Underpowering speakers. Is there a ratio?

[ABNJbassplayer]

Hi:

I bought a used 700 watt 4x10 speaker cabinet at 8 ohms, but my amp is 250 watts at 8 ohms. I called customer service at speaker manufacturer and he said there was no danger in underpowering speakers and causing damage. Two salesmen from two different guitar centers have said the same thing. But I've read many article online about possible damage. Any advice out there? I have 30 days to return the speaker cabinet.

ABNJbassplayer

[WhoDidTheElf]

Under powering is a myth from what I've gathered.

Think about it. If sending too little power to the cab will hurt it, then when the amp is off and no power is sent to the cab, wouldn't it blow?

[BassmanPaul]

Underpowering is a myth long since debunked. That said, you will not be able to drive the cabinet to its fullest extent of 350W.

[lomo]

Underpowering is a myth. Keep it.

[mikeddd]

In general there is no such thing as underpowering a speaker. You can however, damage a speaker (tweeters mostly, very little chance of damaging a 10" driver) from clipping the amp. Know how when you turn a stereo (or your bass amp) all the way up and it sounds distorted? That distortion is the amplifier "clipping". In short, you are trying to make the amp produce more power than it can and the output becomes distorted. Technically, the waveform is clipped, and that's why it's called "clipping." That clipped waveform can hurt tweeters. Highly unlikely to hurt 10's or larger.

So in short, unless you play your 250watt amp wide open for about a week straight, there's pretty much no chance you will hurt your new cab. Hope this helps.

ps
I second what BassmanPaul says about your amp being too small to get the full potential out of the cab. But you would be surprised how loud 250watts can be. Keep the speaker and rock on.

[Marginal Tom]

You won't damage your speaker cab by underpowering it any more than you'd damage your Ferrari by driving it at or below the legal speed limit.

[billfitzmaurice]

Originally Posted by ABNJbassplayer

I've read many article online about possible damage. Any advice out there?

Stop reading at those sites.

[ABNJbassplayer]

Thanks. That helps a lot.

[James Judson]

Those that say underpowering is a myth simply do not understand the phenomenon. A clipped signal has more heating capacity than an unclipped signal. It is very unlikely that your 250 watt amp will approach the 750 watt limit clipped or unclipped. Thus, no problem.

For those of you that say its a myth, here is the scenario: You are running a 250w system when you need a 500w system. Your system is maxed out but you push it harder. Clipping the signal causing voice coils to over heat. The phenomenon is simply mis labeled, it is really "to much power can damage speakers". Where did the extra power come from? A clipped signal (square wave) has a lot more heating capacity (50% more) than an unclipped signal (sine wave).

You don't have to bellieve me. Go to electronics school and learn some ohms law. Anyone here ever heard of RMS (root mean squared).

Extremely unlikely anyone here will experience this but the theory is there, the potential is there.

[ABNJbassplayer]

Thanks, James.

Originally Posted by James Judson

Those that say underpowering is a myth simply do not understand the phenomenon. A clipped signal has more heating capacity than an unclipped signal. It is very unlikely that your 250 watt amp will approach the 750 watt limit clipped or unclipped. Thus, no problem.

For those of you that say its a myth, here is the scenario: You are running a 250w system when you need a 500w system. Your system is maxed out but you push it harder. Clipping the signal causing voice coils to over heat. The phenomenon is simply mis labeled, it is really "to much power can damage speakers". Where did the extra power come from? A clipped signal (square wave) has a lot more heating capacity (50% more) than an unclipped signal (sine wave).

You don't have to bellieve me. Go to electronics school and learn some ohms law. Anyone here ever heard of RMS (root mean squared).

Extremely unlikely anyone here will experience this but the theory is there, the potential is there.

[teleharmonium]

Originally Posted by James Judson

Those that say underpowering is a myth simply do not understand the phenomenon. (...) The phenomenon is simply mis labeled, it is really "to much power can damage speakers".

Right, well, saying the phenomenon is mislabeled is kind of the same thing as saying that underpowering is a myth. Underpowering is not a problem; clipping is absolutely a problem.

