John Curl's Blowtorch preamplifier part II - Page 1111 - diyAudio
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Old 12th March 2011, 03:08 PM   #11101
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In any case, I'm happy, let everyone else be happy.
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Old 12th March 2011, 03:10 PM   #11102
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In any case, I will stick with Lundahl for the moment. It is a PROVEN design, liked by many. Thank you everyone for your input.
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Old 12th March 2011, 03:17 PM   #11103
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Originally Posted by Soundminded View Post
JG, you have your definition of music and I have mine. It's not a matter or which language it's spoken in. An adolescent shrieking his lungs out 2 inches from a microphone, that signal put through fuzz boxes and big muffs, and then amplified to 130 db does not fall into my definition of music. Perhaps yours, perhaps other people's but not mine.
How did you come to the conclusion that this is the music I listen to from what I wrote? What I wrote indicates just the opposite.
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Old 12th March 2011, 03:22 PM   #11104
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Originally Posted by simon7000 View Post
One of the demos we do around here is to play a 30,000 cycle per second sine wave through an old Spica speaker. Everyone says they don't hear any thing. Then I turn it off and just about everyone realizes they can detect it going off and then back on. It does not sound like a clean tone but the energy is certainly perceived.

There are a number of researchers who believe it is possible to perceive small amounts of phase shift at 20,000 cycles per second.

If you tell me you can't hear it I will believe you, If John tells me he hears things who am I to argue?
That's not what I meant when I asked "What is above 20kHz?"

Here's the sequence of events.

First John said:

Cine-Mag will through my design, out of spec. Eddy current losses.

John mentioned eddy current losses. So in that context I replied:

You don't even know what your "spec" is.

I mean, how can you even know what your spec is if you've never quantified it in the first place?


Then John said:

It is above 20KHz, that's for sure.

And that's when I asked "What's above 20kHz?"

I wasn't asking whether there was content above 20kHz or if anything could be heard above 20kHz.

Instead, I was asking John just what the hell he was going on about. He was babbling incoherently and his "above 20kHz" didn't seem to have any connection with anything that I could see.

It appears now that it had to do with the frequency response plot I posted previously for a 10k:10k CineMag input transformer. But that was not obvious at the time I asked "What's above 20kHz?"

se
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Old 12th March 2011, 03:27 PM   #11105
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I am sorry everyone, it is difficult to convey every nuance of engineering design with just a keyboard, and by memory alone. I am not here to teach a course in engineering, just to put forth a few opinions, based on experience, that have worked for me.
Each and everyone, you must do your own research to prove or disprove what you believe to be true. I am in no position to help further on this website.

Last edited by john curl; 12th March 2011 at 03:34 PM.
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Old 12th March 2011, 03:31 PM   #11106
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Quote:
Originally Posted by simon7000 View Post

One of the demos we do around here is to play a 30,000 cycle per second sine wave through an old Spica speaker. Everyone says they don't hear any thing. Then I turn it off and just about everyone realizes they can detect it going off and then back on. It does not sound like a clean tone but the energy is certainly perceived.
And your explanation for this? (I have mine, which I think you can guess)
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Old 12th March 2011, 03:35 PM   #11107
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Thank you, Bob Cordell for your input, of course, you are correct.
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Old 12th March 2011, 03:37 PM   #11108
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Then where is the engineering justification for extending FR in a sound reproducing system beyond 20 KHZ?
One from Cal Tech (I still reserve judgement myself).

There's life above 20 kilohertz! A survey of musical instrument spectra to 102.4 kHz
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Old 12th March 2011, 03:39 PM   #11109
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Originally Posted by john curl View Post
I am sorry everyone, it is difficult to convey every nuance of engineering design with just a keyboard, and by memory alone. I am not here to teach a course in engineering, just put forth a few opinions, based on experience, that have worked for me.
Each and everyone, you must do your own research to prove or disprove what you believe to be true. I am in no position to help further on this website.
Any tinkerer who accidentally chips off the edges of a cube to make it more like a sphere and finds it rolls better can say the same. As someone who claims to be an engineer to somone who IS an engineer, how about some straight engineering answers for a change instead of the usual pap?

BTW, I haven't heard you defending Cheever's paper in a long time, the paper you said should be required reading for all amplifier designers. What happened, you forget about him or the subject just hasn't come up? Or have you changed your mind?

http://www.tubesville.com/cheever_thesis.pdf

As this paper has nothing to do with electrical engineering and is a weak presentation even for a paper about market research, not only wouldn't I have granted him an MSEE on the strength of it had I been on the committee, I might have tried to revoke his BSEE. Ever hear of blind testing using a controlled variable? Obviously he hadn't.

BTW, I once asked you for a working definition of what functions an ideal audio amplifier or preamplifier should perform so that there would be an objective benchmark against which to judge real world amplifiers and preamplifiers. Ever think of an engineer's answer to that question yet or is your answer still whatever pleased John Curl?
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Old 12th March 2011, 03:39 PM   #11110
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Hi Scott, Dick Sequerra says hi. I told him how much you contribute to this thread.
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