amp clipping

[Jim Carr]

Thanks dude. Geezer-hood is the price...

 

[Christov]

The speakers voice coil is used to seeing an AC alternating current sinusoid signal. It then transforms these signals into the notes that you hear through the speaker. The voice coil is designed to work with an AC signal for audio. When you clip, if you were to look at the signal on an oscilloscope you would see the top of the sine wave is cut off, so as others have mentioned it creates a square wave which has a DC direct current voltage to it that heats up the voice coil and usually destroys it. A lot of voice coils are made of Kapton or some other material that is very heat resistant, but not all. Just because your speaker cabinet is rated for 400 watts, and your amp is "only" 200 watts does not mean it is safe. A lower powered amp driven harder into its clipping range will be applying plenty of voice coil killing DC. Pay attention to your lights, just like the gauges in your car, they are there for a reason.

 

[Mark Reccord]

The speakers voice coil is used to seeing an AC alternating current sinusoid signal. It then transforms these signals into the notes that you hear through the speaker. The voice coil is designed to work with an AC signal for audio. When you clip, if you were to look at the signal on an oscilloscope you would see the top of the sine wave is cut off, so as others have mentioned it creates a square wave which has a DC direct current voltage to it that heats up the voice coil and usually destroys it. A lot of voice coils are made of Kapton or some other material that is very heat resistant, but not all. Just because your speaker cabinet is rated for 400 watts, and your amp is "only" 200 watts does not mean it is safe. A lower powered amp driven harder into its clipping range will be applying plenty of voice coil killing DC. Pay attention to your lights, just like the gauges in your car, they are there for a reason.

Oh dear God, not again.......

 

[el_Kabong]

Uh oh, looks like a broken Reccord...... (sorry Mark!)

 

[Richard Lindsey]

Oh dear God, not again.......

It's like weeds, or something.

 

[billfitzmaurice]

The speakers voice coil is used to seeing an AC alternating current sinusoid signal. It then transforms these signals into the notes that you hear through the speaker. The voice coil is designed to work with an AC signal for audio. When you clip, if you were to look at the signal on an oscilloscope you would see the top of the sine wave is cut off, so as others have mentioned it creates a square wave which has a DC direct current voltage to it that heats up the voice coil and usually destroys it. A lot of voice coils are made of Kapton or some other material that is very heat resistant, but not all. Just because your speaker cabinet is rated for 400 watts, and your amp is "only" 200 watts does not mean it is safe. A lower powered amp driven harder into its clipping range will be applying plenty of voice coil killing DC. Pay attention to your lights, just like the gauges in your car, they are there for a reason.

All perfectly logical, and none of it true. Clipping kills midranges and tweeters by increasing the midrange and high frequency content of a signal to far in excess of normal. Woofers are immune to ill effects from clipping, as clipping does not result in an increase of low frequency content to a signal.

 

[ChrisPbass]

If this guy is propagating false information repeatedly then he should be banned from this forum. I say this with all due respect considering my turbo-newbie status on this forum.

/pet peeve/ - people reguritating false information! RARRRWWWW!!!

 

[Sundogue]

All perfectly logical, and none of it true. Clipping kills midranges and tweeters by increasing the midrange and high frequency content of a signal to far in excess of normal. Woofers are immune to ill effects from clipping, as clipping does not result in an increase of low frequency content to a signal.

And that would be true, under the assumption that you have separate woofers and mid-range speakers, and tweeters.

Most commercial cabs are loaded with full range bass speakers, and aside from having a tweeter, they do not have separate woofers.

So while what you said is true, if your clipping blows out your "mid-range" speakers...your woofers are shot too...because they are the same speaker.

Just wanted to clarify, just in case someone took from your reference that their "woofers" were safe from an amp driven into clipping regularly enough to fry them.

 

[Bob Lee (QSC)]

And that would be true, under the assumption that you have separate woofers and mid-range speakers, and tweeters.

