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Re: [dallasaudioclub] Aikido preamp

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  • Robert Cham
    Hi Mike, I ve got a mostly built one that won t be finished anytime soon as I m 2,000 miles away building our retirement house. I gutted a PAS 3 and installed
    Message 1 of 7 , Jun 3, 2013
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      Hi Mike,

      I've got a mostly built one that won't be finished anytime soon as
      I'm 2,000 miles away building our retirement house.

      I gutted a PAS 3 and installed two 9 pin mono boards and a PS 1
      board for separate regulation of each channel's power, after some
      metal work and clear plastic "Contact Paper" on the bottom plate as
      the spacing is a bit tight to the board traces. Separate regulation
      of channels has yielded improvement in crosstalk in SS preamps, so I
      thought that I'd try it in a hollow state one.

      Still to be done is the wiring of the selector switch and Alps volume
      control with Mogami snake cable stripped out of it's overall jacket,
      and the transformer chassis, which will connect to the PAS 3 through
      the already installed Cinch Jones connector. I'm making my own
      multi-conductor cable for the power interconnect by using heat
      shrink tubing over cable of various gauges, depending one whether
      it's for Plate or Filament power.

      I'm going to try using 6H30s for their low output impedance, as I
      want to try using Nelson Pass's passive low level crossover from an
      old Audio Amateur, which requires the ability to drive 5K loads.
      John Broskie doesn't like the sound of that tube, but we'll see what
      I think. The crossover will drive a pair of ST-70s, which will
      bi-amp the Maggie Tympani 1Cs. The phono preamp will continue to be
      the Transcendent Sound kit built unit, easily the most accurate and
      impressive sound stage presentation that I have ever heard.

      So, I still haven't heard an Aikido either, but I also have heard
      much good about them, and as an engineer, I really admire Broskie's
      work. The engineering on them is really solid.

      Bob Cham
      (presently in Virginia)



      >I just recently joined the group and I wanted to pose a question to
      >the group. I am thinking about building the Aikido preamp. I have
      >heard good things about this preamp. Has anyone in the group heard
      >the Aikido? I would love to hear your impressions.
      >
      >Thanks all.
      >
      >Mike
    • Blair Chapman
      It s a fine sounding preamp from what I ve heard. Most of them using. 6DJ8/6922 varieties. Several locals have built them. With all the tube combinations you
      Message 2 of 7 , Jun 3, 2013
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        It's a fine sounding preamp from what I've heard. Most of them using. 6DJ8/6922 varieties. 

        Several locals have built them. With all the tube combinations you can use, it's hard to say something as general as "is this a good preamp?" Because people use various tubes in each position. 

        Blair

        On Jun 3, 2013, at 11:58 AM, "Robert Cham" <cham@...> wrote:

         

        Hi Mike,

        I've got a mostly built one that won't be finished anytime soon as
        I'm 2,000 miles away building our retirement house.

        I gutted a PAS 3 and installed two 9 pin mono boards and a PS 1
        board for separate regulation of each channel's power, after some
        metal work and clear plastic "Contact Paper" on the bottom plate as
        the spacing is a bit tight to the board traces. Separate regulation
        of channels has yielded improvement in crosstalk in SS preamps, so I
        thought that I'd try it in a hollow state one.

        Still to be done is the wiring of the selector switch and Alps volume
        control with Mogami snake cable stripped out of it's overall jacket,
        and the transformer chassis, which will connect to the PAS 3 through
        the already installed Cinch Jones connector. I'm making my own
        multi-conductor cable for the power interconnect by using heat
        shrink tubing over cable of various gauges, depending one whether
        it's for Plate or Filament power.

        I'm going to try using 6H30s for their low output impedance, as I
        want to try using Nelson Pass's passive low level crossover from an
        old Audio Amateur, which requires the ability to drive 5K loads.
        John Broskie doesn't like the sound of that tube, but we'll see what
        I think. The crossover will drive a pair of ST-70s, which will
        bi-amp the Maggie Tympani 1Cs. The phono preamp will continue to be
        the Transcendent Sound kit built unit, easily the most accurate and
        impressive sound stage presentation that I have ever heard.

