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Opinions on Reissue 6CA7 and KT77 tubes

Tom Bombadil

Tom Bombadil

AK Member
I have a Serbian made Korato KVA 20 power amplifier which is wired for triode operation. It's a sweet sounding amp which uses Audio Note output transformers and two 6CA7 tubes per channel to produce 18-20 wpc.

Right now it has its original EI thin base 6CA7s in one channel and a pair of USA-made 6CA7 fat boy tubes in the other channel. Obviously not matched. I'm mulling my options for retubing it. Searching around for another pair of either the EI or the Fat Boys. Both are rather expensive tubes. A NOS pair of the EI's tend to run over $300. The Fat Boys (available under several labels) run $150'ish used and $200-$300/pr NOS. Sometimes even more.

Other options are to go with a new quad. I would likely go with new, reissued tubes, as a new quad of most of the older tubes run several hundred dollars. I've been reading up on what is available and have found several positive reviews of a couple of the new reissues.

Electro Harmonix 6CA7EH Fatboys. Run around $80-$90 a matched quad. Great price. Have read positive reviews from both audio and guitar forums. I've gotten positive feedback on them from a couple of AK'ers in a Barter Town thread, where I was looking for matches for the EI or old Fatboys, for the EH's.

Genalex Gold Lion KT77. The old NOS "real" Gold Lions can go for $2000/quad. The reissues, made in Russia, go for around $160-$180/quad. Again have read several very positive reviews, for example Jim McShane likes them. Much more so than for the JJ KT77s, which are about half this price, but people report that they don't sound as good or last as long.

Anyone here have any experience with these tubes, or suggestions. I'm not considering true EL34s at this time, as the manufacturer recommended I go with a beam tetrode instead of a pentode.

I will be running them at 0.35ma, that's the bias setting recommended by the manufacturer.
 
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When I was searching for new tubes for my Pilot SA-260, I asked Jim McShame what he thought of the new tubes, specifically the EL34's and 6CA7's. He told me the EH 6CA7 was much better than the new EL34's. I have not compared them, but I do like the EH 6CA7's that I ended up with. Mine run at 50ma, but they have been stable since I set them up initially. I've checked a couple times and have not seen any appreciable drift.

Didn't know to ask about the KT77 though, so not really sure how they compare. I expect if you asked Jim for his opinon on the two, he'd be happy to offer it.
 
i like the sounds of the Shuguang Treasures. Black bottles and they are big, so make sure your amp has the headroom to have them fit. I think they sound--by a whisker--better than say vintage Winged C.
The problem is failure rate. Big big concern with any new tube. They have a much much higher failure rate than the old NOS tubes had. In Audio Research tube amps, when that tube goes, it takes out a few parts.

And, don't forget most amps require matched tubes. So, if 1 goes you need to replace 2 tubes.
 
rdka said:
i like the sounds of the Shuguang Treasures. Black bottles
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Okay, so there are the Shuguang Treasures 6CA7-Z and 6CA7-T, and the PSVANE 6CA7, which look very similiar except that the Shuguangs have the black lining while the PSVANEs have gray. Can't find anyone selling these outside of Asia. Did find a few positive reviews. Around $300 or so a quad. That's a pricey reissue 6CA7. But still way under some of the vintage NOS options.
 
Go with new production tubes. Many of the new tubes have surpassed the originals in sonics. I have the JJ, GL KT77's and JJ 6CA7's. All are good. The JJ's are a little fuller sounding and the GL's are more articulate. I have had no issues with either tube. Be sure to get them from a dealer that does additional testing/matching. It's worth the extra money.
 
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The EH fatboys sound great. I've A/B'd them against a very pricey NOS quad of Mullard XF2's in my 8b and they definitely hold their own for a fraction of the price. I am curious about the reissue KT77's too, I wonder how they compare to the fatboys.
 
Crestwood23 said:
The EH fatboys sound great. I've A/B'd them against a very pricey NOS quad of Mullard XF2's in my 8b and they definitely hold their own for a fraction of the price. I am curious about the reissue KT77's too, I wonder how they compare to the fatboys.
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I have not compared them but FWIW a poster on another forum that has the original GL KT77's prefers the reissues.
 
Tom Bombadil said:
I have a Serbian made Korato KVA 20 power amplifier which is wired for triode operation. It's a sweet sounding amp which uses Audio Note output transformers and two 6CA7 tubes per channel to produce 18-20 wpc.

Right now it has its original EI thin base 6CA7s in one channel and a pair of USA-made 6CA7 fat boy tubes in the other channel. Obviously not matched. I'm mulling my options for retubing it. Searching around for another pair of either the EI or the Fat Boys. Both are rather expensive tubes. A NOS pair of the EI's tend to run over $300. The Fat Boys (available under several labels) run $150'ish used and $200-$300/pr NOS. Sometimes even more.

