[sdiy] Novation Bass Station 2
David G Dixon
dixon at mail.ubc.ca
Wed Jun 5 23:37:32 CEST 2013
That would get you one octave down, but not two, and the saw would have to
be perfectly centred about ground or the resulting triangle (and sine) would
look (and sound) like crap.
I would use a ripple counter off of the square wave to get the suboctaves,
and then use a separate triangle integrator driven by the suboctave square
wave through a VCA or OTA with the gain determined by the CV of the VCO.
It's complicated, but it would work well (I think).
> -----Original Message-----
> From: synth-diy-bounces at dropmix.xs4all.nl
> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Stewart Pye
> Sent: Wednesday, June 05, 2013 2:25 PM
> To: Synth-diy at synth-diy.org
> Subject: Re: [sdiy] Novation Bass Station 2
> You'll also have to shape the octave down saw into a triangle
> before going to the sine shaper. The way I had planned doing
> it was to invert every second saw cycle to get a tri wave of
> half the frequency of the original saw, as I was mainly
> interested in sine sub octave waveforms.
> Oops, I just re-read the original post and it doesn't mention
> saw waves, so instead of level shifting every second cycle
> invert every second cycle so you get a tri wave of half the
> frequency. An optional inverter circuit and an analog switch
> could be used for this.
> On 6/6/2013 7:05 AM, Stewart Pye wrote:
> > Hi Tom,
> > I drew a circuit on paper to do this a few years ago but can't find
> > it. It's basically like this....
> > Use a flip flop (probably driven by the saw reset pulse) to get a
> > square wave half the frequency of OSC 1, This is the 1 octave down
> > square output.
> > Use this square wave to level shift every second saw up. I
> think you
> > should be able to do this, and level shift back down to centre the
> > waveform around 0V, and reduce the gain to 0.5 all in one
> inverting op
> > amp stage. The saw wave will be one input, the 1/2 frequency square
> > another, and the DC level shift another.
> > Use standard sine shaping to get the sine. I'd use an
> LM13700 to get
> > both sine waveforms.
> > Use a standard comparator PWM circuit to get the pulse wave.
> > Repeat the process to get another octave down, however this
> time the
> > flip flop is driven from the output of the first flip flop.
> > If that doesn't make sense I can draw a schematic when I
> get home. I'm
> > just about to leave for work.
> > Regards,
> > Stew.
> > On 6/6/2013 6:11 AM, Tom Wiltshire wrote:
> >> Hi All,
> >> The Novation Bass Station 2 claims to have two analogue
> oscillators +
> >> a sub oscillator. The sub osc can be tuned one or two
> octaves below
> >> Osc 1. It offers Square, Sine, or narrow pulse.
> >> -engine-a-brief-overview
> >> Would anyone care to suggest ways that could be done?
> >> I can't figure it out, or rather I can only see convoluted
> ways which
> >> seem highly unlikely in a commercial instrument. No
> particular reason
> >> - I'm just curious about other people's synth designs.
> >> Thanks,
> >> Tom
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