Couldn't we just use a standard LPF for this

On Dec 2, 2008, at 11:46 AM, James Husted wrote:

> The part of this circuit that does the conversion seems pretty
> straight ahead and looks simple enough to make as a stan-alone module.
> If one was needing to make sines and had a triangle VCO already (that
> made a decent Triangle wave) then a converter module would work fine -
> a bit esoteric for mass production though.
> -James
>
> PS - sorry to all for starting this thread with my Z3000 post. I had
> my questions answered a long time ago.
>
> On Dec 2, 2008, at 10:38 AM, laryn91 wrote:
>
> > Sorry, I missed the "will" part :-p
> >
> > I had this link to the Aries VCO in one of the posts on this
> > (endless) thread. This is an
> > excellent tri-to-sine converter (I can't hear any additional
> > overtones). Better than the more
> > common 3080 converter and significantly better than your diode
> > converter. Aries claimed
> > to produce <1% THD.
> >
> > http://www.leinermedia.net/aries/AriesSchematics/AR-317s.gif
> >
> > I'm not sure why you found adding a slightly filtered triangle
> > sounding wave useful when
> > there's already a triangle wave output. My suggestion is if your
> > customers are not
> > interested in a clean Sine output, use the panel real estate for
> > something more useful.
> >
> > --- In Doepfer_a100@yahoogroups.com , <yahoo@...> wrote:
> > >
> > > You find my answers written inline.
> > >
> > > Best wishes
> > > Dieter Doepfer
> > >
> > > > -----Ursprüngliche Nachricht-----
> > > > Von: Doepfer_a100@yahoogroups.com
> > > > [mailto: Doepfer_a100@yahoogroups.com ]Im Auftrag von laryn91
> > > > Gesendet: Dienstag, 2. Dezember 2008 17:20
> > > > An: Doepfer_a100@yahoogroups.com
> > > > Betreff: 1 Re: Sine wave discussion
> > > >
> > > >
> > > > > And we will point out in the module information and user's
> > guide of
> > > A-110
> > > > > and A-111 that the sine outputs should be called more
> precisely
> > > "sine-like".
> > > >
> > > > Dieter,
> > > >
> > > > It's probably just me, but where do you point that out for the
> > A-111
> > >
> > > I wrote that "we will", not that "we did". That's the future tense
> > from what
> > > I learned in scool - but I'm not a native speaker.
> > >
> > > > >If you want a perfect sine you need a VCO with a sine core.
> > > >
> > > > Instead of an impossible "perfect sine", how about just a sine
> > with no
> > > *audible* overtones
> > > > (<1% THD) like Arp, Moog, Aries, Polyfusion, EML,etc. used to
> > make That
> > > would now
> > > > make the A-111 useful for additive synthesis and FM.
> > > >
> > > > All you need to do is copy their simple but superior
> > > > triangle-to-sine converter design. ;-)
> > >
> > > Though I can't believe that they really reach <1% THD (but indeed
> > I never
> > > measured it): do you (or anybody else in the group) know the
> > circuitry of
> > > these converters. Are they made with diodes, OTAs or the JFET
> > circuit (these
> > > are the three triangle-to-sine converter principles I know). I
> > don't have
> > > the schematics of these VCOs.
> > >
> > > We would have offered a VCO with a more perfect sine in the past.
> > But it
> > > took more than 12 years (the A-111 is available since spring 1996)
> > until
> > > someone complained about the poor sine. I'll see what we can do.
> > Maybe we
> > > offer a small tri-to-sine converter board for the A-111-1 that can
> > be used
> > > instead of the simple diode converter.
> > >
> > > There was a similar discussion about 2 years ago (~ September
> > 2006) and Tim
> > > Stinchcombe suggested an improved sine wave converter based on the
> > JFET
> > > principle. We have built a prototype of this converter in 2006 but
> > the
> > > discussion fell asleep very soon and it seemed that nobody was
> > interested
> > > anymore. We could dig this design and offer it as an addendum to
> > the A-111-1
> > > or equip all new A-111-1 with this board. The additional charges
> > would be in
> > > the 15 Euro range (about 10 electronical parts mounted on a small
> > board).
> > >
> > > Best wishes
> > > Dieter Doepfer
> > >
> >
> >
> >
>
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>
>
>



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