Power ratings and speakers. Can you explain this one?

[CB22]

From some of the articles that I've read and video's I watched, people recommend buying an amplifier with a power rating that is greater than what your speakers actually need; saying that the extra power helps the speakers. If this is correct, how would extra power help your speakers if the amplifier has a higher power rating than the speakers themselves?

For example, say you have a pair of efficient speakers with an impedance of 8ohm. + you have 2 good amplifiers of the same brand and product line. Then amplifier 1 has a power rating of 2000 watts. Amplifier 2 has a power rating of 100 watts. Would you hear a difference if you switched between amp 1 and amp 2 while listening at the same volume?

Logic tells me hell NO but what are your thoughts? Seems a hard to get a simple and straight explanation about this.

From my experience, my receiver has 5 channels rated a 140w into 8 ohms. I can't imagine that I'm using more than 40 watts per channel when watching a movie really loud. So say the receiver had a power rating of 80watts I would think the audio would sound the same. Right?

 

[KEW]

You are correct. There is no need for more power than you use.
The closest I can come to agreeing with what you have read is you do want to make sure you have enough power! If you amp is weak, then you can reach clipping where the amp is stressed at/beyond its limits.
Unfortunately, this results in a corruption of the signal to the speakers that is very hard for a speaker to attempt to produce and can destroy the speaker, if you don't catch it quickly. Fortunately, the sound will let you know you are clipping and it is not an instantaneous failure mode.
Your estimate of 40 does sound reasonable. If you have not used one, there are some calculators that allow you to determine a close estimate of your needs once you provide info on your speakers and you listening arrangement.

 

[lovinthehd]

The theory is predicated on headroom/crest factor allowance, that it's better to have more "clean power" capability for peaks/crest factor in material you're listening to (despite many amps being good for such beyond their rated continuous output).

Your use of power ratings without parameters (are they like ratings?) might use some honing, tho. Make sure you're comparing things properly. Also keep in mind it takes a doubling of power to gain merely 3dB spl.

Generally you will not hear a difference in amps with one having simply higher power capability, as long as they're both operating well within their rated parameters. There are some who swear simply by hooking up a more powerful external power amp all of a sudden their speakers come alive and sing etc, but think that mostly relates to new gear excitement than real differences in amp capabilities. It also doesn't hurt amp sales, so there's that....

A couple years ago I was changing some gear around, some different external amps and different avrs and at one point I ended up with just an avr hooked up, and didn't even realize that for quite a while, until I finished moving gear a few weeks later...never missed them. To fully disclose, I'd already made an effort to not listen as loudly, but still I was somewhere between -20dB and -10dB.

 

[CB22]

You are correct. There is no need for more power than you use.
The closest I can come to agreeing with what you have read is you do want to make sure you have enough power! If you amp is weak, then you can reach clipping where the amp is stressed at/beyond its limits.
Unfortunately, this results in a corruption of the signal to the speakers that is very hard for a speaker to attempt to produce and can destroy the speaker, if you don't catch it quickly. Fortunately, the sound will let you know you are clipping and it is not an instantaneous failure mode.
Your estimate of 40 does sound reasonable. If you have not used one, there are some calculators that allow you to determine a close estimate of your needs once you provide info on your speakers and you listening arrangement.

 

[M Code]

Everyone has their own personal idea on how much amplifier output power is required...
Consider the basic factors:

• Room size
• Loudspeaker specs, impedance/sensitivity
• Source material, compressed, uncompressed
• Music or cinema sound tracks
• Average listening level
• $ Budget

IMHO..
Since we have designed/sold/installed multiple home and commercial systems over the years, we have some built-in preferences. We prefer to use higher powered amplifiers, though more expensive they provide better comfort zone as amplifier output stages in an AVR run out of headroom very quickly. And this can be very hard and destructive on a loudspeaker when the amplifier is sending out clipping distortion. More loudspeakers are destroyed using a low powered amplifier trying to deliver a higher SPL driving it into clipping compared to a high powered amplifier. Also AVRs available today, especially ones selling for <$999 SRP have less electrical/mechanical component over-design than previous generations.

