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Comprehensive information on amp/speaker matching

Discussion in 'Amps and Cabs [BG]' started by eleveniseven, Jun 24, 2007.

  1. eleveniseven

    eleveniseven Guest

    Apr 29, 2007
    does anyone have or know where i can find a detailed overview on the proper way to match amp power to speaker ratings?
    for instance: ashdown mag 300, has 307 watts rms into 4 ohms, it has 2 outputs, each one carries well say 153 watts...if the speakers in the cabinet are rated at 200 watts each, should you just run one output from the amp to the cabinet, or should you use a Y connector to run both outputs together to the cabinet to give it the full 307 watts? can you even do that...?
    i read and read and i cant really find a good answer.
    thanks for any help on the matter
  2. Your amp is a SS amp rated at 307 watts into 4 ohms continous. That means it can produce 307 or so watts of clean power continously. However is this rating 20-20,000 cps or is it at just 1,000 hz ? Most good power amps like Crown, Crest, or QSC are rated 20-20K. However, a lot of bass heads are not specific about it so it's hard to tell. Anyway if you pr this amp with a 4 ohm 4x10 cab rated at 300-400 watts you probably will never be able to blow this cab with this amp. However, if the cab has a tweater, you could blow the tweater if you run the amp into hard clipping. This is because most of the tweaters used in cabs are rated at say 50 watts. When you overdrive a SS amp it starts produce large amounts of power in the frequencies where the tweater operates. When a 300 watt amp is operating at say 250 watts, most of the power is going to the speakers and only a small portion of the power going to the tweater. But when the amp starts clipping it starts producing really high overtones (not part of the input signal) so the tweater starts recieving a much larger portion of the power which can fry the tweater. Better cabs have some sort of protection on the tweater to protect this. I personally like to use about 1/4 to 1/3 more power than the cab is rated for. My cab is rated at 700 watts and I use 1200 watts with it. No way I'm ever gonna produce 1200 watts continous of bass. My amp usually runs at about -10 db on a loud gig and that is only 150 peaks and the sound is ultra clean which is what I LIKE.
  3. StoBro


    Jun 2, 2007
    Chances are your Ashdown has two speaker outputs that are simply wired in parallel to each other. You could plug a 4 ohm cabinet into either one and get the full 307 watts. Or you could plug one 8 ohm cab into each and the amp would still produce 307 watts, but they would be shared equally by the two cabinets.

    Unless it's a stereo amp.
  4. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    The amp is rated 307 W at 4 ohms. It has two speaker jacks, but one is speakon and one is 1/4", according to the manual. Just for your convenience depending on what you have.

    So 1x 4 ohm speaker, or 2x 8 ohm speakers will either one be easy to hook up and work fine.

    As for speaker power, with "only" 300W, you can use any credible bass speaker without trouble. Any speaker rated at least 100 to 150W will be fine, and it's pretty hard to find speakers rated for less than that.

    If you use a speaker rated for a LOT more than that, it may not quite produce the tone with 300W that it will with say 1000W. Some high powered speakers "open up" their tone better with more power.

    You only need to use one speaker cable to one speaker from one amp. Don't "y" cord two outputs, that either will make no difference, or cause a problem.

    A very few speakers have separate sections, independently powered, or at least have that option. They are two speakers in one box. But I doubt you need to worry about that.

    Amp info:

  5. eleveniseven

    eleveniseven Guest

    Apr 29, 2007
    cool, thank you all very much for the input on this matter,
    it gets relatively confusing with this stuff, and no one (with the exception of you guys) seems to know what the hell the right answer is, the guy at the local music shop, who has been there for years and years told me that when he buys a speaker, he just looks at the magnet, if it doesnt have a cool looking magnet, he doesnt buy it...??? wow.
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    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

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