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Replacing 6L6 GC tubes what is GE/C/S/R/WGC

Discussion in 'Amps and Cabs [BG]' started by chamigo, Feb 12, 2004.

  1. chamigo


    Oct 7, 2000
    Took out an old bass head from my dad's basement (an Earth B2000) all tube sweet tone through an SWR golliath Jr 2x10. I will need to replace the tubes. The originals are 6L6 GC. When I looked to pick up a set I saw all kinds of designations like GT/GE/C/S/R and WGC.. What the difference between these ??? (please help !) Also they come in sets of 2 and 4 (I need 4) and are designated in degrees of Hardnes from 1-10 what's that ? Thanks in advance for your help.
  2. The 0x

    The 0x

    Aug 24, 2003
    Timonium, MD
    Congradulations on the find!

    I'd recommend you get a matched quad of JJ tubes from www.eurotubes.com , have it biased, and then rock out! :bassist:
  3. chamigo


    Oct 7, 2000
    Hey Ox,
    Thanks for your reply just finnished checking out eurotubes...I'm calling tomorrow...All the best Ox, thanks again.
  4. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL
    those are just different kinds of 6L6 tubes from various manufacturers, and of course, each have a different sound.

    tho a nice NOS (new old stock) tube made from early decades do sound better than most of today's cheaply made tubes, i still like the availability and affordablity of Groove Tubes new line of GE reproductions. NOS GE 6L6 power tubes are one of the more sought after, and GT's reproductions of these sound pretty darn good.

    you can find 'em pretty much at any GC, or on Musicians' Friend, or your local hifi tube guy.

    btw, they come in different hardness ratings, which is a way guitar amp guys find out which tube "breaks up" faster for that power tube overdrive saturation. just means the lower the number, the quicker it breaks up for that power amp overdrive.

    for bass amps, i suggest a higher number like 7, 8, or 9, which makes for a more taut and tighter sound. the lower numbers might saturate too quickly, making for a mushy and inarticulate sound at higher volumes.
  5. First: Have a tech check the amp out. I doubt you even need tubes. If the amp is doing something funny chances are, it's far more likely a capacitor gone bad than a tube gone bad, especially given the age of the amp. You might spend $50 to get the amp checked out and biased, which you'll NEED to do even if the tubes are replaced anyway.

    Second: "Hardness" ratings are TOTAL crap, nothing but BS, complete lies. I can take tubes of ANY "hardness" rating and as long as they're the same type, they will sound and perform EXACTLY the same once the amp is properly biased.

    I can explain to you in detail the differnces between tube post designations, but there's no need for you to go looking for any new ones until you find out what's going on with the amp as-is. If the amp has a problem, you could smoke a brand new set of tubes and seriously damage the amp if you just buy a set and stick them in there.
  6. Man, I love the old Earth's - Superbass B1000, B2000. They are copies of a 1970's Fender Bassman 100.

    I recently rebuilt a B2000 for a guy. Since I'm cheap, I used Sovtek 5881's, the ones with the coin base. You can get a quad of those for like $32 - $40, and they last forever. The only drawback is that it'll only put out about 80 clean Watts instead of 100 since the Sovtek 5881's aren't exactly 6L6GC's.

    Yep, like Psycho said, have the amp checked out and if you want to go ahead and do some preventive maintenance replace the filter caps and power supply / bias diodes and you'll be rockin'. The tubes that are in there now are probably fine and will probably last some more years.

    If you really want to keep your tubes alive longer, find a piece of egg crate foam to put between your head and cab to keep the tubes from getting vibrated.

  7. Finger Blister

    Finger Blister

    Jul 8, 2003
    LinK: 6L6 Shootout

    The Sovtek and Svetlana tubes are made in competing factories in Russia and are the most commonly used tube today in production amplifiers.

    • WGC - Sovtek - Russian
      The tubes also produce clean sound and smooth distortion. They are used by some of the top names in the industry, among them Fender and Crate. $12.95 ea.

    • GC - Svetlana - Russian
      This may be the closest thing available if you really want the vintage sound of the large bottle Sylvania and RCA tubes of yesterday. Tremendous harmonic content and an overall depth in sound make these another excellent choice for the purist. They can handle solid plate voltages and are very well constructed. Consider these tubes as an excellent choice for any type of music, delivering crystal cleans and smooth breakup with plenty of punch."

    • S - Soft Vacuum Tesla
      Tubes matched sets in their soft ratings to work together with this inherent quality so we can have a tube that will "soften up" a hard or harsh sounding amp, get easier breakup, smoother sustain, and lower the power a bit.
      Just the trick for the Peavey 5150, Blues DeVille, Blues Deluxe (with our Bias Kit installed) or Hot Rod DeVille, and those Boogies or Marshall 900's

    • GT GE - U.S. made. New Product. A faithful reproduction of the original General Electric "clear top" tube made on the original GE machines and with many original materials.