Most commercial cabs are loaded with full range bass speakers, and aside from having a tweeter, they do not have separate woofers.

So while what you said is true, if your clipping blows out your "mid-range" speakers...your woofers are shot too...because they are the same speaker.

Just wanted to clarify, just in case someone took from your reference that their "woofers" were safe from an amp driven into clipping regularly enough to fry them.

No, what Bill said is true.

 

[Sundogue]

No, what Bill said is true.

So, I can drive my amp into clipping severely and I don't have to worry about frying my woofers?

Cool!

Except when I fry my mid-range speakers by doing that, I'm going to have to replace my woofers at the same time anyway...because they're the same speaker.

I'm not dismissing Bill's comment at all. But some might take his comment as inferring that you can just go ahead and drive your amp into clipping all night long without worrying about anything but your tweeter.

 

[Bob Lee (QSC)]

So, I can drive my amp into clipping severely and I don't have to worry about frying my woofers?

Cool!

Except when I fry my mid-range speakers by doing that, I'm going to have to replace my woofers at the same time anyway...because they're the same speaker.

I'm not dismissing Bill's comment at all. But some might take his comment as inferring that you can just go ahead and drive your amp into clipping all night long without worrying about anything but your tweeter.

If your woofer and mid-range are the same transducer, then clipping won't damage the mid-range. It might sound like crap, though.

What damages loudspeakers are excessive power and/or excessive excursion. Driving an amp into severe clipping will make it put out much more power than it's rated for. Depending on the amp and the loudspeaker, that additional power may or may not be enough to cause damage. Excessive power is potentially damaging to a loudspeaker, whether the signal is clipped or clean.

 

[seamonkey]

Here's an article that talks about asymmetrical waveforms and how they can impart a DC component. Probably not enough to cause damage to a pro sound woofer.
Link Removed
I have noticed that some HiFi class-d modules are DC coupled so DIYer may want to add some filtering/blocking

Also, clipping itself may not harm the mids/tweeters, but increased mids/highs from the non-clipped portion may harm them. see the Rane article:
[Invalid or Expired Link Removed]
(Hint if the HF sounds bad - turn down the HF)

 

[Sundogue]

If your woofer and mid-range are the same transducer, then clipping won't damage the mid-range. It might sound like crap, though.

What damages loudspeakers are excessive power and/or excessive excursion. Driving an amp into severe clipping will make it put out much more power than it's rated for. Depending on the amp and the loudspeaker, that additional power may or may not be enough to cause damage. Excessive power is potentially damaging to a loudspeaker, whether the signal is clipped or clean.

Well, that certainly muddies things up.

What damages loudspeakers are excessive power and/or excessive excursion.

In and of itself, excessive power is potentially damaging to loudspeakers. Obvious.

Driving an amp into severe clipping will make it put out much more power than it's rated for.

More often than not those who blow their speakers, use heads without sufficient power in the first place, to drive their cabs. When they can't hear themselves, they keep turning up. Eventually they drive their amp into clipping.

Excessive power is potentially damaging to a loudspeaker

As you said, clipping will make it put out much more power than it's rated for. So in essence, clipping is potentially damaging to loudspeakers.

It isn't the clipping that causes the damage, but the resulting excess power generated from that clipping, correct? Because too much power, be it clean or clipped can damage speakers.

Still, just so the techno-talk doesn't confuse anyone...

Don't run your amp into clipping!!! If the clip light is staying on...you might damage your speakers from excess power.

In a way, it's semantics from a user standpoint. Damaged speakers suck, no matter what actually caused it.

I just don't want anyone to be under the assumption that they don't have to worry about anything but the tweeter in their cabs if they clip their amp, because Bill's comment (true as it is) kind of infers there is nothing to worry about regarding your woofers (some will read as "bass speakers")...even though that's not what he meant.

