[ale] OT:Digitizing my old vinyl

[Ryan Curtin]

On Thu, Aug 20, 2009 at 04:58:23PM -0400, Sean McNealy wrote:
> Where a good recording might matter:  You can run equalizers and other
> filters, like trying to remove hiss or clicks, over your recording.  I
> never found this really useful in toying with it, the original
> recording sounded better with what I was trying.  Maybe someone here
> can point you to something better.
> 
> Where a good recording does not matter:  You're probably converting to
> MP3.  Your sound chip that came on the motherboard, while it's pretty
> bad, is more than enough to make a good MP3.  Anything more gets taken
> out to compress the file.

No, this is incorrect.  A properly encoded mp3 (228kbps+ is good enough
usually), even with top-of-the-line equipment, cannot be differentiated from
lossless effectively.  I should know, because I transcode vinyl as a hobby.
Now, because this is a contentious topic especially among audiophiles, let me
dig deeper.

MP3 encoding does indeed insert noise, and if you've seen input sonograms and
output sonograms then you know that MP3 will insert noise at up to around 50dB
below the actual signal.  The human ear certainly has greater dynamic range than
that; however, that is irrelevant in this case.  Consider that we have a signal
at 0dB gain... the human ear cannot pick out a second simultaneous signal below
-30dB (when that 0dB signal is there).  That number may not be exact but it's in
that range.  When we consider the complexity of music, it gets even harder to
hear any lower-level distortion and the MP3 standard is more than good enough.
Where MP3 suffers, though, is sound similar to impulses.  If you encode at some
low bitrate (I can pick these out in 192kbps), drums and cymbals sound a little
bit distorted.

The only other reason a lossless codec may appeal to you is if you regularly
re-encode your music in other formats multiple times... but I still have yet to
meet anyone who re-encodes multiple times.  I have not been able to notice any
inserted noise when going from mp3 to ogg.

> Just to make sure you know, your current turntable outputs the same
> analog data your computer's line-in jack reads.  It's just a matter of
> getting (or making) the correct wire.
> 
> As a note, your sound card and probably most USB turntables, record in
> stereo, so you're losing any quadraphonic data.

Another thing that should be mentioned is that your sound card likely does not
sample with the depth you want.  Bringing out the math again, the human ear can
hear approximately 120dB of dynamic range (I think I'm stretching that number a
little bit).  16 bit samples give you a max of 96dB, and plus noise, that is
insufficient.  24 bit samples are much better with 144dB of possible dynamic
range.  Sampling rate is also important.  I bought the "Amon Infrasonic" USB
recording device as well as a nice preamp so I can sample at 96kHz and 24 bits.

Processing after capture can be done not only with Audacity but with a program I
use called 'gnome wave cleaner' or 'gwc'.  I have not tried to use Audacity to
do processing (the program is too bulky for my tastes) but gwc is fairly simple
to use and works quite well.

-- 
Ryan Curtin       | "You got to stick with your principles."
ryan at igglybob.com |   - Harry Waters