    • C - American - New model, large 'straight bottle' like Sylvania STR tube of the late 70's. Available as matched quartets.

    • C - Chinese - Could also designate Shuguang 6L6c.

    • C - East European - Orginial Svetlana 6L6C

    • B - Russian

    • R - GT Labeled Tube
  8. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL
    are you a guitar player?
  9. Sorry, but I'm kinda dumb. Where can I get some egg crate foam?

  10. Finger Blister

    Finger Blister

    Jul 8, 2003
    Foam Rubber cushion...
    Looks like an egg carton.


    Any piece of foam cushioning will do.

    Be really cool and wrap it in a black velvet casing.

    A plain square of similar material would actually be better.

  11. These are guidelines ONLY for Groove Tubes. They are NOT standard tube designations and are meaningless outside of buying overpriced Groove Tubes.

    For example: The 6L6GC means 6L6 Glass envelope, third version. There were metal cased 6L6's from the early 1930's which led to glass 6L6GA's from the mid 1930's which are very low powered and have coke bottle shaped glass. There were/are 6L6GB's from the late 1940's with short straight envelopes, industrial designation 5881, which have more output and can handle more voltage than the 6L6GA. These were the stock tubes in "classic" Fenders. The "last" revision produced the 6L6GC in the 60's which has the highest power output and voltage handling of all the 6L6 family and is usually what people mean when they say "6L6." A "W" in the tube title means military shock rated.

    Unfortunately, tube marketers have been sticking letters with no regard to their actual designation, hence you have Groove Tubes and their "list," Mesa and their "STR numbers", ect. If you follow GT's designations, an RCA, GE, or Sylvania 6L6GC is supposed to be made in either Russia or China, and a Tungsol 6L6GB is a Russian tube. All are old US made designs.

    I would also like to point ot that the new Groove Tube 6L6"GE" is NOT a US made tube. It is produced in China under contract for Groove Tubes using old US materials and jigs, but it is NOT made in the USA. If you read the fine print, you'll notice it says 95% US content. Their "soft and hard" vaccum is a crock, too. A tube with a soft vaccum is a dying tube and will turn white on the glass from air reacting with its getter flash. Tubes with thicker glass are said to be harder vaccum because they can take more heat, and hence, will put out more power before shorting. Saying "soft vaccum" is just marketing spin so you don't have to say brittle glass.

    Yes I am, but not a very good one. :bassist:

    GT's "hardness rating" is a measurement of plate current disappation derived by using a FIXED bias current (NOT to be confused with a fixed bias scheme, but an actual unchanging amount of bias current). Tubes cannot be standardized to such tight tolerances when being made that leeway has to be allowed in biasing to regulate plate and screen current disappation to the parameters specified for each type. IOW, by varying the bias current, you "tune" the tube to the circuit for the proper amount of plate and screen disappation (power). It's not a matter of "feel" or "performance." A tube with a rating of "1" simply requires a much higher bias current than a tube of the same type with a rating of "10." When both are set for the same amount of disappation, they will perform exactly the same; that's how they were designed to function.

    If it sounds like I hate Groove Tubes, I don't, but I am tired of their marketing being passed off as solid tech info.
  12. notanaggie

    notanaggie Guest

    Sep 30, 2003

    PBG has it correct. The only thing I would quarrel with is the STR. STR really was a Sylvania designation, meaning "special tube requirement". It is meaningless without the "requirement number" after it, and pretty meaningless now anyhow.

    Back in the day, the replacement tubes you got were junk, and the best set of tubes your TV or amp would ever have were the originals. EVERYONE got selected tubes to put in at the factory, selected for whatever was important to that usage.

    The leftovers came to the corner drugstore, along with a "tubetester" that probably hadn't been calibrated ever.

    The STR number was just an internal Sylvania designation for the selection criteria on a particular tube. Once a tube type was selected for something, most everyone else went along with it if they could, because the distributions often overlapped, and the manufacturer would try to center their production on the highest usage's spec.

    Info came from a person at Sylvania when they were still making tubes.

    As far as hardness, you can for sure make a Fender sound good or not very good, just by messing with the bias. You can pretty much set it by looking at a 'scope with a signal in. A particular pattern shows up when it is set about right on, and it will sound good then.

    I won't go so far as to say that "hardness" is all BS. There was an old blues player around here, who never changed tubes. Once someone did it when fixing his amp, and he was mad as heck!
    He came back right away looking for those old tubes. He liked them about dead, soft as heck, so they sounded the way he wanted.

