From: bill@bilver.uucp (Bill Vermillion)
Subject: Re: CD Sound under attack again. Was: Re: Preamp and Amp
Organization: W. J. Vermillion - Winter Park, FL
Date: Mon, 25 Jan 1993 16:00:31 GMT

In article <5494@calmasd.Prime.COM> jpb@calmasd.Prime.COM (Jan Bielawski) writes:
>In article <1993Jan20.014644.14794@midway.uchicago.edu> cal@gsbux1.uchicago.edu (Cal Lott) writes:

>	Which reminds me...  An analog tape recorder cannot reliably record 
>more of the frequency spread than about 8 1/2 octaves.  Beyond that range
>the frequency response is probably too low to be called "high fidelity."
>If the tape moves fast one can record high frequencies very well but
>not the low ones as the corresponding magnetic flux with respect to any 
>tape segment changes too slow to magnetize that segment strongly enough.
>If the tape is moving slow then the highs disappear.  No matter what, the
>recordable frequency range is fixed although it can be adjusted up or
>down by choosing the tape speed.

Jan - from all I have ever seen the response is 10 octaves.   The
design of the head will give a peak output at any given frequency for a
given tape speed.   The response falls 6db/octave on either side.

With some 'diddling' and very wide tape heads that has been stretched a
bit in some machines like the ATR100s.     The 20Hz-20kHz is attainable
in a pro-machine at 15ips, but going to 30ips used to mean you would
lose most below about 40-50Hz.    

If you make the head pole pieces wider you can extend the low frequency
response at lower speed, but they start getting too big.  

When testing an ATR102 in our studio during the installation, John
Stevens (who made a very interesting multi-track) happened to be there.
I made some measurements and he came over with a micrometer, measured
the head and said "they must be doing something electronically".

Eight and one-half octaves would be more typical of a mid-range
cassette system than a pro reel to reel, but the 10 octave limit is
pretty much there, even in video.

>	My question is: why aren't CD critics bothered by this?  To me
>it's a serious problem that seems to indicate that the only analog way
>to record is direct to disk.

Absolutely true.   There are many who will agree with that, and I am
one of them.    Analog direct-to-disk has a wider frequency range than
analog tape or digital.  But whether the upper limit of the latter is a
problem is not something to start talking about again (and again and
again and .... as has been done on the net for the last xx years).

An LP can have frequencies in the single digit CPS range cut on it,
whereas analog tape will lose the bottom couple of octaves.

And the S/N on a lacquer with properly maintained equipment is in the
80 db range.   It's a revelation to listen to a lacquer on a good
system.     There is no intrusion into the sound.   The only noise you
hear is that from the original master tapes and if it's not a top of
the line turntable a bit of rumble.   We had a turntable built into our
recording console that went directly to a PS-Audio phono preamp, and
then directly to the monitor system.   This way we could A/B the
lacquers against the master tapes on the same system the masters were
cut on.

Now as direct-to-disk recording go, there have been many.   And in the
late 70's and early 80's the seemed to spring up everywhere.

And a lot of them really weren't worth it.   I have heard many (and
have many) that suffer greatly from problems in the signal well before
it got to the cutter heads.   They were made for one reason - to be
able to cash in on the high $ the direct-to-disk market commanded.
$15 to $20 per disk in the late 70's (and people thought CD's were
higher priced).

The ones that were done right however are really extremely pleasing to[
listen to - and two of my favorites are the Missing Link and Pressure
Cooker from Sheffield.  The CDs made from the analog tapes of the same
sessions are pretty poor in comparison.   The Arthur Fiedler Boston
Pops on Crystal Clear is also quite nice.   Too many of the other
Crystal Clear recordings, including their 12" 45rpm direc-to-disk
suffer in the audio chain leading up to the mastering.

One really interesting d-d is "A Cut Above" by Dave Brubeck on the
"Direct-to-Disk" Label (I think I have that right).

The first sessions (which I think are side 3 of 4 sides) were cut in
Nashville on an MCI console.   The remaining 3 sides were cut on the
same console that was modified with "Trans-Amps" as mike-preamp and
transformer replacements.   You'd swear they moved to a whole new
studio.  The Trans-Amps were the design of Paul Buff, who did one of
the earliest automation systems.   (Paul, and John Stevens mentioned
above) could easily have been the models for Back to the Future - and I
think either of them would be flattered by being called a "Mad
Scientist" - I consider myself lucky to have met both of them.

BTW - "LaserLight" CD have released several of the Crystal Clear direct
to disk recordings.    There are not technical notes, but one of them
implied a digital recording was made at the same time, and it was not a
full 16-bit system.  They are good for the performances, but don't compare
to the orignal DDs.

I don't miss analog tape problems one bit.  But I am also sorry to say
I have never gotten to work a session with Dolby SR - and do an A/B.

-- 
Bill Vermillion - bill@bilver.oau.org  bill@bilver.uucp
                - ..!{peora|tous|tarpit}!bilver!bill
Newsgroups: rec.audio