303 clone filter and VCO not reproducable

[Fraser, Colin J]

> -----Original Message-----
> From: Benjamin Woenig [mailto:budweiser at ozemail.com.au]
> Sent: 03 November 1998 12:57
> To: Heiko van der Linden; Quinton_Fulsom at Dell.com
> Cc: Colin.Fraser at scottishpower.plc.uk; synth-diy at mailhost.bpa.nl
> Subject: Re: 303 clone filter and VCO not reproducable
> 
> >I'm sorry but I cloned it this weekend and got a great 
> working vco and vcf.
> I
> >even made a mod to the filter so i can work up the resonance 
> all the way to
> >oscillation.
> >A tip for the cloners watch q27 you're sure to blow it up afew times
> >

I tried the extra resonance but didn't like it - I prefer the original
'straining like hell to oscillate but not quite getting there' sound of the
original 303.

> Did you build it following the circuit from the service manual?
> What components did you use if you changed any that are no
> longer in production?

I used substitute transistors (can't remember the number - will check),
closely matched for the pairs. I used a ca3046 heated expo-convertor instead
of the tempco transistor.
I used an original BA662 for the vca, and I also used the correct values for
the resistors at the top of the diff amp on the filter (22k not 2k2) - I
opened my original 303 up to check this when the filter wouldn't give a
decent output level.

In tests, 9 out of 10 owners said their cats couldn't tell the difference
(and cats have sensitive hearing). 1 owner said their cat prefered the
clone.

Another thing to note about a cloned 303 is that with the original 303, the
cv will not go below one volt - this is the lowest note the sequencer will
output. With a clone cv inputs toward zero volts will give some very
impressive sub bass notes...

Colin f