Genalex - Gold Lion KT66

10 Reviews
Best Seller

Availability: Usually ships within 24 hours.

USD $‎50.95
From our reviews ... "At low to moderate volumes you get a big open sound across the guitar spectrum. Very articulate with little compression, excellent touch response and dynamics."

The Gold Lion KT66 tube is a reissue tube that is made in Russia. From the manufacturer, "Exact copy of the original clear glass KT66. The tube that created "The Bluesbreaker Tone". Used in 50's - 60's hi-fi favorites such as the Heathkit W-5M and many Leak amplifiers."

Other Genalex - Gold Lion tubesKT66 Tube Types

Additional Information and Downloads

KT66 Tube Review

Tube Matching Information:
Power Tube Matching FAQ
Perfect Pair System

Genalex - Gold Lion KT66 Datasheet (PDF)

Download Adobe Acrobat PDF reader

Warranty Information and Return Policy

Warranty Period: 3 months

All our tubes are guaranteed for 3 months from the date of purchase. (Any exceptions will be noted on that tube's Warranty tab)

If you receive a tube that does not perform to the manufacturer's specifications, please do the following:

- contact us to get a return authorization
- return it via regular mail within 90 days from when we shipped it, and we will provide an exchange or refund of the full purchase price of the tube.

Returns not related to warranty or defect will be considered at our discretion, and are subject to a 15% restocking fee.

We can not accept returns that don't have an authorization, are past 3 month, or are returned improperly.

These guidelines may be updated without notice.

Ratings & Reviews

10 reviews

Ceriatone JTM45


Just got my Genalex KT66 matched pair. Did a quick bias to get in the ballpark, then left the amp running for an hour to stabilize. When I cam back and rebiased I found the tubes measured exactly the same. Exactly. Never had a set of tubes so perfectly matched.

Plugged in and found the amp sounding rounder, fuller and smoother than with the JJs I was replacing. It may be my imagination, but amp just seemed more powerful. I'll really know for sure on this weekends gigs, but so far I'm impressed.

JTM45/100 Clone


I replaced a quad of JJ's that were getting old with these. They sound absolutely incredible in a Marshall-style circuit. Huge low end with 3D mids that you really have to experience in person. A bit pricier than some other KT66's but well worth it!

Genalex KT66 Reissue Not Worth the Money


Ran 8 of these Genalex KT66's in new Mono Block amps. Burned in for 120 hours. Sound was decent, but not as precise as vintage Made in England tubes. After cool down..I saw that the glass envelope has spider web cracks in it. It is now garbage. No obvious reason for this that I can see. I would not buy these tubes again.

One of my favorites


I’ve been using these tubes for a while. First time I tried them was on an amp I built based on a marshall jcm800. I replaced a pair of el34’s and I liked them so much more that I’ve tried them on other amps. I like them more than el34’s, 6L6’s, 7581A’s, kt88’s and all other similar to mentioned on must cases. They sound big and full, punchy, clear, defined, articulate. Bottom end is deep and beautiful, mid is very present but not humpy as el34’s and the top end is clear and sweet. What i like most about these tubes is the harmonic complexity. They sound so rich and alive. I love them.

These Kick Arse


I have a 1960 brown Fender Deluxe. I was gifted a `62 brown Tremolux output tranny which I installed in my Deluxe! I put the Genalex KT66's in this amp and it sounds huge! I was never a fan of 6V6's... I do have about 12 sets of original M.O.Valve/Genalex and these new ones actually have a little bit more clarity on the highs! They standup against the originals in ever aspect. I've used original KT66's for over 30 years in some of my Marshall's and I have to say these are just as good, especially when my amps are on 8 or 9 and being brutally punished by old Gibson PAF's and early Pat.#'s! I have two Marshall Astoria Custom's and side by side the New Genalex hold up against the originals in nearly every aspect and sound great in my Hand built Marshall Bluesbreaker combo!