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Ashdown ABM500 into 2 4ohm cabs

Discussion in 'Amps and Cabs [BG]' started by 513rocks.com, Mar 8, 2005.

  1. 513rocks.com


    Sep 22, 2004
    Mason, Ohio
    ok here is the deal. i have an ashdown abm500 head, a genz-benz 6x10 cab @ 4ohm, and an avatar 2x10 pro @ 4ohm. i was just play through the genz benz cab and thought i would plug a speaker cord into the benz and run it into the avatar and see what happened. well what happened is the best bass sound ive ever heard!!! i dont know if its the two tweeters (one in each cab), the top cab being at ear level, the fact that the avatar cab if real bright and the benz cab is real full or what but it is so awesome!!! is this safe to do? i guess im only getting half the wattage outta my head but it is louder and clearer than running either cab alone. ive never heard of anyone using 2 4ohm cabs at once. let me no if its safe to do. i might use it live if it is safe. its a 8foot tall monster stack :)
  2. TheChariot


    Jul 6, 2004
    Boston, MA
    The deal with ohms is the opposite of what your thinking...

    Two 4ohm cabs = 2ohms. The ABM doesnt go down that low... or at least, it wasnt designed to.

    The nice sound you have it probably from having more speakers.... that always sounds really nice and new. But... I'm afraid with a pair of 4ohm cabs, you shouldnt continue to do this.
  3. Th9nker


    Mar 18, 2002
    Yes stop doing that.. now...
  4. STOP STOP STOP, if you continue you will fry your amp and cause alot of damage.

    Lets hope you havnt caused any damage already, big no no dont do that again unless you want to buy a new amp fairly soon.
  5. the dude

    the dude Supporting Member

    Sep 19, 2004
    Two 4 ohm cabs (or four 8 ohm cabs) is not a problem as long as you use one of these.

    An alternative is a special cable that basically hooks them up in series so that your amp sees 8 ohms.
  6. 513rocks.com


    Sep 22, 2004
    Mason, Ohio
    yeah i thought it out after i posted this thread. it did sound amazing though. i only did it for a couple min. at a low volume so i didnt hurt the amp. see what a water bong and too much stuff sitting around can get you into..... KIDS DONT TRY THIS AT HOME!!! :)


    Jan 25, 2005
    Des Moines, IA
    Thanks for the knowledge! This is a good list to have access to
  8. Joe P

    Joe P

    Jul 15, 2004
    Milwaukee, WI
    Thanks, Man - that list is valuable to me. I'm thinking of going with four Avatar twelves (8-Ohm each), so it looks like my amp choices are narrowed-down considerably...

    You know, this constantly re-occurring subject of what heads can and can't be used with what, or 'if you use this head with this bottom you'll never achieve even half the power from the head' or whatever, is really driving me nuts. MOST of us aren't getting our money's-worth out of our amps, and most of us think that we have to lug another cab around just to get our amp's rated power!

    This impedance-matching job is a no-brainer with transformers!! I can hardly believe that using an impedance matching transformer is not a completely regular, normal part of bass rigs! ..It IS for tube amps, but those output trasformers are expensive to build because of the huge transformation ratio that's going on! Those things have to be wound with very many turns of very fine wire, and these thousands of turns have to withstand many-hundred-volts of stress.

    I mean for line level stuff or coupling transformers or isolation transformers or high-voltage trasformers or pulse transformer or polyphase or high frequency, etc - designing and building and specifying them can get tricky and expensive, but having a low-Z cab reflect-through to an even lower-Z amp at a not-hugely-different impedance is comparably easy for a magnetics designer! I'm saying easy to design, easy to build, no exotic materials or complex winding methods, no appreciable side-effects or anything that could hurt an amp...

    I've been in the transformer buisness for coming-up on a dozen years now (as a Lab Tech). I'm seriously thinking about doing something about this. I know that there's at least one company that makes something that's supposed to work, but there are a few grey-areas in my mind as to how they're going about designing and marketing these things!

    Wouldn't bassists WANT these if they offered completely transparent, high-fidelity operation, and could optimize the power output of any amp, and could convert impedances either way (match one 8-Ohm cab to a 4-Ohm head OR 2-Ohms-worth of cabs to the same head - getting the same max-watts-out into either)?

    Tell me, People! I could have one of these designed within a month, build and test a prototype in another month or two, build and send-out a couple prototypes to some TB'ers in the next month while I'm dealing with a tranformer house to build the first couple dozen each for maybe 300W or 600W continuous rating... It wouldn't take that long to just simply STOP these decisions - Simple, standard procedure could just be order a universal 'former for the max-wattage or your choice, and never worry about it agian. Just buy or trade any heads and bottoms you want - Let's say I could pull-off a safe, reliable unit that works continuously at full power in up-to say 150° ambient temp, with up-to a 600W head, and converts 1, 2, 2.7, 4, 8, or 16 Ohms to 2, 4, or 8 ohm heads?

    Wouldn't many of us want one of these? I would think that it could be built and sold in not-too-huge quantities for... I dunno, maybe under $0.50-a-Watt?



    Jan 25, 2005
    Des Moines, IA

    I'm in!!! :hyper: