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a simple question..

Discussion in 'Amps and Cabs [BG]' started by fleabass89, Apr 10, 2001.

  1. i know a head that delivers x watts at 4 ohms can work with a 4 ohm cab or two 8 ohm cabs. but let's say the cab handles 600 watts and the head only delivers 400 watts. Will this work? Do the watts matter or not? maybe this question is just totally stupid..
  2. Jerry J

    Jerry J Supporting Member

    Mar 27, 2000
    P-town, OR
    Generally the power rating listed on a cab are to indicate that that is the maximum amount of continuous power that can be handled. There are variations on this but the max amount is the most common listing.

    Now keep in mind that a specific speaker could handle 600 watts max but still get toasted by a 400 watt amp. If an amp is driven to a high level of distortion (clipping) you could damage the speaker.
  3. so the amp should at least deliver the same amount as the cab can handle?
  4. ASR


    Apr 2, 2001
    Houston, Texas
    No, you should NEVER max the cab out. That is playing with fire. As far as the other questions, I'm lost.
  5. alembicbones


    Nov 10, 2000
    Seattle, WA
    In general, I think it's more advantageous to have amp that can deliver more power than the cab is rated for. That being said, you don't want to open your amp full bore in to the lesser cab. The idea is to sent a pure, clean signal to the speaker cabinet from the amp. If you're consistently clipping your amp, thus regularly sending a dirty signal to the speakers, you're probably causing undo wear on your cab, and eventually, frying it.

    Common sense in this department always rules.

  6. 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
    I drive my 700-watt Eden D-410XLT (8-ohm) in parallel with a 350-watt D-210XLT (also 8-ohm) with an Eden WT-300 head. This is a total speaker power capacity of 1050 watts driven by a 300-watt head. It is no problem. The key is just to avoid turning the amp up so high that it clips, producing the speaker-annihilating square waves. I also sometimes just run the D-410XLT and the amp. Since the speaker cab is 8 ohms, the maximum power out of the head is probably about 200 watts. Still no problem.

    I don't think you'll have any problem at all with your setup, unless you're one of these "crank it to 11 at least once" guys.
  7. rllefebv


    Oct 17, 2000
    Newberg, Oregon
    A lot of good points raised here! In this case, since we're talking pretty high wattage, like Munji says, you shouldn't have a problem... When you go into this with a 'seriously' underpowered head, you know, your basic 100 watt solid state head, playing at the local outdoor death-metal get together, that you're going to crank the sucker, bring out all those pretty square waves, and blow something up!

  8. MikeyD


    Sep 9, 2000
    Clipping does not guarantee that speakers will fry. If your speaker has a tweeter, you can certainly damage it, but if it has only woofers - or the amplifier that is clipping is only driving woofers (e.g., in a bi-amped system), it may or may not cause damage.

    Case in point 1: Guitar amps. These are commonly overdriven into severe clipping or distortion, and the speakers can take it for hours because they are rated to handle the signal's entire power content.

    Case in point 2: I have an old Kustom head that probably delivers 50-80 watts RMS into 8 ohms. I've spent many an earlier day in rock bands overdriving it into a 2x15, constantly clipping it heavily with no damage whatever to head or cabinet. Why? The 2x15 can take up to 200 watts continuously, but the clipped output of the head was maybe 160 watts total maximum (i.e., double the RMS sine value).

    So this is just to clarify that not all clipping situations cause damage. If you have a 700 watt RMS speaker, it is highly doubtful you'll damage it with a 200 WRMS amp, no matter how hard you drive it. But you do need to know the limits, because a 400 WRMS amp, driven into heavy clipping, can harm a speaker rated at 700 watts.

    Again, though, if you have a tweeter, you may be asking for trouble unless it has a good tweeter protection system (light bulb or fuse, for example).

    - Mike
  9. thanks guys, i think im starting to understand this.
  10. BassDude24


    Sep 12, 2000
    Now you were wondering about the watts. First you have to look at what kind of watts you are looking at, two different readings are generally given, there is the peak(how much it can handle on a burst) and RMS (how much it can handle continuously) You generally want to match the two readings when you are looking at an Amp/Speaker selection. You want to make sure you get a head and cab. with similar peaks and RMS.

    It is generally better if you have the option, to get a larger amp then cab. cause you can turn down the volume on the amp and not have to worry about blowing it up. On the other side, if you get an amp that is weaker than what the cab. can handle, this can turn into disaster, I once read that this can be worse than overpowering. Apparently, by underpowering a speaker, the AC current will change to direct and screw up the magnet.

    So that is all I have to say about that.
  11. rllefebv


    Oct 17, 2000
    Newberg, Oregon
    Hmmmm... I've blown 2 400W cabs with a 150W at different times. Only took twice to learn that lesson... Since those days I've never driven any cabinet with less than the equivalent of it's rated wattage... Never had a problem since...


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