sue you, sue me

Don Tillman don at
Wed Apr 3 20:25:06 CEST 1996

   Date: Tue, 2 Apr 1996 10:57:15 -0800
   From: haines at (Matt Haines)

   We've all heard how Roland was possibly sued over borrowing Moog ladder
   technology for their filters, but replacing transistors with diodes instead
   (or whatever it is, don't flame me for the details). 

No, we haven't all heard how Roland was possibly sued.  I find this
very difficult to believe.  Can anyone corroborate?  Any actual

I don't know the exact circuit for the Roland filter (I'm sure someone
here could describe it pretty accurately) but if it's implemented
anything like I think it is, it's nothing like the Moog.  It doesn't
work like the Moog, it doesn't have its poles in the same locations as
the Moog, it doesn't sound like the Moog, it wouldn't be covered under
a Moog patent.  I doubt it's even patentable.

(Not that that means anything.  The patent office regulary grants
patents on things that aren't patentable.  It's important to note that
a patent by itself doesn't mean much; you need clever lawyers to
actually do anything with it.  The fact that Moog and Roland are in
different countries with different patent laws further complicates

							What would have
   happened if Roland had put those diodes on a chip? Or for that matter, put
   a transistor ladder on a chip? How would Moog be able to prove it if the
   thing's burned into an IC? You can't just pop the hood of a synth and look.


Putting the circuit on a chip doesn't affect the infringement issue,
and the Moog Ladder circuit isn't really appropriate for a chip


Sure you can.

   Date: Wed, 03 Apr 1996 09:24:52 +0200
   From: Rick Jansen <rick at>

   That's odd, I believe this is exactly what Synthi did in it's VCS filter.
   The Moog patent has expired now by the way, so I guess that means anyone
   can build transistor ladder filters now?

Anyone can always build it, Moog had the exclusive license to use it
for business.

For details check out the us patent office home page.  (Whose URL I
don't remember, but you can use a search engine and find it really

  -- Don

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