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I see the following offerings under 6CA7/EL34 tube listings at Tube Depot
(I am not promoting them, just saying that I see these listed there):
Electro Harmonix EL34EH $14.98
Electro Harmonix EH-6CA7 $19.98 (big bottle tube)
JJ 6CA7 Power Vacuum Tube $17.48 (slender tube)
JJ E34L / EL34 $13.98 (slender tube)
JJ E34L Blue Glass Power Vacuum Tube $18.98
JJ EL34 Power Vacuum Tube $13.98
Sino EL34-B Power Vacuum Tube $14.98 (Chinese?)
Mullard EL34 New Production Power Vacuum Tube $22.48
JJ KT77 Power Vacuum Tube $19.98
Tung-Sol EL34B New Production Power Vacuum Tube $22.48
They also have some others that are quite high priced and out of question to me. The offerings from JJ alone are extensive and there are some descriptions with each one on Tube Depot's website, but honestly do they really sound that different? I do notice that some state that they can use higher negative grid bias and have more head-room to handle transient peaks. To me requiring higher negative grid bias sounds as though the tube has a tendency to run hotter and deliver more current than it should and thus has to be throttled back more to keep it in the normal cathode current range a given amplifier is designed to operate at.
Most of the list above is of slender tubes but there are some that look as though the bottle may be slightly larger than others even from the same manufacturer? I am not sure about that issue, it could just be the photograph.
I will be ordering some new tubes for a ST-70 I have coming from ebay, but would like to make an intelligent choice. One of the JJ series says it has less bass than some other versions?? That sounds strange to me. It is almost as if they produce lots of tubes and then characterize them and sort them according to how they turn out rather than controlling their manufacturing process well enough to produce tubes that always sound the same - just my thoughts.
I have been in electronics professionally since the early 1960s and don't want to start a flame topic. I am just trying to understand the current offerings and whether the differences described in the write-ups are based on technical measurements that are repeatable or if they are just subjective comments by various people who have used them.
Follow Ups:
I really like the Treasure 6ca7 black bottle tubes and prefer them to NOS Mullards in my amp. Unfortunately they are pricey at about $100 each.
If (and this is a big if) you get a well made set of JJ KT77 they are a very good sounding tube. Jon at thetubestore.com told me he has not had any trouble with these and the quad I got from him 2 years ago is still going strong. Can you use 6L6gc in your amp? That's my preferred tube.
I had one of the early pairs of JJ KT77s with the thin pins and shoddy-looking insides and they were pretty terrible. But later an audiobuddy gave me (aka, free tubes) a pair which I didn't try for well over a year, only to find that they sounded terrific. I also have a pair of the Genelex KT-77s and like them too.But my old, old xf1 Mullard EL34s still ruled the roost.
About a month ago I popped for a pair of the new (?) Sophia EL34s, much different looking from the other EL34/KT77s I have. I was warned that they take a long time to break in and lose their ultra brightness, but eventually they do, and the xf1 Mullards are now officially retired.
BTW, I use these as driver tubes for 845s in a pair of SET monoblocks, so I have no idea what they sound like as output tubes. In my amps, though, the driver tubes seem to be at least as critical to the sonics as the 845s, maybe even more so.
EDIT: Forgot something important; MSRP on the Sophias is $100. Each.
Edits: 10/30/14
I like the "big bottle" 6CA7. They sound more like a 6550 than EL-34. They do require more negative bias than the slender EL34's in order to draw the proper current.
Thanks to everyone for their input. The ST-70 I have one its way from Ebay needs a complete set of tubes. I think I may go with the Genalex KT77 versions. I have my own ST-70 and could give them a try in it before installing them in the one I am going to restore. That ST-70 currently has some JJ EL34s in it and they sound pretty decent. I have not had any problems with the JJs yet, but you never know. The big bottle 6CA7 tubes are supposed to be good choices too according to some.
Joe
Of the EL34 I would recommend the Mullard EL34 New Production tubes, but
those Genelex KT77 are divine.
Also, save up and get a top quality 5AR4 / GZ34. Don't know of any current
production ones, but a vintage Mullard or metal based Phillips is worth the investment.
"Once this was all Black Plasma and Imagination" -Michael McClure
Search the archives for the series SS diode tweak. 2X UF4007s and a Sovtek 5AR4 will do quite nicely. FWIW, the series diode tweak is supposed to allow squeezing some extra mileage out of UOS rectifiers too.
New Sensor has begun offering "premium" 5AR4s. I can't comment on their merit or lack thereof.
Eli D.
I can comment on the new Tung-Sol 5AR4/GZ34 and Genalex U77/GZ34 - they are terrific!! And ZERO failures so far, even in amps that push them hard!
And go straight for GEC reissues, seems to be the cry. Do not pass go!
I'm using them in place of some Mullards (XF2) and do not miss the Mullards at all.
Big J
"... only a very few individuals understand as yet that personal salvation is a contradiction in terms."
I second what Eli said about the JJs. In spite of the company having very good sounding tubes,it becomes a crap shoot with the reliability of their octals because they still haven't addressed the issues as they should have.
Talk to Jim Mcshane if you want tubes because he matches them better than the factory and that equates to lower distortion,higher power,and better frequency response and it's very noticeable once the tubes are installed in your equipment.
"
I've been replacing guitar amps that had OEM EL34 with these tubes. Very tough. Tone is just a little different -- and that's at a hefty volume.
Most of these EL34 amps are push-pull, fixed-bias, Class AB1. A lot of the distortion or tone comes from front end setup on the input, gain, tone stages. The specific 12AX7 used makes more difference in overall tone, at reasonable volumes, than the output tubes. IME, at least.
For the few EL34 cathode biased amps --- I try to stick with EL34 output tubes. I have used the NOS GEC/MOV KT77 and it is a great tube. I have no experience with the new Russian made ones.
I agree with Eli, Genalex Gold Lion KT77. They sound great in one of my ST-70's.
From a guitar amp standpoint, I can say with some certainty that the New Sensor Gold Lion KT77 is the meow. They sound like a decent mix between a 6L6 and an EL34, but with more depth, better sound stage, clarity, etc. I imagine some hours are needed to break them in and get them to soften a bit, however. Big bonus: they can withstand some abuse. The screens can truly tolerate what the data sheet says - I've taken them there. And no blue glow, which means good vacuum (more like NOS). Really, they're amazing tubes. And out of 16 quads, only one tube was found off kilter.New Sensor's EH series is pretty nice. I haven't tried the EL34, but the 6CA7 was neat. It's as terrible a comparison as any, but I found the sound the EH 6CA7 gave off the same color and tone of a 70s Polaroid. It can have a charm, it doesn't always bring out the life you're looking for, yet it's entirely acceptable. I guess it has an overall relaxed presentation.
Ya, JJ is a weird deal these days. I've had good and bad experiences with them, mostly erring on bad lately. My KT77's bit it way too soon. I'm looking elsewhere for now.
As for the rest, I find the TubeStore's reviewing and charts are pretty faithful. That said, it depends on the amp and application. If I had to hedge a bet without blowing $200 bones on KT77's, I'd say the New Sensor Mullard or Tung Sols.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
May your tubes be lively and long-lasting. Holy be thy heater.
Edits: 10/28/14
Steer clear of JJ's Octal production! At best, JJ's Octal production is highly inconsistent. :> (( It's a crying shame, as the E34L used be a terrific option.
IMO, New Sensor's Saratov, Russia, made varieties are where the decent options can be found. Talk to AA sponsor Jim McShane or other reliable vendor to get accurate info. Off the top of my head, I suggest the "reissue" Genelex KT77.
Eli D.
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