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World's easiest mod: A-114 DC coupling.

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  • (i think you can figure that out)
    This may be the only mod which will take you less time to do than it will to read this letter. I could have *sworn* i had already posted this...i actually
    Message 1 of 9 , Nov 8, 2005
      This may be the only mod which will take you less time to do
      than it will to read this letter. I could have *sworn* i had already
      posted this...i actually remember typing it, but possibly old age
      has effected my memory along with my sexual stamina.

      Anyway, if i have posted this and for osme reason I just can't find
      it, please forgive the aged of the list.

      You can convert one (or both if you care to) of the A-114 Ring
      Modulators to DC coupling with a single solder bridge. Takes
      about a second. It will give you DC coupling capability - in short,
      the Y input wil now accept DC voltages, making your A-114 a
      VCA (footnote required - see below). At very least it does also
      give timbral differences from the AC coupled half (you get both
      the X and Y sum frequencies I believe with DC coupled
      multipliers). Totally worth the one minute it'll take to do it.

      Here's how!

      1) Take your unit out. No, not THAT unit...the A-114.

      2) You'll notice two capacitors on the board in which the long
      dimension of their case is parallel to the faceplate. One is for
      the top half, one is for the bottom. All you have to do is bridge the
      two contacts of that cap and you're done. You don't even have to
      remove the component. It doesn't get any easier than that, babe.
      You can do this with just a solder bridge or by running a
      component lead across the two contacts and soldering that in
      place. I happen to be rich in cut component leads around here,
      so i opted to do it that way. One less to sweep up at the end of
      the day.

      The differences between the AC and DC rings are significant. I
      keep one as is and mod'd the other. There's room on the
      faceplate to add a switch so that it could be selectable between
      the two states, but with two rings in one module it doesn't seem
      practical to do that.

      (footnote: The DC response of the DC coupled Y input is
      inverted (180 degrees out of phase with the input) In short, if you
      were using this as a VCA, the greater the voltage put into the Y
      input, the more attenuation at the output (output gets softer).
      Usually it's the other way around. No big deal, the sonic
      characteristic of the DC Ring is still worth it. If you wanted to get
      fancy, you *could* add an inverting op amp or discrete transister
      inverter bwteen the Y input and the cap to put the control
      response back into phase - that's up to you.)

      Try this one - you'll like it. And again if for some reason I have
      already posted this and just kind find it....be kind to the ancient
      (and stupid) among us, namely me.

      - P
    • tkrakowiak
      i m gonna try it tonight! i think i can figure that out :) thanks Peter cheers t On 08/11/05, (i think you can figure that out)
      Message 2 of 9 , Nov 9, 2005
        i'm gonna try it tonight!

        "i think i can figure that out" :)


        thanks Peter
        cheers
        t


        On 08/11/05, (i think you can figure that out)
        <peter@...> wrote:
        > This may be the only mod which will take you less time to do
        > than it will to read this letter. I could have *sworn* i had already
        > posted this...i actually remember typing it, but possibly old age
        > has effected my memory along with my sexual stamina.
        >
        > Anyway, if i have posted this and for osme reason I just can't find
        > it, please forgive the aged of the list.
        >
        > You can convert one (or both if you care to) of the A-114 Ring
        > Modulators to DC coupling with a single solder bridge. Takes
        > about a second. It will give you DC coupling capability - in short,
        > the Y input wil now accept DC voltages, making your A-114 a
        > VCA (footnote required - see below). At very least it does also
        > give timbral differences from the AC coupled half (you get both
        > the X and Y sum frequencies I believe with DC coupled
        > multipliers). Totally worth the one minute it'll take to do it.
        >
        > Here's how!
        >
        > 1) Take your unit out. No, not THAT unit...the A-114.
        >
        > 2) You'll notice two capacitors on the board in which the long
        > dimension of their case is parallel to the faceplate. One is for
        > the top half, one is for the bottom. All you have to do is bridge the
        > two contacts of that cap and you're done. You don't even have to
        > remove the component. It doesn't get any easier than that, babe.
        > You can do this with just a solder bridge or by running a
        > component lead across the two contacts and soldering that in
        > place. I happen to be rich in cut component leads around here,
        > so i opted to do it that way. One less to sweep up at the end of
        > the day.
        >
        > The differences between the AC and DC rings are significant. I
        > keep one as is and mod'd the other. There's room on the
        > faceplate to add a switch so that it could be selectable between
        > the two states, but with two rings in one module it doesn't seem
        > practical to do that.
        >
        > (footnote: The DC response of the DC coupled Y input is
        > inverted (180 degrees out of phase with the input) In short, if you
        > were using this as a VCA, the greater the voltage put into the Y
        > input, the more attenuation at the output (output gets softer).
        > Usually it's the other way around. No big deal, the sonic
        > characteristic of the DC Ring is still worth it. If you wanted to get
        > fancy, you *could* add an inverting op amp or discrete transister
        > inverter bwteen the Y input and the cap to put the control
        > response back into phase - that's up to you.)
        >
        > Try this one - you'll like it. And again if for some reason I have
        > already posted this and just kind find it....be kind to the ancient
        > (and stupid) among us, namely me.
        >
        > - P
        >
        >
        >
        >
        >
        >
        >
        >
        >
        > ________________________________
        > YAHOO! GROUPS LINKS
        >
        >
        > Visit your group "Doepfer_a100" on the web.
        >
        > To unsubscribe from this group, send an email to:
        > Doepfer_a100-unsubscribe@yahoogroups.com
        >
        > Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
        >
        > ________________________________
        >
      • thomasborax
        ... hi peter. i ve been using my a132 for ring mod effects, but i realize it s not a traditional ring modulator, though relatively speaking it sounds a bit
        Message 3 of 9 , Nov 9, 2005
          --- In Doepfer_a100@yahoogroups.com, "(i think you can figure that
          out)" <peter@b...> wrote:

