Ei vs Electro-Harmonix KT90

One thing in favor of the EI - it's reputed to be a very rugged military tube that will last a long time. I own the "Type II" variety and really like their clarity in mids/highs. I preferred them to EH KT88s. Haven't heard EH's KT90 variety, though.

I have tried both these and while both are very good and are the best current production output tubes I've heard. The Ei takes it in my rig not even a contest. The Ei's have a tightness, clarity and 3D image that the EH cannot compete with.

The EH did however produce a little more slam and bass so the type of music you listen to and your listening habits might weigh into it.

Personally I'm willing to give up some slam and bass to hear more about whats going on with my tunes.

Enjoy you music

I too, am curious as to what the impressions of the EH KT90 are. I'm thankful EH began production, it is a worthwhile endeavor.

I can personally vouch for the ruggedness of the Ei KT90 tubes. I had them in my Jadis for 5 years, one shorted (no damage to the amp), and the others still measure a little better than "pass".

However, in the past week+, I retubed the Jadis with JJ E34L tubes, and the sonics are MUCH better. Of course, the power, extension, and slam is less. But, I feel the overall sound is improved. The tubes still need to burn in.

Also, I tried some burned in JJ KT88s, which seemed to restore the dynamics, slam, extension, and power of the KT90, combined with the sweetness of the EL34. It's probably the tube I'd choose.

But, if you are considering the Ei, believe me, it is one heck of a tube.