"Max Holubitsky" wrote in message
...


Peter Mulvey wrote:

Hi all,

Anybody have any thoughts on the feasibility of bridging a 2 x 50 W tube
power (guitar) amp? It's a Marshall 9005.

Schematic of one side of the amp is available he

http://www.drtube.com/schematics/marshall/9005.gif

I would like to use this amp to drive a large cab, and 100W would be
nice. I
could strap the inputs together using the link terminals, but what to do
with the OT outputs. Is it common practice to bridge tube amps, or is
this
just a plain bad idea.

Many thanks for your thoughts.......


If you link the inputs together, you can parallel the outputs. This will
not be
ideal, but it will work. the output impedance will be half of whatever
taps you
tie together - i.e. 8 ohm taps tied together gives a 4 ohm output
impedance.

If you want to bridge it, you'll have to invert one of the input signals.
Really
though, if it's a large cab, why not just connect 2 speakers in the cab to
one
50W amp, and the other 2 speakers to the other amp, and then tie the
inputs on
the amp together?



Pete.

Isn't paralleling the outputs dangerous? Why not just run 2 or more
speakers? If you have the inputs bridged then the speakers will be in phase
and you will have effectivelly 100W. Too damn loud IMO, but then again I
like 5W champs...