Converting 2 el-34 amp to 4 el-84

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers T' started by jp-90, Jun 1, 2013.

  1. jp-90

    jp-90 Member

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    Is this possible without an entire rebuild? I know I likely couldn't do it, but if you swapped out/added new sockets, how much more would you have to modify?
     
  2. RussB

    RussB low rent hobbyist Silver Supporting Member

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    Transformers & power supply
     
  3. jp-90

    jp-90 Member

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    So, the transformers likely couldn't handle the change down to lower power? If a transformer swap was needed, I'm guessing it would be a pointless endeavor. But if it could be done (material-wise) for the cost of sockets and a few cheap component swaps in the power supply--maybe worth trying?
     
  4. gldtp99

    gldtp99 Member

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    Most EL84 tubes won't handle the voltage level in a typical EL34 guitar amp---- they would have a very short life span, maybe only seconds.
    Now if you were to use 6V6's (JJ 6V6S will handle the voltage levels) then this is an idea that could be done...........................gldtp99
     
  5. jp-90

    jp-90 Member

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    I see, so voltage would remain constant even across 4 el-84s? I suppose 6v6's could be interesting, I'm just not too familiar with them.

    I love the el-84 amp I have and the el-34 amp I have (traynor ygm and yrm). I'm curious about something in between.

    THANKS for the input
     
  6. RussB

    RussB low rent hobbyist Silver Supporting Member

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    Unless you enjoy doing this kinda stuff yourself, it is not "worth it"
     
  7. jp-90

    jp-90 Member

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    Ha. yeah, well it would definitely be way more than I've attempted, but so far I've really liked tinkering with amps. I thought about building a 4 el-84 kit amp, but it seems it could be cheaper (all amp modding sacrilege aside) to convert an existing amp so long as a minimum of new parts were required.
     
  8. RussB

    RussB low rent hobbyist Silver Supporting Member

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    Frankly, there is nothing cheap about building your own amps, because time is valuable too :)
     
  9. dazco

    dazco Supporting Member

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    try yellowjackets. I see them in the emporium fairly often for about $50-70 a pair.
     
  10. gldtp99

    gldtp99 Member

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    Here is a Hiwatt (Sterling) Lead 30:
    [​IMG]

    Notice the EL84x4 output tubes----- this amp was designed from the ground up to use EL84x4 output tubes------ this means that the power supply and output transformer are spec'd for EL84x4.
    An amp designed for EL34x2 output tubes has a different set of design specs.
    Maybe Weber has some EL84x4 kits you could build ?........................gldtp99
     
  11. jazbo8

    jazbo8 Member

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    Give us the spec for your current amplifier - power trafo and OPT and we can take a look, it may be doable even if not optimal...
     
  12. J M Fahey

    J M Fahey Member

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    Unfortunately, "the iron" is by far the most expensive part in any amp cost calculation.
    Sorry .
     
  13. DGDGBD

    DGDGBD Supporting Member

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    Just the fact that you would have to punch two additional holes in the chassis and retrofit the other wider octal holes for 9-pin holes, IMO, makes it not worth the hassle. Better off building from scratch or just buying a 4-el84 amp to use or re-wire to your liking.
     
  14. jp-90

    jp-90 Member

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    Thanks for the tips everyone. In the end, I imagine a ground up kit build would probably be best, but in the meantime I'll keep asking questions.

    Ok, how about a second option: Start with a ygm-3 (2 el 84) and convert the power section to 4 el-84. I assume the transformer(s) would have to be swapped, but at least I'd only have to add two sockets without converting the existing sockets. Thoughts? Harder, easier, or just as absurd?

    Jazbo, I'll try to find the transformer specs for the YRM. thanks.
     
  15. jazbo8

    jazbo8 Member

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    Converting the YRM-3 is not possible, since its transformers were spec'd for 2 6BQ5/EL84 only, so it can not handle 2 more EL84s... But if you have the transformers for an EL34 push-pull amp, as long as you watch the screen voltage, then putting a pair of EL84 in parallel per side in their place, it could work ok IMO.
     
  16. jp-90

    jp-90 Member

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    Jazbo, if the transformers were changed out, could the rest of tthe ygm-3 circuit be easily tweaked to handle 4 el-84? I realize that would be costly.

    Or are you saying that the way to go would be convert from el-34 to 4 el-84?

    And it could be as easy as running them in two parallel pairs? (Don't worry, I won't attempt this on my own. just want to learn more.)
     
  17. jazbo8

    jazbo8 Member

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    If you change the transformers, then of course, the YGM-3 could be modified for 4xEL84, but I am a bit confused, since you started the thread by asking about the conversion from 2xEL34 to 4xEL84...
     
  18. jp-90

    jp-90 Member

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    Sorry to confuse. Basically I initially thought about converting a Traynor YRM (2 el-34) to a 4 el84 amp. My thought for this was that it may be doable without changing the transformers. When someone mentioned the hassle of converting the large holes to smaller, el84 size, I figured I'd ask about coming from the opposite direction--That is, converting a traynor ygm (a 2 el84 amp) into a 4 el-84 amp.

    So, at this point I could do either and figured I'd just ask which method would be better suited for conversion to 4 el-84's.
     
  19. jazbo8

    jazbo8 Member

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    I see, then YRM is doable if you add two more holes & sockets to the chassis, assuming the space is available, and your DIY skill level ;-)
     
  20. blueworm

    blueworm Member

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    What you could do is to add a small tank under the chassis covering the 2xEL34. With the 4 holes drilled for 4xEL84 sockets. You need have enough room for the 4 tubes not too close, and make sure that it's OK running all the wires through the two holes left by the EL34. That would make the mod reversible, you only need screw hole for fixing that tank.
     

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