          > The differences between the AC and DC rings are significant. I
          > keep one as is and mod'd the other. There's room on the
          > faceplate to add a switch so that it could be selectable between
          > the two states, but with two rings in one module it doesn't seem
          > practical to do that.
          >


          hi peter.
          i've been using my a132 for ring mod effects, but i realize it's not
          a traditional ring modulator, though relatively speaking it sounds a
          bit like one. can you charactorize the difference between AM and
          ringmodulation for those of us who aren't saavy w/ this knowledge?

          i also soldered the ken stone real ring mod into a lightswitch box.
          i understand the diode ring to be the original ring mod design. one
          drawback with the RRM is i guess becuase it is passive, there is a
          pretty dramatic voltage drop. to get it really sizzling i use my
          two doepfer ext input module to push the gain of my x and y signals
          before going into the real ring mod.

          comparing the sound of AM through my a132 and the sound of the RRM i
          would say that the RRM is somehow grainier and gnarlier. it is a
          very gorgeous but abrasive sound.

          perhaps you can shine a little insight.
          thanks-
          tom
        • Tim Stinchcombe
          Hi Peter, I ve just had a quick play around with this idea, and thought I d offer up a few comments. The transistors in the MC1496 chip used for the Y input
          Message 4 of 9 , Nov 9, 2005
            Hi Peter,

            I've just had a quick play around with this idea, and thought I'd
            offer up a few comments.

            The transistors in the MC1496 chip used for the Y input are kept
            biased at around 6V by the coupling cap, C2: thus if C2 is shorted,
            then a 6V input on the Y input gives zero gain, and dropping the
            input below 6V gives increasing *negative* gain, hence
            the 'inversion' effect. If you now supply a bipolar signal to the Y
            input, when it goes negative, you are getting much more gain than the
            design was intended to, and so the transistors in the chip begin
            to 'hard switch', i.e. you get distortion, and (for a sinewave input
            on X) the output will be much squarer than it would otherwise. This
            is most likely the 'timbral differences' you can hear, i.e. you also
            have odd multiples of the frequency of the X input signal.

            On the other hand, the transistors used for the X input are biased
            around ground anyway, therefore shorting out the other coupling cap,
            C10, instead, means you don't get these drawbacks, and quick
            experimentation showed that normal amplitude modulation was easily
            achievable this way.

            I'll see if I can easily convert my scope traces to a gif file, and I
            could then post it to the files section, if anyone is interested!

