RCA tubes?

[jmpizzoferrato]

i just got an amp with RCA tubes. don't know anything about and cant check them out because the amp isnt quite working. they're EL34s. anyone know anything about these tubes? i'm thinking about putting them in my marshall instead of the Mesa tubes that are there now.

[brianroth]

If they're RCA's, they are older than dirt since RCA has been out of the tube biz for maybe 20 years or longer!

Bri

[jmpizzoferrato]

i assumed that. i think the amp is a late 60s model. it also has phillips 12ax7s. any idea how these tubes match up to Mesa or EHX?

[brianroth]

Impossible to say how well a very old, used firebottle is compared to a new part. I know that NOS RCA, Philips, etc bottles fetch a very high price on the market, but they are unused.

Bri

[nclayton]

i just got an amp with RCA tubes. don't know anything about and cant check them out because the amp isnt quite working. they're EL34s. anyone know anything about these tubes? i'm thinking about putting them in my marshall instead of the Mesa tubes that are there now.

If they're marked RCA and EL34 there's a very good chance they're actually Mullards. RCA imported a lot of Mullard EL34's and rebranded them. In fact, I'd say most of the EL34's RCA sold in america were british made Mullards. Most of the american made RCA's will usually just say 6CA7, not EL34. I've also seen a few Japanese and Chinese EL34 rebranded with the RCA logo, but very rarely.

This sounds like a dumb question, but I don't know if you've looked closely at them. Do they say made in great britain on them? If not, also look around the glass near the base and see if they have a code printed on them that looks something like:

xf2
B5H3

Anyway, I don't know what all this means except you probably know most folks will say a mullard el34 sounds better than an american 6ca7. Definitely keep the tubes, don't throw them out. Quite aside from the very subjective "tone" issues, one thing I like (as someone who's fixed guitar amps for a living) about american or w. european made tubes is that when they die, they tend to do it gradually and harmlessly, just slowly emitting less and less. On the other hand, the russian tubes (particularly the EL34's and EL84's in my experience) like to develop brutal shorts that can let the smoke out of your amp's guts. With russian tubes not only do have to replace tubes more often, but when you do, quite often you have to fix your amp simultaneously. This is less common with the old tubes.


Obviously it would be nice if you could find somebody who'd test them for you, but, you know, you can just throw them in your marshall and see how they sound.

Ned

[jmpizzoferrato]

thanks for the all info. i think on my next day off, i'm going to throw them in the ol' marshall. im very interested to hear them!

[???????]

ditto the above. Probably Mullards.

RCA, as far as I know, never actually made an EL34. 5AR4 either... any 5AR4/GZ34 labelled RCA is going to be a Mullard. Good score! Look up prices of NOS mullards (even used pulls) and you will rejoice at your find.

[DrRick]

nclayton said:
...........american or w. european made tubes is that when they die, they tend to do it gradually and harmlessly, just slowly emitting less and less. On the other hand, the russian tubes (particularly the EL34's and EL84's in my experience) like to develop brutal shorts that can let the smoke out of your amp's guts. With russian tubes not only do have to replace tubes more often, but when you do, quite often you have to fix your amp simultaneously.............

NClayton is on the money with the ideas he expressed above. I speak as an electronic engineer with 35+ years experiance who built his first crystal radio at five year old. I worked my way through college and grad school working as a chief engineer at a local botique hi-end audio store. This was in the early 80's and even then I loved tubes. I'm not sure if I ever stopped prefering tubes (for a long while people were dumping thier tube hifi and guitar amps and replacing them with solid-state gear) The big joke was that I was an old man (I was chief from about 25 to 30 years old) who wouldn't give up his tubes. My day consisted of walking around to all the work stations to explain to the techs what to replace in the unit they were into, and why, and I worked on all the tube gear myself. It worked out well because my staff didn't like to work on tube gear and I pretty much only like to work on tube gear.
I'm not sure why I am rambeling-on here, except I was glad to see NClaytons grasp of tube technology. I've seen so much bad or down right incorrect advice in various forums regarding tube engineering/design issues.
Rambel, rambel, rambel-must be the pain killers....LOL.
I do want to add a couple of thoughts regarding poping your EL-34's into your Marshall: even if yhey are real Mullards (and NClayton very elequently explained to you how to identify them as such-keep in mind that the #'s may be a bit different {there are older and newer codes such as XF-1, XF-3, bla bla, I'm old and sometimes have to look things up} the code format is consistant, the #'s change over the years.
Anyway, assuming they are real Mullards if they are really tired out you could have a problem with the Marshall: arc-over between the tube pins. If it lasts more then a second or two it may create a carbon track on the socket between the affected pins which may then cause arcing regardless what tubes you use or, if it is bad enough, arcing may occur with no tube in the socket (amp powered up, of course). Most of the time the only fix is to replace the socket. Yes, I learned all this the hard way-LOL!
If you have no one to check them for you, you are welcome to send them to me to test. I have a 539C, a TV-2, a TV-7, a Tektronics 570 Curve TRacer and a bunch more.

Hey guys, if my post seemed to wander and go on far to long, please forgive me. There is absolutly no one around here with enough interest in tube related technology to have a disscusion with!

