Damaging speakers using an underpowered amplifier

[timechaser]

I was told by someone that I could damage my speakers if I was using an underpowered amplifier and drove it into clipping...

What does this exactly mean? How do I prevent this? For reference, my speakers are rated as 20-100watts and the amp outputs a max of 100 watts per channel (I know this is not the actual power output, but thats the stats).

Help please! I am totally

 

[MDS]

The kind of clipping you are talking about is where the signal is distorted and the waveform is squared off at the peaks as opposed to looking like a sine wave. Clipping can damage tweeters especially.

As an amp is turned up closer and closer to its maximum level, the level of distortion increases. So the idea is that if you are using say a 50 watt amp and have to turn it up near its max to achieve the level of loudness you desire, it is working real hard to reproduce the waveform accurately and may clip. That is why it is better to have an amp with greater power than you will actually need.

While many people point to this rule as justifcation for big amps, you can just as easily blow your speakers with a high powered amp. Feed those 100 watt capable speakers 200 watts of clean power (no clipping) and you could fry the speakers too.

 

[Pyrrho]

The kind of distortion MDS is talking about is audible. Basically, if you put on some music that has a fairly constant level of loudness, you can slowly turn up the volume control, and as soon as you hear any distortion, turn it down a little until you don't hear any. That will be the maximum volume your system can safely play (but it won't tell you whether this volume is limited by the speakers or the amplifier). Also, this does NOT mean that you will always be safe with the volume control turned to that point; if you put on a CD that is recorded at a higher level than the one you used for this experiment, then that would be like turning up the volume. Additionally, depending on your system and the room you are in and how close you are to the speakers, this may be too loud for your ears and might cause hearing loss. In my case, with my system, it gets too loud for me to like it before I hear any distortion, so I have no idea how loud it can safely play (safely, that is, for it).

The reason why clipping tends to destroy tweeters is this: When an amplifier clips, the harmonic distortion increases. Much of the added distortion is higher frequency than the source material, and so the amplifier is putting out much more power to the high frequencies. This can put too much power to the tweeter, and destroy it. It is excessive power that destroys. Your speakers don't care if the original source is good, bad, or indifferent music, with or without distortion. It is the total power (and its duration) that goes to the speaker that determines whether it is destroyed or not.

 

[annunaki]

The average person should purchase an amplifer with an continuous power rating equal to that of the speaker's continuous power rating.

Too much power over time is what causes speakers to fail. The actual clipping or distortion will not damage the speaker, it is the increased power output* associated with the clipping that will damage the speaker. Clipping also induces odd order harmonic information and can cause speakers to operate past their mechanical limits. This is due in part to power spikes that occur at those harmonics also damaging speakers.

*Amplifiers will double their continuous power output (at .1% thd) when fully clipped.

 

[xboxweasel]

Depending on the sensitivity of your speakers (dB @ 1watt @ 1meter) you should not be too concerned. Bigger speakers are more sensitive than small speakers. Those M1's are not very big (hence not very sensitive. Only 85dB@1V@1m). But because they have only have one 4" mid range driver they should not require much power. Bigger drivers require more power. Hence subs come with their own amps.

I have only once heard clipping and that was from a very cheap Keendwood stereo receiver. And some crappy speakers. But in all other cases, none. However, no one that I know turns the volume beyond ear bleeding levels.

In most cases your speakers only use 2-3 watts when used normally. Transients (sudden loud sounds - clap, explosion, etc) require more power to reproduce properly. That's when your hydro bill goes up.

I can't find anything on your receiver at the moment. If you can, set your crossover in the receiver to 100Hz. Your speakers range is 80-23kHz. You want to sub to take care of the lower frequencies that your speakers cannot. Set all speakers so small. Max out your sub's crossover dial. Turn the sub's volumn to 50% or less. Give it a shot.

EDIT: Actually, that Yamaha seems pretty descent. UK model, that's why I could not find it earlier. You have preouts and can always add externals amps to power your speakers. And you can use the YPAO to calibrate your system. Just plug it in, run auto setup. Have fun.

 

[timechaser]

Thanks for the replies... I used the YPAO to calibrate the amp, and have the crossover set to 90hz. the sub's volume usually is around 50-60%... more than that is too loud.

I never turn up the knob beyond -5db on the amp. At least I havent done so till now - it is usually around -15ish db.

Thanks for the replies again.

 

[bandit]

xbox - your post confuses me a bit. You mentioned that the small speaker with 85db sensitivity requires less power because it has a small driver, and large drivers require more power....

The way I see it - if you only have 85db sensitivity in the small speaker it will take more power to get the same sound pressure level in the same setting that in would a larger driver with 90db sensitivity as an example.

The larger driver could likely (but its not a given) handle more power but that doesn't mean it requires that power. There is a good chance it will actually require less power.

Bottom line on clipping - if you hear distortion its time to back it down.

 

[xboxweasel]

Confuses you? I got confuses reading it too. A higher efficiency speaker at the same power level (as a less efficient speaker) would mean more SPL. I agree with that.

But I also thought that a smaller driver would require less power (than a larger driver). Hence the confusion.

 

[danglerb]

Speakers have a lot more distortion than amps, and most speakers have much more distortion the louder you play them. This makes it very hard to tell when an amp is clipping, and a few days later maybe you notice some of the tweeters don't tweet.

In actual practice, very powerfull amps rarely damage the speakers, with a few exceptions they just blow the speaker fuses. The main exception being really loud low bass which can just tear up some woofers in ported designs, or fry them in sealed boxes.

Young kids are fearless with technology, and for the most part tech is forgiving, but the first time they forget to hit play on the dvd, go and select DVD on the receiver and turn up the volume, then remember to hit play, it may not seem that cute. I also worry about any situation where a child needs to "reach up", too much stuff these days weighs almost nothing and could easily be pulled down hitting the child, or just as bad tempting them to climb.