 

[Richard Lindsey]

I just don't want anyone to be under the assumption that they don't have to worry about anything but the tweeter in their cabs if they clip their amp, because Bill's comment (true as it is) kind of infers there is nothing to worry about regarding your woofers (some will read as "bass speakers")...even though that's not what he meant.

They should also not be under the assumption that they don't have to worry about their speakers at all if they're not clipping. As Bob said, excessive power and overexcursion are the problems, and you can get either of those with "clean" as well as "dirty" power. That's why so many people on this board object to the automatic equation of clipping with speaker damage.

 

[Bob Lee (QSC)]

If you have, say, a 4Ω woofer-only bass loudspeaker cabinet rated for 1000 watts continuous power, and a power amp rated at 100 watts continuous into 4 ohms, then even driving it into insane amounts of clipping will not cause damage. The amp just won't put out enough power to damage the loudspeaker, and clipping, though not a good practice, by itself is not dangerous.

But if the cabinet's continuous rating is, for example, 500 watts and the amp's is 400 watts, then during heavy clipping the amp's output could exceed the loudspeaker's rating and cause damage.

 

[billfitzmaurice]

Except when I fry my mid-range speakers by doing that, I'm going to have to replace my woofers at the same time because they're the same speaker.

No, they aren't. A midrange driver is just that, a driver intended to be used in the midrange only and not below a specific frequency, usually 300 to 500 Hz. A tweeter (high-frequency driver) depending on its design is intended to be used only down to 2.5kHz to 6kHz.

A driver that is designed to operate below 100 Hz is a woofer. The fact that you may be using it to reproduce the midrange doesn't make it a midrange driver. You can play golf with a beach ball if you want to, but that doesn't make it a golf ball.

If this guy is propagating false information repeatedly then he should be banned from this forum.

I'd give him the benefit of the doubt and say that he is merely uninformed.

It isn't the clipping that causes the damage, but the resulting excess power generated from that clipping, correct? Because too much power, be it clean or clipped can damage speakers.

No. An amp will put out as much voltage and amperage ( the product of which is watts) as its power supply is capable of delivering and no more. 100 watts of clean sine wave and 100 watts of pure square wave is 100 watts, period.

In an average 100 watt music program signal perhaps 25 watts of the content is midrange, and 5 watts high-frequency. Therefore a midrange driver and tweeter intended for use in a 100 watt system need only handle 25 watts and 5 watts under normal circumstances. Clipping adds to the midrange and high frequency content of the signal. In theory with enough clipping there could be 100 watts of midrange content and 100 watts of high frequency content, and the midrange and tweeters are toasted. But overall power never exceeds 100 watts, so the 100 watt woofer is not affected.

But if the cabinet's continuous rating is, for example, 500 watts and the amp's is 400 watts, then during heavy clipping the amp's output could exceed the loudspeaker's rating and cause damage.

Bob's referring to transient peaks, which can be much higher than the rated amp output but only for very brief periods. With heavy clipping you're more likely to have transient peaks than with a clean signal, but woofers are designed to handle those transient peaks, and the distortion will be so bad well below where driver failure would occur that a prudent person would turn it down first.
__________________

 

[Sundogue]

If you have, say, a 4Ω woofer-only bass loudspeaker cabinet rated for 1000 watts continuous power, and a power amp rated at 100 watts continuous into 4 ohms, then even driving it into insane amounts of clipping will not cause damage. The amp just won't put out enough power to damage the loudspeaker, and clipping, though not a good practice, by itself is not dangerous.

But if the cabinet's continuous rating is, for example, 500 watts and the amp's is 400 watts, then during heavy clipping the amp's output could exceed the loudspeaker's rating and cause damage.

Understood.

 

[Richard Lindsey]

As you said, clipping will make it put out much more power than it's rated for. So in essence, clipping is potentially damaging to loudspeakers.

