Well, we're approaching a technically accurate description of things,
but we're not there yet. Please allow me to fill in some gaps.
DDS-2 and -3 are both rotory head recording schemes not unlike common
VCRs. That said what we need concern ourselves with is the linear speed
of the head movement cross the tape, not the running speed of the tape
past the head drum which is a secondary issue. The smaller the head gap
and higher the rotational speed of the head drum the more "tracks" that
the heads can put down on a given inch of tape. This then permits
recording a greater number of bits on that same amount of tape, which
we generally refer to as packing density...ie. the amount of data per
sq cm of magnetic material.
The linear tape speed employed in DDS-2 and -3 are pretty close I would
guess. Smaller head gaps in the higher capacity format being the key to
writing more tracks (more bits) onto each inch of tape.
Early digital audio at the studio production level added some other
issues. There was for a time non-rotory head multi-track audio
recorders which employed a head stack with a large number of head gaps,
each writing a bit such that the data was written to tape in a parallel
fashion. As I recall The SONY PCM3324 was such a deck although Otari
was a major promoter of the format as well. Tape interchange was a bit
issue with these at first. Often a tape recorded on one machine could
not be played back on another.
The early PCM decks to which someone refered were in fact Sony Betamax
inductrial VCRs with a special PCM encoding unit that converted
analogue audio to PCM data the coded it for recording as a vide signal.
These were widely used to master classical recording when digital audio
was in its infancy. To my ear they sounded harsh.
Some time later Alesis and a couple of other companies introduced
multi-track digital audio recorders based upon VCR transports. However
these did not code the audio signals into a video comaptible stream,
they wrote data to the rotory head recording mechanism in their own
format. These units were mostly 8 track I believe.
Michael Graves
On Sun, 3 Jun 2001 06:33:21 +0100 (BST), md-l-digest wrote:
>Date: 03 Jun 2001 00:56:03 -0400
>From: Stainless Steel Rat <[EMAIL PROTECTED]>
>Subject: Re: MD: DCC?
>
>* "Francisco J. Huerta" <[EMAIL PROTECTED]> on Sat, 02 Jun 2001
>| So, how about explaining why he is wrong? I mean, it's very easy to say "no,
>| nah, ni", but it is a bit more complex to say why. I know the reasons, but I
>| would definitely leave the explaining to an expert.
>
>Square waves taking more space. Just plain BS. The shape of a wave has no
>bearing whatsoever on how much "space" is required to store it.
>
>DDS-2 and DDS-3 (two of the DAT data standards) have nearly identically
>length tapes (120m vs. 125m), and have the same linear speed over the
>heads. DDS-3 has three times the storage capacity as DDS-2. Clearly,
>speed is not a contributing factor to data density.
>
>Doesn't require an expert to show that Jacob has a lot of completely bogus
>information.
>- --
>Rat <[EMAIL PROTECTED]> \ Do not use Happy Fun Ball on concrete.
>Minion of Nathan - Nathan says Hi! \
>PGP Key: at a key server near you! \
>
>------------------------------
>
>Date: Sun, 3 Jun 2001 06:36:17 +0100
>From: "PrinceGaz" <[EMAIL PROTECTED]>
>Subject: Re: MD: DCC?
>
>But it sounds good doesn't it. And on an oscilloscope, a 1v pk-to-pk
>square wave will indeed on average be using up more of the available
>space than the same pk-to-pk sine wave. Of course if we were to carry
>that analogy through to its logical conclusion, recording louder music
>ought to require a greater area of tape to record on also, which we all
>know it doesnt :o)
>
>But I bet I could convince 9 out of 10 peeps by the usual "baffle them
>with bullsh!t" approach :o)
>
>PrinceGaz. -- "An ye harm none, do what ye will"
-----------------------------------------------------------------
To stop getting this list send a message containing just the word
"unsubscribe" to [EMAIL PROTECTED]
