overpower or underpower, a hypothetical..

[Bob Lee (QSC)]

Speakers are damaged due to clipping. That means the waveform (usualy a sinewave) turns to squarewave. Hence the term "clipping" as in, the tops of the wave are "clipped" off. Thus turning an alternating signal into a dc voltage basicly.

This "constant" voltage, does not allow proper speaker voice coil cooling. Then you get a fried speaker.

Wrong. Wrong. Wrong. Clipping is not DC.

Bass waveforms are seldom a sine wave, but are actually a combination of many sine waves comprising the fundamental and harmonics. The distribution of these harmonics is what gives a note its timbre--why the same note on a bass, a harpsichord, or a sax will sound drastically different.

Clipping does not create a square wave except in cases of radically excessive gain. In most cases, it results in a signal with flat-topped peaks.

Loudspeakers don't care at all if the signal voltage doesn't change for a millisecond or two. Above the speaker's resonance, the voltage is simply an accelerative force, not a positional one.

Tweeters are the first to go, since they take the least amount of power, then midrange and woofers, as Bill pointed out.

Now in a bass bottom application, where most bottoms use only woofers, (disregarding the tweeters on newer bottoms) if you UNDERDRIVE a speaker with a distorted signal...it WILL fail.

An awful lot of effects pedals introduce distortion, yet they don't inherently endanger the loudspeaker, and they won't cause damage as long as the power to the driver is not excessive.

The harmonics caused by clipping can cause tweeters and midranges (in multi-way systems with passive crossovers) to fail if the power in them exceeds what the drivers can handle. But even with a square wave--as in a severely clipped signal--the fundamental makes up nearly 85% of the power, and the remaining ~15% is in the harmonics. Therefore, the amount of additional power delivered to the mids and/or tweets depends largely on the fundamental frequency of the note, how much clipping is occurring, and the crossover points.

The main destructive element in clipping lies in its deceptive power. An amp rated for X watts with a sine wave on the threshold of clipping will put out >X watts when clipping. In addition, the dynamic range of the signal will be compressed, since the peaks will be chopped off and the softer portions may be much higher than usual. Thus, with the clipped portions exceeding the amp's rated power and the softer portions greatly amplified, the average power in the signal could be much higher than you would think, given the amp's power rating. It could be high enough to damage the loudspeaker.

 

[theshadow2001]

Here's my thoughts on the whole amp/power thing.

Underpowering is fine. Thinking you can turn up your amp as far as you want because the speaker is rated loads of watts more than your amps is bad.

Clipping is bad also so don't do it(apart from the occasional wink of red from the amp on the extreme peaks that you put out thats ok).

Putting alot of too low a frequency into a cabinet is bad so don't do that.

If your amp is rated at the power you think you need. Then your not going to get the power you need. If its rated 600 watts chances are your not going to get the full 600 watts out of it.

If you have a cabinet rated 200 watts and an amp rated 400 watts then the amp can deliver 200 watts of unclipped power. If you have a cab of 200 watts and an amp of 200 watts chances are you wont get the 200 watts of power unclipped.

If an amp is clipping excessively(but it wont because I told you not to send your amp into clipping), I would rather a cabinet rated higher than the amp see that signal than a cabinet rated lower than that amp, you wont avoid doing damage but a higer rated cabinet will obvioulsy be able to deal with it slightly better than the lower rated one.

Head room is good. Having more power than you need is good. Having more power in your amp than your speakers will allow your amp to output cleanly, the wattage that your speakers are rated at.

Having an amp thats rated higher than your speakers has the possiblity to allow you to output too much clean power for your speakers to handle so be careful not to turn it up too much. Don't ever send it into clipping your speakers will hate your for it.

 

[ricplyrz]

Wrong. Wrong. Wrong. Clipping is not DC.

Bass waveforms are seldom a sine wave, but are actually a combination of many sine waves comprising the fundamental and harmonics. The distribution of these harmonics is what gives a note its timbre--why the same note on a bass, a harpsichord, or a sax will sound drastically different.

