Important Information About Tubes and Tube Products (continued):
The power tubes are the largest tubes used in an amplifier. These tubes convert the
The EL84 is similar to the EL34 but produces less output power. It can be easily driven into distortion and is characterized by a smooth, sweet tone with excellent touch sensitivity.
6L6 tubes produce a big
6550 power tubes are more rugged and stay
Some tubes are available in matched sets. These tubes have been extensively tested for opti- mum performance and longevity.
The Nature Of Tubes — Why (And When) To Replace Them:
Tubes are made up of a number of fragile mechanical components that are
Any time you notice a change in your amplifier’s performance, check the tubes first.
If it’s been a while since the tubes were replaced and the sound from your amplifier lacks punch, fades in and out, loses highs or lows or produces unusual sounds, the power tubes probably need to be replaced. If your amplifier squeals, makes noise, loses gain, starts to hum, lacks “sensitivity”, or feels as if it is working against you, the preamplifier tubes may need to be replaced.
The power tubes are subjected to considerably more stress than the preamplifier tubes. Consequently, they almost always fail/degrade first. If deteriorating power tubes aren’t replaced they will ultimately fail. Depending on the failure mode, they may even cause severe damage to the audio output transformer and/or other components in the amplifier. Replacing the tubes before they fail completely has the potential to save you time, money and unwanted trouble. Since power tubes work together in an amplifier, it is crucial that they (if there is more than one) be replaced by a matched set. If you’re on the road a lot, we recommend that you carry a spare matched set of replacement power tubes and their associated driver tubes.
After turning off the power and disconnecting the amplifier from the power source, carefully check the tubes (in bright light) for cracks or white spots inside the glass or any other appar- ent damage. Then, with the power on, view the tubes in a dark room. Look for preamplifier tubes that do not glow at all or power tubes that glow excessively red.
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