    It wasn't a "leaky" gassy tube he liked, it was one where the emission material was worn out. That made the tube soft in a different way, and really did sound good for him.

    I'm not so sure that the kind of hardness spec the tube folks now are talking about is close to the right deal though. It isn't the same thing, and I don't know how much it really relates, Aspen Pittman notwithstanding. (no I'm not a very good guitar player either, but yes I do play)

    There is a lot of BS about tubes, pretty much because the people who made and designed tubes back when they were all there was have mostly passed away now. So now tubes are mystical devices.........bleaghhh.

    Frankly, we like tubes because music was made with them, the sounds we like were developed by people using tube type amps. They found what an amp (made with tubes) could do sound-wise if you did unusual things with it.

    If solid state stuff had been made first, and tubes second, we would probably have a different palette of sounds now. Nobody would have 50 years of tube sound history to compare them to, it would be the other way around.......kinda an interesting thought.
  13. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    Tubes are very subjective (they're right up there with ears). :)

    When looking to replace a 6L6 tube in an old Earth bass amp (or whatever similar vintage bass amp), there are a couple of things to consider.

    First question is, do you want an exact replacement? Most of those old amps will do just as well with 6550 tubes (which sound a lot better for bass, IMO, the main issue is whether your transformer can stand the extra current draw for the filaments, and secondarily whether the bias is adjustable in the right range).

    Second question is, if you want a new 6L6, do you want a "new" one (i.e. a brand new current production tube), or do you want an "NOS" tube (which is a new but "old" tube, usually one they don't make anymore, that's been sitting up in someone's attic for forty years or something). NOS tubes are usually more expensive, but they also sound (debatably) better. And they also last (debatably) longer. RCA's are probably the NOS tube of choice, but there are dozens of brands that sound just as good (GE, Sylvania, TungSol, etc etc).

    Third question is, if you want current production tubes, which ones do you want? Most of the "commercial" ones (like the Groove Tubes) are either Russian or Chinese. Lately there has been a resurgence in popularity of the eastern European tubes, like the JJ's from the Czech Republic, or the Ei's from Yugoslavia. The JJ's are very nice 6L6's to my ear, they sound great and they're reliable too, very hard to kill. I would vastly prefer JJ's to any Russian or Chinese 6L6 version.

    I agree with the folks who've said that the GT (Groove Tubes) rating system is basically just marketing hype. They do make a specific technical measurement when they rate their tubes, but how much it means in the real world is (debatably) dubious. My guideline would be to ignore the marketing hype, and spend an extra buck or two to make sure that my tubes have been checked out, and matched, by the seller. Sometimes they do get a bum tube or two from the factory, so I'd be more than willing to pay someone a "reasonable" price to pre-screen my tubes and make sure they're behaving the way they're supposed to.

    Currently one can find a brand new matched and tested quad of JJ 6L6's for around 55 bucks. One can find cheaper tubes, and one can also pay more for tubes. For me, the next step up from JJ's would be RCA's. I don't like the sound of the Russian 6L6's, and I would go out of my way to avoid putting any Chinese tubes in my amp. So my choices are either JJ's if I'm looking for a good solid reliable set that sounds halfway decent, or RCA's if I have a specific need for a better sounding tube (like maybe recording or something) and I'm willing to shell out the extra bucks. Only rarely would I go out of my way to find anything other than one of those two primary choices.
  14. I have NO problem with original Sylvania STR numbers. I was talking about Mesa appropriating the letters "STR" for their ratings. Mesa's power tubes were initially STR Slyvania 6L6GC's and later Philips 7581's after Philips bought Slyvania. When they quit making them, Mesa kept on using the STR designation for its imported stuff to imply that it was the same as the old US and Western Europe made tubes and confuse the issue.
  15. I would not advise putting 6550s in an old Earth 6L6GC amp. I've never tried it, but I don't think the power tranny would handle it very well. It runs pretty hot as-is. The old Earths are cool as hell, but they ain't Ampegs! :D

    (4) 6L6GCs will draw 3.6 amps and (4) 6550s will draw 6.4 amps. I^2R losses inside the tranny will be 3 times as much if you plug in 6550s.

    That Earth sounds superb with 6L6GCs anyway. No need for 6550s in it. :D

  16. notanaggie

    notanaggie Guest

    Sep 30, 2003
    Yeah, I agree, more mystic nonsense confusing the issue. Although if they really do select to the same spec, so you can intermix new and old indescriminately and have them work well together, I suppose I could forgive them.
    But I somehow doubt that is true, unless internal construction is identical, and I gather it isn't.

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