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Re: diy keyboard replacement (nach florian's buch)

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  • Stu Grimshaw
    ... hi james, that was actually the original plan, but the pure analog attempt has a few features that i find appealing: power comes from the modular, the
    Message 1 of 10 , Feb 3, 2008
      --- In Doepfer_a100@yahoogroups.com, James Husted
      <the_ersatz_planet@...> wrote:
      >
      > Stu-
      > I know this may be out of your price range - and may not fit your
      > design criteria - but for ease of assembly have you thought of the
      > Doepfer CTM64 or MKE combined with a MCV4 or A-190. The limitations
      > are no portamento and you will be defaulting to tempered scales but
      > you could have LOTS of switches/buttons plus the added modulation and
      > pitch bend inputs.
      >
      > -James
      >

      hi james,

      that was actually the original plan, but the pure analog attempt has a
      few features that i find appealing: power comes from the modular, the
      resistors will not be completely accurate, i save myself a midi-to-cv
      converter (although i have a couple) and it's all so hands-on when it
      comes to adding pitch bend and firing off a gate while holding a note
      etc. i save myself a ton of wiring too - all of which needs to be
      soldered!

      if it is as simple (though rudimentary) as i think it is, then the
      analog way is easier, as well as offering opportunities for more
      individual features/limitations/quirks. i love quirks :)

      relying totally on a single control voltage solution (so no release
      envelopes here unless we inclue a s+h) also allows me to use the a112
      sampler to record melodies and such - the necessary gates are still
      produced by cv>0v and therefore don't need to be recorded separately.
      my dream is to leave the electribe at home :)

      cheers,

      stu
    • James Husted
      I have the schematics for both the Analog and Digital Oberheim 2-voice keyboards if you want to look at them. The digital is pretty complicated but the analog
      Message 2 of 10 , Feb 3, 2008
        I have the schematics for both the Analog and Digital Oberheim 2-voice
        keyboards if you want to look at them. The digital is pretty
        complicated but the analog one is fairly easy to understand. They are
        on my .Mac public folder:

        http://homepage.mac.com/ersatzplanet/

        I understand the lure of analog controllers! Something really basic
        and primal being able to control things with just a battery and a
        resistive element - weather thats a pot, a switch with a resistor, a
        piece of tape recording tape stretched over a metal plate etc etc. All
        fun (and cheap to experiment with!)
        -James


        On Feb 3, 2008, at 12:43 PM, Stu Grimshaw wrote:

        > --- In Doepfer_a100@yahoogroups.com, James Husted
        > <the_ersatz_planet@...> wrote:
        >>
        >> Stu-
        >> I know this may be out of your price range - and may not fit your
        >> design criteria - but for ease of assembly have you thought of the
        >> Doepfer CTM64 or MKE combined with a MCV4 or A-190. The limitations
        >> are no portamento and you will be defaulting to tempered scales but
        >> you could have LOTS of switches/buttons plus the added modulation and
        >> pitch bend inputs.
        >>
        >> -James
        >>
        >
        > hi james,
        >
        > that was actually the original plan, but the pure analog attempt has a
        > few features that i find appealing: power comes from the modular, the
        > resistors will not be completely accurate, i save myself a midi-to-cv
        > converter (although i have a couple) and it's all so hands-on when it
        > comes to adding pitch bend and firing off a gate while holding a note
        > etc. i save myself a ton of wiring too - all of which needs to be
        > soldered!
        >
        > if it is as simple (though rudimentary) as i think it is, then the
        > analog way is easier, as well as offering opportunities for more
        > individual features/limitations/quirks. i love quirks :)
        >
        > relying totally on a single control voltage solution (so no release
        > envelopes here unless we inclue a s+h) also allows me to use the a112
        > sampler to record melodies and such - the necessary gates are still
        > produced by cv>0v and therefore don't need to be recorded separately.
        > my dream is to leave the electribe at home :)
        >
        > cheers,
        >
        > stu



        [Non-text portions of this message have been removed]
      • hardware@doepfer.de
        ... I can send you the scan of an article in the German electronic magazine FUNKSCHAU I wrote in the eighties. It describes an analog working CV/Gate keyboard
        Message 3 of 10 , Feb 4, 2008
          > hi group, especially florian,
          >
          > i'm thinking about building a simple keyboard replacement - different
          > arrangement of the keys but still the tempered scale. i think i know
          > how i want to do it, but i'd appreciate any advice that anybody may have.
          >
          > first question to florian (or anybody that has his book griffbereit):
          > on page 32 of your book "synthesizer" you have a simple diagram of a
          > control voltage generator, each resistance corresponding to one key on
          > the keyboard. what would you recommend as a suitable value for the
          > resistors? and should i be using 5v as shown in the previous diagram,
          > or 12v as stated in the text?
          >
          > secondly, i intend to produce the gate by simply putting the control
          > voltage through a comparator - everything above 0v opens the gate.
          > does anyone foresee any problems here?
          >
          > and any other problems i've overlooked?
          >
          > all comments much appreciated,
          >
          > stu

          I can send you the scan of an article in the German electronic magazine
          FUNKSCHAU I wrote in the eighties. It describes an analog working CV/Gate
          keyboard with a resistor chain. Simple send me an email directly to
          hardware(at)doepfer(dot)de.

