KT66

One of our favorite tubes here at Eurotubes. The JJ KT66 is a true beam aligned Kinkless Tetrode. For those not familiar the KT66 is like a Brit version of the American 6L6GC. In a lot of applications they can be substituted freely for one another (heater, bias, and space constraints considered).

The KT66 is renowned amongst both guitar players and audiophiles alike. In general KT66’s have a deep and clean bass response, slightly forward and articulate mids, and a high end that is crisp and clear without being overbearing. Compared to the 6L6GC, which is known for it’s scooped mid-range, KT66’s will immediately reveal a more detailed mid-range and a denser harmonic structure.

Guitar players will notice that KT66’s tend to breakup in the highs and upper mids first, while the bass stays big and clear. This gives the KT66 it’s characteristic crunch. Like all true KT types the JJ KT66 has a very harmonically rich sound with lots of overtones and “swirl” when pushed into their sweet spot (just like the originals).

For those looking to substitute KT66’s in place of 6L6GC’s, you need a minimum of 2-1/4″ as measured from center to center between the power tube sockets for proper ventilation.

After a 24 hour burn in all power tubes are tested for noise and matched at multiple operating points for plate current (± one milliamp) and transconductance. Please leave us a note in the comments section as to what amp they’re going into and or if you’re looking for a specific grade.