Bottom line..
Noting U have an Anthem AVR, Klipsch loudspeakers, HSU subwoofer those are good, quality system components and the Klipsch loudspeakers are very efficient (>93dB) not requiring extreme power. Using your present components and source material if the SPL volume level of your components meets your expectations than there is little need to upgrade.

Just my $0.02..

 

[gene]

Recommended reading:

Matching Amplifier Power To Speakers

When you Upgrade Receiver Power with External Amplification

 

[PENG]

More loudspeakers are destroyed using a low powered amplifier trying to deliver a higher SPL driving it into clipping compared to a high powered amplifier.

Nice post M Code, the only part I have difficulty agreeing with is the part in the quote. As someone mentioned long ago, people blasted their ghetto blasters all day long, so loud that you typically can hear sever distortions from a mile away, and they still seemed to last forever.

so the second bottom line is, it depends on many factors, and I highly doubt there are facts to back up the claim that "more" loudspeakers are destroyed using a low powered amplifier..............". In practice, lower powered amplifier would clip sooner, providing feedback to the user to turn it down earlier so the speaker may actually see less thermal energy overall from the time it gets powered up to the time the applied voltage get reduced at the amp output (say, by the user/listener). It is hard to say, we just don't know. All we know is, as Paul said in the article Gene linked, "You’re the guy most likely to blow up your speakers, and it’s totally your fault."

 

[PENG]

From some of the articles that I've read and video's I watched, people recommend buying an amplifier with a power rating that is greater than what your speakers actually need; saying that the extra power helps the speakers. If this is correct, how would extra power help your speakers if the amplifier has a higher power rating than the speakers themselves?

For example, say you have a pair of efficient speakers with an impedance of 8ohm. + you have 2 good amplifiers of the same brand and product line. Then amplifier 1 has a power rating of 2000 watts. Amplifier 2 has a power rating of 100 watts. Would you hear a difference if you switched between amp 1 and amp 2 while listening at the same volume?

Logic tells me hell NO but what are your thoughts? Seems a hard to get a simple and straight explanation about this.

From my experience, my receiver has 5 channels rated a 140w into 8 ohms. I can't imagine that I'm using more than 40 watts per channel when watching a movie really loud. So say the receiver had a power rating of 80watts I would think the audio would sound the same. Right?

As HD mentioned, you can use an online calculator, such as the one we linked a million times on AH. That calculator will let you figure out the peak spl your system can deliver in your own room at or below clipping. If used properly, there is sort or a build in safety factor of 3 dB, but I highly recommend you allow for at least another 3 dB just to be sure. So if the calculator shows that you have 6 dB, or more spare on hand, then your 100 W amp should sound the same as the 1000 W amp, all else being equal.

 

[highfigh]

Nice post M Code, the only part I have difficulty agreeing with is the part in the quote. As someone mentioned long ago, people blasted their ghetto blasters all day long, so loud that you typically can hear sever distortions from a mile away, and they still seemed to last forever.

so the second bottom line is, it depends on many factors, and I highly doubt there are facts to back up the claim that "more" loudspeakers are destroyed using a low powered amplifier..............". In practice, lower powered amplifier would clip sooner, providing feedback to the user to turn it down earlier so the speaker may actually see less thermal energy overall from the time it gets powered up to the time the applied voltage get reduced at the amp output (say, by the user/listener). It is hard to say, we just don't know. All we know is, as Paul said in the article Gene linked, "You’re the guy most likely to blow up your speakers, and it’s totally your fault."

WRT ghetto blasters not dying- they did, but they may have been replaced when that happened. We saw plenty that had blown speakers when I worked at a stereo store, but there was also zero chance that the person carrying it would turn it down just because it sounded like crap. I still hear the same thing from people driving around with their car stereo cranked to total distortion (an Amazon driver was the most recent) and I can't imaging doing that. These aren't custom systems, they tend to be the stock system or a head unit and new speakers, usually without an amplifier- total mush.