To state the former is not to deny the latter.

[mikeddd]

[bichibreaker]

When your amp is off you are ultraunderpowering your cab

[LiquidMidnight]

Is there anyway we can get a huge 72 point font flashing banner at the top of the Amps Forum that says, "THERE IS NO SUCH THING AS UNDERPOWERING SPEAKERS!!!!!!!!!!!!!!"?

[Fuzzbass]

Originally Posted by ABNJbassplayer

I called customer service at speaker manufacturer and he said there was no danger in underpowering speakers and causing damage. Two salesmen from two different guitar centers have said the same thing.

I'm surprised that Guitar Center is two-for-two on this issue. Cheers to them!

The only caveat is that clipping can damage tweeters.

[Richard Lindsey]

Originally Posted by teleharmonium

Right, well, saying the phenomenon is mislabeled is kind of the same thing as saying that underpowering is a myth. Underpowering is not a problem; clipping is absolutely a problem.

To state the former is not to deny the latter.

Clipping per se is not a problem, as the discussions in the sticky make clear. (1) Overpowering and (2) overexcursion are the potential problems. Those things can happen with a clipping amp, but also with a nonclipping one; hence, clipping per se is not the issue.

[teleharmonium]

Originally Posted by Richard Lindsey

Clipping per se is not a problem, as the discussions in the sticky make clear. (1) Overpowering and (2) overexcursion are the potential problems. Those things can happen with a clipping amp, but also with a nonclipping one; hence, clipping per se is not the issue.

Ok, I'll buy that, but I do think it's obvious that overpowering can be a problem, nobody is going to ask why their 1000 w amp destroyed their 100 w speaker; while the way that a relatively low power amp can destroy speakers that are rated higher than the amp through clipping can surprise a person that isn't that into this stuff.

[Richard Lindsey]

Originally Posted by James Judson

Those that say underpowering is a myth simply do not understand the phenomenon. A clipped signal has more heating capacity than an unclipped signal. It is very unlikely that your 250 watt amp will approach the 750 watt limit clipped or unclipped. Thus, no problem.

For those of you that say its a myth, here is the scenario: You are running a 250w system when you need a 500w system. Your system is maxed out but you push it harder. Clipping the signal causing voice coils to over heat. The phenomenon is simply mis labeled, it is really "to much power can damage speakers". Where did the extra power come from? A clipped signal (square wave) has a lot more heating capacity (50% more) than an unclipped signal (sine wave).

You don't have to bellieve me. Go to electronics school and learn some ohms law. Anyone here ever heard of RMS (root mean squared).

Extremely unlikely anyone here will experience this but the theory is there, the potential is there.

Well, we do understand the problem, and that's exactly why we say underpowering is a myth. What you describe is a species of OVERpowering, as you yourself say. Referring to it as underpowering isn't just mislabeling, it's a fundamental misunderstanding (not on your part) that causes a lot of people to think they have problems when they probably don't (as, perhaps, in the case of the OP, if he takes those vague online sources too seriously) and to think they can't have problems when they might (as in the idea, not uncommonly seen here, that the best way of protecting a speaker is invariably to use a much bigger amp with it).

[Richard Lindsey]

Originally Posted by teleharmonium

Ok, I'll buy that, but I do think it's obvious that overpowering can be a problem, nobody is going to ask why their 1000 w amp destroyed their 100 w speaker; while the way that a relatively low power amp can destroy speakers that are rated higher than the amp through clipping can surprise a person that isn't that into this stuff.

OK, but it's important to point out that the problem is really the overpowering. If you don't, people get the idea that merely connecting an amp capable of output X to a cab whose power handling is X + Y immediately creates an inherently dangerous situation. Which is nonsense and creates needless worry. I've seen this many times, and in fact the OP seems almost to be leaning that way, depending on the amount of credence he's willing to give those mysterious online sources.

[BassmanPaul]

Originally Posted by James Judson

You don't have to bellieve me. Go to electronics school and learn some ohms law.

I did, for quite a few years. That's how i got my qualifications!

Underpowering has nothing to do with clipping!