BassStation Filter: What is it?

[Harry Bissell]

If this is the one I'm thinking of... the CPU sets a rough current
source charging a cap, and the counter tick is the reset pulse to discharge
the cap...

so this way the sawtooth is pure linear (no steps) and the frequency is
pure digital...  any errors show up as amplitude variation. Nice way to go.

I have no problem with digital oacillators either, except they are really hard
to modulate with CV's....  Its funny that it is the imperfections in real analog that
everyone likes....

For some things I prefer digital... like digital delay lines.  BTW I consider the
BBD a digital delay, albeit a Sh!tty one. The fact that it has an analog range of
oh... a couple volts in the Y axis does not cover up the sampled data nature of
the X axis....  so just saying analog does not mean good !

(if this don't draw some flames then the list is dead....;^)

H^) harry

Bjorn Julin wrote:

> Yeah, there it is,one thing that are missing
> are the DCO tickers, they are created in a
> wery odd MCU, from matshusita if i remember right.
>
> No wave tables just a counter tick to a integrator
> who charges in a odinary whay to create sawtoth.
>
> I remmber the "OLD and "LIVELY" discussion on diy list
> about why a DCO was a VCO, and the reverse,in my opinion
> there is absolutely nothing wrong whit DCO's,in my
> opinion i prefer them "if" high enough resoulution
> of the charge ticks are used. Besides DCO'dont soft
> sync. :-)
>
> Thanks for the link!
>
> Reg
> BJ
>
> >you are all in luck....
> >
> >http://www.asahi-net.or.jp/~WZ4K-TNK/syoyuu/bsk.html
> >
> >Rob wrote:
> >
> > > Well, I remember way back when, I looked into the unit and I didnt see
> >the
> > > telltale signs of a ladder filter ie neat rows of
> >transistors/capacitors.
> > > Unfortunately, I don't have one on hand to check out right now.. I am
> >sure
> > > once the rack unit I bought comes in, it will prlly only take me an hour
> > > with my scope to figure the thing out.
> > >
> > > Also, a state variable filter would definitely be easier to produce the
> >2
> > > pole/4 pole configuration that they used.
> > >
> > > As far as the VCO, I question whether it has a VCO at all. I get the
> >feeling
> > > that it has a DCO driven from lookup tables in the uP.. I dont remember
> >it
> > > ever going out of tune, so this would point to to a uP DCO.
> > >
> > > Nothing wrong with this, but you definitely don't get the warmth of
> >analog
> > > with the DCO.. Still sounds good, but just a bit too perfect.
> > >
> > > Thanks
> > >
> > > Rob
> > >
> > > ----- Original Message -----
> > > From: <metamatic at webtv.net>
> > > To: <synth-diy at node12b53.a2000.nl>
> > > Sent: Saturday, November 25, 2000 8:51 PM
> > > Subject: Re: BassStation Filter: What is it?
> > >
> > > > cyborg_0 at iquest.net wrote:
> > > >
> > > > >Anyone know what kind of filter is
> > > > >crammed in there? From what I
> > > > >remember, it was some sort of state
> > > > >variable filter, but I am not all that sure.
> > > >  >Perhaps someone has some schematics?
> > > >
> > > >  I have the keyboard version. The VCF has two modes, both lowpass. The
> >2
> > > > pole mode is meant to suggest a TB-303 filter, somewhat
> >unconvincingly,
> > > > IMO. The 4 pole mode, however, does a wonderful job of emulating a
> >Moog
> > > > VCF. I think it sounds quite a bit like my ancient Source, and along
> > > > with the bonus of factory MIDI, I don't have to worry about damaging a
> > > > rare membrane switch panel.
> > > >
> > > >  I'd love to see schematics as well, if only to see how the different
> > > > cutoff slopes are achieved.
> > > >
> > > > Richard Hess
> > > >
> > > > metamatic at webtv.net
> > > >
> > > >
> >
> >--
> >mark verbos
> >
> >"if you want something done right, build it yourself."
> >
> >verbos at simple-answer.com
> >www.simple-answer.com
> >
> >watch out for...
> >on my new label SIMPLE ANSWER "only a danger to myself"  and "Culture
> >Shock"
> >out now.
> >also...
> >coming soon "World of Illusion" Simple Answer 003 now distributed by
> >Integrale,
> >UK
> >I have moved to Berlin!
> >
> >
>
> _____________________________________________________________________________________
> Get more from the Web.  FREE MSN Explorer download : http://explorer.msn.com