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  #1  
Old 02-12-2018, 12:24 AM
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High Frequency Audio sources

After I read the thread; "YouTube Debate About Vinyl Frequency Range"
by latreche34,

I'm reminded about the challenge to find High Frequency sources to test the capability of the recording equipment.

I recorded a live production back in the early '70s using the best Microphones I could find, a pair of condensers.

Recently I hauled out the tape to see what the frequency range I could see.

I was a bit disappointed in what little I saw in the content above 10K.

I was thinking that was it.

Then at the end of the recording, an unexpected thing happened.

Now to back up a little, I had been to a few rehearsals with the recording setup to get a feel for mic positions and volume levels.

But, there was no audience.

So at the end of the performance and the applause started, I was NOT ready for the volume level.

I quickly decided that if it was too loud, I would just gingerly reduce the input levels.

But as it turned out I just left them as they where, as I thought it would be OK.

As it turns out, the frequencies in clapping clearly and convincingly shot past the 20K "upper limit of human hearing."

And there doesn't seem to be any noticeable distortion.

If it ever rains any more this winter I may even take a closer look to see just what the more detailed frequency content of applause is.
  #2  
Old 02-12-2018, 03:55 AM
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Quote:
Originally Posted by tapedr View Post

I was a bit disappointed in what little I saw in the content above 10K.
There is usually not much above 10KHz , or the level is quite down - to give you a little idea of which instruments to produce high frequency notes :

  #3  
Old 02-12-2018, 04:10 AM
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In that figure there is a thin line halving each segment into two.
The first, lower segment represents the main spectrum.
The second, upper segment represent the harmonics.
Otherwise, the main spectrum sits comfortably below 9kHz.
From that figure misses the organ, that has the largest/longest spectrum.
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Old 02-12-2018, 08:16 AM
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quote; From that figure misses the organ, that has the largest/longest spectrum.

Due to lower frequencies Ghit? I'm picturing that ultra massive pipe unit seen somewhere in Europe I believe. Certainly not the one my Grandmother had / but maybe...shrug
John
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Old 02-12-2018, 08:29 AM
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The forum software changed the size, but one can see the otrgan as the longest black segment, (the second from top), almost reaching 16kHz on fundamentals.
Attached Images
File Type: jpg 2024_FreqGraph.jpg (19.3 KB, 145 views)
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Old 02-13-2018, 08:06 AM
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As a matter of fact...

...The performance included a Pipe Organ.

BUT, the point WAS the applause, on first look, has MORE higher frequency content.

I don't see applause on the chart...

AND, MORE to the point, some things we take for granted have more

high freq content than given credit for!......

...I have YET to analyze the Freq content of ALL the (high quality) coughing.....
  #7  
Old 02-13-2018, 08:49 AM
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Have you tested your hearing to see how high you can hear?

It is just a thought if you cannot her above a certain level then it doesn't really matter.

.
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Old 02-13-2018, 09:22 AM
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Quote:
Originally Posted by tapedr View Post
BUT, the point WAS the applause, on first look, has MORE higher frequency content.

I don't see applause on the chart...
Applause is noise. A sort of cacophony of frequencies, that not really allow one to see/notice/hear/realise what is pure sound and what is/are distortions.
Consequently, one can drive applauses rather hard in distortions, without adverse effects.
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Old 02-13-2018, 12:05 PM
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Not only is applause noise, it is created from two relatively hard objects impacting each other. The waves created are not sine waves but are basically high frequency transients. What we hear are basically lower amplitude undertones of the transients, as opposed to music where we hear the mixed fundamental frequencies and some lower amplitude overtones. It's not surprising that applause shows much more high frequency content than music.

Dave
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  #10  
Old 02-13-2018, 04:16 PM
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Yes, I was going to say a bunch of transients recorded at the same time might be registered as high frequency mixed together but one clap by itself will not show that as it is a lower frequency noise.
I really do not evaluate any equipment based on pink noise or applause.
That is like asking is any audio comes out of the deck or not.
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  #11  
Old 02-13-2018, 10:14 PM
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Frustrated Well, I never....

...As someone has said, "Some music is noise and Visa versa"..

BTW, I just talked to a retired sound guy friend.

I asked him if he considered applause noise.

He said "applause is not noise"

Just put me in the camp that says applause is a SOUND.

And I want my equipment to record it and play it back with as little adding

to, or subtracting from the original SOUND.

...In the OLD days, it was known as High Fidelity.

Excuse me now, I'm going to go listen to some sine waves...in High Fidelity...
  #12  
Old 02-14-2018, 06:55 AM
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kiethatroachdale I have more then once told folks anything that can't be heard is not worth recording. My hearing runs out at 17.5 so all past is nothing.

I have also found out most if not all musical content runs out at 15 kHz. Tapetech has shown this with a graph of Dave Brubeck and "Time out" and nothing was above 15 kHz and everyone in the turntable forum agreed that was one of the best albums they have ever heard from older recordings.

Many threads prove the simple premise out that the search for "audio nirvana" is so much a fools dream.

I did, just to prove to myself, get my Teac A 6300 to go -3 dB at 27 kHz and +1 dB at 10 kHz, damn good, but what was gained? It sounds just as good at 3 3/4 IPS with reduced record levels around -3 to 4 dB at 185 nWb reference at 0 dB and utilizing dbx type II. Roll off is -3 dB at 16.5 kHz with a small + 2 dB bump at 9 kHz, something I can handle, once biased for that speed. Sure wow and flutter is not as good BUT if bellow audible then what the hell. Less critical recordings do not suffer for sure and 99.9% of musical content is retained.

SO in closing, keep looking for that "fools gold" (iron pyrite) and 30+ kHz response. For myself, I just want to listen.
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  #13  
Old 02-14-2018, 07:08 AM
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Exactly what 'Johns' has eluded to.... I might go and get my hearing tested....

The 'For sale' section on TH's might be full of Nakamichi decks, and I will go back to AMSTRAD units when I discover that I cannot hear above 4khz!!

I think I actually have reasonable hearing...but who knows!

If I cannot hear it, I really do not care..... Unless it is a mugger sneaking up behind me of course!!

PC
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  #14  
Old 02-14-2018, 07:42 AM
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I wonder why everyone bashes the CD for brickwalling 18-19-20kHz but conveniently forgets that the CC rarely reaches 20kHz (with the exception of a very few decks, both in terms of models as well in terms of sold items), the allegedly 16-17-18-20kHz quotations are based on DIN which foresees a -7dB (so -27dB below ) difference.
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Old 02-14-2018, 11:02 AM
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Quote:
Originally Posted by Skywavebe View Post
Yes, I was going to say a bunch of transients recorded at the same time might be registered as high frequency mixed together but one clap by itself will not show that as it is a lower frequency noise.
I really do not evaluate any equipment based on pink noise or applause.
That is like asking is any audio comes out of the deck or not.
Actually, one clap would be very close to the technique of transient response. This is not used very often but is useful in looking at the performance of circuit design blocks, particularly in op amps that operate with lots of feedback.

Essentially a very fast risetime and long duration square wave is input. It can be model as a infinetly fast rise followed by DC at finite volume (voltage). The Fourier transform of this wave is an analog signal containing all frequencies. The resultant signal out of the circuit is a wave form that approximates the input with a measurable rise time and fall time. The rise time is the high frequency pole and the fall time is the low frequency pole. The method doesn't tell you anything about response between the poles, but it is a quick look at ends of the frequency response.

Dave
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