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Too many watts?

Discussion in 'Amps and Cabs [BG]' started by Spinmaster, Jan 21, 2005.


  1. Spinmaster

    Spinmaster Guest

    Jan 21, 2005
    London
    I've got a gig this weekend and I need advice fast!

    Basically, my previous amp head (a Warwick 300W) broke last year leaving me with my 350W 4ohm 4x10 cab. I got a 400W head for Christmas and haven't got round to buying an extension cab to cope with the extra 50W that my new amphead has brought. Now, the gig is on Sunday so I need some advice ASAP!

    Can I run my 400W head through my 350W cab? I know it sounds like a silly question because it will probably blow the cab but I thought I'd check first.

    Any answers?
     
  2. Your cab will befine, firstly your cab is probably rated at 350w rms, most cabs will take twice this short term peaks etc.

    You would have to run your amp flat out to ever worry the cab, as long as you dont start clipping ( distortion ) this causes more blown speakers than 50w extra power.

    Have a great gig
     
  3. Bigwan

    Bigwan

    Feb 22, 2002
    Ballymena (hey)
    Yes, you can. Most people around these parts will recommend that you use an amp with double the power rating of your speaker cabinet(s) rating.

    I can't imagine that you'll have any trouble at all - if you're that worried about it just don't turn the amp up all the way...
     
  4. Spinmaster

    Spinmaster Guest

    Jan 21, 2005
    London
    Cool, that's great news. But something I don't get, why have your speakers set at a certain wattage only to get recommended that you can push it double that?
     
  5. Really? I've heard the exact opposite - Your cabs should have twice the wattage of your amp to handle it properly...

    Strange.
     
  6. Spinmaster

    Spinmaster Guest

    Jan 21, 2005
    London
    Yeah, this has got me stumped. I always thought it would have been common sense to have your speakers having a higher threshold than the amp can throw out.
     
  7. wulf

    wulf

    Apr 11, 2002
    Oxford, UK
    The reason for having a more powerful head than cab is that what tends to damage speakers is a distorted signal. Therefore, it's healthier to have the amp working well within it's capacity and sending a nice, rounded signal, than turning everything up to 11 and forcing the speakers to jump to the loud, clipped, distorted sound.

    Of course, that does presume the discipline of not turning all the controls all the way up!

    Wulf
     
  8. Spinmaster

    Spinmaster Guest

    Jan 21, 2005
    London
    Cool, so I should be alright for this gig if I use my 400w head into my 350w speakers provided I don't get anywhere near clipping, yeah?

    I'm not so much worried about the head because it's under warranty, I'm mainly worried about the speakers because they're not under warranty.
     
  9. Dont worry it will be just fine, keep your bass input to the amp so it doesnt clip, all will be just great.

    Mart
     
  10. I like the idea of power amps pushing twice as much power as the cabs rating. A powerful amp gives your headroom to work with. You can achive nice volumes without pushing your amp towards clipping. At least that is what I figure. I am running a QSC-RMX 1450 (1400 watts bridged @ 4 ohms) into 2- 8 ohm cabs that are rated 250 watts each. I have no problems. Of course I never need to turn it up past half way up acheive high volume.

    I would think the best deal would be a powerful head and pretty high rated cabs (ie- 1,600 watts into a cab with 800 watt rms). That way you can get major power without really pushing the amp amd you would not have the power to harm your speakers.


     
  11. ARRRRRRRRRRGGGGGGGGGHHHHHHHH!
     
  12. Eric Moesle

    Eric Moesle Supporting Member

    Sep 21, 2001
    Columbus OH
    Let's see how many times, in how many threads, this exact issue can be discussed . . . . arg. :meh:
     
  13. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    My thought exactly. How many times, in how many ways? There really should be a sticky on this stuff.
     
  14. IvanMike

    IvanMike Player Characters fear me... Staff Member Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    :D :D :D

    a couple of things
    1st off, i don't think your head can handle a 2 ohm load so an extension cab is out. most heads are rated as being able to safely power a minimum of a 4 ohm load. adding another 4 ohm cab will give you a net impedance of 2 ohms, adding an 8 ohm cab will give you 2.67 ohms. either way is no good.
    you are so close with 400 watts going into a cab rated for 350 i wouldnt sweat it at all. You're really only going to be putting the full 400 into it at your loudest peaks, and if you're that close to the amp's limit you're probably going to hear some clipping anyway and have to turn down.
    clipping in and of itself won't damage speakers. however, most solid state amps start producing twice their rated power when they clip. clipping a 350 watt amp into your cab would give you 700 watts. not cool. A lot of us use a good amount of headroom to keep our signal clean. Say i was using a 700 watt amp with that speaker. 700 watts is only 3 dB louder (just noticeable) than 350. If i was running it as loud as you would with the 400 watt amp, most of the time i might only be putting a max of 175-200 watts into it at most. Probably more like 100 watts. that woudl give me 6-9 dB of "headroom". i wouldnt be turning it up to the point where the speaker would start to be overdriven as i could hear that. every once in a while i might have a transient not that went up to four or five hundred watts, which your 350 watt cab should be able to handle as short "peaks". Using the 400 watt amp the same way woudl have me "clipping" every once in a while, putting 700 watts of icky sound into that cab, possibly blowing it if i kept it up.
     
  15. You have to know what to expect on these type forums (especially one this large). It is like listening to pop radio. If you listen long enough you hear the same song "over and over again" ..... (cause it's all in my head)!

    Why would you read all the way down to the bottom of a thread that has been beat to death anyway? The title was far from deceptive.
     

  16. My 'ARGH' was more about erroneous information......
     
  17. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    +1
     
  18. Joe Beets

    Joe Beets Guest

    Nov 21, 2004
    PLX 2402 bridged into one Eden 112XLT, no problem, and I will never get tired of posting about it.
     

  19. OK :D. Get a tone generator. Set it so that it's putting out a 100Hz (or pretty much any other frequency in the audio band) sine wave at about 1.5V RMS. Connect that to the input of your 2402 and your 112XLT. The 1.5V input will drive the 2402 to full power (1500W@8Ohms). Time how long the 12 lasts before the VC melts. I'll bet dollars to donuts that it will fail in less than 30 seconds. Then you will understand that there's a huge difference between powering a 250W rated cab with a 1500W amp and actually putting 1500W into the cabinet.

    On second thought don't do that. ;)

    It is totally ok to power cabs with more powerful amps because music is dynamic. So on average, even if you're hitting the clip lights from time to time, you're only putting a fraction of the amp's power into the cab.
     
  20. 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'm getting some new EAW SBX 220 subs for my PA. They're rated at 1,400 watts program. The tech folks at EAW recommend power amps having 1.5 to 2.0 times the rating of the cabinet. I'm going to bridge one PLX 2402 into each one of the subs, for 2,400 watts each. It's all about headroom.