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.
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?"
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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.
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.
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And your explanation for this? (I have mine, which I think you can guess)
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
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?
That wasn't Allen's motivation, if I'm reading you correctly- he maintained that cutters started rolling off at 50kHz (probably extended to that frequency exactly as you said), so putting in a compensating zero would flatten the overall (mike to preamp output) response. He was well aware that this caused a rise of nearly a dB at 20k- in fact, in his book, he suggested that as a way to measure that you had that zero tuned correctly. Like I said, I tried it both ways and couldn't hear a difference, but I'm 56 years old, so it's possible a younger person could.
Well, then why insist on 0.1dB response to 100k? Moot for a phono stage, the Lundahl, Sowter, Jensen, and Cinemag MC transformers all meet that spec, but why feed that stuff to your power amp? Nonetheless, we're in deep agreement on the other point, the 50k resonance and its potential effects, something I talked about a bit in the phono stage article.
I would recommend that people get the designers spec sheets on disc cutting systems and understand their operation. They work by suppressing a dominant resonace of 1KHz or 2KHz or so, and extending the bandwidth to 30KHz or so. So, the ACTUAL response of the disc cutter operating at normal speed, in real time, is limited to below 40KHz.
Bees can see ultraviolet light humans can't. Does that mean we should manufacture and buy film and cameras that record and reproduce it too...unless we happen to be studying how bees find nectar? What's the difference if musical instruments produce tones at 100 khz or 100 mhz if humans can't hear above 20 khz? Unless you want to know what a bat might think of a blowtorch preamp...assuming there's a signal to be reproduced above 20 khz.
I read an interesting report about that some time ago. A Japanese professor of electrical engineering wanted to demonstrate to his students that they couldn't hear sounds above 20 khz. So he devised a test with recordings made to well beyond it and switched a filter in and out. To his surprise they consistently heard the difference. Then he realized that what they were hearing was tweeter distortion in the audible passband caused by driving the tweeter above 20 khz. When he changed the setup and used a separate driver for the sound above 20 khz, he got the expected results. This is why peer review of well documented scientific claims is requried to establish real knowledge, not just the opinions and observations of someone who was put up on a pedistal.
Exactly Allen's point. So if you want the mike signal to be replicated more accurately, he argued that you needed to compensate for that rolloff (presumably not a brick wall!).
If I ever decide to go into the business of manufacturing vinyl phonograph records I'll be sure to do exactly that. Thanks for the advice.
Hello, DiY'am.
And greetings !
Lieutenant Steve, lieutenant Steve, let's play some music.
Okay Frenchy, what would you like to hear ?
Well...., i love a good Polka as much as the next man.
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