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From: ken@argus.UUCP (Kenneth Ng)
Newsgroups: sci.electronics
Subject: Re: 3800 Hz notch filter [will] be used on CD masters
Message-ID: <922@argus.UUCP>
Date: Sat, 27-Jun-87 02:42:25 EDT
Article-I.D.: argus.922
Posted: Sat Jun 27 02:42:25 1987
Date-Received: Sun, 28-Jun-87 04:50:11 EDT
References: <598@neoucom.UUCP> <67@sdeggo.UUCP> <1597@ihuxi.ATT.COM>
Organization: NJ Instit. of Tech: TEIES Project
Lines: 27
Keywords: with possible icky results!

In article <1597@ihuxi.ATT.COM>, store2@ihuxi.ATT.COM (Kit Kimes) writes:
> In article <67@sdeggo.UUCP>, dave@sdeggo.UUCP (David L. Smith) writes:
> > Instead of messing about with the audio signal, why not just reach in with
> > a soldering iron and clippers and tweak the chip out of the circuit, or
> > make it think that it always has some noise there with a little 3800 HZ
> > oscillator tied to its input.  How much do you want to bet that 
> > Radio-Electronics has an article "for experimental and educational purposes"
> > on how to do it within a month after they come out?
> Sorry, but the protection circuit will be buried deep in one of the LSI's.
> There will be no way to remove it and even if you could, the notch will
> still be there on the source CD.

Hm. after thinking this over, there is a good chance that the device will
be by-passable.  The CBS copycode scheme is only for DAT machines sold
in the United States.  Manufacturers will probably make the copycode
circuit either a plug in module or switchable by soldering a pin high
or low.  Either way, there may be an easy way to remove it!

... This signature was put in in a way to bypass the 
... bogus artificial line limit on the .signature file.
... Also, by its length it adds fodder to help avoid having
... my followups being bounced due to the restriction on
... followup articles.

Kenneth Ng: Post office: NJIT - CCCC, Newark New Jersey  07102
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