Clipping does not create a square wave except in cases of radically excessive gain. In most cases, it results in a signal with flat-topped peaks.

Loudspeakers don't care at all if the signal voltage doesn't change for a millisecond or two. Above the speaker's resonance, the voltage is simply an accelerative force, not a positional one.



An awful lot of effects pedals introduce distortion, yet they don't inherently endanger the loudspeaker, and they won't cause damage as long as the power to the driver is not excessive.

The harmonics caused by clipping can cause tweeters and midranges (in multi-way systems with passive crossovers) to fail if the power in them exceeds what the drivers can handle. But even with a square wave--as in a severely clipped signal--the fundamental makes up nearly 85% of the power, and the remaining ~15% is in the harmonics. Therefore, the amount of additional power delivered to the mids and/or tweets depends largely on the fundamental frequency of the note, how much clipping is occurring, and the crossover points.

The main destructive element in clipping lies in its deceptive power. An amp rated for X watts with a sine wave on the threshold of clipping will put out >X watts when clipping. In addition, the dynamic range of the signal will be compressed, since the peaks will be chopped off and the softer portions may be much higher than usual. Thus, with the clipped portions exceeding the amp's rated power and the softer portions greatly amplified, the average power in the signal could be much higher than you would think, given the amp's power rating. It could be high enough to damage the loudspeaker.

" What Does "Clipping" Mean and Why is it Bad?
Clipping usually means that the maximum output of the amplifier is being exceeded and the tops of the signal peaks are being "clipped" off. During these times the cones of the loudspeakers are essentially receiving a DC signal. This means that most of the energy from the amp is heating up the voice coil instead of moving the cone. Usually loudspeakers fail or burn-up because of this heat. (aka. Thermal Failure) You should also be aware that any clipped signal in the chain can blow a loudspeaker even if the amplifier isn't at full output. Most loudspeakers fail because they are driven by too small an amplifier. The power ratings for a loudspeaker are only valid for unclipped input signals. So, to avoid problems, always operate your gear safely below "clip level".


[Invalid or Expired Link Removed]

Such an easy explanation.

 

[seamonkey]

For car audio, here's a sight with some expanation what's going on.
http://www.bcae1.com/2ltlpwr.htm

It summarizes:
" * If your speakers are capable of handling significantly more than your amplifier can produce, driving them with a clipped signal will not likely hurt them.
* If the speakers can handle 3 or 4 times the power that your amplifier can produce, there's virtually no way to damage your speakers (no matter how clipped the signal is).
* If your speakers are rated for the same power handling as your amplifier is capable of producing cleanly, driving them with a clipped signal for extended periods of time may cause speaker damage and/or premature failure.
* If your speakers are rated for the same power handling as your amplifier is capable of producing cleanly, driving them with a square wave signal for extended periods of time will likely cause speaker damage. "

Looks like good solid advice even for bass amps/cabinets.

 

[Bob Lee (QSC)]

" What Does "Clipping" Mean and Why is it Bad?
Clipping usually means that the maximum output of the amplifier is being exceeded and the tops of the signal peaks are being "clipped" off. During these times the cones of the loudspeakers are essentially receiving a DC signal. This means that most of the energy from the amp is heating up the voice coil instead of moving the cone. Usually loudspeakers fail or burn-up because of this heat. (aka. Thermal Failure) You should also be aware that any clipped signal in the chain can blow a loudspeaker even if the amplifier isn't at full output. Most loudspeakers fail because they are driven by too small an amplifier. The power ratings for a loudspeaker are only valid for unclipped input signals. So, to avoid problems, always operate your gear safely below "clip level".


[Invalid or Expired Link Removed]

Such an easy explanation.

It's also a wrong explanation.

