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thanks brian...that approach sounds cool...I have a
multimeter...maybe the amp tech dude can clue me in...
dp
--- Brian Neal <> wrote:
> Its my understanding there are two ways to bias an amp.
> The old school
> multimeter approach, and the oscilliscope approach. I've
> heard some pretty
> knowledgable people on the Fender Forum denounce the
> oscilliscope method.
> With the multimeter approach you simply measure the
> current at some point in
> the circuit, while tweaking a variable resistor until you
> get it into the
> right range. The exact point to measure the current and
> the magic resistor
> to tweak will all vary according to your amp circuit.
>
> This web page shows you how to do it for the Hot Rod
> DeVille/Deluxe family
> amps:
>
> Its bound to be different for a Bassman.
>
> My advice would be to get a tech to do it for you. The
> power supply filter
> capacitors can store *lethal* voltages for days, so its
> best to know what
> you are doing for your sake and the equipment's. Don't
> get me wrong, you can
> hang out on the Fender Forum and/or find web sites that
> tell you how to do
> it. Its not rocket science. You do have to know what you
> are doing though.
>
> You can also buy these "bias meters" that plug right into
> your tube sockets.
> These may be handy if the resistor to tweak is already
> accessible without
> taking the amp out of the chassis. However, these are
> expensive, and if you
> have a multimeter already you are probably wasting your
> money.
>
> Good luck,
> BN
>
> > -----Original Message-----
> > From: D. P. [mailto:]
> > Sent: Wednesday, March 12, 2003 3:59 PM
> > To:
> > Subject: [SurfGuitar101] setting tube bias
> >
> >
> > Hi group:
> >
> > Many of you all seem to be quite knowledgeable about
> amp mods and
> > fixes. My question seems simple: I need to learn how
> to adjust and
> > set the tube bias for my 1963 Bassman 50...I have NOS
> GE 6L6's that
> > need to be installed...
> >
> > will I need an oscilloscope or any other specialized
> tools?
> >
> > does anyone know a cool link that describes the bias
> process?
> >
> > should I just forget about the DIY and seek the
> assistance my
> > friendly amp tech?
> >
> > as always, any wisdom shared would be appreciated,
> >
> > dp
> >
> > (ps: the Bassman 50 through 4X12" Celestion/Utah cab
> with outboard
> > Fender Reverb sounds awesome...sort of like Brian
> Setzer but
> > surfidelic)
>
>
>
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