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John Curl's Blowtorch preamplifier part II
John Curl's Blowtorch preamplifier part II
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Old 2nd January 2018, 09:03 PM   #99121
mmerrill99 is offline mmerrill99
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Originally Posted by billshurv View Post
accurate direction finding as an evolutionary need I can understand. Not sure our savanna dwelling ancestors needed good jitter detection though
Playback systems weren't too refined among cave dwellers
 
Old 3rd January 2018, 01:20 AM   #99122
Tournesol is offline Tournesol  Belgium
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Playback systems weren't too refined among cave dwellers
Even at the Rock age ?
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Old 3rd January 2018, 05:50 PM   #99123
Jakob2 is offline Jakob2  Germany
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If I could inject, I'd argue the "BS game" portion is trying to hang one's hat on the ostensible bandwidth above 22.1 to some sort of superiority. Sure, it's there, but, as you write, there's no energy in any recording to leverage it. And we only need as much rise time (bandwidth!) as our ears can hear anyhow, which makes the whole argument kinda null. Nor am I arguing that NOS 44.1 kHz digital doesn't need more bandwidth to get a decent antialiasing filter in there, which is largely obviated by oversampling.

There's a large element of the "make up the justification after you've decided the conclusion" that is getting push back.
Welcome to the groupies. (SCR)

As i cited the original statement that got the "BS mark" , pointed to it as part of common knowledge and (at least implicitely) for an explanation several times there would be have been the opportunity to provide something; maybe of the kind that you expressed above.
But why should i have to conjecture about it?

Unfortunately it seem that in our days of "post factism" people tend to be less interested in arguments than in shouting . Does "itīs BS" and "no itīs not" in repetition really help?

Wrt your comment, the "plain BS" mark stil imo isnīt justified because how could you know?
You could point to the fact that it might be not important to each and everyone, but the mere technical fact canīt be disputet.
There is some evidence that bandwidth extension above 20 kHz (letīs say to 35/40 kHz) would possibly provide ""better" listener experience. Kunchur comes into mind (again) whose experiment could have provide corrobation for the results of the Leishovitz article Mark4 mentioned.

And of course, as said before, the assertion that something was "proven" by listening experiments can be refuted but it canīt be done by results of another listening experiment.
 
Old 3rd January 2018, 08:29 PM   #99124
john curl is offline john curl  United States
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Guys, the problem with restricted bandwidth is that it significantly changes the transient response of music developed below 20KHz. Without somewhat extended above 20KHz bandwidth, we lose both rise-time and the time 'signature' of the original acoustic event. Is this important? I think so, based on my own listening experience. Now will it help EVERY audio system? Probably not, as many audio systems do not have extended 20KHz+ response, but that does not mean that it isn't audible with some people with more extended response.
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Old 3rd January 2018, 08:48 PM   #99125
Tournesol is offline Tournesol  Belgium
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Probably not, as many audio systems do not have extended 20KHz+ response, but that does not mean that it isn't audible with some people with more extended response.
Well, imagine a tweeter able to reproduce a 20kHz sinus at 0dB, but with a rapide slope after this frequency.
Apply to it a sinus at 0dB peak or a square wave at 0dB peak. Where is going the extra power in the square wave ?
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Old 3rd January 2018, 08:48 PM   #99126
DPH is offline DPH  United States
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How? That doesn't make sense at all, John.

They're interrelated and bandwidth limited by microphones already. This is all classic signal theory. If you want to go about step responses without reconstruction filters, fine, but then you're in a place where you've long since violated sampling theory. Certainly some overprovision is good to ensure we don't get too time-variant of response, but wouldn't time variance show up as gross distortions (not necessarily harmonic)?
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Last edited by DPH; 3rd January 2018 at 08:52 PM.
 
Old 3rd January 2018, 09:18 PM   #99127
john curl is offline john curl  United States
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Here is the transient response of the B&K microphone that we all settled on 45 years ago as a 'reference' condenser mike: The 1/2" B&K 4133. The GD, Mark Levinson, Crystal Clear, and Stellavox used it as their primary mike in the '70's. It is the MIDDLE row of screen shots. Fast enough for most things, BUT we could do faster with a smaller mike width, if necessary.
Attached Images
File Type: png B&K trans resp.png (178.2 KB, 261 views)
File Type: png Picture 149.png (724.4 KB, 262 views)
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Old 4th January 2018, 03:21 AM   #99128
simon7000 is offline simon7000  United States
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Derfy,

Even the 40s and 50s had condenser and ribbon microphones that had response above 20,000 hertz. They often were deliberately resonant at 15,000 hertz or so as they really were voiced by ear. But having played with them they really did peak there and then have extended high frequency response.

I lost one of the vacuum tube condenser microphones in a flood. It had a gold diaphragm. Gold was chosen as it is possible to roll it thinner than any other metal.

RCA used to make different ribbon microphones their limit was the step up transformer.

Last edited by simon7000; 4th January 2018 at 03:49 AM.
 
Old 4th January 2018, 04:04 AM   #99129
DPH is offline DPH  United States
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And yet, still there's basically no music that has any energy up there. And many of the other classic microphones (not saying all!) are pretty much dead at 10k.
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Old 4th January 2018, 04:05 AM   #99130
scott wurcer is offline scott wurcer  United States
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Gold was chosen as it is possible to roll it thinner than any other metal.
I can only imagine there is an issue with resistance to damage, that amount of culinary gold leaf is only a few dollars.
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