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Clean octave up/down schematic

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  • Clean octave up/down schematic

    After playing around with a Micro POG for a bit, I'm thinking of designing a guitar organ pedal. Essentially all I would need would be a filter (to get the guitar signal as close to a sine wave as possible), a compressor (to add sustain), and several pitch shifters. A Leslie sim would be nice too, but that's probably way out of my league.

    Anyways, basically what I'm wondering is how a clean octave up works (I understand how and why a rectifier works, except I'm looking for something that's relatively clean). How about an octave down?

    Also, I'd ideally like to have a full 9 drawbars, which would mean having non-octave harmonics (for example, octave + 5th) as well. Is it possible to do this without going digital?
    Main Setup: Godin Freeway Classic with P-Rails in neck position -> Digitech Whammy IV -> various dirtboxes -> Line 6 M9 -> Kaoss Pad -> Fender FM65R with V30

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  • #2
    Wow, an ambitious project I'd say. I wish I had some answers for you, but instead I can wish only you good luck and I'd like to see how this goes...
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    • #3
      The Dan Armstrong Green Ringer is a clean octave up. The MXR Blue Box is an octave down fuzz. You should be able to separate the fuzz from the octave without much trouble. That's two of your effects right there!
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      • #4
        Doesn't the Blue Box do 2 octaves down? I guess it would probably be pretty easy to change it to 1 octave down (or, if I have to, just pair it with an octave up). But I doubt it uses a clean octave down in the first place, since there's no point in going out of your way to make it clean when there's just going to be a crapload of fuzz applied to it anyways (and I wouldn't be surprised if the fuzz is created by their method of octaving down in the first place).

        Also, I realized something that might make this project a lot harder... is a clean octave up going to be polyphonic? If the answer is "not necessarily" then does anyone have a schematic for one that is? If not, well, then I guess I might as well give up now.
        Main Setup: Godin Freeway Classic with P-Rails in neck position -> Digitech Whammy IV -> various dirtboxes -> Line 6 M9 -> Kaoss Pad -> Fender FM65R with V30

        Other goodies: 60s Keil amp (EF86 + 2x EL84), Epi Valve Jr, reel-to-reel tape recorder (tape echo!), Danelectro 63 baritone reissue, 60s Decca hollowbody, OLP Stingray bass, 60s MIJ non-reverse Gibson Thunderbird clone, various parts guitars, MacBook/M-Audio Fast Track Pro/Logic Studio

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        • #5
          There is a mod to make it do one octave, but ime (so far) it's not that clean either way.
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          • #6
            Good luck with your project!


            I am currently planning the design of my own Leslie rotating speaker system. The treble rotor is the hard part.
            Originally Posted by Spacehog26


            Sonic Maximisers are...the musical equivalent
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            "This isn't 4chan you idiot"- anon.






            Originally Posted by lfrz93


            btw petejt,
            is that you in your avatar?









            Originally Posted by petejt







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            • #7
              Most "analog" octave down boxes use a modified flip-flop circuit. More modern devices such as a PS3 or POG do the shifting with digital signal processing.

              The basic idea is the input is filtered and used as a clock source for a toggling flip flop. This creates a square output with 1/2 the frequency of the input.

              To clean up the signal, the envelope from the original signal is re-applied to the flip flop output.

              If you want 2 octaves downs, you use a divide by 4 flip flop circuit instead of divide by two. You can also get very close to a 1.5 octave down by using a divide by 3 circuit.

              The only think I know of that did this is the Korg PME Octave V module. It gave 2 down, 1.5 down, 1 down, normal and 1 up with additional sliders for distortion.
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              • #8
                How's the progress?

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                • #9
                  After playing around with a Micro POG for a bit, I'm thinking of designing a guitar organ pedal. Essentially all I would need would be a filter (to get the guitar signal as close to a sine wave as possible), a compressor (to add sustain), and several pitch shifters. A Leslie sim would be nice too, but that's probably way out of my league.

                  Anyways, basically what I'm wondering is how a clean octave up works (I understand how and why a rectifier works, except I'm looking for something that's relatively clean). How about an octave down?

                  Also, I'd ideally like to have a full 9 drawbars, which would mean having non-octave harmonics (for example, octave + 5th) as well. Is it possible to do this without going digital?


                  It isn't just a filter. Think about it.

                  To go down you divide, to go up you multiply.

                  I would do the pitch detection in digital and then drive a number of sine wave oscillators for a true organ generator.

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                  • #10
                    How's the progress?


                    ^^
                    Originally Posted by Spacehog26


                    Sonic Maximisers are...the musical equivalent
                    of a turd polisher.




                    "This isn't 4chan you idiot"- anon.






                    Originally Posted by lfrz93


                    btw petejt,
                    is that you in your avatar?









                    Originally Posted by petejt







                    -----
                    My list of gear is here
                    Mesa/Boogie Mob

                    Comment



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