Do low powered amps damage speakers?

[dave2010]

I forgot to mention that the XO is not there to limit power to the drivers, only to discriminate between highs, mids and lows. Any resistors in circuit are to balance the inevitable differences in sensitivity of the respective drivers.

I'm not really disputing that tweeters do get blown, but perhaps the way in which that happens. Presumably a manufacturer could test these devices out to destruction using perfectly clean signals with a suitably high powered amp, to find out how much power they could take before they give up the ghost.

The under powered amp argument relies on high frequency components being generated "due to clipping" which are of sufficient power to cause a problem.

Also, if tweeters are mostly just about inaudible, do many people really notice if they are blown?

It also seems to me possible that if tweeters do have extended frequency range and if modern amps are also capable of extended frequency range, that some recordings which have been made using digital filter techniques which trade signals in audible ranges for signals way above the audible range, that that could also be a source of problems. Unless there are filters in the circuits to limit ultra high frequency signals, some drivers may be subjected to relatively high energy signals which we mere humans cannot hear.

[Macca]

Most tweeters come in around 1KHz to 5Khz so there's no question their contribution is audible to pretty much anyone no stone deaf.

Heat is the problem, like anything you run power through it's going to get warm, run too much through it will get too hot and fail.

Amplifiers tend to run up to at least 30Khz, usually much higher so if it's in the signal to the amp it will go to the tweeter.

Ultrasonic frequencies will heat up the tweeter even though they can't be heard, a good argument for not using 'hi rez' playback.

[dave2010]

Most tweeters come in around 1KHz to 5Khz so there's no question their contribution is audible to pretty much anyone not stone deaf.

Does it depend on the overall speaker design? I have had 3 drive unit systems in the past, and I'm not sure that there was much coming out of the topmost driver.

I was assuming a lower frequency cut off somewhere around 5-7kHz or even higher, so obviously if the actual range for current system models is 1-5 kHz there will be audible sound for most people.

Heat is the problem, like anything you run power through it's going to get warm, run too much through it will get too hot and fail.

Amplifiers tend to run up to at least 30Khz, usually much higher so if it's in the signal to the amp it will go to the tweeter.

Makes sense.
Though how much heating is going to be needed to push these things out of operation - not sure. I suppose heat could do one of several things:

1. burn out the coils
2. change the dimensions of the vibrating parts - causing them to jam - with consequent further heating and catastrophic failure

Ultrasonic frequencies will heat up the tweeter even though they can't be heard, a good argument for not using 'hi rez' playback.

Noise shaping techniques in some recordings and playback devices deliberately shift some noise up above audible limits. If this really is a problem, then filters to avoid it should be installed - preferably before the damage occurs.

[Macca]

Does it depend on the overall speaker design? I have had 3 drive unit systems in the past, and I'm not sure that there was much coming out of the topmost driver.

yes it does but i did say 'most' not all. With a three way it depends on the midrange driver and how far up it is run.

I was assuming a lower frequency cut off somewhere around 5-7kHz or even higher, so obviously if the actual range for current system models is 1-5 kHz there will be audible sound for most people.

yes, assuming undamaged hearing you're going to hear up to at least 10Khz even of you're very old.


Though how much heating is going to be needed to push these things out of operation - not sure. I suppose heat could do one of several things:

1. burn out the coils
2. change the dimensions of the vibrating parts - causing them to jam - with consequent further heating and catastrophic failure


I'd say burnt out voice coil is the most usual reason for failure

Noise shaping techniques in some recordings and playback devices deliberately shift some noise up above audible limits. If this really is a problem, then filters to avoid it should be installed - preferably before the damage occurs.

probably not an issue in practice as there'd be a lot more people complaining of blown tweeters but it won't help if already playing near the limits of the tweeter's power handling. Best way to filter it is to use the 44.1 setting and steep/brickwall roll off filter on the DAC which will cut off anything above 23 Khz from going to the tweeter. Many/most supposedly hi-res recordings are just noise above that frequency anyway.