Happy Thanksgiving and happy tube amp season!

Picking and Changing 6L6 Tubes

6L6 Tube Types

6L6 tube is used in many mainstream guitar amps today. 6L6 has a characteristic pop, snap and sizzle sound that makes it an excellent fit int guitar amps, notably Fender Amps.

6L6 was originally developed in USA in mid 1930s. After almost 80 years, more powerful and improved versions are being produced by factories in Slovakia, Russia and China.

6L6 evolved from its original form from higher powered 6L6GB to bigger higher powered 6L6GC type through many years.

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6L6GC, 6L6GB/5881 and KT66 Tubes

Different Power Ratings

While all 6L6 types are pin compatible with one another, some amps are designed only for the higher powered 6L6GC.

When you replace your 6L6, you should make sure that you replace with the right type.

6L6 / 5881 Tubes For Amps


Common Types and their rating

There has been many 6L6 variations, but the most common ones today are:

  • 6L6GC - 30W version. Can be used anywhere
  • 6L6GB / 5881 - 25W version. Can only be used on amps that call for 5881
  • KT66 - A 30W variation of 6L6, requires higher heater current

You can use 6L6GC where any of the other tubes are used, so if you aren't sure, go with 6L6GC types and you will be fine.