KT88

The JJ KT88 is a modern replacement for all classic KT88 applications. They can also be used in place of 6550’s when space allows. These are a higher power tube with lots of headroom, thunderous lows, thick detailed mids, and a very natural top end.

The JJ KT88 is just as at home in an Ampeg SVT, or Sunn Model-T, as it is in a classic Mcintosh MC275. The JJ KT88 is a true beam aligned Kinkless Tetrode. Unlike most other modern KT88 variants (Sovtek, EH, Genelex reissue) the JJ KT88 reflects true KT construction techniques which are reflected in the screen grid efficiency (max 7mA at typical conditions) and improved turn-on linearity. Like the original GEC’s, the JJ KT88’s can develop 50 watts per tube in the right push-pull applications (Ampeg, Hiwatt, Sound City).

If you’re considering these as a 6550 replacement, we recommend a minimum of 2-1/4″ as measured from center to center between the sockets for adequate ventilation. Sonically the KT88 tends to provide more harmonic complexity and richer overall sound to a standard 6550 type.

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.