= Bogner Custom Shop =

-CHANGING TUBES-

Most amp problems, ie: 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 works great one day and it blows 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 for affects how often you need to re-tube your amp. If you play alot, changing the power tubes once a year is normal , pre-amp tubes can often last twice as long, 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. CHINESE or Sovtek 12ax7 pre-amp tubes work great to maintain the original tone of your amp. SEAN'S TIP: Keep an extra set of tubes around, tubes always seem to go bad when you have that really big gig at the FORUM!

To remove tube shields on preamp tubes, turn caps a few degrees counter clockwise and pull them off, to put them back on align correctly, push down and turn a few degrees clockwise to lock them. Be careful they might be ver hot!

V1: Input tube both channels a and b, 12ax7 > check that one if your amp gets noisy or microphonic!

V2: 2nd stage for Channel b and Reverb Return, 12ax7

V3: 3rd stage for Channel a and b, 12ax7

V4: FX Loop, Send and Return, 12ax7

V5: Phase Inverter, 12ax7

V6: Power Tube, 6V6 (6L6 30W)

V7: Power Tube, 6V6 (6L6 30W)

V8: Rectifier, 5Y3 (12W) or 5AR4 (15W/30W)