[geeks] Audio Recording

[gsm at mendelson.com]

On Mon, Jan 24, 2011 at 11:28:19AM -0800, Sheldon T. Hall wrote:
>I have a large box of old analog tape recordings I'd like to transfer to a
>digital medium.  I have appropriate tape players, but I could use some
>advice on the digital end.
>
>In particular, I'd like some opinions (and other braindumps) on the
>hardware/OS/application end of things.  I'd like to produce either
>non-compressed files (WAV or similar) or very-high-quality compressed ones
>(MP3 or equivalent.)  Many of the tapes are amateur recordings of live
>performances, so additional quality degradation would be undesirable.  All
>the tapes are pretty fragile, so I'd like to minimize the number of
>head-passes required.

The problem is that PC sound cards stink. They are built for playing sound to
small speakers, chatting with $1 condenser microphones and recording old
tapes to low bitrate MP3s.

What you need to do is to identify which PC you have is the quietest in terms
of electrical noise. You also have to get a good sound card with high 
quality line in ports. A good music store (or on-line vendor) will have
them. 

Another possibility would be a USB sound coverter also designed for music
capture. Again a good music store would be the place to get them. 

As for software, you can use audacity. It is available for windows and Linux.

You record the tapes to uncompressed audio files (I believe audacity uses it's 
own format). Once you have those files you can perform post processing on them
to split tracks, remove noise, etc if you need to. Once that is done you can
compress them as you see fit.

I think the only compression available for general use is MP3. Most portable
devices only decode MP3 files, although there are plenty that decode the 
MP4 audio compression, also known as AAC. 

The good news is that if you keep a backup of your audacity files, years
from now when your compression needs change, you can recompress the files.

You will need plenty of disk space and lots of backups. 44.1kHz samples record 
at 10 megabytes a minute. 48k slightly more. DO NOT expect to use a USB 
device to store your data while recording. 


To minimize your playback problems, especially since you have such old tapes,
you will need to clean your heads often and demagnatize them regularly.
Old tapes often stick, so it is best to run them through to the end and rewind
them before you do the transfer. Usually you can do that at high speed, but 
really bad tapes may have to be run through at low speed first.

Geoff.

-- 
Geoffrey S. Mendelson N3OWJ/4X1GM
Those who cannot remember the past are condemned to misquote it.