[sdiy] Legal issues of cloning

[Florian Anwander]

Hello

 > Roland had to change their filter for instance.


Do we really know that roland had to do so? Or maybe Roland wasn't keen 
any longer to pay the patent fees?

The history of the filters is quite interesting:

The SH-1000 started in 1973 with the diode ladder filter.
In 1974 came the SH-3 still with the diode ladder filter,
then the SH-2000 with the moog filter and
then the SH-3a with the moog filter too.
Then SH-2000 then changed with serialnumber 578050 to the transistor 
-as-diode-ladder filter, which they used later in the System 100, the 
SH-5 and in the 303. I don't know it, but I assume this happened in 
1975. They did not change the SH-3a again, because it did not sell that 
well. Instead they came up with the SH-5

I doubt, that they decided to infringe the patent, after having produced 
already two synths with a non patente depending circuits.

I more assume, that they started the with the Moog filter, payed the 
patent fees to Moog. But than they decided, that the difference is not 
that big, that it would have been worth the fees.

Florian