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Can't blow a speaker by under powering it.......
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A 120v 5 watt practice amp hooked up to 220v?
that'll sound sweeeeet for 3 milliseconds
Funny. The OP never asked for you discuss whether 'underpowering' a cab can or will damage a speaker.
He asked for someone to provide an idiot-proof way to explain that underpowering is a load of rubbish. Yet there are still people out there that won't let up...
He asked for someone to provide an idiot-proof way to explain that underpowering is a load of rubbish. Yet there are still people out there that won't let up...
...can one of you who are in the 'underpowering happens' camp please just post a YouTube video featuring, say, you playing a bass through a 250-watt head and 600-watt cabinet, and show us how it happens?
Erm... I'm tempted to retract my previous concession.
I won't, because you were correct about "CAN" being a different question from "WILL", and I'd only given evidence against the latter.
But Post #3 gives reasons *against* the former, not evidence for it.
The answer to *both* is "no".
An ideal speaker would stop.
Sure, speakers cones have mass, and inertia causing artifacts like overshoot and back emf.
But an ideal speaker cone would stop on the plateau of the square waves.
A parallel would be a moving coil meter. They have springs to hold the needle in place. Compare that to a basket and suspension on a speaker. These needles are light and ideally they would stop on the flats of a square wave.
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Apparently, despite the utter simplicity of some of the provided explanations... we've yet to discover such a thing as an "idiot-proof explanation" for it.
Here's something similar, I'm running a 500 watt head into a 300watt rated cab. trace Elliot ah500-7 > fender bassman 1x15. I have maxed out the volume on the head (no worries I don't really care it the cab blows, I got it for a wicked steal) just to see if it could handle it and it held it up just fine. Only when I touched the last 1/16th-1/32 on the volume knob did it start to slightly distort.
Think this cab can take a hell of a beating like I plan to give it and have it for a while? I've already had it for about 9 months
Think this cab can take a hell of a beating like I plan to give it and have it for a while? I've already had it for about 9 months
This thread has been there.
To go back to the original post, no, you can't blow a speaker by under-powering it. However, I suspect the OP meant to ask "Can you blow a speaker by using it with a grossly under-powered amp compared to the speaker rating?" As has been mentioned in a few posts, it certainly has happened. There are mechanisms where an under-powered amp can overpower elements of the cab. It depends on the design of the components and how it was operated. The high frequency drivers are most vulnerable. You don't hear about it so much any more, and I can't say I've heard about it for many years.
But I can't think of too many exceptions to the rule that if there is a way to break something, people will find it. My advice would be listen to your gear. The OP's granny said it best, "If you're gonna be stupid, you gotta be tough."
To go back to the original post, no, you can't blow a speaker by under-powering it. However, I suspect the OP meant to ask "Can you blow a speaker by using it with a grossly under-powered amp compared to the speaker rating?" As has been mentioned in a few posts, it certainly has happened. There are mechanisms where an under-powered amp can overpower elements of the cab. It depends on the design of the components and how it was operated. The high frequency drivers are most vulnerable. You don't hear about it so much any more, and I can't say I've heard about it for many years.
But I can't think of too many exceptions to the rule that if there is a way to break something, people will find it. My advice would be listen to your gear. The OP's granny said it best, "If you're gonna be stupid, you gotta be tough."
This topic sort of reminds me of the monty hall problem. Think about one way and one might be inclined to say it doesnt matter if the doors are switched. Think about it another way and you find out that the first way is just wrong.
Even if you don't believe the proof for the Monty Hall puzzle, you still may win 1/3rd of the time. I think some here have won or lost at some time and think it applies to all cases.
If you ask "will a speaker be in danger from underpowering"...... not in general
If you ask "can you blow a speaker with an amp with a true power rating below the speaker rating?"..... the answer is "yes you can". But usually NOT with a useful music signal, although it is "possible" in theory
Speaker voice coils are cooled in general by heat radiating to the cooler magnet structure, through the small gap between coil and magnet.
The amount of "air cooling" is very small by comparison.
You can burn the voice coil if a substantial amount of it is outside the gap even with low power. A very low frequency can do that, for instance, the voice coil may spend a goodly amount of time outside the gap due to poor cone control at that frequency. You will see a burnt stripe at each extreme of the coil.
