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What Size Amp Do I Need?

Discussion in 'Amps and Cabs [BG]' started by Wildman83, Jul 29, 2012.

  1. Wildman83


    Jul 29, 2012
    I am building a Dual 15" Sub Box and do not know what size amp I need to power to 15 inch subs. The Subs are coming out of MXT 115 Pro Loud Speakers. Newbie here..just getting started. This is will be for live Sound.

    thanks Guys
  2. Did you get the T/S parms to build a proper sized and tuned box? What are the power handling specs of the speakers? If the box doesn't match to the speaker's needs the two may only handle a 100 watt amp at low frequencies.
  3. Wildman83


    Jul 29, 2012
    See this is how pathetically new I am...I dont know anything about it. I am planning on following a pre maid plan for a dual 15 sub box.......So lets just say I get everything right on the box....the How do I know what size amp I need to run the Subs
  4. Wildman83


    Jul 29, 2012
    4/8 OHMS IMPED

    60 H2-21 KH2 FREQ. RESP.

    200 WATTS RMS


    Here are the speakers info....I am just going to use the subs though

  5. As subs I would not run more than 300 watts RMS into the two (well matched cab to speakers). Low end eats the power handling of speakers REAL fast, faster if the box is not a match for the speakers. 200 watts "thermal" handling is not very good for a 15" to be used as a sub.
  6. Wildman83


    Jul 29, 2012
    So your saying....no more than 300 watt amp to run the subs...What is RMS...and what are you talking about thermal handling...Sorry man..seriously Learning...everything as I go....Do u mean to 15's arent a good idea as a sub...or what
  7. You need to do some learning young wildman. The learning path you seem set on is commonly known as "the hard way". It is littered with broken and fried speakers.

    The other way is to download winISD and design a box with the parameters of your speakers.

    Failing that, copy the specs of the MTX box and double up for two speakers in the one cab.

    Plainly you don't know the first thing about anything speaker related. It's not fair to expect a forum to educate you in the common terms of use in that forum. You can't come on an amp forum and ask "what is RMS?" You might as well be asking "what is a subwoofer?"

    Read some stickies for a few days. Google terms you don't understand and come back with a decent question.
  8. majortoby


    Jul 2, 2009
    Tampa, Fl USA
    Perhaps many issues and questions could be sidestepped by asking the OP just what they are trying to accomplish? Further more to that, is there any reason 15" speakers have been decided upon?
  9. Speakers of opportunity.
  10. majortoby


    Jul 2, 2009
    Tampa, Fl USA
    Opportunity, or misfortune? :D
  11. Watch this space. Odds are on misfortune. Who knows what box has been cooked up with no idea of RMS watttage.
  12. majortoby


    Jul 2, 2009
    Tampa, Fl USA
    I'm right there with you, my (insert adjective for people who inhabit New Zealand) buddy!
  13. The stickies in the FAQs are a very good resource for learning. You do have much to learn, I hope not the expensive way.
    RMS is a mathematical formula to give a reference for power handling or output (in the case of an amp). All speakers are not designed equal. A well designed (and usually expensive) 15" can be a very good sub. A cheap 15" can be a complete disaster.
    Power ratings on most speakers are the "thermal limit" of the voice coil, the point where the speaker starts to overheat and usually measured at 1000 Hz. Most subs run below 120 Hz where the cone movement available (Xlim and Xmax are the T/S parameters here) limits the amount of power the speaker can take before mechanical damage.
    Enough for now ;)
  14. Bassamatic

    Bassamatic keepin' the beat since the 60's Supporting Member

    Speakers of the same size can have vastly different operating characteristics. Putting them in any box without knowing what you are doing is like buying tires without knowing what size, width or type your vehicle requires. Get some help with this from someone with some experience, or you will surely be wasting your time and money.

    If you have plans for a box, it is probably designed for a specific pair of woofers. If not, it may be designed to be tuned to suit the drivers that will be installed. There is no "one size fits all".

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