Forgive me here as I'm not familar with speakers themselves as I tend to focus on playing guitar. Our sound man regularly mentions that passive speakers can be damaged from being underpowered by an amplifier WHEN the underpowered amp reaches the clipping point. Is this true or false?
Will Underpowering Speakers Cause Damage?
- Thread starter Jack Karie
- Start date
By underpowered I mean when the passive speakers support much more wattage than the amp can output to each channel. Example; two 400w RMS speaker cabs on a 200w powered mixer powering 100w or less to two channels.
A 400 watt speaker being driven by a 100 watt amp that is running with the random flicker of the clip light, not a problem other than that you need larger amp. Getting a larger amp then increases the chance of damaging the speaker depending the amp and the speaker power rating.
Thanks for the reply. I'm begining to understand that speakers deteriorate from a distorted sine wave form - which is released from a clipping amp. Horns and tweeters from what I understand take the most abuse.
A clipped audio waveform starts to turn into a square wave, as in "clipping" the tops off the audio wave form.
The very general amp power rating guide for a speaker is double what the speaker is rated at, That will give you 3db of head room. Again that's a very general guideline, depending on real operating conditions results may vary.
The very general amp power rating guide for a speaker is double what the speaker is rated at, That will give you 3db of head room. Again that's a very general guideline, depending on real operating conditions results may vary.
A clipped waveform (square wave) has more power than a sine wave of the same amplitude and is why smaller amps got a reputation for being detrimental to speakers.
"Why did my 100w. amplifier blow the 200 watt speakers?"
Because all speakers have a limited amount of time before the voice coils can no longer dissipate the heat... and most operators who clip amplifiers continuously have no clue that the square waves have more more nor how long the loudspeaker will dissipate it's rated power.
So it's not just that an amp is clipping, it's how "hard" the clipping is and for how long.
Compression drivers/tweeters have very small voice coil wire and not much thermal capacity so they will die first, usually.
Jack, keep this in mind: loudspeaker transducers die for one or both of 2 reasons (there are no other operational reasons) - physical damage to the cone, voice coil "spider" or cone suspension due to over-excursion; and heat due to overpowering.
"Why did my 100w. amplifier blow the 200 watt speakers?"
Because all speakers have a limited amount of time before the voice coils can no longer dissipate the heat... and most operators who clip amplifiers continuously have no clue that the square waves have more more nor how long the loudspeaker will dissipate it's rated power.
So it's not just that an amp is clipping, it's how "hard" the clipping is and for how long.
Compression drivers/tweeters have very small voice coil wire and not much thermal capacity so they will die first, usually.
Jack, keep this in mind: loudspeaker transducers die for one or both of 2 reasons (there are no other operational reasons) - physical damage to the cone, voice coil "spider" or cone suspension due to over-excursion; and heat due to overpowering.
A square wave has 2x the power of a sine wave of the same amplitude, with the extra energy taking the form of harmonics (specifically, the harmonics are all odd harmonics, with each harmonic having the amplitude 1/n, where n is the number of the harmonic). What this means in practice is that if you drive an amplifier into hard clipping (so that you are getting square waves out), the power delivered to the loudspeakers may be up to 2x the rated power of the amplifier. Now, as for the high drivers, if we consider the case of a 100W amplifier driving an 800Hz into hard clipping (so it becomes a square wave), the high driver is going to see a bit less than 100W (and your low driver will also see around 100W). Now, high drivers aren't generally rated for the same full power as the low driver, so that's generally a bad situation. But in practice, the crossover will be dissiapting a good chunk of that power (through the frequency dividing function, and through the pad that's likely present to get the sensitivity of the high driver in line with that of the low driver), so that will help matters. But you still run the risk of frying equipment. OTOH, if you aren't clipping your amplifier, you have nothing to worry about.
Hello
One more explanation - as others already said in other words - when clipping, your signal gets much more harmonics - odd and even - or overtones - and the x-over in the cabinets puts them all into your tweeter - just the way it is designed to do. This will kill your tweeter. Because if we have a - for example - 100W passive two-way speaker - the high frequency driver NORMALLY handles about 10-20 Watts of full 100W input. So the driver is maybe capable of 10-30 Watts. When the amp gets overdriven, the high frequency part will be up to 50 watts and up - thus burning your tweeter. The woofer will probably be ok.The sound not !!!
And while the amp is too small - it is likely, that it will be overdriven to reach desired SPL. Therefore amp can never be too big - unless operator is maniac and blasts full regardless what´s receiving the output ...
One more explanation - as others already said in other words - when clipping, your signal gets much more harmonics - odd and even - or overtones - and the x-over in the cabinets puts them all into your tweeter - just the way it is designed to do. This will kill your tweeter. Because if we have a - for example - 100W passive two-way speaker - the high frequency driver NORMALLY handles about 10-20 Watts of full 100W input. So the driver is maybe capable of 10-30 Watts. When the amp gets overdriven, the high frequency part will be up to 50 watts and up - thus burning your tweeter. The woofer will probably be ok.The sound not !!!
And while the amp is too small - it is likely, that it will be overdriven to reach desired SPL. Therefore amp can never be too big - unless operator is maniac and blasts full regardless what´s receiving the output ...