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TROUBLE SHOOTING (continued)
Weak Output Level
Verify the signal output from your instrument first. Check guitarÕs controls and that the cables
are working properly. Also, check any effects pedals that may be connected in between the guitar
and the amplifier.
Adverse Sounds-Hum, Whistle, Loss of Dynamics, Feedback, Howling
Check loudspeaker cones, frayed guitar cables, controls on your instrument, the guitarÕs pickups
and any other devices that many be connected to your amplifier such as effects pedals or rack
processors. Some of these devices are ÒamplifiersÓ in their own right with gain and boosted
volume levels and they may cause hissing and unwanted feedback if set too high in front of the
amp.
Shut down the amp and check the tubes. Wait for the amp to cool down. Remove the back panel
of the amplifier. Avoid handling hot tubes as they can cause sever burns. Check the larger
output power tubes first by carefully removing the tube shields or by loosening the clamps, and
then unseat the tubes from their sockets but note from which socket you removed the tubes.
Inspect the integrity of the filaments in the tubes. If one or more of these tubes are bad, you will
need to replace the entire set of the power tubes. If all the tubes are OK, you can eliminate the
adverse sounds by swapping the location of these tubes. If this fails to fix the problem, you may
need to replace the entire set of power tubes with a new matched set. Use of inferior quality
(untested and no-rated) tubes may cause damage to your amplifier.
You should also check the preamp tubes, especially the first input stage tube (far right if youÕre
looking at the amp from the back). Micro-phonics (feedback noise that cannot be controlled by
turning down the volume pot on you guitar) indicates a bad preamp tube(s). You may want to
swap the position of preamp tubes to see if this will fix the micro-phonics problem. Preamp tubes
can go bad without warning but can also last many years without any problem whatsoever.
As you can see when handling tubes, they are sensitive, fragile and somewhat prone to
inconsistencies. Please handle your amp with care when transporting it. Although your Bad Cat
amp is sturdily built and designed to take years of rugged use, the tubes are not. ItÕs always a
good idea to keep extra tubes (both preamp and output power tubes) handy, especially for
performance situations. An overwhelming majority of minor problems on tube amps are tube-
related and itÕs just a matter of swapping one or more out to have your amp performing like
brand new again.
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