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.

Hey Trelja

Don't be fooled buy the results of your tube tester. I find new production tubes must be changed every year to year and a half regardless of what the test reuslts are. When I do so the difference is astounding even if the tubes test over 90%. Comparing 5 yr old Ei's with new JJ's is not a fair comparison of these tubes.

Buy another set of the Ei and then do a comparison again I think you will be presently surprised. Assuming both sets of tubes are well matched, non microphonic and in good condition the Ei I think you will find will out perform the JJ by a wide margin.

They certainally do in my rig.

Thanks for the input. I like both Ei KT90 and the Tesla EL34 ( preferbly the NOS ) but they are miles apart in sonic signature. Both of course have a certain application where on will out shine the other.

Yes, the old Tesla tubes form the 70's were very good if you can find them in shape and at a decent price. I believe they took over from Mullard when they got of it and used there tooling.

As far as current tube the Ei is ano brainer IMHO