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under powering speakers

Discussion in 'Amps and Cabs [BG]' started by GreyBeard, Sep 18, 2008.

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  1. Here is a direct quote from the Epifani Manual.

    2. Don’t severely under-power the cabinets. More
    speakers are blown by under powering than by over
    powering. This is due to the fact that when an amplifier
    is exceeding its ability to deliver a quality wave it will
    put out square waves (bad distortion) and square
    waves rip a speaker.

    What do you guys make of it?
  2. sevenorchids

    sevenorchids Supporting Member

    Hmm...just another reason not to buy Epifani? :) I kid, but...

    My understanding is that the whole concept of "underpowering" speakers is and has been shown to be complete bunk.

    Unfortunate that a manufacturer is still spreading this information as fact. At least we know why people insist on believing it, especially when their cabinet maker tells them it's the truth.

  3. spode master

    spode master

    Jan 21, 2007
    Normally the component that takes the most abuse is The Horn or Tweeter, or at least the L pad in the Passive Xover

  4. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    After it was pointed out here that this is incorrect a retraction was issued and a re-write of the manual was supposedly going to happen.
  5. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    I'd like to know who started this business. Probably someone with high power amps to sell.
  6. Vintage-Blue

    Vintage-Blue Gold Supporting Member Commercial User

    Feb 13, 2008
    Cincinnati, OH
    Owner, Vintage Blue (repro cabinets)
    I've seen this topic show up in many other threads and have always wondered about something. JBL has a document on their website that seems to describe this very thing (http://www.jblpro.com/pages/tech_lib.htm, 9th document from the top). On one hand I wondered if there might be some validity to it, perhaps since it seems to refer more to high-frequency drivers. On the other hand it appears to be a scan of an old document so I'm wondering if it is actually just out of date based on current knowledge in the industry?
  7. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Mark, the way I understand it, if a transient blows a tweeter, it's because the transient clocked in at above its rated power, which can happen on an amp that is underpowered but cranked past its RMS rating. So it wouldn't be the transient that caused it, but the transient being momentarily way too loud for the horn to handle.

    One of you geniuses spot me on that, but that's how I remember it. I've caused a lot of transients in my day and the only time I ever blew horns is on a ridiculously loud one past what it could handle.
  8. jamespetkau


    Aug 27, 2008
    Kelowna, BC
    basically it is saying that driving a small amp into heavy clipping can make bad things happen to good speakers. the reason is partly to do with how some amps can create voltage spikes when being pushed beyond what they are capable of. there is a fine line there between not having enough power to do damage (a headphone amp won't kill your 810 no matter how hard you are clipping it) and having the power to smoke your shiny new cab (think of a 100watt head into your 1000watt cab and trying to squeeze every last db you can out of it). so if you are running your amp at 11 and still are trying to get more, watch out.
  9. Jazzman


    Nov 26, 2002
    Raleigh, NC
    I hear you on that, nothing against Epifani (great cabs), but a statement like that makes me seriously question the companies credentials.

    Similarly AMS's Summer 2008 catalog has an advertisement/article/review about the QSC GX amps, which appears to be endorsed by QSC...it states that "amplifier clipping is what kills speakers." That one little line has had me swear off the entire QSC produce line. :meh:
  10. I understand how it might damage hf drivers but, how could it damage woofers?
  11. mrniceguy715


    May 2, 2006
    I think they where in the car audio world. I lot of there logic is distortion (not the effect, clipped signal) causes stresses that do indeed do harm. But thats mainly because how alot of kids set the car amp. ie crank the gain to get more bass. Only thing I can figure. Until tonight I was using a swr350 redface to power a acme 410 and 8 ohm at that. The amp was rated at 240 at 8ohm and it got lowed without clipping but turn the vol past 2 o'clock and watch that limit light dance.

    I digress, um they where spreading misinformation but as posted they admited they where wrong.
  12. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    I'm not crazy about QSC's cucumbers and onions, but I like their lettuce and broccoli ;)

    It's possible that QSC had nothing at all to do with it other than pay AMS to write a "review advertisement." Or it may have been an oversight someone missed in proofreading. I'd still buy a QSC amp if I needed an amp. Good stuff.
  13. If a square wave kills a speaker...... :confused:

    i thought the idea of a distortion pedal was to create square waves
    Why don't distortion pedals blow our cones?
  14. 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
    Bill ... oh, Billll.
  15. bongomania

    bongomania Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    Distortion does not blow woofers or midrange drivers. And it does not blow tweeters unless the peak amplitude of the clipped waveform stays above the rated maximum power handling of the tweeter.

    The Epifani thing was retracted, and the JBL thing is written for home and car audio where it is common for the high-frequency drivers to be extremely cheap and puny.
  16. Scott in Dallas

    Scott in Dallas Commercial User

    Aug 16, 2005
    Dallas, north Texas
    Builder and Owner: DJ Ash Guitars
    After much thought, I've concluded that the verbage in this discussion is quite often flawed. Over powering a speaker will fry it as certainly as anything else. It's just that a power amp that's capable of cleanly supplying power for the signal, no matter what it's rated, is less likely to cause damage than a smaller power amp that's turned up too loud. In most real-world cases, that could mean a high powered amp that never actually is called upon to deliver too much power because it's always within its range of operation, whereas an amp that's too small is too easy to turn beyond the point where it can cleanly reproduce the signal.

    Funny how human nature is. A guy with an amp that's too small is almost certainly going to turn it up too far at some point, and someone with an amp that's too big is almost certainly going to be really careful with it for fear of blowing something up. :)

    I've got my popcorn ready for the next round of the same fight.
  17. bongomania

    bongomania Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    OK, since you have some popcorn handy, can you explain why all of the speaker and amp manufacturers who have participated in this debate in the past have asserted that they have never once seen an instance of "underpowering" causing damage, except re: tweeters being overpowered?
  18. How true.


    This "underpowering" idea makes my head hurt. :confused::eyebrow::confused:
  19. Scott in Dallas

    Scott in Dallas Commercial User

    Aug 16, 2005
    Dallas, north Texas
    Builder and Owner: DJ Ash Guitars
    As I've already stated, the terminology is flawed. Underpowering a speaker isn't going to blow it. I'm certainly not going to claim that I know what everyone else has stated. I'm not that married to my own opinion on the matter.
  20. bongomania

    bongomania Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    It's not a question of opinion. We're talking science here, physics. The terminology is clear enough.

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