6L6/5881 in a deluxe?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by frank62, Oct 28, 2005.


  1. frank62

    frank62 Member

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    i have a 65 non reverb deluxe. is there any merit in using 6L6/5881 tubes? my old rca 6v6s are going bad. i have some nos tung sol 5881s. don't want to spend $100 for a new set of rca 6v6s. anyone done this and what are the results? thanks.
     
  2. drbob1

    drbob1 Silver Supporting Member

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    I believe it can be done, I'm not sure it's worth it. You'll spend $50 getting your tech to replace the bias resistort to get it into the right range, and the PT won't really have the guts to get the most out of those tubes. Why not sell them (they're even more valuable than 6V6 RCA Blackplates) and then buy the tubes you want?
     
  3. bob-i

    bob-i Member

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    When I did that I had enough range on the bias to handle it. Sounded great, more headroom and bottom end.
     
  4. Wakarusa

    Wakarusa Member

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    A 6L6 draws twice the heater current and can develop about twice the output power of 6V6. The filament winding of the power transformer won't like the extra load. The output transformer and speaker aren't rated for the extra power. All may eventually fail.

    The failure is usually not immediate. Instead, the overloaded components (transformers, speaker, etc.) will suffer a much shorter life under the abuse.

    When you jack a set of big bottles into a 6V6 amp and everything seems to work, think about the person who jumps off a 100 story building and announces "so far, so good" while falling past the 50th floor. The pavement is still coming.
     
  5. bob-i

    bob-i Member

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    Hmm... you're right on the first point. I forgot that I had a replacement xformer in there that could handle it.

    As for the extra power, you won't actually get enough at the voltages the Deluxe runs to blow the PT. I ran mine for years that way with no ill effects.
     
  6. Wakarusa

    Wakarusa Member

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    Don't think I agree with your second point (the bit about transformers, not about yours surviving.. if it lived, it lived).

    Your average user can and will bias a set of 6L6 to somewhere between 60% and 70% of full power. The additional current draw will drag B+ down to anywhere from 350-380VDC, and, of course, as B+ is pulled down it takes even more current to set the desired static dissipation. For example, a set of 5881 biased for 70% static dissipation at 350VDC will draw 50mA each. By comparison, a set of 6V6 at 70% with the spec 425VDC on the plates draws 23mA each. Finally, the PI in these amps is more than capable of swinging the grids of a correctly biased 6L6 (or 6L6GC) to full power.

    So the result is around twice the current draw on the PT and around twice the power through the OT. Any way you slice it, that's harder on the transformers. (there's also an impact from the fact that you're driving into an 8K primary, but I'm tired and don't feel like doing the rest of the math ;))

    If you're lucky (or don't play it for long periods) then the extra heat may not be enough to kill it. Or you may be unlucky -- I've replaced transformers in more than one Deluxe that's had 6L6 installed.

    Frank asked if it was a good idea to try his Tung Sol 5881. I'd say no. There are decent NOS 6V6 available for less than $100. Might also want to try the JJ 6V6 if he hasn't already (which will be tonally closer to a 6L6 type as well)
     
  7. Wakarusa

    Wakarusa Member

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    One last thought.. I'm betting you can find someone who'll swap you a fine set of 6V6 for those Tung Sols in the Emporium :p
     
  8. frank62

    frank62 Member

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    thanks todd and bob. given the risk of possible component stress and damage i will just use another set of 6v6s and possibly a weber california. the jjs seem to have a very good reputation so i will try some. i may get lucky and find a 62 bassman for the 5881s.
     
  9. Reeek

    Reeek Member

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    I have many, many NIB matched pairs of super fine 6V6GTY's, 6V6G's and 6V6GT's that I would consider a trade for those Tung Sol 5881 in a heartbeat. PM me or email me if you're interested in what I have.
     
  10. Swarty

    Swarty Member

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    FWIW, I've had Tungsol 5881s in a Deluxe Reverb for about 8 years, I just like the way they sound; a bit bigger/bolder. Is it taxing the power transformer? Hard to tell, no seems to have specs for Fender transformers (but mine is regullarly run for hours at a time). If the possibility of a tranformer meltdown makes you squeemish I'd suggest mating it with the proper tubes.
     
  11. bob-i

    bob-i Member

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    It' true that it's hard to find Fender specs, but most replacement Deluxe Reverb PT's have a 5A heater supply.

    So .9 for each 5881
    .3 for each 12AX7

    that's less than 3A.

    The best way to determine if there's an overload is to measure the ACVolts with the 6V6's and then wieh the 5881's. If it drops more than a few % it's overloaded.
     
  12. frank62

    frank62 Member

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    i have asked about this on three different boards and the answers are...don't do it it will burn up your amp and go ahead it will be fine. this is a huge spread. i am going to put them in and see what happens. too many people have said they have done this with no problems.
     
  13. SarasotaSlim

    SarasotaSlim Member

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    Yes it works but it's more fun when you replace the power and output transformers along with upgrading to 6L6s - that way you get a 40-50 watt amp in a small cab with a single 12. If you just stick the bigger tubes in there you won't get the tighter bottom end definition that bigger transformers give. Don't forget to upgrade the speaker too. People have been making steriod Deluxes for years. The Mesa Boogie amp company started when the boogie-man modded a Deluxe (tweed I think) for Carlos Santana (I think).

    I saw Pete Anderson with Dwight Yokum many years ago and he had 2 BF Deluxes with bigger transformers - 6L6s - and EV speakers and it sounded GREAT.
     
  14. Swarty

    Swarty Member

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    FWIW, the DR that I referenced above has a reissue JTM45 OT and an alnico SRO.
     
  15. wgs1230

    wgs1230 Fully Intonatable Silver Supporting Member

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    I've got a 64 non-rv Deluxe which I ran for about 2 years with a pair of GE 5881s during a stretch in the early 90s when dependable 6V6s for bf circuits were hard to come by. Ran it at club volume (7-9), never had a problem with the iron (not sure I see how the speaker would be adversely effected, barring OT failure), but watch out with old rectifier tubes and filter caps: once they burn in at a 6V6 draw, the strain of supplying a 6L6 type can result in bias drift (from an overtaxed bias supply cap), usually apparent as a "cold" or "metallic" sound at the clipping threshold, to plate load fluctuations from a rect. in slow-fail, causing the occasional crackling noises and drop-offs in the clean headroom.
     

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