        So, I still haven't heard an Aikido either, but I also have heard
        much good about them, and as an engineer, I really admire Broskie's
        work. The engineering on them is really solid.

        Bob Cham
        (presently in Virginia)

        >I just recently joined the group and I wanted to pose a question to
        >the group. I am thinking about building the Aikido preamp. I have
        >heard good things about this preamp. Has anyone in the group heard
        >the Aikido? I would love to hear your impressions.
        >
        >Thanks all.
        >
        >Mike

      • Rich Davis
        I built from scratch using a steel chassis and a power tranny I had on hand. Phonostage is a conventional dual triode with shund/shunt riaa filter interstage.
        Message 3 of 7 , Jun 3, 2013
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          I built from scratch using a steel chassis and a power tranny I had on hand. Phonostage is a conventional dual triode with shund/shunt riaa filter interstage. Linestage is a common cathode dual triode with a little local neg feedback in the output. My goal was lots of headroom and a very low impedance output to swamp parasitic capacitances. Linestage is stunning with output impedance 2200 ohms at 400 cps going up to 8800 ohms at 20 cps, limited I think by the output cap. Phonostage is nice sounding but I've challenges chasing hum and a tendency to motorboat with both channels wide open. I used 5965s all the way around. My original idea was to use 5687s on the output, and I still might, but they are terrible current hogs.
           
          Audio Expressed is interested in the article if I ever finish it.
           
          Best regards,
          Rich Davis
           
           
           
          ----- Original Message -----
          Sent: Monday, June 03, 2013 12:06 PM
          Subject: Re: [dallasaudioclub] Aikido preamp

           

          It's a fine sounding preamp from what I've heard. Most of them using. 6DJ8/6922 varieties. 

          Several locals have built them. With all the tube combinations you can use, it's hard to say something as general as "is this a good preamp?" Because people use various tubes in each position. 

          Blair

          On Jun 3, 2013, at 11:58 AM, "Robert Cham" <cham@...> wrote:

           

          Hi Mike,

          I've got a mostly built one that won't be finished anytime soon as
          I'm 2,000 miles away building our retirement house.

          I gutted a PAS 3 and installed two 9 pin mono boards and a PS 1
          board for separate regulation of each channel's power, after some
          metal work and clear plastic "Contact Paper" on the bottom plate as
          the spacing is a bit tight to the board traces. Separate regulation
          of channels has yielded improvement in crosstalk in SS preamps, so I
          thought that I'd try it in a hollow state one.

          Still to be done is the wiring of the selector switch and Alps volume
          control with Mogami snake cable stripped out of it's overall jacket,
          and the transformer chassis, which will connect to the PAS 3 through
          the already installed Cinch Jones connector. I'm making my own
          multi-conductor cable for the power interconnect by using heat
          shrink tubing over cable of various gauges, depending one whether
          it's for Plate or Filament power.

          I'm going to try using 6H30s for their low output impedance, as I
          want to try using Nelson Pass's passive low level crossover from an
          old Audio Amateur, which requires the ability to drive 5K loads.
          John Broskie doesn't like the sound of that tube, but we'll see what
          I think. The crossover will drive a pair of ST-70s, which will
          bi-amp the Maggie Tympani 1Cs. The phono preamp will continue to be
          the Transcendent Sound kit built unit, easily the most accurate and
          impressive sound stage presentation that I have ever heard.

          So, I still haven't heard an Aikido either, but I also have heard
          much good about them, and as an engineer, I really admire Broskie's
          work. The engineering on them is really solid.

