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Driver failure causes

laurelkurt

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Do drivers fail from underpowered amp clipping or being fed too much power? I see this argued over in Kef speakers FB groups. Seems their full-range uni-q drivers self destruct fairly often, like every other day people post horrific pictures their shredded drivers, as if it's some kind of badge of honor. I've never seen 1 of their mids destroyed though. Thanks.


I already posted this in Newbie area. Nobody responded....
 

richard12511

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Do drivers fail from underpowered amp clipping or being fed too much power? I see this argued over in Kef speakers FB groups. Seems their full-range uni-q drivers self destruct fairly often, like every other day people post horrific pictures their shredded drivers, as if it's some kind of badge of honor. I've never seen 1 of their mids destroyed though. Thanks.


I already posted this in Newbie area. Nobody responded....

I've never destroyed a driver, so no first hand experience. I would think that both problems can damage them, but I'd guess clipping is more likely to. There are AMPs like the Benchmark AHB2 which have sophisticated clipping protections in place, but I'm not sure if most other amps do.
 

Inner Space

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Do drivers fail from underpowered amp clipping or being fed too much power?

Both, but vastly more often from clipping. If a powerful LF waveform is clipped, the elbow of the clip is read by a passive crossover as a HF signal, and the full power of the amp is directed to the tweeter, instantly melting the voice coil wires.

And too much power for too long will melt anything. Once or twice I worked stadium gigs, where the subwoofer arrays are as big as military vehicles, with dozens of 24" drivers, and routinely two or three would need replacement every night.
 

sergeauckland

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Drivers fail from excessive power. With bass drivers it's a case of mechanical damage due to excessive excursion, together with overheating of the voice coil that can melt the glues that holds it together and/or the excessive heat distorts the coil former so the coil rubs against the magnet pole pieces.

Tweeters tend to burn out the voice coil, again from excessive power.

As to amplifier clipping, this generates higher levels of high frequencies due to distortion, and if this is combined with a higher powered amplifier, then the combination will burn out the tweeter. If it's a low powered amplifier that's being used, then even with clipping, it's unlikely that there will be enough HF energy to burn out the tweeter. Possible, but unlikely depending on the actual power of the amp and the rating of the tweeter. The worse possible combination is a highish powered amplifier overdriven to clipping, if the tweeter is a fairly fragile one.

It's mostly a myth that tweeters are burnt out more by a low power amp clipping than a high power amp. It depends on how much power, what tweeters, what type of programme material, i.e. how much HF there is in the music, It's excessive power that does for drivers, LF or HF.

One more benefit to active loudspeakers, drivers and amplifiers can be matched, and with DSP crossovers, HF limiters can act to protect the more fragile tweeters.

S.
 

MRC01

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... It's mostly a myth that tweeters are burnt out more by a low power amp clipping than a high power amp. It depends on how much power, what tweeters, what type of programme material, i.e. how much HF there is in the music, It's excessive power that does for drivers, LF or HF. ...
I agree, but like many myths, it is based on a thread of truth. With normal sounds (like music), amplitude gradually drops with frequency (roughly 6 dB / octave, so each doubling of frequency has roughly 1/4 the power). This means most of the amplitude in a musical signal comes from the low frequencies, and the high frequencies have far less amplitude. So the tweeters don't have to work very hard, most of the time, even when you're cranking it up they're only handling a small fraction of the power.

When the amplifier clips, it changes the frequency/power spectrum of the signal. Now, suddenly there is a lot more amplitude/power at high frequencies than there was in the music. Of course, whether this blows the tweeter depends on other factors.
 
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