Avoiding Tube Amp Troubles

There’s not much worse than getting together to jam and having your favorite amp go on the fritz. Tube amps require care and feeding that solid state amps do not, but hey, they are worth it for sound we get, right!?  So here’s some things to help keep your amp healthy.

  1. Keep liquids and dirt away!  Tube amps are especially vulnerable.  Liquids and dirt can lead to arcing, causing crackling noise or damage.
  2. Speaker Impedance – make sure to properly match the amp and cabinet impedance ratings. Don’t plug in a cabinet rated with a lower impedance. Rapid tube wear and early failure is the likely result. This problem often occurs when extension cabinets are added.    Say the amp is rated for 8 ohm output and you plug in two 8 ohm cabinets. Since the cabinets are connected in parallel, the amplifier sees a combined impedance of 4 ohms.  Check with someone who understands electronics on the proper way to handle this problem.
  3. Tube Substitution – guitar players are famous for seeking new sounds. A common method is substituting different tube types. BE CAREFUL! Just because a tube will plug into to the socket does not make it a good substitution. For example replacing a 6V6 tube with a 6L6 is generally a risky modification. Different tube types require different voltages and currents to work correctly. Consult or research before substituting.
  4. Capacitor Replacement – if you have a vintage amplifier and it has the original electrolytic capacitors, consider replacing them soon; they are on borrowed time! Commonly known as a “cap job,” replacing these caps assures you will have minimum hum and reliable power for the tubes.

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