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
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Warranty Information and Return PolicyWarranty 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
Depends on the amp
Bought these to try in my Traynor YBA-1 MOD-1 just for fun. Overall very good, quiet hi-fi like sounding tube. However I think they would be better in an amp that naturally has strong mids. The YBA-1 MOD-1 comes with EL34 stock and it's a great sounding amp that's more Fender Bassman like despite the EL34's. These tubes sound great but took a lot of the important mids away from the amp and really enhanced the lows and highs, which were very clear.
Bought matched quad of these and so far they are very, very stable. Perfect bias keeping in my SIPP audio amplifier. Vg/Ia closer to 6L6 than the specs provided by JJ, though.
I noticed small pieces of solder-like material in the tubes, which I think is a manufacturing issue. My observation is that this is not affecting the performance at all. Internal cage assembly riveting is poorly executed (many cracked rivets), but again this is more manufacturing problem than performance concern.
Overall great sounding tube and great service from thetubestore. Will buy again.
That's how a Marshall should sound
by Sol. Williams
Recently replaced some junk tubes (won't mention the brand name, but it starts with an R) that a repair shop slipped in my Marshall JCM2000 100 watt head without even asking me if I wanted them replaced with the like JJ EL34s that were in it. Checked around for pricing on different tubes and came across these. Thought I'd try something different. Have not been disappointed so far. Actually I'm very pleased with how they've brought my head to life. Almost like they've found the best tones out of all of the commonly used tubes you'd find in a Marshall and stuffed them in one tube. Very smooth distortion, bass and highs for days. Don't be thrown off that they come in a slightly smaller envelope than the EL34s. They pack a lot of "heat". I think I've found my go to tubes.
by David Norman
This is a real winner - real value for money. I run them in a Audio Innovation 500 and they gave new life to the old girl. Sound stage was really open and and added re punch to all types of music - that makes you want to re-listen to your whole collection. I love them.
I am a bass player using a DIY Dr103 hiwatt clone. My amp has switchable ultra linear mode. These bring a bit more headroom and pull spectrum sound compared to the El34l I had before.less mid focus. I think any bass player using an el34 amp should give these a go.