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How far can you overpower a cab?

Discussion in 'Amps and Cabs [BG]' started by bassman11302, Dec 24, 2003.

  1. bassman11302


    Dec 3, 2003
    I have an swr 750x and i am going to get a goliath 3 the 4 ohm version. I am curious as to how much i can over power it by. I am going to be running 750 watts into a 700 watt cab and i was told this would be okay but i want to be sure i wont damage anything. Is this okay to do? I also want to know what the highest safe wattage to over power this cab would be.
  2. Gabu


    Jan 2, 2001
    Lake Elsinore, CA
    I have seen a lot of people here that use double the cabs rated power.
  3. BruceWane


    Oct 31, 2002
    Houston, TX
    As long as you avoid clipping the power amp, you can safely use an amp that is 2x the speaker cabinet's RMS rating. A 700 watt cab can be used with a 1400 watt amp. I must emphasise that this is as long as you avoid clipping the power amp. If you see a clip light flashing or hear distortion, you need to back off immediately.

    (actually, you can push even more than that, but you really have to understand a lot of technical stuff to keep from blowing things up, so the best rule of thumb is 2xRMS, avoid clipping)
  4. bassman11302


    Dec 3, 2003
    Thanx for your help guys makes me feel more confident with my rig.
  5. Eric Moesle

    Eric Moesle

    Sep 21, 2001
    Columbus OH
    I regularly run 1500 watts into a 4x10 cab rated for 700 watts. Never a problem, and feeding lots of juice will usually make your cab come alive. Just don't clip your power amp and you'll be fine.
  6. Stephen Soto

    Stephen Soto

    Oct 12, 2003
    Yeah, i hear double. my cab is rated at 600 watts, so i'd probably run 600-800 at most. that's just me though man.
  7. Just be aware that powering a cab with an amp rated for twice the cab's rating is not the same as actually putting that amount of power into the cab.

    Music is dynamic, so for any given period of time, the average power being put into the cab is the average of all the peaks and dips in the signal level over that time period. Even if you're getting the full power of the amp on peaks, the average power will be way less than that. For an example, most amp manufacturers spec AC current draw at 1/8 rated power, because that's about the average power developed when music input hits full power on peaks. This is whay you can do that. If you actually put 1400W average power into a 700W rated cab you'd certainly cook the voice coils.

    Merry Christmas everyone!:D
  8. bassman11302


    Dec 3, 2003
    Hey everyone, I went to the guitar center today to buy the 4 ohm goliath 3 but the sales person was telling me it is better to get two 8 ohm cabs. He was saying that it will sound alot louder because of sound pressure. What do u guys think about this should i get the 4 ohm or get 2 8 ohm cabs. I also wanted to ask you if the goliath 3 and big ben is a good combo for two cabs. Im looking foward to your replies.
  9. There's advantages and disadvantages either way, to me there's not a clear answer. Yes, two cabs will sound a little louder, but you've already got plenty of power, so to me the extra SPL isn't an isue. To me, a real issue is the amount of gear I have to carry around, the old back gets tired of schlepping gear.

    So for me a single 4 ohm cab is better, but if you're young and don't mind carrying another refrigerator, get the two 8 ohm cabs. Remember this though: the salesman wants to make money. And he can make more money selling you 2 cabs than he can selling 1 cab. So what do you think he will advise you to do????

    And as far as power to the cabs, IMHO it's OK to out 750 watts into a cab rated 700. I'd be reluctant to put 750 watts into a cab rated 375, I think that's its getting a little risky when you're grossly overpowering a cab, but that's my opinion.
  10. Mike Dimin

    Mike Dimin Banned

    Dec 11, 1999
    Amen to that.

    The real danger is underpowering your cabinet. That will more readily put you amp into clipping. Mark Reccord is absolutely right. You are rarely, if ever putting the rated amp power into the speakers. Go for the single 4 ohm cabinet and forget about the lifting

  11. bassman11302


    Dec 3, 2003
    Hey I think i am going to get the 4 ohm cab but i am just curious as to how much louder it would be. Would it be noticably louder or just slightly louder. I also wanted to ask you guys about the goliath 3 cab, it says it goes down to 40hz and I wanted to know if it is able to handle the low notes on my five string bass.I am concerned with this because i was told a low B is around 31hz. I will be looking foward to your replies.
  12. Acepiloto


    Aug 25, 2000
    I would probably go with the single 4 ohm cab. The reason I have two 8 ohm cabs is so I can put one on each side of the stage, for my band to hear. You should have seen the look of shock on my face when after the second gig the lead guitarist told me we "HAVE" to bring the second cab every time so he can hear me. Now if I could only get my rhythm guitarist to actually listen to what I'm playing.
  13. Unless you're playing arenas or stadiums, you'll probably not be running your amp wide open. In a regular bar, if you cranked out 750 watts (whether into a single cab or two cabs), the audience would probably be going deaf, and the manager would be asking you to turn down or else.