 

[Bob Lee (QSC)]

For car audio, here's a sight with some expanation what's going on.
http://www.bcae1.com/2ltlpwr.htm

It summarizes:
" * If your speakers are capable of handling significantly more than your amplifier can produce, driving them with a clipped signal will not likely hurt them.
* If the speakers can handle 3 or 4 times the power that your amplifier can produce, there's virtually no way to damage your speakers (no matter how clipped the signal is).
* If your speakers are rated for the same power handling as your amplifier is capable of producing cleanly, driving them with a clipped signal for extended periods of time may cause speaker damage and/or premature failure.
* If your speakers are rated for the same power handling as your amplifier is capable of producing cleanly, driving them with a square wave signal for extended periods of time will likely cause speaker damage. "

Looks like good solid advice even for bass amps/cabinets.

Now that's a switch … info more accurate from a car audio source that from a somewhat "pro" source!!

 

[chucko58]

Such an easy explanation.

Let's see, whose explanation should I trust? Some newbie with less than 50 posts, or a gent who's worked for one of the premier power amp makers in the US for years? (scratches head) Oh yeah...

 

[Bob Lee (QSC)]

Dynamic loudspeakers are grossly inefficient, as typically well over 90% of the power put into them turns into waste heat instead of acoustic power. Thus, it doesn't matter at all if the signal voltage briefly stops changing during a portion of the waveform. The cone doesn't stand still when this happens, either. Most of the power heats the voice coil whether or not the amp clips; it comes down to how much power and for how long.

 

[klharper]

Bottom line - avoid pushing either of them.

Get as much power as you can (within pricerange - headroom is always good) and keep your knobs closer to the COUNTER-clockwise position.

The only possible bad thing about too much power is that you may not be getting the best "full" sound out of your amp. That's only if you have a grossly large amount of power in a very small situation (where its not likely you need your best sound anyways).

 

[Bob Lee (QSC)]

The only possible bad thing about too much power is that you may not be getting the best "full" sound out of your amp.

That issue applies mainly to tube amps, which often add some euphonious distortion as they're pushed harder. It's less of a problem with pro power amps, which are designed to be accurate at all levels up to clipping.

 

[Jerrold Tiers]

Dynamic loudspeakers are grossly inefficient, as typically well over 90% of the power put into them turns into waste heat instead of acoustic power. Thus, it doesn't matter at all if the signal voltage briefly stops changing during a portion of the waveform. The cone doesn't stand still when this happens, either. Most of the power heats the voice coil whether or not the amp clips; it comes down to how much power and for how long.

It is often 97% wasted as heat....

And, the coil loses MOST of its heat into the magnet structure, which is relatively cool compared to the voice coil. It wouldn't matter if the cone did stay stationary for a moment, (but it won't).

If you are clipping enough for this to be an issue, you are probably going to sound pretty bad, unless you are in a Soft Machine cover band or the like........

As far as the whole under-over powering issue, shouldn't be an issue.....there are three power levels:

Not enough

Enough

Way too (*&%(& much.

Way too much is somewhere probably above 3 or 4 times the amp power as speaker handling. There, if you hold a note or get a little feedback, or bump the bass on the mic stand you risk frying/shredding things. Probably you would never have a problem with low volume......until you fry something or tear the cone out, or beat the voice coil to death on the magnet.

Not enough is if you have so little power or the speakers are so inefficient (which high power speakers DO tend to be) that you don't get what you need sound-wise from your low power amp.
Then its a possible issue, because you may clip the daylights out of the system trying to get "there". Probably it will be no problem because of course your musical ear will tell you something is wrong first.

Everything else is "enough", and you can deal with it.

It's pretty hard to get more than about 1/3 to 1/2 the amp power as a long term average output. Hence the 2 or 3 times lower speaker capability being "ok".

The higher the power, the more likely you are to damage something if you boost the low EQ though...... that would probably be "mechanical" damage...

 

[ricplyrz]

Lets make it real simple. 50 volts dc (simular to clipping)to a speaker or 50 volts ac. Which would burn out a speaker first?

Oh, I forgot. The speaker in question is a, say 3inch voice coil, 500 watt rms rated speaker.

