Subject: Re: Frequency response was Re: [linux-audio-user] Audiophile CD's
From: Len Moskowitz (vze24hrw_AT_verizon.net)
Date: Sun Jan 27 2002 - 08:07:31 EET
SACDs use a variable width pit to prohibit copying, so standard DVD drives
can't read them.
----- Original Message -----
From: "Jason" <hormonex_AT_yankthechain.com>
To: <linux-audio-user_AT_music.columbia.edu>
Sent: Sunday, January 27, 2002 12:29 AM
Subject: Frequency response was Re: [linux-audio-user] Audiophile CD's
>
> > So I have number of questions:
> > 1) Can regular CD/DVD drives on a PC read them? (If the answer here is
no
> > then the rest is irrelevant).
> DVDROM drives SHOULD be able to read SuperAudioCDs. I say should because I
> kind of doubt that the ones that exist in the real world actually do.
> SACD's if memory serves are 20bit 88.2 kHz. Which is inferior to
> DVDAudio's 24bit96k, so having a DVD laser read them should just be a
> software issue. I think.
>
> > 2) If so, then is there any Linux software to read and play them?
> no clue. it shouldn't be too hard though, I imagine.
> > 3) What about writing? (Surprising as it may sound, the regular CD
format
> > is actually not quite adequate for fully representing the sound on 78's,
> > I've even seen signal [and I really do mean SIGNAL not the spectrum of a
> > click] going up to 29kHz on an _acoustic_ disk [probably a resonance in
> > the horn]).
>
> The human ear can hear fundamentals roughly between 20Hz and 20kHz. It is
> this poorly understood fact that led to CD's sampling at 44.1kHz.
> According to the nyquist theorem in order to accurately represent a simple
> signal
> digitally, you have to sample it at twice it's own frequency, the result
> of sampling at less than that frequency is a phenomenon known as Aliasing,
> in which the samples actually give tehm impression of a mathematically
> related lower frequency. It actually sounds kind of cool as an effect.
>
> So anyway, A/D converters put these brick wall filters in line to
> eliminate the frquencies above 22.05kHz. Since they have to be cheap in
> most cases, they start doing that cuttoff a lot sooner. hence why sound
> blaster and similar sound cards aren't really suitable for quality
> recordings. cheap card = cheap converters = cheap filters = sound
> attenuation above 15 kHz.
>
> Any way, It's not really fair to compare CD's to vinyls because vinyl
> doesn't have a flat frequncy response; it's an intentional distortion in
> order to allow for higher dynamic range. In fact, a lot of the alleged
> "warmth" of vinyl doesn't come from the vinyl at all, but rather the built
> in compensation in the phono preamps. That having been said, vinyl is
> allegedly supposed to be capable of accurate reproduction up to 25kHz,
> although I don't have the kind of dog ears necessary to be able to comment
> intelligently on that. However, I defy anyone short of geoff emerick or
> carl beatty to point me to a sound system that isn't accurately
> reproducing frequencies above 18k. It's really an issue that too much is
> made of, IMHO, because most people can't hear it, and of the ones who can,
> it's such a small portion of the available information, that it's
> practically irrelevant.
>
> What I do know, is that it is possible to hear into a much higher spectrum
> than 20k when it comes to harmonics, and this is the one argument That I
> acutally feel is valid when it comes to the dismissal of 44.1 as adequate.
> Most people who can still hear 20k can distinguish between a 20k sine wave
> and a 20k square wave. which means that they are at least hearing a few of
> those overtones that you wouldn't be able to hear as a fundamental.
> however, I do think that a bit too much has been made of the issue,
> because as everyone knows, there are only two octaves between 20k and 80
> k, so there isn't MUCH useful information there, so while 96k recordings
> do sound nice, I really personally don't feel that it's nice enough to go
> replacing my CD collection once DVD audio comes down the pike in a big
> way. Good mixes and good converters mean much more than higher sampling
> rates.
>
> In other words, I wouldn't worry about buring SACD's, and I'd spend my
> time and money on some really good EQ's, learning the exact implementation
> of the RIAA reproduce curve in whatever phone preamp you're using,
> buying fantastic apogee A/D converters and making really good standard
> CD's. I think you'll find that reduced noise, the more even reproduction,
> and the flatter response will be much more satisfying sonically that
> simply upping the sampling rate ante.
>
> somebody take away my soapbox, please...
>
> ~jason
>
>
> --
> YankTheChain.com - You can pretend we're not here. That's what I do.
>
> ,
>
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