Effect of clipping on subwoofers ... and tweeters

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Date: August 01, 2003 at 16:05:50
From: Richard Greene, [frasier.ford.com]
Subject: Effect of clipping on subwoofers ... and tweeters

Too much power for too long can damage any voice coil.

Tweeters are especially vulnerable due to lightweight thin wire voice coils needed to keep cone mass low.

If there is frequent amplifier clipping, the cause is 90-95% the person who last touched the volume control and 5-10% amplifier clipping harmonics when a tweeter blows.

For woofers (and for tweeters when there is no clipping) the cause is 100% the person who last touched the volume control when a driver blows.
However it is easier on the ego for that person to blame the amplifier! I hate to blame amplifiers for driver damage!

YOU WROTE:
"I always thought damage could still come from the driver cone moving out of control as the wave form was cut at the peaks and started to look like DC. coil rubbing, spider damage, surround damage. "

RG
Overexcursion damage is possible and the more powerful the amplifier, "the more possible it is"!
Sealed enclosure speakers are less vulnerable than ported speakers.
There is no DC current.
Clipping the peak AC voltages actually sends less power to the subwoofer ... but if you keep increasing the volume control after clipping begins, the sound gets more and more compressed and the average power output continues to increase even though peak voltages can't increase.
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.
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YOU WROTE:
"I guess these problem would also depend on the box design (actual mechanical power handling vs. thermal power handling), but sending a clipped signal to the driver does not help . . .not true?"

RG
The subwoofer driver doesn't care about the clipping harmonics ... just too much voltage from the amplifier for too long and voice coil adhesives melt ... and then the wires break. ... I guess you could say a clipped signal has compressed dynamics and that means a higher average power level (like a TV commercial --consistently loud) which is more dangerous ... but then compressed bass also sounds LOUDER so maybe you wouldn't turn the volume control as high if an amp was clipping (versus a non-clipping amp)?

Clipping is typically intermittent "flat topping"
of bass or lower midrange transients in music.
There are clipping harmonics that add distortion to the tweeter's output without one touching the volume control ... but this only happens when there is clipping ... so constant clipping of a sine wave test tone would be the worst case. Fortunately the clipping harmonics only add about one watt extra power to the tweeter's voice coil. In the old days when paper cone tweeters could not handle much power one more watt was much more dangerous than it is today when even cheap dome tweeters can handle 10 or 20 watts through their high-pass filters.
There is no DC current.
The driver's cone does not stop moving.
If a tweeter can handle 20 watts power than it's possible a 20wpc amplifier can end its life if played LOUD enough for long enough. I guess that means any amplifier can damage a tweeter.

Subwoofer drivers can handle a lot more power although maybe less than they are rated for. Some amplifiers will not be powerful enough to damage a high-power handling subwoofer driver played at maximum output indefinitely, whether there is clipping or not.

If a sub driver can handle 200 watts power then any amplifier rated at more than 100wpc could damage the voice coil. I'm assuming the amp is capable of +3dB over rated output (typical of a decent amplifier,
believe it or not, although distortion would be out of spec and quite high at the +3dB point).

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Follow Ups:

Amplifier Feedback djk 02-Aug-2003 09:34:29 (18)

Right on! Adrian Mack 10-Aug-2003 00:06:29 (6)

isn't he just that good !!!!!!!!!!!!!!!!!!!!!!!!!(NT) norman bates 11-Aug-2003 20:59:22 (0)

Rane Corp. white paper on amplifiers and clipping Richard Greene 11-Aug-2003 12:16:02 (2)

Average Power Increase djk 12-Aug-2003 04:15:13 (0)

Re: Rane Corp. white paper on amplifiers and clipping Adrian Mack 11-Aug-2003 19:16:14 (0)

Adrian!! Derek 10-Aug-2003 00:23:47 (1)

Have not forgot about you Adrian Mack 10-Aug-2003 04:52:13 (0)

Any examples for DIY subwoofers used in homes? Richard Greene 05-Aug-2003 10:22:46 (8)

JBL B380/BX63 djk 08-Aug-2003 03:58:12 (0)

Adire Audio comment on low power amp NOT damaging their sub driver Richard Greene 07-Aug-2003 14:28:01 (6)

Tempest clipping of small and large power amps Adrian Mack 07-Aug-2003 19:27:11 (5)

"You won't protect your speakers by using a larger amplifier" Richard Greene 08-Aug-2003 08:10:19 (4)

Small vs Large powered amplifiers Adrian Mack 09-Aug-2003 22:19:05 (3)

Clipping harmonics not that dangerous Richard Greene 11-Aug-2003 11:12:54 (0)

About DC components in clipping Adrian Mack 10-Aug-2003 00:02:33 (1)

The cone does not stop due to clipping - there is no DC component Richard Greene 11-Aug-2003 11:14:10 (0)

Re: Amplifier Feedback Brian 03-Aug-2003 20:48:15 (1)

Re: Amplifier Feedback djk 03-Aug-2003 21:24:13 (0)

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