KT66 Tube History
Internally, the KT66 tube is an improved and redesigned 6L6 tube.
This linearity resulted in the KT66 tube producing less distortion than the 6L6.
Famous KT66 Amps
Very well known amps were designed with KT66 tube. For example, legendary LEAK Quad II and Heath W5M use KT66 tube in Williamson circuit.
KT66 tube amps were not as popular in the US, but we find KT66 amps to be a sleeper. We have yet to hear a KT66 amp that we didn't like.
KT66 vs 6L6
The KT66 tube draws 1.27A filament current, where 6L6 tube draws only 0.9A. This extra current shouldn't be a problem in most cases, but when in doubt, you should check the amp's filament supply rating.
Some of the current production KT66 is actually a 6L6GC in KT66-like bottle. These tubes are essentially super-sized 6L6GC. These tubes can dissipate more power than a true KT66 or even 6L6GC.
There are several current production KT66 on the market today, but our favorite is Genalex Gold Lion KT66.
Genalex Gold Lion KT66 is beautifully constructed, with the gorgeous looks of the original GEC KT66. Gold Lion KT66 is a true KT66. It excels at the audio application, and it shines in guitar amps.
If you are re-tubing a KT66 amp, or considering trying KT66 in place of 6L6, we have accurately matched sets in our KT66 tube catalog page.