[sdiy] help finding roland filter schematics?

[Florian Anwander]

Hello Louis

Thank you for the hint. This seems to be wrong indeed. The 
servicemanual, where it is taken from says clearly "SH3" on its 
frontpage - I always overlooked that and took for an SH3A manual.

If this diode ladder filter is an SH3, all the rumours on patent 
infringements in the SH3 (which shall have caused the change to SH3A) 
would be false. Now: why did roland change the filter design?

Florian

> What I find interesting in the link below is that it lists the SH-3A 
> filter as
> a diode ladder (and even includes a schematic for that), when the SH-3A 
> actually
> has a transistor ladder.  It's clearly a traditional Moog transistor 
> ladder in
> the Service Notes, which I have verified against the actual SH-3A I have 
> here.
> 
> And the Service Notes list the transistor ladder in all revisions, so 
> Roland aren't
> hiding it in any way.  Not sure where the diode-ladder versions comes 
> from, but
> I'm sure it's not the SH-3A.