TUBE Facts and Info by MartyStrat54

Discussion in 'The Workbench' started by MartyStrat54, May 6, 2011.

  1. southbound suarez

    southbound suarez Member

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    Anyone try any of the late model Sylvania 5881 JAN tubes that are starting to appear on the market? I Noticed that these keep popping up on Ebay in small lots and are the black plastic base with green lettering. True NOS in unopened generic white boxed military packaging with black stamped lettering. Great bargains to be found from a few different vendors. Someone must of uncovered or discovered and released a large lot of these somewhere or are being released at some govt. auction? I purchased four unmatched and untested brand spanking new off Ebay for under $90
    I cant wait to test them. Hopefully we have close enough matching for use as a quad, or at the very least get a pair outta the deal. Otherwise its mod a PP amp or SE use. I think these baby bottle beam driven power tubes might be pretty decent in 5881 Marshalls such as JCM 900's or perhaps a Mesa Lonestar. I will let ya guys know , but I am very curious to hear what others have discovered with these tubes. I also have noticed numerous Raytheon 12Ax7's and made a purchase of supposed NOS tubes but looking at condition of the pins and such I doubt true NOS but likely used test as new like they so often describe as being NOS.... These seem pretty quiet and balanced but not real powerhouse. I am happy with how transparent and resilient they are against microphonics. Especially for a long plate.
    I also scored two Telefunkens from n old 1959 console high fi. These are original tubes with ribbed grey short plates and they are excellent. I am using one inside of a tweed champ circuit and it is nice!
    So what beautiful gems have others scored recently? WHat about those SYL/Jan 5881?
     
  2. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    Yes I have some. The green lettering came off of the ones I was using over time. They are just as or almost as good as Tungsol. They ran on 470V B+ rail with no problems.
     
  3. southbound suarez

    southbound suarez Member

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    Tungsol 5881??? Thats a good thing right? Doh! No experience with the Tungsol. These ones that I got ended up pretty darn closely matched. At least as far as current draw. They certainly are cute little bottles. I bet these would work very nicely to swap out the 6v6's in a fender deluxe reverb.
    Here they are being installed in a JCM 900
    i have faith that they will work out just fine. Good ol' made in the USA genuine New Old Stock, JAN military surplus from cold war era stocks.
    I just gotta get off my duff , offline and back to the bench,,,, er I meant kitchen table!
    1464330636079.jpg Put a Baldwin by Raytheon blackplate 12ax7 in V1 and a very strong RCA in V3 and left original chinese Marshall in V2 inside this JCM900 4102 ..... Be interesting if there is much noticeable difference. 1464330476240.jpg
     
  4. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    Whoops. When I saw yours I had to think back. You have later 5881 black base, good tubes. The Sylvania I was referencing were my earlier brown base 6L6WGB; the precursor, a substitute and sometimes called 6L6WGB/5881. The green lettering was on the glass.

    Oh those tube retainers aint right and will rattle. They should be taut. Those are for larger tubes.
     
  5. southbound suarez

    southbound suarez Member

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    Yes, I know, I noticed the tube retainers right away. I simply rotated the spring bracket 90 degree and bent the bracket flat. This took up the slack without shortening or cutting the springs... I also use those silicon dampners that go between the metal retainer and the top of the tube.
     
  6. zack603

    zack603 Active Member

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    this maybe a stupid question but he was talking about "rolling" all sorts of different brand tubes and trying different ones...im assuming this is mainly for people who are tone chasing with an amp that they are fairly familiar with, but I have an amp that ive only had for about 5 months and have never changed the tubes and am doing a little research on what tubes I want to try...would it help or hurt my cause to figure out what tubes I want then just buy 4 of the same power tubes and 4 of the same pre amp tubes and put them all in at the same time???
     
  7. Micky

    Micky Well-Known Member VIP Member

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    No, it wouldn't hurt. But when buying power tubes, it is important to get a matched quad, and then insure the bias is set correctly after installation.
    You can replace preamp tubes one-at-a-time or all at once. No bias required.
     
  8. zack603

    zack603 Active Member

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    ok thank you...this Is my 1st experience with a tube amp and trying to do as much reading as I can an trying to figure out what I want to try is a little mind numbing
     
