High Def Formats again

[Edmund[_2_]]

Hi Guys,

Since I now finally have a HD player I like to buy HD material. There is a
possibility to buy HD tracks on line. However when I open such a file with
"Audacity" I don't SEE any frequency above 20 kHz, but I must admit I did
not totally analyze this data I just looked at it in the graphics of Audacity.
But I still wonder if any of these tracks actually contains frequencies above
20 kHz.
What do you guys make of this?
Any of you have a source for HD which has music information above 20kHz?
Let me make clear that I don't want to start whether or not higher frequencies
are audible, only that HD music should have recorded higher frequencies in
the first place.

Edmund

[jwvm]

On Apr 20, 8:47=A0am, Edmund > wrote:
> Hi Guys,
>
> Since I now finally have a HD player I like to buy HD material. There is =
a
> possibility to buy HD tracks on line. However when I open such a file wit=
h
> "Audacity" I don't SEE any frequency above 20 kHz, but I must admit I did
> not totally analyze this data I just looked at it in the graphics of Auda=
city.
> But I still wonder if any of these tracks actually contains frequencies a=
bov
> 20 kHz.

There are a number of reasons why there is a lack of energy at these
very high frequencies. Microphones commonly used to make the
recordings often do not get much above 15 KHz such as the SM58. The
human voice certainly is frequency limited and most musical
instruments have little harmonic content above 20 KHz. You might want
to look at recordings that feature the percussion section of the
orchestra since here you will find instruments like cymbals that will
be very rich in harmonic content.

[Arny Krueger]

"Edmund" > wrote in message

> Hi Guys,
>
> Since I now finally have a HD player I like to buy HD
> material. There is a possibility to buy HD tracks on
> line. However when I open such a file with "Audacity" I
> don't SEE any frequency above 20 kHz, but I must admit I
> did not totally analyze this data I just looked at it in the
> graphics of Audacity. But I still wonder if any of these
> tracks actually contains frequencies above 20 kHz.
> What do you guys make of this?

Many so-called hi definition recordings are actually 24/96 or 24/192
transcriptions of analog tapes and 16/44 or 16/48 masters. Analog tapes were
ususally made at 15 ips which pretty well eliminates response above 25-30
KHz.

> Any of you have a source for HD which has music
> information above 20kHz?

As Jwvm correctly points out, nature abhors the creating of true hi def
recordings. His list of reasons is good and relevant.

> Let me make clear that I don't want to start whether or
> not higher frequencies are audible, only that HD music
> should have recorded higher frequencies in the first
> place.

I agree that it is very nice when so-called hi def tracks are actually hi
def! ;-)

[Arny Krueger]

"jwvm" > wrote in message

> On Apr 20, 8:47 am, Edmund > wrote:
>> Hi Guys,
>>
>> Since I now finally have a HD player I like to buy HD
>> material. There is a possibility to buy HD tracks on
>> line. However when I open such a file with "Audacity" I
>> don't SEE any frequency above 20 kHz, but I must admit I
>> did
>> not totally analyze this data I just looked at it in the
>> graphics of Audacity. But I still wonder if any of these
>> tracks actually contains frequencies abov 20 kHz.
>
> There are a number of reasons why there is a lack of
> energy at these very high frequencies. Microphones
> commonly used to make the recordings often do not get
> much above 15 KHz such as the SM58.

You're being generous. The response curve of the SM57/58 and many mics like
it is on a fairly steep downward slope starting as low as 8-9 KHz.

> The human voice
> certainly is frequency limited and most musical
> instruments have little harmonic content above 20 KHz.

This is true in many cases, but not so true in other cases. James Boyk
explains the exceptions quite eloquently and with a lot of real world
evidence in:

http://www.its.caltech.edu/~boyk/spectra/spectra.htm

> You might want to look at recordings that feature the
> percussion section of the orchestra since here you will
> find instruments like cymbals that will be very rich in
> harmonic content.

Cymbals generally have their peak output in the 7-9 Khz range and roll off
steeply above that.

One other strong factor is the fact that high frequencies encounter a lot of
loss while being transmitted through the air.

Reference: http://www.sengpielaudio.com/calculator-air.htm

Example: At 10 KHz, standard room temperature and 50% RH, the attenuation
due to air is 16 dB per 100 meters.

Another example: At 20 KHz, 25 degrees C, 50% RH, the attenuation due to
air is 47 dB per 100 meters.

Finally, at 40 KHz, 30 degrees C and 50% RH, the attenuation due to air is
134 dB per 100 meters.

[Audio Empire]

On Wed, 20 Apr 2011 07:13:16 -0700, Arny Krueger wrote
(in article >):

> "Edmund" > wrote in message
>
>> Hi Guys,
>>
>> Since I now finally have a HD player I like to buy HD
>> material. There is a possibility to buy HD tracks on
>> line. However when I open such a file with "Audacity" I
>> don't SEE any frequency above 20 kHz, but I must admit I
>> did not totally analyze this data I just looked at it in the
>> graphics of Audacity. But I still wonder if any of these
>> tracks actually contains frequencies above 20 kHz.
>> What do you guys make of this?
>
> Many so-called hi definition recordings are actually 24/96 or 24/192
> transcriptions of analog tapes and 16/44 or 16/48 masters. Analog tapes were
> ususally made at 15 ips which pretty well eliminates response above 25-30
> KHz.

Actually, it's difficult to maintain even a pro 15 ips analog tape recorder
to much above 15 kHz. Self erasure, poor head contact at ultra-short
wavelengths all make analog tape "iffy" at much above 15 khz. Back in analog
days, most studios only maintained their tape decks to 15Khz. More than that
took too long and wasn't practical. Before I recorded the SF Symphony back in
the 1970's I would carefully align both Otari MX5050s for head azimuth, bias,
frequency response, and Dolby 'A' level AFTER I set up the equipment (the
tape recorder was not moved after that). I never tried to get response beyond
15 Khz, but I scrupulously maintained the recorders to that level.
>
>> Any of you have a source for HD which has music
>> information above 20kHz?

Not really. Let's say that the recording was made at 24 or 32- bit and 192
KHz (or perhaps DSD). The recording equipment might have that kind of
bandwidth, but I'll guarantee that the microphones used don't. Most
condenser mikes fall-off like a rock above the resonant frequency of their
diaphragms - and that is usually 16 -18 Khz. Not much there above those
frequencies. Doesn't matter, though. You likely wouldn't be able to hear it
anyway.

> As Jwvm correctly points out, nature abhors the creating of true hi def
> recordings. His list of reasons is good and relevant.
>
>> Let me make clear that I don't want to start whether or
>> not higher frequencies are audible, only that HD music
>> should have recorded higher frequencies in the first
>> place.

Why would it? A chain is only as strong as its weakest length. In the case of
recording, as elsewhere in audio, the weakest length is always the
transducers - speakers, phono cartridges, microphones. In this case it's
microphones.
>
> I agree that it is very nice when so-called hi def tracks are actually hi
> def! ;-)

The hi-def doesn't refer to recordings filled with extraneous and inaudible
ultra-high-frequency information, it refers to the fact that the bandwidth of
the medium is wide enough that only gentle slope filters, located high above
the highest audible frequency, need to be employed on either end of the the
chain (recording and playback) to satisfy Nyquist. Many insist that this
sounds better. Certainly, recording information that only small dogs can hear
is of no use to most humans in and of itself. The advantage (if any) is in
the process of recording and playing back with a very high sampling rate, not
the information that such a sampling rate is capable of quantizing. Hint, if
any part of high-resolution recording is beneficial, its the word length (24
or 32-bits) not the sampling rate.