JJ KT77 Power Vacuum Tube (Matched)

20 Reviews

Availability: Usually ships within 24 hours.

USD $‎31.95

Need matched power tubes? Don't worry! Price includes matching in any quantity you need for no extra charge. Need a matched pair? Just order "2" tubes. For a matched quad order "4" tubes. Matched sextets and octets are available as well.

The JJ KT77 vacuum tube is an alternative to the common EL34 power tube.

From our review: "Overall a nice balance of tone in bass, midrange and treble. The breakup is earlier than a 6L6 with more compression but not as compressed as the EL34. If you have a Marshall amp and find EL34’s too compressed and 6550’s too crunchy the JJ KT77 may be just the ticket."

The now rare KT77 tube was introduced by MO-Valve in the late 1950's and has recently been brought back by JJ. They use the same base and biasing as any EL34 tube so they are a great option for substitution in any EL34 amp.

If you are curious about how these fare in a hifi stereo amplifier be sure to read the Wall of Sound EL34 tube comparison for details.

Other JJ Electronics tubesEL34 Tube Types

Additional Information and Downloads

EL34 Tube Review for Guitar Amplifiers
EL34 Tube Review for HiFi Audio

Tube Matching Information:
Power Tube Matching FAQ
Perfect Pair System

JJ KT77 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

20 reviews

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JJ KT77 | JJ Audio KT77 Tubes RULE!!!


After my Bogner Uberschall chewed through several brand new full sets of typical EL34 tubes I got serious and took voltage readings in the power tubes sockets. I learned that that particular amp has 500 V going to the plates of the power tubes which is much higher than any of the other EL34 amps that I own. The JJ-KT77's sound incredible in all of my amps that I've tested them in which consist of my Bogner Uberschall, 1984 Mark II C+, and Victory VX100.
Simply put, JJ KT77 tubes absolutely rule and are probably THE BEST tube that JJ Audio manufacturers.
The only complaint (that really isn't a complaint) that I have about them or any EL34 option is that I wish at least 1 manufacturer would put some research in to seeing with they could get the plate current draw down from 1.5 amps down to around .9 or 1 amps. I'd love to see a tube like the KT77 be developed so that it could be ran completely as a drop in replacement in a 6L6 circuit but have all of the goods of an EL34.

JJ KT77 | My Great Improvement Over EL34 tubes


Well after trying a few sets of tubes in my EL34 amplifier using x2 EL34/ch. I after one blew I decided to forgo limping on the unmatched Back-Ups. An said why not grab a slightly different tube. Glad I did. It really opened the Mids beyond what I thought my Amp could do. JJ-KT77 blew the EL34 tubes away there. Clarity increase for sure. Less Crispy up top(my biggest issue), I assumed it was my Amp being a $700 Chi-Fi amp. Now it is silky liquid. Like it Moisturized the sound. Lows I assume will come in further as I burn them in. Started very thin, but after 2-3hrs, and some tweaking to Phono settings, it came through. I can assume from my past with EL34’s it will get even thicker. If youre on the fence with these tubes, or buying from The Tube Store yours nuts do it. You’ll have a great experience.

JJ KT77 | Excellent EL34 Alternative


While on the hunt for an entire set of replacement tubes (which consists of 12 power tubes), I decided to look into the JJ-KT77s. Other reviews I read below and elsewhere were on point. I can surely confirm that these do offer good low end extension, buttery/silky midrange that's so full you feel like you can taste it, and highs that don't shimmer or scream. Rather, they sound much like the midrange in that silky category but are in no way held back. Excellent tube and great alternative to the 34.

JJ KT77 | absolutely

by -

I was meaning to write a review. Although, it's usually when I have just started to listen to something wonderful and then I forget all about sharing a note.

I changed out some EL34 in a SET amplifier for these JJ-KT77. Let me qualify this: I don't know what was in the amplifier before but these tubes differentiated themselves absolutely.


JJ KT77 | Perfect tube for Dual Rectifiers


JJ-KT77 is one of best sounding tubes that I’ve tried for my dual Rectifier.