 

[ricplyrz]

Let's see, whose explanation should I trust? Some newbie with less than 50 posts, or a gent who's worked for one of the premier power amp makers in the US for years? (scratches head) Oh yeah...

So, if he says step in front of the moving car, you would because he says it won't hurt?

 

[Bob Lee (QSC)]

Lets make it real simple. 50 volts dc (simular to clipping)to a speaker or 50 volts ac. Which would burn out a speaker first?

Oh, I forgot. The speaker in question is a, say 3inch voice coil, 500 watt rms rated speaker.

Simpler: 50 volts DC is not similar to clipping.

 

[Aj*]

Ric why do you insist on arguing with someone who works for a power amp company? You've argued with Jerold who works for ampeg in another thread and now you argue with Bob who works with QSC. It's doing my head in, can't you just respect that these guys know better? I study history and as you learn in history, sources can say what they like but wether they're worth a thing is entirely different. A primary source from an expert in the field would always be classed as far more reliable than an anonymous secondary source. And when the company behind that second source doesn't even make power amps then you really have to question it!

Anyway, back on topic, I'd always choose the headroom, so long as you're sensable with the volume control you aren't going to endanger your cabs, just keep an eye on them to watch for excessive speaker excursion or any other nastys and you'll be fine.

 

[Aj*]

So, if he says step in front of the moving car, you would because he says it won't hurt?

Yes but as a sane individual he is hardley likely to say such a thing. On the basis of previous posts, it is far likely to be you who advises people to step in front of moving cars - "Lets make it real simple. stepping in front of a car (similar to stepping in front of a matress)" .

 

[ricplyrz]

Ric why do you insist on arguing with someone who works for a power amp company? You've argued with Jerold who works for ampeg in another thread and now you argue with Bob who works with QSC. It's doing my head in, can't you just respect that these guys know better? I study history and as you learn in history, sources can say what they like but wether they're worth a thing is entirely different. A primary source from an expert in the field would always be classed as far more reliable than an anonymous secondary source. And when the company behind that second source doesn't even make power amps then you really have to question it!

Anyway, back on topic, I'd always choose the headroom, so long as you're sensable with the volume control you aren't going to endanger your cabs, just keep an eye on them to watch for excessive speaker excursion or any other nastys and you'll be fine.

I question them, not argue. I learn this way. I also doubt, as anyone should when they somtimes are in direct dissagreement to many pages of information on the net.

I always respect their experience and worth, but don't always aggree.

I like to post here as you do, so please let me.

 

[ricplyrz]

Yes but as a sane individual he is hardley likely to say such a thing. On the basis of previous posts, it is far likely to be you who advises people to step in front of moving cars - "Lets make it real simple. stepping in front of a car (similar to stepping in front of a matress)" .

I was being funny, sarcastic.....I will refrain from this...as it is difficult when you can't hear a persons voice or see their body launguage. It was in jest.

 

[Herman]

Wrong> A clipped amp does not allow soft and loud passages of the signal. It "compresses" the signal to a constant level, thus not allowing the speaker any time for cooling.

The signal is compressed but not to a constant level. The average power of the clipped/compressed signal is increased - it's this higher average power that is potentially damaging to the speakers.

Hence the term "clipping" as in, the tops of the wave are "clipped" off. Thus turning an alternating signal into a dc voltage basicly.

No, it doesn't become a DC voltage and speakers aren't damaged by clipping in and of itself - it's the increased average power of the clipped waveform that causes the damage.

...if you UNDERDRIVE a speaker with a distorted signal...it WILL fail.

What does "underdrive a speaker" mean? If your amp is cranked high enough to clip the output then the amp is being overdriven and is producing a higher average output power then when it's not being driven to clipping. It's the high(er) average output power that will cause the speaker damage.

 

[theshadow2001]

What is clipping? Clipping is when the little clip indicator LED turns red on your amp.

If its on more than it's off adjust your amp to counteract that. After that people shouldn't really give a crap.