jbensh wrote:
> Thanks for another information packed response. I am still digesting
> it all, but I have a couple of simple questions.
>
> 1) are minidisc recorders prone to wear in the way that tape units
> wear? As its laser technology I'm pretty sure that this is not the
> case, but I am considering trying the technology by buying a
> secondhand unit so I would want to know if this is a bad idea.
> Obviously everything used wears in some way, but I am more concerned
> with invisible wear thats not obvious.
The disk is actually contacted on the back side, but not like regular
tape. The magnetic field that's the other part of Magneto-Optical is
supplied that way, but does not have to be finely detailed as the laser
provides that, so contact pressure is very light. The record surface is
not contacted at all, except for light from the laser. I've never heard
of a magnetic head wearing out, or any part of the drive mechanism.
Occasionally a laser will die, but not very often.
MD is a type of Magneto-Optical disk. Just like the archival opticals
used on computers. Though the info that's read is polarization angle,
not reflectance.
The rating of a million rewrites for a disk is based primarily on a
estimate of how long it would take for enough wear to accumulate from
the back magnet to effect the front surface. The time rating, btw is in
excess of 50 years for a stored disk. Those disks will hold the
information for long after we have the stuff to read them, I expect.
The parts that are most vulnerable on walkman MD's are the tiny switches
under the buttons. That's almost always the first to go. Most used
buttons are first. For me that was pause. My oldest MD has had the
switches replaced, they were in groups on small circuit boards. I just
got the parts and did it myself. It was pretty cheap except for the ones
right beside the LCD, which are part of it's assembly.
It's not uncommon for MD's to be dropped and sustain only cosmetic
damage. I've dropped a MZ-R30 while it was recording 4' onto pavement.
When picked up it was still recording. And that recording did not even
skip. The case did sustain a small dent on a corner and some scratches.
I don't recommend being rough to a MD, but it happens no matter how
careful you are. I record mostly at night, and hooked the mic cord on
something pulling the MD out of my hands.
> 2) can minidisc recordings easily be downloaded to PC and can they
> uncompressed for computer analyses? I'm a bit confused by this, and
> would value your comments as to whether there are shortcomings in
> this are.
Minidisc recordings are mostly played by the recorder and recorded by
the PC software. It's 1X speed, just like tape. With walkman MD you only
have analog outputs, so have to do it that way unless you buy more
equipment to do it digitally. The Portadisc has digital outputs, and I
actually use it's optical digital output via a Roland UA-30 usb I/O into
my G4 mac. Still 1X, of course. I don't use the Portadisc's built in usb
due to problems monitoring, the usb insists on switching both input and
output to it. Which means connecting and disconnecting as you switch
back and forth between input and checking the recording in the computer.
By using the Roland I avoid that.
There is a faster system, but it depends on finding one of the obsolete
MD data drives and some special software that includes decoding of the
ATRAC. There is at least one member of the group who has that setup.
The organization of the data on a minidisc was copied from the audio CD
format, with a few changes. It's not computer files. So it's really not
a transfer of files but a analog or digital audio stream. The digital
stream is the output of the ATRAC decoder chip, the analog is put
through the recorder's D/A as well before being output. The fast system
I mentioned above does make files by reading the data and assembling it
in a file format. That's the only way you would have any ATRAC
compressed data in the computer side. And to use that it would have to
be uncompressed by the software ATRAC decoder of that system.
The digital audio you get in is uncompressed, 44k 16bit, same as audio
CD, I record it to aiff files in my G4, windows folks usually use .wav.
Obviously if you are using a analog path you set the sample and bit rate
in the computer, for digital transfer it's set. Once it's in it's no
different than if it had come from cassette or DAT as far as how you
handle it or what you can do to it. All regular computer analyses works
fine. I routinely do a lot of sonograms on my stuff. That's one of the
reasons why I'm so confident about ATRAC, I've not just listened, but
looked. And I've mangled it with filters too.
> Did i forget to mention the flies? I guess I've made peace with the
> flies and I'm just thankful that they don't bite. Also, I think they
> are not as bad as they used to be before dung beetles were introduced
> to process cattle poo. I don't know when you were here last Walt,
> but you might get a pleasnat surprise
I was there in 1979, spent three months in the outback touring in a
rented camper. I already know that a awful lot of the dirt I drove is
now paved. Apparently Ayer's Rock is all tied up in rules I did not have
to deal with. I bet a lot of the roads I drove are still dirt, however.
My impression was that a lot of the fly problem was also all the
roadkill livestock. Where there was less of that, there were less flies.
Yes, I remember they did not bite, just very friendly. Actually the ones
I found most annoying was all the tiny insects that would go right
through screening when I set up next to water out there to photograph. I
did that a lot, set the camper in the right location to be a blind in
the morning. At the time I was primarily interested in parrots, and of
course I saw lots of those. Wish I had the audio equipment I have now
back then. I've lots of photos, but no audio except in memory.
Walt
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