Matching speakers to reciever wattage

[wilmeland]

what was the original question?

I guess that all the discourse above is sorta interesting, but for the post that asked the original question, I have to go with the common sense approach. For me that is better to have a higher rated amp & lower rated speakers. I believe this is the pragmatic answer to the question since I tend to believe most quality speakers will handle brief power spikes that far exceed their rating better than clipped power surges that would tend to be greater in duration.

I guess you can analyze the physical science at the root of clipping, but to me the result would generally seem to be damaging (if not to the equipment, at least to one's sensibilities).

More power = less potential for clipping.

 

[sudyke]

At the begining I thought I understood what you guys were saying, but in the end, I got confused again!
1. Clipping is caused by the amp? I thought that it is caused by a speaker, that can't give off as much power, as recieved from the amp! Is that incorrect?
2. If my amp, aprox. 80-85wpc drives a lets say 500W speaker, then if I turn my amp to the max, clipping will occure? Even if I only give 1/5 of the speakers max durability? 3. Will it get any louder if my speaker can handle more Ws? For eg. If I have a 100W, a 200W, and a 500W speaker, will there be any significant difference in volume if I'm running the same amp? I know the sound will be cleaner!

Pls someone explain! I feel totally confused...

 

[annunaki]

What's funny about the all the posts trying to explaining sources of speaker damage is no one mentionned the fact that we're talking about an electromechanical device.

Yes voice coil damage is real, so is power compression, clipping, distortion, harmonics, etc... But no one mentionned the fact that speakers can also be damaged mechanically by driving it beyond what the suspension can handle. Mechanical damage is generally caused by driving the speaker with too much power.

Most of the time, thermal damage to the voice coil is probably more common but don't forget mechanical damage.

Out of all the practical comments posted, I agree more so with MacManNM.

More Amplifier Power than Speaker rating is not a bad ideal, as long as you don't go to the extreme either like double the recommended speaker power rating.

That you would just plain silly!

The posts seemed pretty intense, lighten up folks! Listen to the music and have a great day!

While it is true mechnical damage can occur, it typically does not happen until a speaker is grossly overpowered. By grossly, that would be 2x or higher of the rms rating for more that slightly brief periods, usually. The reason this happens, is that many speakers (individual drivers) are designed to have their motors run out of force before their suspensions pass their mechanical limits.

I understand that having more power than recommended is beneficial to certain users. I am one of those people. I like dynamics. However, not everone who owns a system needs 200 watts a channel or "double their speaker's rms". Some poeple, no matter what equipment they have, beat on it. They will always push things past their limits no matter how big or small. For that type of person, a smaller amplifier is actually recommended. By smaller I mean one that does not exceed the speaker rms rating, even when fully clipped. They are the type of listeners who think that music does not sound good until your ears hurt. Distortion is usually a very big factor there.

 

[Porcupine]

This is an interesting subject. When I first started out in the world of improved fidelity audio ten years ago (a step up from being a total idiot like I was all through high school, where I didn't know the difference between a TV's built in speakers, computer speakers, boombox speakers, or real speakers) I was very concerned about power matching my amplifier to my speakers. When I bought new speakers, after playing them for a week, I turned the volume knob all the way up to see what would happen, to make sure they would not blow up (Circuit City had a return policy if they did, and the salesperson assured me my speakers would not blow up because he would help me match my components). I had a Onkyo TX-8511 Receiver rated at a true 100 watts per channel RMS, with Infinity Reference 2000.3 bookshelf speakers rated at 125 watts per channel. What happened? My woofers smoked and blew out after 1 minute of play.

So contrary to what people have said here earlier I feel that blowing our your woofers is a serious problem. I returned my speakers to the same salesman, and traded them in (full refund, in a sense) for more expensive and better Infinity Kappa 5.1 Series II bookshelf speakers rated at 150 watts per channel (which I had wanted to begin with but thought were too expensive at $800 a pair). After another week, I turned up the volume knob again all the way to see what would happen. I don't know if the amplifier was clipping or not. I know what a badly overdriven, clipping amp sounds like. But my Onkyo TX-8511 with the volume knob all the way up for the 3 particular songs I played was not clipping too badly (actual power output depends on the source volume too, not just where the volume knob is) though it was probably clipping a bit. What happened? After 3 songs (10 minutes of play) my planar magnetic ribbon tweeters cut out. Fortunately, Infinity was smart and had built a tweeter-protection circuit into their Kappa series to prevent the tweeter from truly blowing out permanently. After a few minutes to cool down, my tweeters came back on-line and have worked perfect ever since (and I have never done the same test again, though I have played my music quite loud at times).

 

[Porcupine]

Since then I have thought for years about this subject and learned much about audio, mathematics, physics, circuits, etc. I have formed my own thoughts regarding what power amp should be matched to what power speaker. Here they are, anyone feel free to comment or point out anything that is wrong:

First off, why do you care about your speakers blowing up? Identify this reason. Obviously your speakers will blow when they are forced to play at too loud a volume. *Why do you fear this will occur?*

Possible reason #1 - You will want to play extremely loud on rare occasion either because you like loud music, or you want to blast out the window so all the neighbors can enjoy. Solution? Buy the strongest power amp you like regardless of speaker wattage. 100000 watts if possible. You want to generate loud music so you need that power. Your speakers WILL blow out though if you play too loud, but at least you can reach your speaker's potential if you know when to stop turning the volume knob. A more powerful amp will produce higher quality sound at lower volumes as well, so more power is always good.

Possible reason #2 - You are afraid you will accidentally trip over and push the volume knob all the way up, and want to make sure your speakers don't suddenly break when this catastrophe occurs. Or you are afraid your children or little siblings will turn the volume all the way up to see what happens. Or you can't resist yourself turning the volume knob all the way because you are curious.

