[sdiy] Filters

[harry]

Dave and I are kind of in the same business
(guitar / electric tuba) where we have input waves
that have too few harmonics to start with.

I'm using a fuzz unit, then some direct waveshaping to get
quasi saw, triangle, etc... direct from guitar waves. Then I filter
with a 12dB  (spelled OK ???  ;^)    SVF.  I tried the
K0rg filters but they didn't sound right.

(yeah, yeah... to me, that is....)

I also built a copy of the VP-330 chorus filter, thanks to
Mike Irwin of s-diy.  It did NOT work for guitar at all... because
the acoustic feedback plus the high Q bandpass sections just
feed back like crazy.

Fortunatly, it worked beautiful with theremin synth.

Sorry Dave (and after that @sskick u gave me last night ;^) but
the filter might not work for you either (same feedback reason...)

This is a fixed formant filter, a thingy that most of us do ont have in
our synths.  There is a triple filter clone from MOTM, and a similar one
from Wiard (maybe no longer available?) which would be
similar. The VP-330 has seven bandpass filters. Set JUST right (not easy)
they give a kind of vocal sound. I got close... but not perfect yet.

If you use an LPF with no resonance, you are just cutting the highs.  With
resonance, you are probably accenting certain harmonics rather than just
losing harmonics.

If you like 6dB filters, try one of the tapped filters... resonance feedback at

24dB... but take the audio from the 6, 12, or 18dB points.  I'm doing this with

the CEM3320 filter in my ProOne and its really nice !!! Much brighter but with
good resonance.

H^) harry

Dave Krooshof wrote:

> About 12 dB vs 24 dB/oktave filters:
>
> I used to think I liked the 24 dB better as they are more resonant.
> But while making filters, I found out that I like the 6dB even more.
> My feeling is LPFs are not used to reduce overtones, but rather
> add a certain range of meaningfull overtones.*
> So I found myself pre distorting, then filtering.
> I found I liked a resonant filter, yet I do want the freqs above the
> filter to be present for brilliance. 24dB is just too "sinusidal" for me.
>
> Then again, it's the world of sinusses that is so apart from the
> phisical world that it sounds alien to us.
> 24dB might be the fascination of the other.
>
> How do you guys think about filtering? what is it, what does it do for you?
>
> Dave
>
> *I would like to see a brain scan of someone listening to a filtered synth.
> Would it show that the speech centre is lit up, as happens when listening
> to song?

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