31 Aug
2014
31 Aug
'14
10:26 p.m.
On Sun, Aug 31, 2014 at 09:00:08PM +0100, gordonjcp(a)gjcp.net wrote:
Correct. Even the "18dB/octave" Roland
TB303 ladder filter has four stages.
Why isn't it 24dB/octave? Because they're more honest about the real-world
performance than Moog :-D
Or they may be some IP related issues.
Once you go hanging weirdass source and load
impedances off your ladder the
response can vary wildly. Tim Stinchcombe has an incredible analysis which
shows all sorts of odd bumps and peaks in what you'd typically expect to be
flat passband.
Yes. In a first approximation the filter isn't to difficult - each stage
is in fact nicely isolated from the following once (since emitter current
will determine collector current, and collector voltage won't affect that
very much since the bases are almost grounded for AC.
Fons - ever considered turning your analytical skill
to the MS20 and Steiner
Synthacon diode-chain Sallen-Key filter?
If you can provide a schematic I may be tempted...
Ciao,
--
FA
A world of exhaustive, reliable metadata would be an utopia.
It's also a pipe-dream, founded on self-delusion, nerd hubris
and hysterically inflated market opportunities. (Cory Doctorow)