Succeeded! OB-8 has Multimode Filter now!

[J.D. McEachin]

On Thu, 15 Feb 1996, Haible_Juergen#Tel2743 wrote:

> (They know
> they have trouble with me, since I tried to buy a hundred TL074's
> for my Vocoder!)

One of the greatest things about the US is being able to call up Mouser, 
Newark, Digikey, or another electronics supplier at 4:59PM, order 100 
TL074's, pay maybe US$75 on credit card, and receive them the next 
morning, even if you live in a town w/ no electronics store besides Radio 
Slack.

> Believe me, I had trembling hands and a prayer on my lips, when I
> took the little rotary grinder to cut the tiny pcb traces!

Maybe drinking 10 beers with your friends beforehand wasn't a good idea.
;-}

> I couldn't do a cross-check with a real n-Voice, but at least it sounds
> as good as my SEM-filter clone. All the famous HP filter tricks work.
> Nice bass boost with low cutoff  and high resonance!

Now I wish I hadn't passed on an OB-8 w/ MIDI for $250 to Neil.

> Upper and Lower. It definetly works, but I don't get the Notch filter
> effect with Upper=HP, Lower=LP and otherwise identical settings.
> But then again, I have 4 VCO's per voice instead!

It sounds like the cutoff frequency is identical for both.  You would 
need to offset the cutoff CV, wouldn't you?

PLEASE post your mods, Juergen.  I may buy an OB8 yet.  I'm glad someone 
else is hacking their polysynths.

JDM