Peace,
DrRick

[DrRick]

BY the way, there is a much larger % of folks on these (TapeOp) forums that sound like real EE's, with a very clear and accurate understanding of electronic engineering theory and practice then on most of the hifi forums I frequent.
Then again, they don't discuss issues like having speaker wires marked not only with polarity, but with direction as well in engineering school. It's as if they think that AC alternates so therefore it makes no difference which end of the speaker wire goes to the speaker or to the amp!

Peace,
DrRick

[brianroth]

I am dying to hear a rational scientific explanation of how a bunch of stands of copper can "know" which way electrons are flowing, and then in turn causes the copper stands behave differently.

I'm only interested in reading an explanation from a reputable scientific source (preferably peer-reviewed). I would also be interested in any double-blind listening tests that have been repeated by several unrelated testers that came up with essentially duplicate results.

Bri

[DrRick]

Brian,
If you ever come accross such data I would love to see it.
I have a close friend that is an "over the top" audiophile who is absolutly sure that the little directional arrows on his speaker wires and RCA cables (sorry, interconnects) are there for a reason.

I asked him what "the reason" was and his answer was twofold:
1) Why would the manufacture put them there if it makes no difference.
2) When he hooks them up "Backwards" it just doesn't sound right.

I thought I could nail him into reality by asking him about the one pair of RCA Cables he has that have no little arrows. I should mention here that they are .5 meter with very nice silver over copper RCA plugs. The cable itself is "Pure" silver strands that don't look like they are much thicker then a human hair. These silver strands look like they were braided together at a beauty parlor in Beverly Hills. The inner conductor is the same strands, unwoven (and they don't twist the ends it will mess up the sound). The outside jacket is some sort of clear polly-something material that is very soft.

I have to admit that they are certianly the most beautiful pair of cables I've ever seen. I think they should be mounted, framed and displayed at MoMA.

They are .5 meter, so a total of 1 meter. They cost him $3000. and he said he got a grate deal because he buys so many cables from the dealler.

That is $3000. (three-thousand dollars), not three hundred.

As to the little arrows, he told me that the dealer told him that at $3K they shouldn't need the little arrows, THATS PROOF of how good they are!

I kid you not!

Peace,
DrRick

[mingus2112]

Brian,
If you ever come accross such data I would love to see it.
I have a close friend that is an "over the top" audiophile who is absolutly sure that the little directional arrows on his speaker wires and RCA cables (sorry, interconnects) are there for a reason.

I asked him what "the reason" was and his answer was twofold:
1) Why would the manufacture put them there if it makes no difference.
2) When he hooks them up "Backwards" it just doesn't sound right.

I thought I could nail him into reality by asking him about the one pair of RCA Cables he has that have no little arrows. I should mention here that they are .5 meter with very nice silver over copper RCA plugs. The cable itself is "Pure" silver strands that don't look like they are much thicker then a human hair. These silver strands look like they were braided together at a beauty parlor in Beverly Hills. The inner conductor is the same strands, unwoven (and they don't twist the ends it will mess up the sound). The outside jacket is some sort of clear polly-something material that is very soft.

I have to admit that they are certianly the most beautiful pair of cables I've ever seen. I think they should be mounted, framed and displayed at MoMA.

They are .5 meter, so a total of 1 meter. They cost him $3000. and he said he got a grate deal because he buys so many cables from the dealler.

That is $3000. (three-thousand dollars), not three hundred.

As to the little arrows, he told me that the dealer told him that at $3K they shouldn't need the little arrows, THATS PROOF of how good they are!

I kid you not!

Peace,
DrRick

I'm realy curious about the audio that your friend listens to. There's no doubt in my mind that there's a quality difference between a $10 set of RCA cables and a $3000 set. The real problem here is "how much of a quality difference?"

I'm willing to bet that whatever he listens to wasn't recorded with $3000 RCA cables. If he's spending $3k on RCA CABLES, why isn't he just spending more and buying BALANCED GEAR? It just all seems unreal to me.

As for the "directional cable," i know a friend of mine has a Monster "Jazz" cable for his guitar. I think it has a resistor inn it or something. . .in this case. . .it makes sense. In straight wire, however, I'm with Brian. How can it be directional? I think they just use the same wire with the arrows printed on it for everything they make. . .

[earl parameter]

the arrows are only printed to help resolve tangles. short lengths don't get tangled...



a sucker really is born every minute.




i can't believe the state of the world

[nclayton]

I think some shielded unbalanced high end cables are "directional" not because supposedly the signal flows better in one direction than another, but because some of them have two internal conductors for signal and ground, and then an external shield that's connected to ground only on one side. THis isn't a completely baseless way to build a cable, and I THINK it's how the "directional" cable originally got its start. I think some companies have added other little doodads and pieces of junk such as ferrite rings or inductors or capacitors in series with the shield, etc, and they supposedly work better when attached closer to or further from the star ground point of the system, or whatever.

Some of these things probably sort of make some sense or at least have some semi-rational justification, even if it's just gilding the lily. On the other hand, what could possibly make speaker cables "directional" in any real sense, I can not even begin to imagine.

Ned