat loss of very large copper conductors required for 5 or 10 kiloamp operation. If they can use a kilovolt or 2 and drop the current to 50 amps, the refrigeration expense goes down.

John
Never been down there, had a few amps that still worked at 130K or so. Never published the data which is too bad, it was a nice survey of GR noise across several manufacturers over extreme temp ranges.
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Old 19th May 2012, 11:26 PM   #23208
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Quote:
Originally Posted by simon7000 View Post
It did and it was based on an error. (Jan in editing changed a symbol in the schematic which led him solo on a merry trail of errors.) My response corrected that and added a few details.

Read the article, it is quite complete. The technique is being used by two test equipment manufacturers and one resistor maker that I know about.

Next try my article on how to measure distortion in solder joints and audio interconnects.
What happened to the "feedback goes round and round" article?
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Old 19th May 2012, 11:26 PM   #23209
jcx is online now jcx  United States
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I believe I specified that the added distortion was of substantially the same character, and a many thousands of times less in magnitude when talking feedback R vs dynamic driver voice coil heating effects

anyone want to bet they can tell 5% 2nd order nonlinearity from 5.01%, or 5% 2nd cascaded with 0.01% 2nd - that 0.0005% 4th sure must stick out like a sore thumb - right?

we might be able to construct test signals that give a IMD products from the above guestimated 4th term that clears the masking threshold - but with music I really doubt it can be heard
and I've still got a couple of orders of magnitude "in my pocket" if you really followed the Z-Foil vs voice coil numbers at all
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Old 19th May 2012, 11:34 PM   #23210
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Teledyne has a 3.3V mixed analog and digital ASIC (called a SIDECAR) operating down below 40K.

Thanks
-Antonio
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