            Tim

            --- In Doepfer_a100@yahoogroups.com, "(i think you can figure that
            out)" <peter@b...> wrote:
            >
            > This may be the only mod which will take you less time to do
            > than it will to read this letter. I could have *sworn* i had
            already
            > posted this...i actually remember typing it, but possibly old age
            > has effected my memory along with my sexual stamina.
            >
            > Anyway, if i have posted this and for osme reason I just can't find
            > it, please forgive the aged of the list.
            >
            > You can convert one (or both if you care to) of the A-114 Ring
            > Modulators to DC coupling with a single solder bridge. Takes
            > about a second. It will give you DC coupling capability - in
            short,
            > the Y input wil now accept DC voltages, making your A-114 a
            > VCA (footnote required - see below). At very least it does also
            > give timbral differences from the AC coupled half (you get both
            > the X and Y sum frequencies I believe with DC coupled
            > multipliers). Totally worth the one minute it'll take to do it.
            >
            > Here's how!
            >
            > 1) Take your unit out. No, not THAT unit...the A-114.
            >
            > 2) You'll notice two capacitors on the board in which the long
            > dimension of their case is parallel to the faceplate. One is for
            > the top half, one is for the bottom. All you have to do is bridge
            the
            > two contacts of that cap and you're done. You don't even have to
            > remove the component. It doesn't get any easier than that, babe.
            > You can do this with just a solder bridge or by running a
            > component lead across the two contacts and soldering that in
            > place. I happen to be rich in cut component leads around here,
            > so i opted to do it that way. One less to sweep up at the end of
            > the day.
            >
            > The differences between the AC and DC rings are significant. I
            > keep one as is and mod'd the other. There's room on the
            > faceplate to add a switch so that it could be selectable between
            > the two states, but with two rings in one module it doesn't seem
            > practical to do that.
            >
            > (footnote: The DC response of the DC coupled Y input is
            > inverted (180 degrees out of phase with the input) In short, if
            you
            > were using this as a VCA, the greater the voltage put into the Y
            > input, the more attenuation at the output (output gets softer).
            > Usually it's the other way around. No big deal, the sonic
            > characteristic of the DC Ring is still worth it. If you wanted to
            get
            > fancy, you *could* add an inverting op amp or discrete transister
            > inverter bwteen the Y input and the cap to put the control
            > response back into phase - that's up to you.)
            >
            > Try this one - you'll like it. And again if for some reason I have
            > already posted this and just kind find it....be kind to the ancient
            > (and stupid) among us, namely me.
            >
            > - P
            >
          • tkrakowiak
            ... i am!
            Message 5 of 9 , Nov 9, 2005
              > I
              > could then post it to the files section, if anyone is interested!

              i am!
            • Tim Stinchcombe
              ... Three clumsy gif files posted in the files section, in folder DC coupled A-114 ! Tim
              Message 6 of 9 , Nov 10, 2005
                > I'll see if I can easily convert my scope traces to a gif file, and I
                > could then post it to the files section, if anyone is interested!

                Three clumsy gif files posted in the 'files' section, in folder 'DC
                coupled A-114'!

                Tim
              • tkrakowiak
                thanks Tim!
                Message 7 of 9 , Nov 10, 2005
                  thanks Tim!

                  On 10/11/05, Tim Stinchcombe <timothy@...> wrote:
                  > > I'll see if I can easily convert my scope traces to a gif file, and I
                  > > could then post it to the files section, if anyone is interested!
                  >
                  > Three clumsy gif files posted in the 'files' section, in folder 'DC
                  > coupled A-114'!
                  >
                  > Tim
                  >
                  >
                  >
                  >
                  >
                  >
                  > ________________________________
                  > YAHOO! GROUPS LINKS
                  >
                  >
                  > Visit your group "Doepfer_a100" on the web.
                  >
                  > To unsubscribe from this group, send an email to:
                  > Doepfer_a100-unsubscribe@yahoogroups.com
                  >
                  > Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
                  >
                  > ________________________________
                  >
                • tkrakowiak
                  hello group, i ve changed mine according to Peter s notes. works great , gives more grunge to multiharmonic events, harsher than original rm. overall great and
                  Message 8 of 9 , Nov 12, 2005
                    hello group, i've changed mine according to Peter's notes. works great
                    , gives more grunge to multiharmonic events, harsher than original rm.
                    overall great and simple mod, thanks Peter.