  9. southbound suarez

    southbound suarez Member

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    Just a quick followup, on those sylvania nos 5881's ....
    They so far seem to be a very stout and clean tube... very transparent and able to take alot of current too! I haphazzardly ran the plate current up to 49-50 mA for approx 22-24 watts dissapation. The tubes ran hot but barely if any plate glow whatsoever. They did get some saturated creamy goodness but these NOS tubes are too nice for sacrficial tone at no cost type of setup.... we brought em down to a more aporopriate 36mA @ 472V for about a much more reliable and pleasant sounding 17 watts dissapation per tube.
    To really hear the sweetness really requires cranking this amp up to the power tube sweet spot. The preamp in this model amp makes the voicing of the poweramp a bit decieving.... I have bypassed part of the B channel tone circuit and lowered op amp preamp gain to raise input into the tube buffer higher instead, then I run the effects loop with a jumper and run it wide open. This amp is an interesting hybrid with many op amps... I am getting off topic and much has been written on the 900 series. Probably not the best testbed for rolling tubes. But just wanted to mention that if you come across any of these JAN 5881 surplus that are oem late model sylvania, if mine are any indication they are a good bet! I like them and will be looking forward to getting my hands on more as long as I can still find em... Probably the best and only real deal NOS tubes that I have seen in recent days, Made in the USA! Brand new unopened packages, unmatched yet all biased within a just a few 1/10ths of a mA. Outstanding! Very clear and transparent... maybe too transparent, might be better audiophile tube?
     
  10. southbound suarez

    southbound suarez Member

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    QUESTION??? or Survey?
    What would be considered a fair price and what is the current price on those holy grail RCA blackplate side getter 6l6GT tubes
    True NOS in the box and price on used test NOS?
     
  11. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    All you can really do is gauge tube stores, ebay and other sellers to figure high/low pricing. But prices from unreliable sources will not help.
     
  12. southbound suarez

    southbound suarez Member

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    True, that does make good sense, and I suppose I asked a question that is difficult to really answer definatively. I suppose there are many variables and that market prices really are all over the board and that it is anyones guess.... In other words, it is likely that I have or can secure my own preferred reputable sources just as well as anyone.... Ebay prices are easily enough accessible and universally accepted to be indicative of current market trends. Seemingly, kinda lame question on my part! Doh!!!!
    Well, yes ! We do all know those to be the High Digit commodity and is like gold or platinum.... Kinda rude to approach a stranger and ask her how much did that diamond ring cost!? But WtF!? Its only rock n roll... so perhaps I shall rephrase this question and bring it into a more topic worthy subject, more interesting that promotes more discussion.... Ok, with that said,
    A collectible is only worth as much as whatever the amount you may find someone willing to pay...Right?
    (Remember the baseball cards frenzy in the eighties?)
    What would you (anyone) be willing to pay for the NOS tube of your dreams? Such as I find a fascination in the BlackPlate 6L6GC RCA's, of which I think are worth true NOS .... well I dont believe true NOS really exist. So dunno bout true... but I think that nice strong test as new and look clean and minty should be worthy of no more than $200-$225 a matched pair... how realistic am I ? Well if I had a specific application thats the max I would spend... My other Holy Grail is most any of the Telefunken variations of the Diamond 12AX7's.... I have paid $40 per tube for strong late 50's vintage used ribbed short plate with 50%-70% of the white lettering flaking off.... I have come along bargains of these tubes and have bought some that were only medium strength and recieved three or four for under $60.... These I doubt any true NOS are really left .. for a minty clean nice strong test as new I could imagine paying $70-$100 however these are probably usually being sold as true NOS in repro boxes for much more.
    Both of my examples I dont believe in true NOS so in my imagination a true NOS would be a rather priceless thing....
    I very well may have found a source with a very few true NOS RCA but I am skeptical, so not sure what I may be willing to pay, should I get serious about attempting too acquire. The source is indeed reliable and is NOT a electronic vendor that specializes or provides to the AUDIO market segment.
     
  13. aussiebluesville

    aussiebluesville Active Member

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    hi, can anyone tell me if using this tube will harm amp ?
    JJ 12DW7 / ECC832 Vacuum Tube in v2 of a dsl 401 combo
    looking to tame the distortion a little on od1 and od2
     
  14. Matt_Krush

    Matt_Krush Well-Known Member

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    It shouldn't...but with that gain difference, it may be difficult to compensate for volume differences between the channels..
    Try it and do a review. I am interested in this as well.
     
  15. EndGame00

    EndGame00 Well-Known Member

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    You can try a 5751 preamp tube.
     
  16. pedecamp

    pedecamp Well-Known Member

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    I cant post the chart picture but here's how preamp tubes measure up:

    12AX7 - gain factor 100
    5751 - gain factor 70
    12AT7 - gain factor 60
    12AY7 - gain factor 45
    12AV7 - gain factor 41
    12AU7 - gain factor 19
     
  17. Riffraff

    Riffraff Well-Known Member

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    I picked up a Bogen M330 a few weeks ago to do a conversion to and found these beauties sitting under the tube shields.

    [​IMG]
     
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  18. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    Nice tubes.
    What are the codes on them?
     
  19. Coronado

    Coronado Well-Known Member

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    HA! That's awesome! Nice score!!!
     
  20. Riffraff

    Riffraff Well-Known Member

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    I haven't bothered to look yet. All of the other Mullards I have are I63 Blackburn tubes.
     

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