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How important is matching wattage to cabs?

Discussion in 'Amps and Cabs [BG]' started by morebass!, Dec 29, 2004.

  1. morebass!

    morebass! I'm all ears Supporting Member

    May 31, 2002
    Madison WI
    The power ratings on the Avatar cabs are sky-high! If I have 550 SS watts would I be able to drive the 1400-watt 4x10 or should I just get the 700-watt 2x10? Do I really need 700+ watts to drive a 2x10? I remember the days when 200 watts was a lot. Now some folks say to have twice what you're cabinet is rated at. By that logic I'd need 5600 watts to drive a couple Avatar 4x10s ?!?

    All I want to do is get a nice complement to my 400 watt Tubeworks 4x10 cabinet. Both will be driven by my Crest V900 (bridged) in parallel so I won't be able to separately control the level going to each cabinet. So I'd like something roughly equivalent. I know power rating does not equal efficiency but efficiency does not equal efficiency either if you know what I mean.

    So many questions. Thanks for your input.
  2. metron

    metron Supporting Member

    Sep 12, 2003
    Your 550 watt amp is fine. No need to have more power dissipated from your amp then your cab is rated at unless thats what you want. Dont forget that 'underpowering speakers' is a bit of a myth. Be aware that you may be able to blow your speaker with an amp thats has an RMS output rating thats less then your cab rating.
  3. jdagger


    Nov 21, 2004
    With headroom versus power amp clipping issues aside (already covered in this forum), a ratio of lower power amp watts into higher watt rated speakers is not going to be a problem.

    IMHO, while it is relatively well understood what is considered to be a harmful SPL level (your gonna fry your ears if you do this), everyone of us probably has a different definition of what "loud enough" is. The goal SPL level of the band is going to be a driving factor in determining the desired power output. Some cabs are just rated for those that like it "cranked."

    Knowing that bass frequencies are not as well perceived by the human ear as higher frequencies is one basis for the theory that bass needs lots of watts to achieve the same apparent sound level.
  4. eots


    Dec 18, 2004
    Morris, IL.
    using an i800 amp(1000watts @2 ohms) on a pair of wizzy cabs(250 watts each @ 4ohms). Yeah, you could blow the speakers if you max'd it out but he said the cabs like being overdiven as long as you don't get crazy with it. He compared it to flooring the gas pedal when going around a corner.
  5. The secret is in what sort of signal you put into them. If you keep your gain down and present a nice clean signal to the power amp, you're not going to have any trouble.
  6. wneff

    wneff Supporting Member

    May 27, 2003
    Woburn, MA

    from the way you asked the question there seems to be a misunderstanding how the whole speake / power amp thing works.

    1) The power amp pushes power into the speakers, the speakers don't "suck" power out of the power amp (but they push some of the power back into the amp which the amp then has to deal with. Thats called damping. ). The power rating means: "How much power is this amp able to supply to a speaker."

    2) How much power you really push into the speakers depends on how high you turn up your amp and how hard you plug the strings. You can have a 500 W amp and a 1000 W speaker, and when playing in your church you actually only put 0.1 W into the speaker.

    3) The speaker has the job of dealing with all that power it gets. Speakers use most of the power for heat and about 10 percent to make niose. The rating here means: "How much power can the speaker handle before overheating".
    A little note here: Bass speakers usually don't die of overheating, so the power rating really doesn't mean much for bass. Most speakers die because of the movement of the cone being excessive. This movement is strongly dependent on the signal and usually not specified. Even though your speaker is rated at 350 W, it can be killed with about any amount of power (lets say 100W) by applying the "right" signal.

    Here is the deal:
    1) Power amp: As long as the power amp sounds clean in the loudest situation you're fine. A power amp cannot have "too much power for a speaker", but your speakers may not have enough power to handle the power you're putting into them. In this case turn down or add another speaker, but to use a smaller amp will make the situation worse.
    2) Speakers: A speaker can never have too much power handling. The more power handling the speaker has, the less likely it is to die.
    You can find out how much a speaker can handle by turning up your amp in an otherwise silent room and listen for the point where the speaker doesn't sound clean anymore. Back off until it sounds clean and remember these settings. As long as it sounds clean it is very unlikely that you'll damage anything, no matter what the funny numbers (power ratings) say.

  7. to put a simple answer to your question, I used to use a SWR SM-500 into an Avatar B120 and B212, bridged it was rated at 500 watts and never had any problems getting a good sound out of the cabs.

    I think the power ratings on avatar cabs are a little crazy, they will take a lot of power but you can get by just fine with a lot less. you should not have any troubles shaking some widows with 550 watts into the B410 cab.
  8. morebass!

    morebass! I'm all ears Supporting Member

    May 31, 2002
    Madison WI
    Thanks everyone. The source of my concern is that when speakers started getting rated higher, thinking of when 200 and 300+ watt drivers became available, they also seemed to get less responsive at lower volumes. I don't want a speaker that only sounds good when it's really loud. Some of the best sounding speakers I've played through have relatively low power handling and so I'm starting to think that I should look for that. Yeah it means more speakers are needed for larger venues but that might be the ticket for my sound.

    Funny that the whizzy came up. That's a cab I've been considering. Probably won't get one now though as I'm in a loud band. I'm looking at going with two 400 watt 4x10s. At 550 watts for each out of my Crest it should be a pretty good match.
  9. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    You have to be careful when your amp has less power than your speaker ratings. You can safely drive a 1,000-watt speaker with a 500-watt head, to a point. The problem arises when you turn the amp up far enough that it wants to exceed its maximum power. Suddenly, it begins to clip and send those hideous square waves over to the speaker. So the bottom line is, if you hear a crappy sound coming through your cab, turn it down, not up. The problem with this setup is some folks discover that 500 watts of amp doesn't give them the volume they want, and they keep turning it up and ask, "Why does my amp keep farting?" then turn it up some more. Then, dead speakers.

    So, bottom line, go ahead and hook it up, but be very carefull about how hard you drive the amp. I just got reprimanded by the folks at EAW for mentioning that I was going to run two 1400-watt subs off of one PLX 3402 (1100 watts a side at 4 ohms). I really need at least 2,100 watts a side for those subs. For the time being, I doubt those subs will see more than 600 or 700 watts, so I'm going to wait 'til I get a PL6 or something before I crank them up.
  10. IvanMike

    IvanMike Player Characters fear me... Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    as long as you get the volume you need with the rig you have and you aren't clipping the amp or overdriving the speakers (you'll hear it - especially if you play byyourself for a sec) then it's all good.
  11. wneff

    wneff Supporting Member

    May 27, 2003
    Woburn, MA
    I agree with your observation.
    Here is what I think happened, but I am not a Historian on Speakers.

    In the "olden days", like when I started, power was really expensive, my 400 W head was one of the strongest amps out there.
    Since there were not a lot of high power amps out there there was no demand for speakers that could absorb a lot of power. Instead the focus was on efficiency of the cabinets so you could get loud even at low power.

    Then MOSFets came along and power got much more and cheaper, following the demand for higher power speakers companies used glue that can stand higher temperatures and Kapton coil formers. With the higher power handling capabilities of the speakes it was now not that important that they have an extremely high efficiency and companies instead made the speakers more afforable (smaller magnets) or made them sound better (fewer resonances)