[sdiy] Running a Moog Filter off a single power supply

[Michael Buchstaller]

Hello list Gurus,

i am working to finish my Monovoice SID based synth.
The MIDI interface, preset storage and glue logic between
CPU and SID is working, and i can get sounds out of it when
i send MIDI notes.

But the SID´s internal filter is not that good, so i want to add
an additional external 24 dB LPF and an hardware ADSR for
it. The ADSR is no problem, but when i look for filter circuits,
like Moog, ARP, EMS and others, they all demand dual
power supplies.

As i have had several inquiries from people who wanted to buy one,
i want to keep the power supply simple (it has now 2 outputs, +5V
and +9V, simple Xformer-->C-->78XX-->C type), and want to avoid
the need for a scondary output winding or a Xformer with a CT output,
which seem to become hard to get new.

So my question to the gurus out there: Can i change the Moog ladder
to work from +9V (+12V would be an option, because i can supply that
too) ?
Or any other good sounding LPF that i might use for this project ?

Please bear in mind that i might be able to sell some of these synths, so
i would prefer a schematic that is not patented (or whose patents have
expired) to avoid trouble.
If it is your own special filter, and you are willing to let me use it, i want to
give proper credits, and we can talk about some form of compensation.
(maybe some amount of money per unit sold, or a free Monovoice board
tor you)


-Michael Buchstaller