          Best wishes
          Dieter Doepfer
        • hardware@doepfer.de
          ... By the way: the new A-100CGK (CV/Gate keyboard) will be availabe as an OEM version too (i.e. without keybed and case). Christian is about to finish the
          Message 4 of 10 , Feb 4, 2008
            > Stu-
            > I know this may be out of your price range - and may not fit your
            > design criteria - but for ease of assembly have you thought of the
            > Doepfer CTM64 or MKE combined with a MCV4 or A-190. The limitations
            > are no portamento and you will be defaulting to tempered scales but
            > you could have LOTS of switches/buttons plus the added modulation and
            > pitch bend inputs.
            >
            > -James

            By the way: the new A-100CGK (CV/Gate keyboard) will be availabe as an OEM
            version too (i.e. without keybed and case). Christian is about to finish the
            firmware and I think it will be ready still in February.

            Best wishes
            Dieter Doepfer
          • Florian Anwander
            Hi Stuart, ... The Resistors depend on the range of the keyboard and the used voltage. If you want well tempered tuning, then the voltage around one resistor
            Message 5 of 10 , Feb 4, 2008
              Hi Stuart,

              > first question to florian (or anybody that has his book griffbereit):
              > on page 32 of your book "synthesizer" you have a simple diagram of a
              > control voltage generator, each resistance corresponding to one key on
              > the keyboard. what would you recommend as a suitable value for the
              > resistors? and should i be using 5v as shown in the previous diagram,
              > or 12v as stated in the text?
              The Resistors depend on the range of the keyboard and the used voltage.
              If you want well tempered tuning, then the voltage 'around' one resistor
              should have 1/12th Volt.

              Exmaple: You provide 5 Volts, the keyboard should have two octaves. Then
              it might look like this:

              R1 Rx Rx Rx Rx Rx R2
              Ground--RRRR--rrrr--rrrr--rrrr--[...]--rrrr--rrrr--RRRR--+5V

              The Resistor R1 should have 120 kOhm, R2 should have 240 kOhm, each of
              the 24 Rx's should have 10 kOhm. The lowest "key" will be between R1 and
              the first Rx and will provide 1Volt.

              > secondly, i intend to produce the gate by simply putting the control
              > voltage through a comparator - everything above 0v opens the gate.
              > does anyone foresee any problems here?
              The lowest note must provide more than 0 Volts (and it should be
              noticable above 0 Volts to prevent erronous triggerings)

              > and any other problems i've overlooked?
              You need also a sample & hold to store the keyboard after you released
              the key. The S&H has to be triggered by the gate.


              Florian
            • Florian Anwander
              Hi ... These aren t only limitations. Having the gate and S&H-triggering separated provides also some features, which are usually not available. (think of
              Message 6 of 10 , Feb 4, 2008
                Hi

                > if it is as simple (though rudimentary) as i think it is, then the
                > analog way is easier, as well as offering opportunities for more
                > individual features/limitations/quirks. i love quirks :)
                These aren't only limitations. Having the gate and S&H-triggering
                separated provides also some features, which are usually not available.
                (think of transposing a sequence within the timing of some external clock).

                Florian
              • Stu Grimshaw
                hi florian, that s pretty much the idea - the smaller the modules, the more spielraum you have for weird ideas like... externally clocked transposition?? so
                Message 7 of 10 , Feb 4, 2008
                  hi florian,

                  that's pretty much the idea - the smaller the modules, the more
                  spielraum you have for weird ideas like... externally clocked
                  transposition??

                  so release phases, pitch bends and all that will be realised using
                  modules that exist already anyway.

                  thanks for the resistance values, which i understand. but the line
                  that looks like you're quoting my dog !?? sorry, it's rose monday and
                  the house sounds like a stadium. i know i should get it, but i can't
                  think.

                  :)

                  stu
                • Stu Grimshaw
                  thanks for the help with this, especially james, dieter and florian. i ve now got schematics for a mono keyboard, a two voice keyboard and florian s original
                  Message 8 of 10 , Feb 7, 2008
                    thanks for the help with this, especially james, dieter and florian.
                    i've now got schematics for a mono keyboard, a two voice keyboard and
                    florian's original diagram :)

                    which should keep me busy for a while.

                    stu
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