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HELP design of switchable SE amp el84/el34 ?!

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  • #16
    PS design with choke

    HI All,

    could people comment help me with the following idea power supply.

    as the rest of this thread discusses I'm planning on having an SE amp with an octal socket for a 6L6 tube and a noval socket for an EL84, the amp operating on one or the other tube- you just put one tube in at a time and ideally don't need to adjust anything.

    So, cathode bias for both tubes, just choose the correct resistance based on tube type and plate voltage.

    for the plate voltage, Ideally want more for the 6L6 so...

    use a choke in the power supply, with the EL84 plate voltage taken downstream of the choke, but the plate voltage for the 6L6 taken upstream of the choke.

    so it would be

    bridge recto -> cap1 (plate B to 6L6) -> choke -> cap2 (screen to 6L6) {plate to el84} ->

    then the usual resistor and cap nodes for the el84 screen and 12ax7 tubes (two).

    If i understand it right the voltage at the cap1 node is much higher than the voltage at the cap 2 node ?

    the choke I have is 10H (150ohms) 100mA . (current rating seems enough?)

    I was think in 47 uF caps, not sure about the size resistor between cap2 and cap3 to make the screen node for the el84.

    Is this an OK idea ? any advice as to resistor cap values ?

    thanks All.

    Gareth.

    (sorry about the lack of a diagram)

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