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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)
Hi dp,
Well, it's not easy to to. I watched a tube tech do this and it's not
that easy.
You need oscilloscope for sure and you have to know how to alter the
values of the Voltage of the various components in your amp.
(I hope I use the right words, for my tech English is not that well)
If these voltages are not right you won't get the full of your amp also
it will be bad for your amp as well.
My advice, get it properly done by an expert and ask him if possible to
show it how it's done.
You don't want to ruin your "63 amp nor your new NOS tubes....
Just my two cents,
Jerry S. from Belgium.
-----Original Message-----
From: D. P. [mailto:]
Sent: woensdag 12 maart 2003 22:59
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)
To unsubscribe from this group, send an email to:.
Visit for archived messages,
bookmarks, files, polls, etc.
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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)
For those who want to know more about tube amps and biasing, a good place to
start is the tube amp faq
More technical and with more math but very interresting is the tech info at
------------------------ 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)
>
>
>
>To unsubscribe from this group, send an email to:
>.
>Visit for archived messages,
bookmarks, files, polls, etc.
>
>
>
>Your use of Yahoo! Groups is subject to
>
Thanks Roland!
BN
--- In , "roland.bettenville@p..."
<roland.bettenville@p...> wrote:
> For those who want to know more about tube amps and biasing, a
good place to start is the tube amp faq
>
> More technical and with more math but very interresting is the
tech info at
Great links, Roland! That first one is particularly good for the
safety section - like Brian said, tube circuits have *lethal*
currents - you can't be too careful! If you're not sure, have a pro
do it until you gain enough knowledge to work on the amp safely.
I learned about how dangerous capacitors can be "the hard way"
several years ago . . . and it wasn't even in a tube circuit! I
built a homemade Van de Graaf generator (you know, one of those
things that makes your hair stand on end if you grab the top
terminal) and charged up a homemade Leyden jar type cap. This cap
was built from a small prescription medicine bottle with aluminum
tape on the outside - it was stuffed with steel wool and had a copper
wire going through the lid as the other terminal. I would charge
that little thing with the Van de Graaf generator . . . once, I
*thought* it was discharged - but it wasn't. I grabbed the cap with
both hands and could feel the shock travel across my chest - very bad
situation! The shock actually made my chest muscles involuntarily
contract so that my hands smacked together - picture a non-body
builder doing the "crab" pose! Not a comfortable feeling!
Since then, I've tried to be super careful with *any* project
involving electricity. Sorry about the long story, but it just goes
to show that it doesn't take much to fry yourself! Whatever you do,
be careful!
-Dick (with 8 lives left)
--- In , "roland.bettenville@p..."
<roland.bettenville@p...> wrote:
> For those who want to know more about tube amps and biasing, a good
place to start is the tube amp faq
>
> More technical and with more math but very interresting is the tech
info at
>
> ------------------------
> 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:noetical1@y...]
> >> 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)
> >
> >
> >
> >To unsubscribe from this group, send an email to:
> >
> >Visit for archived
messages, bookmarks, files, polls, etc.
> >
> >
> >
> >Your use of Yahoo! Groups is subject to
> >
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)
>
>
>
> To unsubscribe from this group, send an email to:
> .
> Visit for
> archived messages, bookmarks, files, polls, etc.
>
>
>
> Your use of Yahoo! Groups is subject to
>
>
>
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