[sdiy] Back, and Buchla 291 simulation

[harrybissell]

Hi JH...

I could confirm that my EFM VCF6 has a response like the lower trace...
I have mine built with LEDs so I thought they might be involved, my dip
is right where the LEDs go visible.  (this is a clone of the EMS diode
ladder)

I was unable to get any simulation to model this.  Can I see your model
for the Buchla (I'll copy it and try for myself)

Hmmm interesting

H^) harry

jhaible wrote:

> Hi,
>
> I'm back from holidays
> 2 weeks without a soldering iron
> But with a Korg Lambda and a book on music theory
> Good to shift the focus from technical stuff to music
> for a while
> Think I finally understood the tritone substitution (;->)
>
> Back to electronics:
>
> Before I left for holidays, I made some quick simulations
> of the Buchla 291 BPF.
>
> I found that the level of the resonant peak varies a lot with
> the center frequency. There is also a trimmer to adjust
> _how_ it varies, but it's not possible to get a even response.
> In the low range, peaks are always higher. It can be adjusted
> to fall monotonously towards high frequencies, or to create a "dip"
> in the mid frequency range.
>
> Can anybody confirm this?
> Was this intentional? (Like, creating less emphasis in a region
> where harmonics of the source material might have higher
> levels anyway?)
>
> It's just a quick and dirty simulation, so I may just have made
> a mistake. But I vaguely remember somebody mentioning
> the unique character of this filter. Maybe that's an explanation.
>
> Simulation scans attached to this mail.
>
> JH.
>
>  [Image]