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Amp/Cab advice needed

Discussion in 'Amps and Cabs [BG]' started by 2coulin, Jan 26, 2004.

  1. 2coulin


    Nov 3, 2003
    Hi all,

    I've been hanging around these forums for a while now, but have never posted. I've been unable to get help with this anywhere else, so I thought I would ask here.

    Basically, I saw an older model Ashdown A(K)BM200 head on Ebay. The seller claims that it puts out 200 watts at 8 ohms, however this seems a bit odd to me, as I thought that most amps were rated at 4 ohms.

    Does anyone own this particular amp? - or know anything about its technical specs?

    Anyway, assuming that the amp is 200 watts at 4 ohms, will this be sufficient to power a David Eden 210XLT (350 watts/8 ohms)? I'm not after a ridiculous amount of volume, but enough to power small-medium size gigs. Or will I be at risk of damaging the cabinet from "underpowering" it?

    Any advice would be greatly appreciated!
  2. luknfur


    Jan 14, 2004
    There's plenty of 8 ohm amps around. Go to harmonycentral.com and look it up under user reviews, if you don't find that particular unit you'll find enough Enden info to draw you're own conclusion but the dude should know his amp and I'd bet it's 8 ohm, though I'm not into Edens.

    Running an 8 ohm speaker through a 4 ohm will get you half the volume output, but you can do it. Whereas throwing a 4 ohm speaker load on an 8 ohm amp will stress it and perhaps toaste it, especially if it's tube and cranked.

    As a rule, you want the power of you're amp to be about 75% of your speaker power load (so you don't sweat blowing speaekrs) or you're just wasting speakers. But you want the ohm load to match your amp for a fact.

    Good luck
  3. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    He probably means it puts out 200W @ 8 ohms and 300W-ish @ 4 ohms. Ashdown haven't been around for very long and I'm pretty sure that all their amps will drive a 4 ohm load happily.

    It really depends on how loud your gigs are and how bassy your tone is. Watts are so cheap I'd keep an eye out for something more powerful.

    There is no such thing! So called 'underpowering' is actually overpowering caused by running the amp into clipping so that it puts out up to twice its rated power. However you'll only get this kind of damage if the amp's RMS power is greater than half the speaker's RMS rating. (You can still cause damage due to over-excursion rather than voice coil overheating with low powered amp but that's a different matter).

    So in this case, if you drove the amp into hard clipping it could be putting out more than 350W which could overheat the speakers.

    If you want to get the greatest volume out of a speaker cabinet, your best bet is to use an amp with twice the RMS rating of the cabinet, which will give you enough headroom to not clip on peaks whilst still being unlikely to deliver an average power level greater than the RMS rating of the speaker due to the dynamic nature of bass signals (and music in general). That's what the 'program' rating of speakers is based on.

  4. 2coulin


    Nov 3, 2003
    Thanks a lot for your responses guys - I appreciate it. I think I'll play it safe and let the ashdown go.

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