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How much clipping can an cab take?

Discussion in 'Amps and Cabs [BG]' started by semborg, Jul 22, 2005.


  1. So I was in a studio last night. And the engineer took control over my amp and tweaked a little bit.

    The input level was way to high and distorted like **** (If I played loud).
    As I were in another room it took me some time to go and check the amp.

    I was to tired to check if the amp was fine later on.
    Can cabinets take this?
     
  2. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Can it hurt the cab? Yes and no.

    When an amp clips, it puts out more power than it is rated for. The danger with clipping is that you might run a 400W amp into a 400W speaker. If the amp is clipping, it's putting out more than 400W so the speaker might be damaged.

    On the other hand, that same 400W into a 1000W speaker can't hurt it. Even at 100% clipping, that amp can put out 800W or thereabouts of horribly distorted sound. So the 1000w speaker will be fine.

    Clipping in itself isn't the problem. After all, distortion and overdrive pedals clip your signal deliberately and they don't damage anything. It's the increased wattage delivery that you have to be carefull of.

    How many watts was your amp and what's the wattage rating of the speaker?
     
  3. I think its more to do with it putting a flat signal out (when it clips oin SS), this means that the AC is acting almost like a DC current, and the speaker moves out to its maximum excursion point for longer than it should

    I think its something along that line anyway :)
     
  4. 500 watt head (250watt 4ohm)
    250 watt cab (4 ohm)
     
  5. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Nope that's a myth. Clipping is in no way DC. If is mistaken for DC because the speaker "appears" to lock into place as it would if you applied a DC current such as a 9v battery.
     
  6. i never said it was DC, more a flatlining (along top end) AC signal instead of actual peaks
     
  7. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    No, as Mark Reccord and others have explained, this doesn't really happen. First because it's still AC; second, because you're unlikely to get perfectly square waves even with hard clipping; and third, because inertia doesn't let the speaker stop the way you'd think it would just from looking at the plot of an ideal sqaure wave.
     
  8. Ok, fair enough, learn somethin new everyday

    (and yeah, i knew the speaker wouldnt just stop, if it did it wouldnt make the horrible noises you get with SS clipping)
     
  9. Steve S

    Steve S

    Jul 26, 2000

    So my Eden WT 550 will not be able to hurt my 1000 watt Schroeder if it clips?
     
  10. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    It's probably better to think in terms of likelihoods than absolute guarantees. It would depend, I guess, on exactly what's in the Schroeder and how hard you push the amp. I assume the cab has a tweeter? Clipping of that amp probably wouldn't hurt the woofers. However, if you push things hard, it's possible that your tweeter might get hurt. Tweeters, as you know, typically have a rating that's only a fraction of the total cab rating. According to an interesting technical note on the Rane site, clipping can eventually result in a higher proportion of higher frequencies in the signal (which under other circumstances might only be 5-10% of the total signal) than normal, which could lead to the tweeter seeing more power than it can handle. It should be noted, though, that it's also possible to overwhelm a tweeter (or any component) with perfectly clean power if it's delivered in an amount too great to handle.

    A cab can also be damaged by overexcursion, which can occur with clipping but can also occur without any clipping.
     
  11. Jazzin'

    Jazzin' ...Bluesin' and Funkin'

    Let's say there are two cabs in parallel... A 1000W handling cab and a 600W handling cab. What's the maximum wattage they can handle together? is it 1000W+600W or 600Wx2?
     
  12. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Th marketing man's answer is 1600W. The engineering answer is 1200W:-

    If they're connected in parallel, the voltage is split evenly at the amp, so each amp gets the same number of watts (presuming of course they have the same nominal impedance).

    At 1600Watts, each speaker cab sees 800w. Your 600W speaker may run into problems. At 1200W, Each speaker sees 600W and is definitely the safer option.

    But as Richard says, there's more then one way to blow a speaker. Watts is part of the equation. Excursion has to be taken into account. You can have perfect wattage delivery, but if you ask for more lows than the speaker can handle, or feed a vented cab signals which are significantly lower than the cab's tuning frequency, you could creat problems.
     
  13. Jazzin'

    Jazzin' ...Bluesin' and Funkin'

    That's what I thought might be the answer.
     
  14. Ben Clarke

    Ben Clarke Liquidating to fund a new business. Buy My Gear!

    Jan 6, 2005
    Western NY
    If you were just clipping the input with the output at a reasonable level, it would be similar to using a fuzzbox anyhow, at least from the speaker's perspective.
     
  15. The 'flat' portion of the clipped waveform also generates heat. The more sustained the clipping the more heat generated. In excessive amounts the heat can damage the voicecoil. I've seen the aluminum dust cap on a JBL deformed from the heat generated by very excessive clipping.
     
  16. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    The power delivered is what causes the heat, not clipping per se.
     
  17. I Respectfully disagree. The 'flat' 'DC' waveform absolutlely generates heat. Please refer to the many posts re: Underpowered amps. However, if I've overlooked something please let me know. I'm always willing to learn.
     
  18. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    All voltage delivered to a speaker ends up primarily as heat; only a small portion of it is ever converted to musically useful purposes. Lot of power = lot of heat, and in principle it shouldn't matter all that much whether too much power is delivered as a result of clipping or as a result of excessive amounts of clean power. Any time you're delivering more juice than the speaker can deal with, you have a potential problem.

    I've read most of the threads on "underpowered" amps. In most of them it's explained that clipping is not tantamount to a square wave and that a square wave is not DC or anything like it. Check in particular posts by Mark Reccord and Bob Lee.

    here's one:

    http://www.talkbass.com/forum/showthread.php?t=187065
     
  19. IvanMike

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

    Nov 10, 2002
    Middletown CT, USA
  20. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Exactly! Every speaker ever made has a mechanism for dissapating heat. Some have porus dust caps and use the movement of the speaker itself to generate a flow of air through that dust cap, effectively removing hot air from the voice coil region. Other speakers vent to the rear instead via a hole in the magnet.

    More power = more heat. Clipping generates more power.