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I have two models of tubes stored away with a ST-70 amp. I don't know enough about different manufacturers to understand what is desirable and what is run-of-the-mill.
Realistic Lifetime 6CA7: made in England, slim glass narrower than the base, single getter, gray plate has four crimps along each edge and two slots front and rear.
Raytheon International 6CA7: made in Japan, fatter glass same diameter as base, single getter, black plate has three crimps along each edge and two slots front and rear. To the side of the label is R.T.N. enclosed in an oval.
They all test strong on a B&K 707.
My basic question is how each of these might compare with something like current Electro-Harmonix 6CA7 or El34 tubes?
"You can’t know what the “best” is unless you have heard everything, and keep in mind that given individual tastes, there really isn’t any such thing." HP
Follow Ups:
Why not post one, so we can investigate further?
Cheers,
Dman
Analog Junkie
But I know less about computers than I do about tubes! :^(
A couple of times I've tried posting pics but the files were so large it took forever to load. I'll call Apple for help and see if I can put something up for both tubes. That is why I attempted a detailed verbal description.
"You can’t know what the “best” is unless you have heard everything, and keep in mind that given individual tastes, there really isn’t any such thing." HP
...Here's a pic of what I believe is your EL34...East German RFT...from my stash. Notice the "dimple in the top of the envelope...a defining characteristic as are the "toy tabbed" anode structure and dual g1 radiator "flags at the top. Not shown: single "halo" getter holder hidden by getter flash.
Looks like yours?
Including the small dimple in the glass at the top. Although mine are labeled "ENGLAND" in the same yellow ink as the Realistic LIFETIME and 6CA7 printing. So likely screened for Radio Shack by OEM.
So, is RTF the manufacturer? I assumed because they are English they might be Mullard.
Now does this suggest they are decent quality and likely better than current modestly priced versions such as Harmonix?
"You can’t know what the “best” is unless you have heard everything, and keep in mind that given individual tastes, there really isn’t any such thing." HP
...during the days of the Cold War when there were restrictions on what could be imported into the U.S. from places like Soviet Union and East Germany. It was a scheme to hide the place of origin of non-strategic stuff from the anti-commie police. That it was so effective says something about the power of supply/demand economics. Real British stuff almost always carried the phrase "Made in Gt Britain" or "British Made".
While not British Mullards, I think the East German RFTs are pretty good, just keep the anode voltage down to 450-475V. I'm sure aome would disagree but I find these to be better than the Sovtek EL34 and on par with the =C= Svetlana although somewhat different sounding. =C= are more rugged IME but unfortunately are considered largely NOS at this point.
The English made tubes just may be genuine Mullard EL34s, which are true 3 grid pentodes. I suspect the Japanese Raytheon stuff is 6CA7 beam power tetrode.
I believe you have MONEY on your hands. The construction experts will have the last word.
Eli D.
Can't speak to your Raytheon 6CA7 except to say that Japanese tubes are usually quite good.From your description, the Realistic 6CA7 sure sounds like the East German RFT EL34. Dimple in the glass on top? I really like the RFTs. Good sound, consistent and stable operation. Don't use above about 450-475V on the anode for long life.
Edit: Pics are always helpful.
Edit 2: Both tubes are probably better all round performers that the current production Russian stuff.
Edits: 01/22/15 01/22/15
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