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Another Wattage Question

Discussion in 'Amps and Cabs [BG]' started by steriogenesis, May 21, 2003.


  1. I have a peavy bass head (really old)...Pushing 210 watts@4ohms into a Hartke 410xl (400rms) and an Avatar B115H (600rms)

    I am assuming that I will need a more powerful amplifier to keep away from any big problems...

    But for the time being, at safe volumes and with minimal peak light indications, will this be safe and adequate?
     
  2. You'll be fine. The only problem is that people tend to push their amps harder with under powered cabs to get more volume from them, thats where the damage can come from. As long as you are good to your amp, it will be good to you.
     
  3. hey. would that head happen to be a mark iv model? two channels, bi-ampable... i have a mark iv that has the same wattage and i was really just wondering if you have any suggestions as to obtaining a decent slap sound from this amp. if you could help me work out some eq, it'd be greatly appreciated. thanks dude.
     
  4. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    Much depends on how much volume you actually need, i.e., how loud you play. Only you know that. If your current amp gives you all you need at moderate settings, then you don't have an urgent problem that you need a bigger amp to solve. However, if you're constantly pushing your current amp too hard, so that it distorts, or your amp sounds like it's straining, or you can't get the oomph you need from your sound, then yes, you'd most likely benefit from a bigger amp. Don't worry about the cab ratings too much; they don't have anything directly to do with whether your amp is big enough or not.
     
  5. Reefer

    Reefer Guest

    Mar 9, 2003
    The most common problem is pushing your under powered amp where distortion will fry your voice coils. Your safer with a 1000 watt amp into a 200 watt speaker than a 200 watt amp into a 1000 watt speaker.
     
  6. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    This has been gone over many times in many threads, and it's not quite true. It's not distortion per se that fries speakers; if it were, there would not be a Celestion guitar speaker alive on earth (think of all those Marshalls), and all SVT users would blow all their speakers as soon as they got a little "hair" on their sound. One way or another, it comes down to too much power, whether "distorted" or "clean", being delivered to a component that can't handle it. If you push that 1000 W amp hard, you quite possibly will blow that 200 W speaker. And even if you push that 200 W amp hard, it will most likely only put out 300-400 W max, meaning you are not likely to blow that 1000 W speaker. Though if it has a tweeter, you might blow that, because tweeters typically have a relatively low power handling capability.
     
  7. Reefer

    Reefer Guest

    Mar 9, 2003
    What kills speakers? Simple CLIPPING

    CLIPPING
    Clipping is the result of asking an amplifier to try and make a voltage signal larger than it is capable of. We know speakers move back and forth. The amount by which they move is determined by how voltage we apply to the speakers voice coil. If we can't increase the voltage, then the speaker can move no further. The problem is that which we are listening to music, and all is going along fine, and suddenly some guy bring in a deep bass line, the speakers are asked to move much further, If the amplifier can not provide enough voltage to move the speaker far enough, it simply stops at the end, and waits there to return backwards.
    Since no movement is occuring, you essentially have a stove element. Yep, the one where you make your macaroni and cheese. This voice coil continues to heat up untill the glues hold the wires in place fail, or the connection to the cone or spider overheat and fail. And there you have it, a blown speaker.
    Sure you can over power a speaker, but as I said you are safer with more power than not enough!
     
  8. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    I don't think it's quite that simple. If you do a search, Bob Lee, Mark Reccord, and others have made some good posts on this subject.

    If simple clipping is the problem, why don't the speakers in all rock guitar amps fry? When you crank a Marshall, you are getting a clipped signal. Why doesn't your speaker immediately blow when you use a fuzz box? Why have I been able to overdrive a 130 W Peavey into a 400 W E-V for a full 3 set, 5 hour gig without harming the speaker?
     
  9. NeedMoreBass

    NeedMoreBass unregistered

    Feb 14, 2003
    Acme Bass Co. is correct, clipping will fry speakers. He obviously confused distortion with clipping on his first post. More power is better than not enough.
     
