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Filter Suggestion

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  • mss_panzer
    So when might we be able to see a Polivoks VCF? Perhaps based on the A- 124 design, with a HP/LP mix potentiometer and a solo BP pot? Anybody have any
    Message 1 of 5 , Jun 2 1:27 PM
      So when might we be able to see a Polivoks VCF? Perhaps based on the A-
      124 design, with a HP/LP mix potentiometer and a solo BP pot?

      Anybody have any thoughts on this?
    • ilanode
      If DIY is an option: http://m.bareille.free.fr/modular1/vcf_polivoks/vcf_polivoks.htm Rgds, Ingo
      Message 2 of 5 , Jun 2 4:41 PM
        If DIY is an option:
        http://m.bareille.free.fr/modular1/vcf_polivoks/vcf_polivoks.htm
        Rgds, Ingo

        --- In Doepfer_a100@yahoogroups.com, "mss_panzer" <mss_panzer@...> wrote:
        >
        > So when might we be able to see a Polivoks VCF? Perhaps based on the A-
        > 124 design, with a HP/LP mix potentiometer and a solo BP pot?
        >
        > Anybody have any thoughts on this?
        >
      • hardware@doepfer.de
        We designed a Polivoks filter about one year ago but we stopped the project as Shawn Cleary of Analogue Haven informed us that such a filter is under
        Message 3 of 5 , Jun 4 12:27 AM
          We designed a Polivoks filter about one year ago but we stopped the project
          as Shawn Cleary of Analogue Haven informed us that such a filter is under
          development by the Polivoks inventor Vladimir Kuzmin. It should be available
          soon from Analogue Haven.

          Best wishes
          Dieter Doepfer


          > -----Ursprüngliche Nachricht-----
          > Von: Doepfer_a100@yahoogroups.com
          > [mailto:Doepfer_a100@yahoogroups.com]Im Auftrag von mss_panzer
          > Gesendet: Samstag, 2. Juni 2007 22:27
          > An: Doepfer_a100@yahoogroups.com
          > Betreff: [Doepfer_a100] Filter Suggestion
          >
          >
          > So when might we be able to see a Polivoks VCF? Perhaps based on the A-
          > 124 design, with a HP/LP mix potentiometer and a solo BP pot?
          >
          > Anybody have any thoughts on this?
        • Tim Stinchcombe
          There is nothing particularly special about the design, it is simply one of the standard state-variable configurations, albeit using the inherent integrator
          Message 4 of 5 , Jun 4 1:58 PM
            There is nothing particularly special about the design, it is simply
            one of the standard state-variable configurations, albeit using the
            inherent integrator action of a (compensated) op amp - it is to be
            found in at least one of the filter books that I have. The only
            real 'novelty' aspect in the Polivoks appears to be the use
            of 'programmable' op amps to provide a variable cut-off frequency. It
            should be relatively simple to add another op amp in order to make
            the high-pass output available, and the method of setting the current
            which 'programs' the op amps could possibly be improved, as the
            transistor-resistor set-up is dealing with some pretty small currents
            (nano-amps), and I dare say is very sensistive to differences in
            individual components, perhaps making initial set-up tricky (but this
            is pure conjecture, I've not tried actually breadboarding the circuit
            to find out).

            Tim

            --- In Doepfer_a100@yahoogroups.com, <hardware@...> wrote:
            >
            > We designed a Polivoks filter about one year ago but we stopped the
            project
            > as Shawn Cleary of Analogue Haven informed us that such a filter is
            under
            > development by the Polivoks inventor Vladimir Kuzmin. It should be
            available
            > soon from Analogue Haven.
            >
            > Best wishes
            > Dieter Doepfer
            >
            >
            > > -----Ursprüngliche Nachricht-----
            > > Von: Doepfer_a100@yahoogroups.com
            > > [mailto:Doepfer_a100@yahoogroups.com]Im Auftrag von mss_panzer
            > > Gesendet: Samstag, 2. Juni 2007 22:27
            > > An: Doepfer_a100@yahoogroups.com
            > > Betreff: [Doepfer_a100] Filter Suggestion
            > >
            > >
            > > So when might we be able to see a Polivoks VCF? Perhaps based on
            the A-
            > > 124 design, with a HP/LP mix potentiometer and a solo BP pot?
            > >
            > > Anybody have any thoughts on this?
            >
          • mss_panzer
            I appreciate everyone s suggestions thus far. Time to find my solder. ... simply ... It ... current ... currents ... this ... circuit ... the ... is ... be
            Message 5 of 5 , Jun 6 11:30 PM
              I appreciate everyone's suggestions thus far. Time to find my solder.

              --- In Doepfer_a100@yahoogroups.com, "Tim Stinchcombe" <timothy@...>
              wrote:
              >
              > There is nothing particularly special about the design, it is
              simply
              > one of the standard state-variable configurations, albeit using the
              > inherent integrator action of a (compensated) op amp - it is to be
              > found in at least one of the filter books that I have. The only
              > real 'novelty' aspect in the Polivoks appears to be the use
              > of 'programmable' op amps to provide a variable cut-off frequency.
              It
              > should be relatively simple to add another op amp in order to make
              > the high-pass output available, and the method of setting the
              current
              > which 'programs' the op amps could possibly be improved, as the
              > transistor-resistor set-up is dealing with some pretty small
              currents
              > (nano-amps), and I dare say is very sensistive to differences in
              > individual components, perhaps making initial set-up tricky (but
              this
              > is pure conjecture, I've not tried actually breadboarding the
              circuit
              > to find out).
              >
              > Tim
              >
              > --- In Doepfer_a100@yahoogroups.com, <hardware@> wrote:
              > >
              > > We designed a Polivoks filter about one year ago but we stopped
              the
              > project
              > > as Shawn Cleary of Analogue Haven informed us that such a filter
              is
              > under
              > > development by the Polivoks inventor Vladimir Kuzmin. It should
              be
              > available
              > > soon from Analogue Haven.
              > >
              > > Best wishes
              > > Dieter Doepfer
              > >
              > >
              > > > -----Ursprüngliche Nachricht-----
              > > > Von: Doepfer_a100@yahoogroups.com
              > > > [mailto:Doepfer_a100@yahoogroups.com]Im Auftrag von mss_panzer
              > > > Gesendet: Samstag, 2. Juni 2007 22:27
              > > > An: Doepfer_a100@yahoogroups.com
              > > > Betreff: [Doepfer_a100] Filter Suggestion
              > > >
              > > >
              > > > So when might we be able to see a Polivoks VCF? Perhaps based
              on
              > the A-
              > > > 124 design, with a HP/LP mix potentiometer and a solo BP pot?
              > > >
              > > > Anybody have any thoughts on this?
              > >
              >
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