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Re: Question for the designer regard Single-Ended Triode Parallel Feed Line Stage kit

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In Reply to: Re: Question for the designer regard Single-Ended Triode Parallel Feed Line Stage kit posted by kevinc on October 13, 2002 at 14:20:05:

Can I use 6C45, 417A or 5687 instead of 6H30 in the Single-Ended Triode Parallel Feed Line Stage kit?

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Re: Question for the designer regard Single-Ended Triode Parallel Feed Line Stage kit - Dave Davenport 19:28:42 10/13/02 (6)
My original design used a 5687. Most of the listening tests were performed on Kevin Carter's system because he has the best-sounding system I know of. Plus he and I agree pretty much on the sound of things. As part of the line stage development we auditioned The ECC99 and 6H30. I won't go in to all the details here but the result is that we both preferred the 6H30 to the 5687 or ECC99. We did not audition the 6C45 or the 417A because I consider both of thost tubes to have a too-high mu for this application and I had to draw the line somewhere for candidates.
Dave Davenport
- Re: Question for the designer regard Single-Ended Triode Parallel Feed Line Stage kit - SuperB 20:40:46 10/13/02 (5)
  A friend of mine told me the problem of "depletion mode" MOSFET recently. He claimed:
  "Depletion Mode will make the quiescent plate voltage of the tube to be much less predictable in mu-stage circuitry. With the simplified depletion mode MOSFET plan, the quiescent plate voltage of the triode is able to vary all over the place."
  Therefore, how you address the wild variations from depletion mode FET in both Single-Ended Triode Parallel Feed Line Stage kit and two-terminal current source?
  - Re: Question for the designer regard Single-Ended Triode Parallel Feed Line Stage kit - Dave Davenport 21:04:43 10/13/02 (4)
    I am not aware of this problem, if in fact it exists. I have about six months of operation on this MOSFET since my first prototype and the plate voltage is rock-solid. Of course I do not use a mu-stage. The schematic of the line stage is on the K&K Audio site at http://members.aol.com/_ht_a/kevinc927/images/ls schematic.jpg
    I did have a problem with oscilation early on but solved that problem with a gate stopper (similar to grid stopper) resistor. I also added a drain stopper (similar to plate stopper) resistor for good measure.
    Dave Davenport
    - Hi Dave, it seems to me that the link to the schematic is not working - Tanker 10:21:03 12/19/02 (1)
      .
      - Re: Hi Dave, it seems to me that the link to the schematic is not working - KevinC 15:03:34 12/19/02 (0)
        
        In Reply to: Hi Dave, it seems to me that the link to the schematic is not working posted by Tanker on December 19, 2002 at 10:21:03:
        
        That is because Dave very recently sent me a revised schematic that I haven't uploaded yet. I will do so tonight, the gods of my computer willing.
        
        Kevin Carter
        K&K Audio
        www.kandkaudio.com
    - Re: Question for the designer regard Single-Ended Triode Parallel Feed Line Stage kit - SuperB 22:19:16 10/13/02 (1)
      What is the major difference between your Two Terminal Current Source and Plate Load Choke (with low DCR) if use in parafeed transformer coupled type preamp circuit?
      - Re: Question for the designer regard Single-Ended Triode Parallel Feed Line Stage kit - Dave Davenport 06:47:30 10/14/02 (0)
        
        In Reply to: Re: Question for the designer regard Single-Ended Triode Parallel Feed Line Stage kit posted by SuperB on October 13, 2002 at 22:19:16:
        
        Well, I don't know if I would call it "my" CCS. Kevin Carter introduced me to it, and manufactures data sheets show the application as a CCS. So as with so many other things we stand on the shoulders of those that come before.
        The major difference and final arbiter is the sound. We auditoned a choke load and the MOSFET sounded better.
        Dave Davenport

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