  10. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    Clipping IS distortion, by definition, though not all distortion is clipping. You don't have to have a pure square wave to have a clipped signal; clipping happens as soon as you start to shear off the top of the wave. Of course more power is good for bass players, I just react to what I think makes no sense, i.e., the idea that having a cab rated at a much higher power than your amp renders you more likely to damage the speakers. If your amp is big enough for the level of acoustic output you're going for, and your speaker can handle the level of power typically used, you don't have a problem.

    Take this thought experiment. Imagine an amp that puts out 200 W at 4 ohms. Then imagine two speakers, both 4 ohms and both with the same sensitivity, so that they have equal acoustic output for the same input. Imagine further that speaker A has a power handling capability of 200 W and speaker B 1000 W. Finally, imagine that the amp-speaker A combination and the amp-speaker B combination are both used by the same player, playing the same music in the same setting in the same place. Can you seriously argue that when these variables are controlled for, speaker damage is *more* likely when the 200 W amp is used with the 1000 W speaker than when it is used with the 200 W speaker? If so, that renders the whole idea of power handling capability nonsensical.

    And neither of you are addressing the other point, which is that if clipping is so dangerous to speakers, you ought to see much more speaker damage than you do. Namely, nearly every speaker in nearly every guitar amp in nearly every rock band on earth.
     
  11. NeedMoreBass

    NeedMoreBass unregistered

    Feb 14, 2003
    When the amplifier clips it is sending raw DC current through your speaker, and it WILL destroy your voice coil, and hence the driver itself. Never ask an amp to do more than it can do. If you DO have 100Wrms and an 18" speaker for example, then to avoid clipping I would not turn the volume control up very far at all, and thus this will greatly limit your SPL output. Your much less likely to blow a 10" with 800W than an 18" with 100W. Remember that if you have your volume control at the 12o'clock position, this does not guarantee that your pumping 50% of the amps total power output, it is a very poor indication.
    If you want your 100W amplifier to produce this at 0.5% THD, it can be made to provide 200W, but at a much higher distoriton level. It is also using DC signal (harmful), rather than the normal AC signal operation (safe).
    Clipping sounds like a type high frequency, hard distortion.
     
  12. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    From everything I've seen, read, and experienced, this just isn't true. Clipping simply is NOT the same thing as DC. I've just never seen the slightest evidence that you can blow, say, an 800 W 18" with a 100 W amp. If that happened routinely, I'd have a lot of dead speakers!

    Check out this thread, particularly with regard to what Bob Lee, who's a QSC engineer and thus has far greater expertise than I do, has to say:

    http://www.talkbass.com/forum/showthread.php?threadid=47193&highlight=clipping
     
  13. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    I hate to keep coming back to this but ... maybe it's because I'm a guitar player too and so have direct experience with guitar gear.

    When you crank a Marshall or a Vox AC30, what do you think is happening in that power amp? That's right, it's clipping. By your argument, that should fry the speakers. Why doesn't it? If that question can't be answered, then it makes no sense to say that clipping, *in and of itself and regardless of the power handling capacity of the speaker*, damages speakers.
     
  14. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    No, the speaker doesn't stop moving when the signal clips. That's a myth that seems to have originated with someone who knows very, very little about amplifiers or loudspeakers.

    Speaker damage from clipping is the result of excessive power: either overexcursion (too much power at too low a frequency) or overheating (too much power for the voice coil to safely dissipate).

    You can clip a 200-watt amp into a 1000-watt (continuous power) speaker driver and it won't harm the speaker unless the frequency is too low, although it will sound like crap.
     
  15. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    No, it isn't, unless the amp was designed and manufactured by grossly incompetent people.
     
  16. so after reading this all...would you consider, at reasonable volume levels with no distortion, that this setup is safe for the amp and speakers?
     
  17. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    Yeah, pretty much.
     
  18. I believe it is (I'm not near it right now)...But its a Mark 'something'....I just picked it up last weekend...I need to take it to my rehearsal area before I can really make it sound how I like (I do play alot of slap) ...Sometime around Saturday or Sunday I'll tell you how it goes...
     
  19. Reefer

    Reefer Guest

    Mar 9, 2003
    We are talking about an OLD Peavey here!
     
  20. Are you saying that is a good thing or a bad thing (I apologize if I'm sounding stupid...)