    So it's like this: Car A can do 135 miles per hour. Car B can do 136 miles per hour. But the speed limit is 55 mph. Which car is faster?

    With two cabs versus one, the theoretical difference in SPL probably would only be a decibal or two, I'm sure somebody else here can tell you exactly.
  14. zoxbassist


    Dec 13, 2003
    Providence, RI
    what is the danger in underpowering a pair of cabs? i.e. if an amp's output is 235 W @ 8 Ohms, can it loudly power a pair of 500 W RMS cabs without damage?
  15. Mike Dimin

    Mike Dimin Banned

    Dec 11, 1999
    OK, let me see if I an explain this. If you don't have enough power to run the cabinets, you, often times, end up boosting the bass, mid and/or treble. If you are boosting frequencies on both your amp and active bass, you might be boosting certain frequencies or ranges up to 30 dB. It takes twice the power to handle every 3dB power increase. IF you think about it - if you boost your amp and/or bass up just 15dB, your asking your power amp to put out 30 times the power. Your power amp, putting out 235 watts is being asked for almost 6,000 watts. This can easily put the amp into clipping. A constant clipping state of the amp will fry the speaker

  16. bizzaro


    Aug 21, 2000
    Someone please correct me here if I am wrong as I am only repeating what have read, and deducted from similar threads here at TB.

    You will get the best performance from your amp cab combination if the Amp is rated for about 3 times the wattage of your cabs. cab=500 watts amp=1500 watts. This will give you plenty of head room and actually help to keep you from clipping your amp. Underpowering your cabs is more likely to cause amp clipping.

    And the answer is:confused:

    EDIT ......This post is regirgitated garbage :eek: ........MY BAD........I would delete it but it has been referenced in other posts in this thread:bawl:
  17. The answer is, do a search on clipping, as this topic has been discussed at great length here. I'm not saying this to be a smartass; it's just that I know for a fact there's been a lot of useful information posted, by people like Bob Lee/QSC and Mark Reccord, and rather than have people post the same stuff all over again, it makes sense to make make use of what's already available.

    As a short answer for the moment, your real headroom gain comes from having a bigger amp than you need to get the volume you want. Once you have a sufficiently big amp, it doesn't matter in the slightest whether the amp is twice the cab's power handling, the same, or half the cab's power handling, as long as none of the components of the cab is being handed too much power to digest or being asked to move more than it can.
  18. 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
    A little caution here. Last night, I played my WT-800 bridged into my 8-ohm 750-watt D-410XLT. No problem, ever. BUT, you can blow a speaker with clean, unclipped power, especially if you're boosting the bottom. If you put enough power in the bass frequencies to drive the speaker past its excursion limit, you will indeed blow the speaker.

    Even though you can use an amp rated at twice the power of the cab, you're looking for trouble if you put that much power through the cab for any length of time. The cab can typically handle transients of twice the cab's rating, but speakers will overheat and self-destruct if you drive it at that level for a set.

    The advantage to having an amp with ample power is headroom to accommodate momentary volume increases. I would recommend against playing a song with continuous eighth notes on the E string all the way through at full power. Many speakers die because people run their amps at full throttle, even though there's no clipping of the pre or power amps. Take heed.
  19. bizzaro


    Aug 21, 2000
    QUOTE]Originally posted by Richard Lindsey
    The answer is, do a search on clipping, as this topic has been discussed at great length here. [/QUOTE]

  20. Undert0ad


    Oct 28, 2003
    nr Philly
    Aiyyo, here's a followup question then. If you have a certain amount of common sense, and have a passive bass, and don't do any outrageous equalization or even compression, and never turn up your amp past 7 because it's loud enough at 6, ...

    THEN it should be no problem to "underpower" a speaker, right?

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