Other options are to go with a new quad. I would likely go with new, reissued tubes, as a new quad of most of the older tubes run several hundred dollars. I've been reading up on what is available and have found several positive reviews of a couple of the new reissues.

Electro Harmonix 6CA7EH Fatboys. Run around $80-$90 a matched quad. Great price. Have read positive reviews from both audio and guitar forums. I've gotten positive feedback on them from a couple of AK'ers in a Barter Town thread, where I was looking for matches for the EI or old Fatboys, for the EH's.

Genalex Gold Lion KT77. The old NOS "real" Gold Lions can go for $2000/quad. The reissues, made in Russia, go for around $160-$180/quad. Again have read several very positive reviews, for example Jim McShane likes them. Much more so than for the JJ KT77s, which are about half this price, but people report that they don't sound as good or last as long.

Anyone here have any experience with these tubes, or suggestions. I'm not considering true EL34s at this time, as the manufacturer recommended I go with a beam tetrode instead of a pentode.

I will be running them at 0.35ma, that's the bias setting recommended by the manufacturer.
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I'd get the EH's from McShane and spend the difference on some 12AT7's and 12AU7's. Often, small signal tubes have a larger influence on sonics than power tubes.

NOS power tubes have a lot of *rarity* in the pricing and there is not a lot of true NOS around.
 
Tom Bombadil said:
Okay, so there are the Shuguang Treasures 6CA7-Z and 6CA7-T, and the PSVANE 6CA7, which look very similiar except that the Shuguangs have the black lining while the PSVANEs have gray. Can't find anyone selling these outside of Asia. Did find a few positive reviews. Around $300 or so a quad. That's a pricey reissue 6CA7. But still way under some of the vintage NOS options.
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Grant Fidelity on this site has them. They are the North American distributor for them.

I got tired of coughing up another $5 or 10 bucks every time I thought of getting some winged C's. Close to the same price, so I took a chance.

I've been running these things for 30 years. I also had some gold lion re-issues when they were the hot thing. 2 failed out of 8. Sound good but not as good as Shuggies or certainly not original Gold Lions. Audio Research and CJ amps only.

I've used PSVane black bottles also. 1 failure out of 8. For new tubes, that is actually more than acceptable failure rate. I sure don't think that failure rate was that poor for Tung sols or Mullards though.

But those shuggies/psvane are big. If your amp does not have a lot of room for height and width, they may be too big. They are maybe twice the size of a normal tube.

And remember, if 1 fails, you have to buy a matched pair for your amp. So in essence, there is never a single tube failure.
 
Tom, I've tried a bunch of new production EL34-compatible valves, and the EH 6CA7s are my favorites. EH, Mullard Reissue, JJ, and Tung Sol Reissue EL34s simply do not sound as pleasing, and are not as stable, but the Tung Sols are a close second. My amps bias at 50ma, FWIW. I have not tried any KT77s.

I'd love to have a quad of NOS RCA/Sylvania fatboy 6CA7s, but cannot justify the cost at this time. The Shuguang Treasure 6CA7s look very interesting.
 
Thanks for all of the feedback. A lot of love for the new reissues, on the whole. This is consistent with what I've read in other forums and from tube dealers who tend to be straight shooters.

As to reliability, what I've heard was that it was more of a problem with the earlier production reissues, but that over the past 5 years, it has improved a lot. Two tube dealers told me that in recent years they have had few reports of tube failures and that feedback from customers has been very positive.
 
Les Lammers said:
I'd get the EH's from McShane and spend the difference on some 12AT7's and 12AU7's. Often, small signal tubes have a larger influence on sonics than power tubes.

NOS power tubes have a lot of *rarity* in the pricing and there is not a lot of true NOS around.
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I've got a lot of good NOS 12AU7s. I have a Conrad Johnson PV10A preamp which uses them and I stocked up over time. I'm thinner on 12AT7s, but so far I've been liking what I'm hearing from the stock EI 12AT7s which were original to the amp and still good. I will probably try others over time.
 
Les Lammers said:
I have not compared them but FWIW a poster on another forum that has the original GL KT77's prefers the reissues.
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Second time I've heard this. A tube dealer told me that he's had similar feedback. Quite the compliment, considering that the reissues can be had at less than 10% of the price of the originals.
 
Just noticed someone on that auction site has listed a pair of NOS Genalex KT77 for $1499 !!!! A rather astounding price. $2998 for a quad at that price.
 
Thats really why I didn't want to get into the vintage / rarity tube realm with my Pilot. I have a mismatched set of old tubes for it but new, strong ones sounded much better and the price was something I could swallow. Being extra cheap, I actually bought Jim's "cosmetically challenged" tubes to knock the price down a bit. 3 have a slight tilt to the bottle, one is a "normal" to finish out the quad. Honestly you can't see them with the cage on so that didn't bother me at all.
 
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