Changing Tubes - Bogner Alchemist 212 User Manual

Changing Tubes

Make sure you turn your amp off when you switch tubes and be careful, the tubes might be very
hot!! Do not touch tube sockets with fingers! Even after turning your amp off and unplugging it from
the power outlet there could be enough voltage stored in the capacitors to give you a lethal electrical
shock.
Most amp problems (microphonic squeals, crackling, low power, mushy bass response etc.) can be
traced to bad or weak tubes. Remember, tubes are like car tires—they get worn out through use and
need to be replaced. Sometimes they can go bad very quickly, even when new. Just as a light bulb
can work great one day but blow the next time you hit the power switch, it's unfortunate but a fact of
tube life. How loud you play and how long you play affects how often you need to re-tube your amp. If
you play a lot, changing the power tubes once a year is normal. Pre-amp tubes can often last twice
as long as power tubes, sometimes even longer.
When changing power tubes you should use a matched set of power tubes. As always, biasing these
tubes is a good idea for optimum tone. Premium 12AX7 pre-amp tubes work great to maintain the
original tone of your amp.
TIP: Keep an extra set of tubes around. Tubes always seem to go bad when you have that really
big gig!
Speakers
The 1x12" combo is loaded with an 8 ohm Celestion® Vintage 30* speaker.
The 2x12" combo and 2x12" extension cab are loaded with a combination of one (1) 16 ohm Celestion®
G12H 70th Anniversary* speaker and one (1) 16 ohm Celestion® G12M Greenback* speaker, wired
together for 8 ohm operation.
*Subject to change, depending on speaker availability.
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Alchemist User Manual