          Bob Cham
          (presently in Virginia)

          >I just recently joined the group and I wanted to pose a question to
          >the group. I am thinking about building the Aikido preamp. I have
          >heard good things about this preamp. Has anyone in the group heard
          >the Aikido? I would love to hear your impressions.
          >
          >Thanks all.
          >
          >Mike

        • Blair Chapman
          Hi Rich, Have you tried to add 2-5K resistance to the output of the line stage or the grounded part of the pot? You could be making an oscillator at wide open.
          Message 4 of 7 , Jun 3, 2013
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            Hi Rich,

            Have you tried to add 2-5K resistance to the output of the line stage or the grounded part of the pot? You could be making an oscillator at wide open. 

            I'd love to hear your design. Where are you? I'm in McKinney.

            Blair

            On Jun 3, 2013, at 10:59 PM, "Rich Davis" <fly46davis@...> wrote:

             

            

            I built from scratch using a steel chassis and a power tranny I had on hand. Phonostage is a conventional dual triode with shund/shunt riaa filter interstage. Linestage is a common cathode dual triode with a little local neg feedback in the output. My goal was lots of headroom and a very low impedance output to swamp parasitic capacitances. Linestage is stunning with output impedance 2200 ohms at 400 cps going up to 8800 ohms at 20 cps, limited I think by the output cap. Phonostage is nice sounding but I've challenges chasing hum and a tendency to motorboat with both channels wide open. I used 5965s all the way around. My original idea was to use 5687s on the output, and I still might, but they are terrible current hogs.
             
            Audio Expressed is interested in the article if I ever finish it.
             
            Best regards,
            Rich Davis
             
             
             
            ----- Original Message -----
            Sent: Monday, June 03, 2013 12:06 PM
            Subject: Re: [dallasaudioclub] Aikido preamp

             

            It's a fine sounding preamp from what I've heard. Most of them using. 6DJ8/6922 varieties. 

            Several locals have built them. With all the tube combinations you can use, it's hard to say something as general as "is this a good preamp?" Because people use various tubes in each position. 

            Blair

            On Jun 3, 2013, at 11:58 AM, "Robert Cham" <cham@...> wrote:

             

            Hi Mike,

            I've got a mostly built one that won't be finished anytime soon as
            I'm 2,000 miles away building our retirement house.

            I gutted a PAS 3 and installed two 9 pin mono boards and a PS 1
            board for separate regulation of each channel's power, after some
            metal work and clear plastic "Contact Paper" on the bottom plate as
            the spacing is a bit tight to the board traces. Separate regulation
            of channels has yielded improvement in crosstalk in SS preamps, so I
            thought that I'd try it in a hollow state one.

            Still to be done is the wiring of the selector switch and Alps volume
            control with Mogami snake cable stripped out of it's overall jacket,
            and the transformer chassis, which will connect to the PAS 3 through
            the already installed Cinch Jones connector. I'm making my own
            multi-conductor cable for the power interconnect by using heat
            shrink tubing over cable of various gauges, depending one whether
            it's for Plate or Filament power.

            I'm going to try using 6H30s for their low output impedance, as I
            want to try using Nelson Pass's passive low level crossover from an
            old Audio Amateur, which requires the ability to drive 5K loads.
            John Broskie doesn't like the sound of that tube, but we'll see what
            I think. The crossover will drive a pair of ST-70s, which will
            bi-amp the Maggie Tympani 1Cs. The phono preamp will continue to be
            the Transcendent Sound kit built unit, easily the most accurate and
            impressive sound stage presentation that I have ever heard.

            So, I still haven't heard an Aikido either, but I also have heard
            much good about them, and as an engineer, I really admire Broskie's
            work. The engineering on them is really solid.

            Bob Cham
            (presently in Virginia)

            >I just recently joined the group and I wanted to pose a question to
            >the group. I am thinking about building the Aikido preamp. I have
            >heard good things about this preamp. Has anyone in the group heard
            >the Aikido? I would love to hear your impressions.
            >
            >Thanks all.
            >
            >Mike

          • Rich Davis
            that s a helluva good idea. I ll give it a try. I went so far as to build a regulated power supply into the phonostage and increase the isolation caps with no
            Message 5 of 7 , Jun 4, 2013
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              that's a helluva good idea. I'll give it a try. I went so far as to build a regulated power supply into the phonostage and increase the isolation caps with no effect.
               