From now on, I assume Possible reason #2 is the issue.

First, make sure you know the specs of all your equipment as much as possible. Unfortunately as previous people said I think speaker/amplifier makers often lie about their true stats, sometimes for the better, sometimes for the worse. So you can't really be sure what is true and what is not. A good amplifier will list its true RMS power output per channel. A bad amplifier will lie and list its power output per channel as 10x more than it really is (how this is legal I don't know). The speaker maker may give you a conservative rating of what it can handle, or it may give a true rating. Never assume the speaker maker is giving you a conservative power handling estimate or you may be in for disappointment, as happened to me long ago.

If possible find out the Dynamic Power Output of your amp. For my Onkyo dynamic power output was 140 watts per channel. 10 years ago I did not understand the difference between RMS power and peak power. Peak power is what you must look at if you really want to be safe.

Make sure your speaker's rating power handling wattage is greater than or equal to the amplifier's peak power. This ensures that your *woofer* is protected in all circumstances. Most likely this will also ensure that your midrange driver, if you have one, is protected as well. But I think midranges rarely blow.

Unfortunately just doing this does not ensure your tweeter's protection.

 

[Porcupine]

Your tweeter may blow regardless, because of several possibilities:

1) Your amplifier is forced to play too loudly, beyond its power rating, causing the signal to clip and thus send extremely loud signals/power to the tweeter, which may blow it out.

2) You accidentally play a terrible source signal into your amplifier. For example you could change the channel on a TV to a nonworking channel filled with only static and possibly a terrible superloud high-freq noise. Or you could play a downloaded computer mp3 that has errors in it and pops/glitches/cuts out/etc due to improper CD ripping, downloading errors, etc. Or someone could make a weird song that has a high frequency 15000 Hz noises that are at max volume and blow out your tweeter.

Either way, there is only one foolproof way to protect your tweeter. First, find out what power handling your tweeter itself is capable of. Unfortunately this information is generally not made public so you probably won't know. Ribbon tweeters are the most fragile and easy to blow. I happen to know the power-handling specs of my Bohlender-Graebener ribbon tweeters -- 10 Watts RMS, 20 Watts "Program" (I don't know what this means) -- 50 Watts Peak.

Thus, if I want to be 100% safe from tweeter blowout due to amplifier clipping (which would happen constantly at clipping volume, thus you must look at the RMS power handling), I must buy a 10-Watt per channel amplifier!!! But a 10-Watt amp sucks. I won't be able to play loud, and my sound quality will be poor even at lower volumes. Unfortunately there is no better solution that is 100% safe.

If you want to get around this, there are a couple risky ways. One, know the limits of your amplifier and know when to stop turning the volume knob up. Two, make sure the original source signal you put into the amplifier is never loud enough to cause the amplifier to clip even with the volume knob all the way up. I'm not really sure how to achieve this though. Some players (CD player, gaming console, computer, DVD player) put out louder signals than others. Some CDs and DVDs play louder than others. I guess if you had some way to control this that would work. And your amplifier would have be made such that its volume knob turned all the way would never reach its max rated power. But this never happens. So you just have to be responsible and know when to stop turning the volume knob I guess.

If I only worried about accidental terrible source signals (TV static, bad mp3 file, etc) I could go up to a 50-watt amplifier, which is still a bit sucky.

 

[Porcupine]

Another thing you can do if this worries you is to get a speaker with a tweeter that can handle lots of power. They might distort at high volume and not play correctly, but at least they won't break. I think softdomes can usually handle the most, maybe I'm wrong. And ribbons can handle the least. Or, you can get a tweeter with an electronic protection circuit built-in, like my Infinity Kappas had. I don't know what kinds of speakers have them though.

So there isn't really an ideal solution. To sum up, here are the various alternatives:

1) Buy a relatively weak 10-Watt amp. Now you are 100% safe from speaker damage but you can't play very loudly, and your sound quality will be poor. Maybe you can buy a "tube" amp or something. I'm not that experienced with audio though and I've never even seen or heard a tube amp before. But I heard they play at good quality even with low power ratings...

2) Buy an amp with *Peak* Power equal to or less than your speaker's rated power. Your woofers are now protected, but your tweeters are at risk. You can protect your tweeters either by buying speakers with tough tweeters, or you will just have to be responsible with how far you turn the volume knob and try not to play broken mp3s.

3) Buy the most powerful amp you want and can afford. Just be responsible with how far you turn the volume knob. Both your tweeters and your woofers are now at risk. Though this choice sounds dumb, in actuality it is a good choice because you can now enjoy the good quality music that comes with a powerful amp, even at lower volumes.

Personally right now I have 3 different speaker <--> amplifier setups. My Onkyo/Kappa pairing obeys philosophy 2). But my other 2 setups obey philosophy 3). And I do recognize the dangers and fully expect my woofers to blow out if I were ever to turn the volume knob all the way up.

To answer the original question, YES I believe your amplifier can blow out your speakers. If you slowly turn the volume louder and louder until the knob is all the way up, your Klipsch woofers will blow out and your tweeters will live. If you suddenly turn the volume knob to max because you fell over, both your tweeters and woofers might blow out together....or if you are lucky just your woofers will blow out (sacraficing themselves to save your tweeters).

But I think that setup is fine. Just don't turn the volume knob all the way up.

 

[Porcupine]

By the way 75-watts is very very loud. Unless you are trying to share your music with the neighbors you should not have any need of turning the volume knob all the way no matter how loud you like your music if you are sane. But if you do turn the volume knob all the way I would bet your speakers will blow out.

 

[mrboomble]

Thanks Porcupine, I'll try to keep the cat away from the volume knob.