Amp/Preamp Asylum

Posted by Budrew (A) on November 13, 2002 at 21:59:21

In Reply to: FT Audio LW-1 Preamplifier (SS) posted by LarBO on November 13, 2002 at 21:38:43:

nt

• If I was able to do it - LarBo 22:34:03 11/13/02 (3)
  In Reply to: Is this an easy tweak (I'm not technically literate, but willing to learn)? nt posted by budrew on November 13, 2002 at 21:59:21:

  it can't be that difficult!

  With the TKD the biggest issue is mounting the attenuator. Rather than using a nut over the attenuator shaft as most do, the TKD uses three standoffs surrounding the shaft at about 3/4" radius. So the deal is that you have to drill holes in the LW-1 chassis (after removing the faceplate) that will match these standoffs. I just made a cardboard template with the attenuator shaft holding the cardboard in place to mark the standoff holes....then placing the cardboard on the LW-1 chassis with the shaft hole centered in the chassis volume knob hole I marked where the standoff holes should be drilled. Simple. The faceplate covers the standoff screws and once completed there's absolutely no change to the way the LW-1 looks.

  The DACT is even more simple as it is mounted using a nut around the shaft (same as the stock Alps pot). No drilling required.

  The wiring is simple. If I remember right for each channel on the TKD pin 1 is the input, pin 2 is the output (wiper) and pin C is the ground. Using a multimeter, the input to ground should always read 100K (as the Alps pot and replacement attenuator are 100K), and with the volume turned down the wiper should read just below 100K to ground. As you turn the volume up the impedence should drop compared to ground. (Bob Crump helped me figure this out.....Thanks Bob!). You can use this to figure out which pins on the stock Alps pot are input, output (wiper) and ground. Then just wire up the TKD (or DACT) the same way as the Alps was wired and voila!

  One thing, I don't know about the DACT but the TKD really took about 300 hours of signal through it to really settle out. It sounded much better than the Alps right out of the gate, but steadily improved (over a bumpy path) to where the soundstage really grew in width and height over many hours of play.

  Hope this helps.
  
  

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  • Isn't 100K too high for most amps? nt - frank 07:26:14 11/14/02 (1)
    In Reply to: If I was able to do it posted by LarBO on November 13, 2002 at 22:34:03:

    nt
    
    

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    • Re: Isn't 100K too high for most amps? nt - Paul L 08:19:04 11/14/02 (0)
      In Reply to: Isn't 100K too high for most amps? nt posted by frank on November 14, 2002 at 07:26:14:

      Frank,

      The implementation of the volume control in the LW-1 is different from traditional passive. This is the value that we need in our x-coupler.

      Paul Lam
      P.L.C.Lam Consulting Inc.
      
      

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  • Re: If I was able to do it - Paul L 06:20:18 11/14/02 (0)
    In Reply to: If I was able to do it posted by LarBO on November 13, 2002 at 22:34:03:

    You need to do some drilling for the DACT mod. The thread hole need to be bigger and cut the notch at 9 o'clock position.

    e-mail to me if you need more detail.

    Paul Lam
    P.L.C.Lam Consulting Inc.
    
    

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