                    On 10/11/05, tkrakowiak <traktorman@...> wrote:
                    > thanks Tim!
                    >
                    > On 10/11/05, Tim Stinchcombe <timothy@...> wrote:
                    > > > I'll see if I can easily convert my scope traces to a gif file, and I
                    > > > could then post it to the files section, if anyone is interested!
                    > >
                    > > Three clumsy gif files posted in the 'files' section, in folder 'DC
                    > > coupled A-114'!
                    > >
                    > > Tim
                    > >
                    > >
                    > >
                    > >
                    > >
                    > >
                    > > ________________________________
                    > > YAHOO! GROUPS LINKS
                    > >
                    > >
                    > > Visit your group "Doepfer_a100" on the web.
                    > >
                    > > To unsubscribe from this group, send an email to:
                    > > Doepfer_a100-unsubscribe@yahoogroups.com
                    > >
                    > > Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
                    > >
                    > > ________________________________
                    > >
                    >
                  • daad_noise
                    ... What would happen if you shorted both c1 amd c2 on the same unit.?
                    Message 9 of 9 , Jun 2, 2008
                      --- In Doepfer_a100@yahoogroups.com, "Tim Stinchcombe" <timothy@...>
                      wrote:
                      >
                      > Hi Peter,
                      >
                      > I've just had a quick play around with this idea, and thought I'd
                      > offer up a few comments.
                      >
                      > The transistors in the MC1496 chip used for the Y input are kept
                      > biased at around 6V by the coupling cap, C2: thus if C2 is shorted,
                      > then a 6V input on the Y input gives zero gain, and dropping the
                      > input below 6V gives increasing *negative* gain, hence
                      > the 'inversion' effect. If you now supply a bipolar signal to the Y
                      > input, when it goes negative, you are getting much more gain than the
                      > design was intended to, and so the transistors in the chip begin
                      > to 'hard switch', i.e. you get distortion, and (for a sinewave input
                      > on X) the output will be much squarer than it would otherwise. This
                      > is most likely the 'timbral differences' you can hear, i.e. you also
                      > have odd multiples of the frequency of the X input signal.
                      >
                      > On the other hand, the transistors used for the X input are biased
                      > around ground anyway, therefore shorting out the other coupling cap,
                      > C10, instead, means you don't get these drawbacks, and quick
                      > experimentation showed that normal amplitude modulation was easily
                      > achievable this way.
                      >
                      > I'll see if I can easily convert my scope traces to a gif file, and I
                      > could then post it to the files section, if anyone is interested!
                      >
                      > Tim
                      >
                      > --- In Doepfer_a100@yahoogroups.com, "(i think you can figure that
                      > out)" <peter@b...> wrote:
                      > >
                      > > This may be the only mod which will take you less time to do
                      > > than it will to read this letter. I could have *sworn* i had
                      > already
                      > > posted this...i actually remember typing it, but possibly old age
                      > > has effected my memory along with my sexual stamina.
                      > >
                      > > Anyway, if i have posted this and for osme reason I just can't find
                      > > it, please forgive the aged of the list.
                      > >
                      > > You can convert one (or both if you care to) of the A-114 Ring
                      > > Modulators to DC coupling with a single solder bridge. Takes
                      > > about a second. It will give you DC coupling capability - in
                      > short,
                      > > the Y input wil now accept DC voltages, making your A-114 a
                      > > VCA (footnote required - see below). At very least it does also
                      > > give timbral differences from the AC coupled half (you get both
                      > > the X and Y sum frequencies I believe with DC coupled
                      > > multipliers). Totally worth the one minute it'll take to do it.
                      > >
                      > > Here's how!
                      > >
                      > > 1) Take your unit out. No, not THAT unit...the A-114.
                      > >
                      > > 2) You'll notice two capacitors on the board in which the long
                      > > dimension of their case is parallel to the faceplate. One is for
                      > > the top half, one is for the bottom. All you have to do is bridge
                      > the
                      > > two contacts of that cap and you're done. You don't even have to
                      > > remove the component. It doesn't get any easier than that, babe.
                      > > You can do this with just a solder bridge or by running a
                      > > component lead across the two contacts and soldering that in
                      > > place. I happen to be rich in cut component leads around here,
                      > > so i opted to do it that way. One less to sweep up at the end of
                      > > the day.
                      > >
                      > > The differences between the AC and DC rings are significant. I
                      > > keep one as is and mod'd the other. There's room on the
                      > > faceplate to add a switch so that it could be selectable between
                      > > the two states, but with two rings in one module it doesn't seem
                      > > practical to do that.
                      > >
                      > > (footnote: The DC response of the DC coupled Y input is
                      > > inverted (180 degrees out of phase with the input) In short, if
                      > you
                      > > were using this as a VCA, the greater the voltage put into the Y
                      > > input, the more attenuation at the output (output gets softer).
                      > > Usually it's the other way around. No big deal, the sonic
                      > > characteristic of the DC Ring is still worth it. If you wanted to
                      > get
                      > > fancy, you *could* add an inverting op amp or discrete transister
                      > > inverter bwteen the Y input and the cap to put the control
                      > > response back into phase - that's up to you.)
                      > >
                      > > Try this one - you'll like it. And again if for some reason I have
                      > > already posted this and just kind find it....be kind to the ancient
                      > > (and stupid) among us, namely me.
                      > >
                      > > - P
                      > >
                      >

                      What would happen if you shorted both c1 amd c2 on the same unit.?
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