IN CASE OF TROUBLE
All X-Amps all fully tested with a 10 hr break-in period before they leave the factory. However, on those rare
occasions when an X-Amp fails to operate properly, the problem is almost always with the vacuum tubes.
Vibrations from shipping is usually the cause. The solution to fixing the problem could be as simple as
replacing the defective tube. As the owner of a tube amp, it is to your advantage to learn the symptoms of a bad
tube so that you can avoid the inconven- ience and expense of returning your amp to the factory for service. We
think the trouble shooting hints provided below should prove helpful. However, if you're not sure your problem
is a bad tube, then the best way to proceed is to replace all the tubes in the amp. For this reason we recommend
carrying spare tubes.
12AX7A PRE AMP TUBES
The most critical 12AX7A tube for low noise and controlling acoustic tube feedback is V1. A poor V1 can
also cause a rattling sound when certain notes are played. If this is the case, the tube will have to be replaced.
Viewing the amp from the rear, V1 is the small tube at the far right. At CARVIN we select this tube for low
microphonics. You may switch V2 or V3 into V1 for possible improvements. Some of the symptoms of a
bad 12AX7A tube:
1. Premature feedback
2. Rattle sound at certain notes
3. Ringing
4. Popping
5. Week Lead Drive
6. Intermittent Channel
EL34 POWER TUBES
The symptoms listed here could indicate a bad EL34 power tube. There are a total of 4 tubes to be checked (2
tubes
on the X-50B and X-60). These are the large tubes at the very back of the amp. Caution, these tubes normally
run hot and may be hot to the touch.
If in doubt, simply replace the tubes with new ones. Some of the symptoms of a bad EL34 tube:
1. Loud Hum
2. Popping
3. Early Distortion
4. Low Power Output
5. Glowing Red Hot
Note: The EL34's normally have a "bluish-red" glow.
CHECKING TUBES
Tubes need to be checked under load. Bad tubes will generate a lot of noise when plucked. We also
recommend rotating a new tube in with the old tubes to help determine the bad tube. Caution, there is the
possibility that several tubes may be bad.
FACTORY SERVICING / TUBE
PROBLEMS
Typically over half the service calls on tube amps are bad tubes! Be sure to replace your tubes before your have
your amp serviced. Shipping is expensive. We at CARVIN are be happy to help you through any problems
you are having. Give us a call at 800-854-2235.
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