No, not exactly. Bob's formulation was really a better way to think about it, and here's why. The fact that a clipping amp puts out more power than it's rated for does not, in itself, mean that that power is an any way "excessive" in terms of the speaker's power-handling capacity. As an example, take a 30 W Behringer amp and a 1000 W subwoofer. You can indeed make that amp put out more than it's rated for, but nothing it's capable of doing is anywhere near excessive in terms of what that speaker can deal with. Practically speaking, clipping is a problem when it results in overpowering or overexcursion, and not otherwise.

 

[Sundogue]

They should also not be under the assumption that they don't have to worry about their speakers at all if they're not clipping. As Bob said, excessive power and overexcursion are the problems, and you can get either of those with "clean" as well as "dirty" power. That's why so many people on this board object to the automatic equation of clipping with speaker damage.

I agree, but I think most (not all certainly) speakers get damaged by those who have a 300 watt head and pair it to say, a 500 watt cab and drive the head too hard. You know...the old scenario of not having an adequate power amp in the first place, but still trying to crank it to hear themselves.

Obviously you don't want to go full power with a 1000 amp into a 500 watt cab either, but I think the first scenario is the one that happens more frequently.

I would think a 1000 watt head driving a 500 watt cab would get sufficiently loud enough to not even get to the point of cranking it to stupidly loud levels and damaging speakers (though I'm sure it does happen). Considering the cab has decent enough sensitivity, that is.

 

[Jerrold Tiers]

A DC component to a clipped signal is from an AMPLIFIER issue.....

If it DOES exist, YES it can cause a problem by "biasing" the voice coil partly out of the gap, so that part of it is never in the gap and does not get cooled by the magnet structure.

No woofer has ever been damaged by clipping. Clipping only damages midranges and tweeters.

That is SO CLOSE to being true, but it IS NOT COMPLETELY TRUE....... I have had the pleasure of seeing and dealing with the results when it happens.

It all depends on the clipping, AND on the speaker power vs the amp power.

First, yes, it DOES depend on teh speaker power handling.... BUT THAT IS NOT "ONE" NUMBER...

Power handling is based on cooling. And cooling happens, 80% plus of it does, by the voice coil dumping heat (300 deg maybe) into the much cooler and very close magnet structure. Like putting your hand near but not touching a block of ice, you can "feel the cold" as the heat leaves your hand.

OK....

Now, a lot of woofers have a voice coil LONGER than the magnet top plate......for cone movement reasons. So they depend on the coil spending some time in the gap to cool it. That happens naturally at low frequencies as the cone moves fairly slowly through the gap, getting cooled when it is in the gap.

Clipping, if hard clipping at more power than the speaker should handle, tends to shove the coil through the gap fast, and "bottom" it at the limit of travel, then reverse that. The rate of that movement may be pretty fast, not like a sine wave, but a square wave.

And, the cone tends to stay "stuck" at the end of its travel if clipping is at a low frequency.

If you have your low EQ boosted so that the speaker is operating below box tuning, its even worse.

So, what happens? If any part of the coil is exposed at both ends of the cone travel, it can get cooked but good. You see a charred ring around the coil, and the wire typically falls off into the gap as the glue fails. Kapton formers may be distorted and melted

The charred area may be at one end, for a DC-biased clipping, or in the middle, if that area is shoved out at both ends of travel.

In really extreme cases of over-powering, the coil can be pushed right out, and may land misaligned on top of the pole piece. And/or the paper tears or is folded, mushed, whatever.

Now, basically, if you have ears, your speaker can handle reasonable power relative to the amp, and your band is not out of the "Hitchhiker's guide", this SHOULD not be an issue for you.....

But to say flat that it CAN'T be an issue, is not so. Bands and players vary...... don't assume *nobody* does what you don't do, because, somewhere, somebody is doing that very thing now..... I used to know a player who routinely played loud enough to bang the voice coils against the magnet, AND KINDA LIKED THE EFFECT......