[sdiy] Re:freq shift allp filter ?

[jhaible]

> Thanks all for the help.
> I will try to build JHs Dome filter. I hope I can manage calculations...
BTW, anyone built it? At
> least to have the values calculated correctly, I'm not a maths one...

If you can do simple multiplication / division, that will be fine. (;->)
More seriously: You must measure capacitor values and resistor values
accurately - otherwise all the effort is in vain.


> Anyhow, it looks like not any quadrature oscillator will work well, but
JHs looks too complicate for
> me

Wait until you see the Moog / Bode oscillator ... *that* one is tricky.

The only thing about my FS-1 that is a bit complicated is the combined
triangle/sine shaper and multiplier. It's an "economic" design (why
linearize a gilbert cell if you want soft clipping for sine shaping
anyway?),
but this makes it a bit more complicated to understand. Much easier
to build than a Moog / Bode, though.

The best solution would be a digital implementation (counter, sin/cos
lookup table, high resolution DAC). Maybe you can replace the two
multipliers
with multiplying DACs? (But I don't know if there are 12 or even 16bit
multiplying DACs available.)

JH.