You can also mechanically damage a speaker in a ported cab with a frequency below the box frequency (except some co-ax Cerwin Vega which had a perforated horn that also damped the cone). Even a few watts can push the cone past the damage point if the suspension is a looser one depending on the cabinet for cone control.
None of these things is common in real life use with an instrument amp...... You'd usually need to have a tin ear to put up with the sound while it was happening.
If you ask "can you blow a speaker with an amp with a true power rating below the speaker rating?"..... the answer is "yes you can". But usually NOT with a useful music signal, although it is "possible" in theory
Speaker voice coils are cooled in general by heat radiating to the cooler magnet structure, through the small gap between coil and magnet.
The amount of "air cooling" is very small by comparison.
You can burn the voice coil if a substantial amount of it is outside the gap even with low power. A very low frequency can do that, for instance, the voice coil may spend a goodly amount of time outside the gap due to poor cone control at that frequency. You will see a burnt stripe at each extreme of the coil.
You can also mechanically damage a speaker in a ported cab with a frequency below the box frequency (except some co-ax Cerwin Vega which had a perforated horn that also damped the cone). Even a few watts can push the cone past the damage point if the suspension is a looser one depending on the cabinet for cone control.
None of these things is common in real life use with an instrument amp...... You'd usually need to have a tin ear to put up with the sound while it was happening.
This post displays a fundamental misunderstanding of what the voltage in an audio system represents.
The voltage that comes from a microphone is proportional to the speed that the diaphragm is moving at, with the zero voltage point occurring when the audio wave is at a maximum or minimum.
A speaker reproduces the same way, with the voltage applied causing the speaker to move at a given speed. An ideal speaker, when DC was applied would cause its cone to move in a single direction forever, a real speaker will have an increasing push back from the surround and spider as its travels further from its centre point while the force provided by the voice coil decreases as it travels out, resulting in the speaker stopping at some point, but this stopping is a result of the non linearity of the speaker itself and not the fact that DC is applied.
Here is some math ya'll can look up to see if I got it right.
A 100v Peak to peak sinusoidal wave has the heating capacity of 70% of 50v DC.
A 100v peak to peak square wave has the same heating capacity as 50v DC.
Now which is more likely to burn up a speaker?
a.) 35 volts DC (same as a 100v sine wave)
b.) 50 volts DC (same as a 100v square wave)
Don't take my word for it, look it up yourself and let us all know how James got it right/wrong.
Problem with this "theory" of underpowering speakers is it happens almost never and doesn't "sound" right. Not easy to prove/disprove. Probably a phenomena more conducive to a PA amp pushing 3-4 thousand watts.
45 years of playing with sound reinforcement and I've never seen it.
A 100v Peak to peak sinusoidal wave has the heating capacity of 70% of 50v DC.
A 100v peak to peak square wave has the same heating capacity as 50v DC.
Now which is more likely to burn up a speaker?
a.) 35 volts DC (same as a 100v sine wave)
b.) 50 volts DC (same as a 100v square wave)
Don't take my word for it, look it up yourself and let us all know how James got it right/wrong.
Problem with this "theory" of underpowering speakers is it happens almost never and doesn't "sound" right. Not easy to prove/disprove. Probably a phenomena more conducive to a PA amp pushing 3-4 thousand watts.
45 years of playing with sound reinforcement and I've never seen it.
Right but the probability is better than 1/3 if you switch. The right answer is its always better to switch. The point im making is that many refuse to accept the solution because the approach of simplified logic can lead one astray.
It isn't possible to blow a speaker, except with too much power. But it is very possible to get too much power from an amp with a rating below that of the speaker.
The basis of the myth is people who don't understand how speakers work, trying to explain how speakers work. For this reason, explaining how speakers work is the starting point to debunking the "underpowering" myth. And understanding how speakers work is the starting point to explaining how speakers work.
Since this is an area where the theory is difficult and misconceptions abound, it will always generate lengthy debates.
bongomania
Commercial User
Why on earth are you adding junk to the thread with this irrelevant nonsense? What an "ideal" mechanism "would" do, if it existed, has no bearing whatsoever. In fact the whole point is people misunderstanding what the actual devices do under actual operating conditions.
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