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Tube amplifiers for large 15" and 18" speakers

Discussion in 'Amps and Cabs [BG]' started by jsa0100, Apr 6, 2005.

  1. jsa0100


    Apr 6, 2005
    Hi !

    I have a Peavey 60/60 watt tube amp.
    (2 x 6L6 tubes pr. channel)
    Driven by an alpha tube preamp.
    I am using one of the channels to drive
    a 2x 10" system.
    I would like to add a larger 1 x 15" or 1 x 18".
    And used the built inn crossover ano channel for
    the 15" and another for the 2 x 10".

    How does tubeamps controll / manage larger cone
    speakers ?
    I don't mean sound level, but more about "starting and stopping"
    the speaker.

    The reason that i am asking is that in another band i used to play, we discoverd that som of the smaler power amps.
    Did not handel the 18" very well.

    Do i need a larger power amp (tube or transistor ) ?
  2. popinfresh


    Dec 23, 2004
    Melbourne, Aus
    Well it depends really on what speakers they are and how loud your amp is (I havn't tried one).

    Les claypool pushed four 15" speakers back in the day with one Mesa Bass 400 (300 watt tube amp) easily and it sounded great.. I'm playing on running 3x15"s, 1x10" and 2x6"s with my Boogie 400 when I get one (Or sunn 300T, another 300 watt tube amp)
  3. tombowlus

    tombowlus If it sounds good, it is good Gold Supporting Member

    Apr 3, 2003
    Fremont, Ohio
    Editor-in-Chief, Bass Gear Magazine
    There are certainly tube amps that would do a great job pushing large speakers (Aguilar DB359 and 728, Mesa Boogie 400+ and Strategy 400, Demeter VTHF-300M, SVT, Trace Elliot Valve Series or V4/6/8, ,etc. all come to mind). But, I would have my doubts as to how well two 6L6's would push a bass cab of any size...
  4. BurningSkies

    BurningSkies CRAZY BALDHEAD

    Feb 20, 2005
    Seweracuse, NY
    Peavey listing 2 6L6's as 60 watts is a bit rosy of a spec.

    6L6's tend to run between 20 to 25 watts output per tube, so it's most likely between 40 and 50 watts total. I'd be worried about pushing more than a single 15 without strain.
  5. protoz


    Nov 30, 2000
    The Sunn Sorado is rated at 60 watts and came with a 2x15 cab. But then again it came with 6550's/KT88's which have more head room than 6L6's

    18's are very hard to push unless syou have an efficient cab an a high power head. I would stick with a 1x15 or a 2x12 for your low end.
  6. tombowlus

    tombowlus If it sounds good, it is good Gold Supporting Member

    Apr 3, 2003
    Fremont, Ohio
    Editor-in-Chief, Bass Gear Magazine
    Two 6550's/KT-88's are much better than two 6L6's in this regard, from what I can tell.
  7. IvanMike

    IvanMike Player Characters fear me... Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    i dont think its really about tubes, its about watts. fifteens are atually pretty forgiving of low wattage levels unless they're high wattage subs. almost all eighteens sound kinda "eh" unless powered by some serious watts, and much more so if they're dedicated subs (and face it, a lot of 18's are designed to be subs). when using 18" subs with just the lows crossed over to them, it's not uncommon to use 600+ watts per 18.
  8. protoz


    Nov 30, 2000
    Yea that's true since 6550/KT88 can go over 100w a tube from what I have read.

    Too bad you can't switch out the 6L6 for some KT88's to get more power...

    If you can try a 2x10+1x15 before you buy try it to see if your amp can take it.
  9. I have a D-180 w/an old Fender BXR-115b. I would like to replace the cab w/a Diesel 1x15, but the BXR actually sounds good(so far- I have not used it live). I'm curious as to how tube guys approach amp/cab matching- is it better to overpower, underpower or match as closely as possible? I'm thinking match, as my current setup is 200watts of power w/a 150 continuous/300 peak watt speaker, & it sounds surprisingly good to me.
    I don't mean to hijack; I hope this relates.
  10. The 0x

    The 0x

    Aug 24, 2003
    Timonium, MD
    With tube amps, better to "underpower".

    God, I hate that term. :spit:
  11. This is good to know, & seems to be what most people do w/tube amps. Of course it makes sense since w/tubes you're more likely to push the amp at least close to its limit- I know I will!
  12. The 0x

    The 0x

    Aug 24, 2003
    Timonium, MD
    If I were you, i'd look into Schroeders, as long as the power amp can run at 4 ohms per channel.
  13. It can, & the previous owner(who had two of these)loved Schroeders. I actually just passed up what may have been a great deal on a Schroeder cab- I just wasn't tempted enough. Oh, well- I'm no pro, this is just a(VERY)expensive hobby/obsession!
  14. The 0x

    The 0x

    Aug 24, 2003
    Timonium, MD
    Well, if you want efficiency, but are cheap, you can download some of the Bill Fitzmaurice designs for 10 bucks apiece and build them yourself. Dunno how they compare to the Schroeders, which sound incredible btw.