Conference napalm::guitar

1769.0. "7027 to 6550 conversion question" by DNEAST::RAMSEY_CHUCK (Save a tree; use BookReader.) Mon Apr 09 1990 14:11

    A departing friend blessed me with his slightly abused Ampeg VT40 which
    he retired from regular service upon purchasing a Fender Super Champ.
    The amp was sans one speaker (out of 4 10s), and has mostly original
    tubes (except maybe the 7027 power tubes); there is currently a
    high power (several watts) 10 ohm resistor replacing the missing
    speaker until I can replace the speaker, and I've gotten a quote from
    my local music store on what it will cost to retube the beast.
    
    Now to my question: in a 1983 book on Groove Tube replacements for
    original equipment tubes, the blurb on 7027As says something to the
    effect that if ever there was a candidate for extinction, the 7027 was
    it and that when such extinction became reality, they would publish a
    scheme for converting Ampegs from the Magnavox era to use 6550s. Has
    this scheme, in fact, been published, and does anyone have the details
    of this conversion? I know it will, at the very least, involve changing
    the biasing resistors; I don't know what difference there is (if any)
    in the pinouts of the two tubes, etc.
    
    --Chuck (a read-mostly -- as opposed to read-only -- guitar_noter)