Tung-Sol KT66 Power Vacuum Tube

4 Reviews
Out of Stock
USD $‎39.95
Note: Due to low stock only pairs and single tubes are available.

From our review of the Tungsol KT66 vacuum tube: "Big and open with very solid lows and smooth treble response. The mids are well balanced and don’t go to the extremes of sounding scooped or nasal."

If your amp has "bear trap" tube retainers they will have to go because of the size of the power tube's base but also the bear trap clamp will ground the metal base to the chassis and cause a malfunction. The Tung-Sol name and trademark have been acquired by the New Sensor Corporation. This new production Tungsol tube is manufactured at their Xpo-Pul factory (also known as Reflektor) in Saratov, Russia. New Sensor is an American corporation and since taking ownership of this factory has been steadily improving the quality of current production tubes.

Other Tung-Sol tubesKT66 Tube Types

Additional Information and Downloads

KT66 Tube Review

Tube Matching Information:
Power Tube Matching FAQ
Perfect Pair System

Tung-Sol 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

4 reviews

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Maybe my favorite tube so far


I have a pair of these on a ceriatone AH deluxe 50. It’s a Friedman be based amp. After trying preferred series el34’s and gold lions kt66’s, I decided to keep these in the amp. They sound big, full, and balances just like the gold lions but the top end in kind of extended and more detailed. They sound brigher in a beautifully way. Still love the gold lions. The low end and mids are very similar. But the high end is different. I think I like them just a bit more than the gl’s. I think that among all the tubes I’ve tried on the 25 to 42 watts plate dissipation range, this might be my favorite. They sound very similar to a kt88 but less bright which is what makes me prefer it over. It has the perfect balance to my ears. Deep but controlled bottom, not scooped not humpy mids, beautiful clear highs not harsh at all, and a complex harmonic content that makes notes bloom.

An awesome tube for audio


This review focuses on the TungSol KT66 for use as an audio(phile) tube. I am using a matched quad (one pair each) in some Quicksilver Mid-Mono amps and I am most impressed. I replaced some TungSol 6L6STR tubes with the KT66 tubes and what a difference! While the STR tubes are good, the KT66 tube is the STR on steroids! The sound is huge while the midrange is clean but not hard sounding, detail is excellent, the bass is more pronounced and the highs are also clean, clear and sweet without sounding etched or "screechy". I actually like these better than the Gold Lion KT66 tube, at least in the Quicksilver amps as the TungSol is sweeter and to me, sounds more lifelike. I am glad my amps allow me to use these for these are a true high end bargain.

Fantastic in a W5-M amp


Nice tube. The sound is very detailed, top to bottom with deep bass and super clear high. These tubes have a headroom with a lot of reserve. Bias is super stable. No complaints so far.

Tung-Sol TS-KT66 review


WOW!! What an improvement. Put a set into a JTM 45 that I use as a clean platform for pedals.
Huge sounding valve. The entire frequency spectrum is enhanced by this tube.
My Strat has never sounded so good. Highly recommended.