[net.audio] Phase Linear model 1000 questions

mancuso@psuvax.UUCP (10/19/83)

     
     I recently acquired a Phase Linear model 1000 Dynamic Range Recovery
System from a friend of mine.  Does anyone out there know anything about this
animal??  I would really appreciate a copy of the manual for it, or 
any information on it (how it works, *proper* settings for the controls, 
what it's worth, etc.)  It also has a noise reduction section in it,
which works great for when I'm playing records, but 
what will it do when I rec/play a tape with Dolby?  Will the two
NR's get along OK, or should I just use one?  Which one?

                              Thanks in advance,

                                 :*: Pat Mancuso
                                 :*: Penn State University
                                 :*: {burdvax, allegra}!psuvax!mancuso

sdyer@bbncca.ARPA (Steve Dyer) (10/21/83)

The Phase Linear 1000 "Auto Correlator" noise reduction unit is a one-way
device much in the spirit (if not in execution) of the Burwen Dynamic
Noise Filter and the more recent National Semi DNR chips.  Any program
material will work with it, regardless of whether it's been previously
unprocessed, or if it's been thru the two-way Dolby noise reduction.

Here's a diagram of how both work:

input signal                   encoded signal                 output signal
--------------> [DOLBY ENCODE] ---------------> [DOLBY DECODE]------------>
+ original		       on tape + tape                 less tape hiss
  noise					 hiss                 All original noise


input signal                   output signal
--------------> [PHASE 1000]   --------------->
+ noise                        + less noise


These one-way noise reduction systems are more "powerful" than Dolby, because
they do not "care" about the source of the noise--Dolby only reduces noise
added in the duplication process.  It cannot remove noise in the original
signal.  On the other hand, the Phase has to "guess" as to what is noise
and what is original signal, and this is why it doesn't always do a perfect
job.  But, with careful calibration, it works very well.

/Steve Dyer
decvax!bbncca!sdyer

hlh@linus.UUCP (Henry L. Hall) (10/25/83)

Once quite a while ago I heard about another "noise quieting" system
put out by a company called SAE.  As I recall the name of the machine 
was called "Impulse Noise Quieting system".  According to the literature
it would sense and eliminate the transients caused by scratches and 
dust on an albums surface.  Having been out of stereo for the last 3-4
yrs. I am curious if anyone knows anything about this system (ie. is it
still in existence, does it work, etc.)

			Thanks in advance,

	Henry Hall

 {allegra, cbosgd, decvax, ihnp4} !linus!hlh