              I'm in south Grand Prairie, which is a hike, but I have a brother in Whitewright, so maybe I would combine a trip.
               
              I have some test equipment if you need to use some sometime. Low freq oscillator, distortion analyser etc.
               
              Best regards,
              Rich
              ----- Original Message -----
              Sent: Monday, June 03, 2013 11:08 PM
              Subject: Re: [dallasaudioclub] Aikido preamp

               

              Hi Rich,

              Have you tried to add 2-5K resistance to the output of the line stage or the grounded part of the pot? You could be making an oscillator at wide open. 

              I'd love to hear your design. Where are you? I'm in McKinney.

              Blair

              On Jun 3, 2013, at 10:59 PM, "Rich Davis" <fly46davis@...> wrote:

               

              

              I built from scratch using a steel chassis and a power tranny I had on hand. Phonostage is a conventional dual triode with shund/shunt riaa filter interstage. Linestage is a common cathode dual triode with a little local neg feedback in the output. My goal was lots of headroom and a very low impedance output to swamp parasitic capacitances. Linestage is stunning with output impedance 2200 ohms at 400 cps going up to 8800 ohms at 20 cps, limited I think by the output cap. Phonostage is nice sounding but I've challenges chasing hum and a tendency to motorboat with both channels wide open. I used 5965s all the way around. My original idea was to use 5687s on the output, and I still might, but they are terrible current hogs.
               
              Audio Expressed is interested in the article if I ever finish it.
               
              Best regards,
              Rich Davis
               
               
               
              ----- Original Message -----
              Sent: Monday, June 03, 2013 12:06 PM
              Subject: Re: [dallasaudioclub] Aikido preamp

               

              It's a fine sounding preamp from what I've heard. Most of them using. 6DJ8/6922 varieties. 

              Several locals have built them. With all the tube combinations you can use, it's hard to say something as general as "is this a good preamp?" Because people use various tubes in each position. 

              Blair

              On Jun 3, 2013, at 11:58 AM, "Robert Cham" <cham@...> wrote:

               

              Hi Mike,

              I've got a mostly built one that won't be finished anytime soon as
              I'm 2,000 miles away building our retirement house.

              I gutted a PAS 3 and installed two 9 pin mono boards and a PS 1
              board for separate regulation of each channel's power, after some
              metal work and clear plastic "Contact Paper" on the bottom plate as
              the spacing is a bit tight to the board traces. Separate regulation
              of channels has yielded improvement in crosstalk in SS preamps, so I
              thought that I'd try it in a hollow state one.

              Still to be done is the wiring of the selector switch and Alps volume
              control with Mogami snake cable stripped out of it's overall jacket,
              and the transformer chassis, which will connect to the PAS 3 through
              the already installed Cinch Jones connector. I'm making my own
              multi-conductor cable for the power interconnect by using heat
              shrink tubing over cable of various gauges, depending one whether
              it's for Plate or Filament power.

              I'm going to try using 6H30s for their low output impedance, as I
              want to try using Nelson Pass's passive low level crossover from an
              old Audio Amateur, which requires the ability to drive 5K loads.
              John Broskie doesn't like the sound of that tube, but we'll see what
              I think. The crossover will drive a pair of ST-70s, which will
              bi-amp the Maggie Tympani 1Cs. The phono preamp will continue to be
              the Transcendent Sound kit built unit, easily the most accurate and
              impressive sound stage presentation that I have ever heard.

              So, I still haven't heard an Aikido either, but I also have heard
              much good about them, and as an engineer, I really admire Broskie's
              work. The engineering on them is really solid.

              Bob Cham
              (presently in Virginia)

              >I just recently joined the group and I wanted to pose a question to
              >the group. I am thinking about building the Aikido preamp. I have
              >heard good things about this preamp. Has anyone in the group heard
              >the Aikido? I would love to hear your impressions.
              >
              >Thanks all.
              >
              >Mike

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