The speakers should be able to provide more SPL than needed, the amplifier should be able to provide more power than the speakers require to produce their maximum SPL and the system should be able to provide more SPL than the user needs/wants/can handle. Those maximums need to be determined before any system can be designed. There's no reason to operate the system at the limits of the equipment for more than a few seconds, if that. If it is, something is going to fail. Let's compare top fuel dragsters and street-legal cars as an equivalent- dragsters have a limit for displacement and the fuel used in each is the same, so the differences are in the engine tuning, lane, driver, frame and setup. These are often run at their limits and sometimes they blow up, even with their 8000+ Horsepower. Street legal cars aren't used at their limits (for a variety of reasons) and passing their limits is rarely the cause of engine failure.

Ultimately, the things that become too hot to survive will fail and choosing speakers and amps that prevent this up to and beyond the application's maximum limits makes for a system that will continue to operate normally.

 

[highfigh]

From some of the articles that I've read and video's I watched, people recommend buying an amplifier with a power rating that is greater than what your speakers actually need; saying that the extra power helps the speakers. If this is correct, how would extra power help your speakers if the amplifier has a higher power rating than the speakers themselves?

For example, say you have a pair of efficient speakers with an impedance of 8ohm. + you have 2 good amplifiers of the same brand and product line. Then amplifier 1 has a power rating of 2000 watts. Amplifier 2 has a power rating of 100 watts. Would you hear a difference if you switched between amp 1 and amp 2 while listening at the same volume?

Logic tells me hell NO but what are your thoughts? Seems a hard to get a simple and straight explanation about this.

From my experience, my receiver has 5 channels rated a 140w into 8 ohms. I can't imagine that I'm using more than 40 watts per channel when watching a movie really loud. So say the receiver had a power rating of 80watts I would think the audio would sound the same. Right?

If one amplifier operating at its limit can't reproduce the dynamics in the program material and the other can, the difference may be audible, but if the amplifiers aren't running at their limit, it's unlikely. A 40 Watt amp at its limit vs a 2000 W amp at the same power level will produce the dynamic peaks without distorting, so that may be audible if the SPL isn't so high that the listener's ears haven't been adversely affected.

 

[PENG]

WRT ghetto blasters not dying- they did, but they may have been replaced when that happened. We saw plenty that had blown speakers when I worked at a stereo store, but there was also zero chance that the person carrying it would turn it down just because it sounded like crap. I still hear the same thing from people driving around with their car stereo cranked to total distortion (an Amazon driver was the most recent) and I can't imaging doing that. These aren't custom systems, they tend to be the stock system or a head unit and new speakers, usually without an amplifier- total mush.

Oh I agree, everything dies eventually. I thought it was obvious that I exaggerated things to the nth degree to make a point. It is however, a fact that I have seen some ghetto blasters survived after playing for hours with absolute signs of clipping and I had no idea at what point they died. To me that confirms my thinking that the so called too little power killed more speakers is likely overrated, key word is "more", sorry about nitpicking though.

 

[M Code]

Nice post M Code, the only part I have difficulty agreeing with is the part in the quote. As someone mentioned long ago, people blasted their ghetto blasters all day long, so loud that you typically can hear sever distortions from a mile away, and they still seemed to last forever.

so the second bottom line is, it depends on many factors, and I highly doubt there are facts to back up the claim that "more" loudspeakers are destroyed using a low powered amplifier..............". In practice, lower powered amplifier would clip sooner, providing feedback to the user to turn it down earlier so the speaker may actually see less thermal energy overall from the time it gets powered up to the time the applied voltage get reduced at the amp output (say, by the user/listener). It is hard to say, we just don't know. All we know is, as Paul said in the article Gene linked, "You’re the guy most likely to blow up your speakers, and it’s totally your fault."

Don't mix the apples & oranges..
Comparing an audio system with @ least 30-50 Watts/channel is very different vs a ghetto blaster having 3-5 Watts/channel.. I don't have any data or experience for loudspeaker failure for ghetto blasters but I do for audio products/amplifiers...
However having brand marketing profit $ responsibility for a couple of the more popular audio brands field failure rate for all components including loudspeakers was under constant review for warranty purposes.. Also I may add that in many of the field failures for loudspeakers it was apparent the listener had no clue he was driving the loudspeaker into distortion until it started rattling and/or sounding distorted... Common reasons for the failure was using a source component of high THD such as an analog tape cassette and/or simply jacking up the tone & loudness controls.. Another major reason for the failure was the system was using a smaller woofer such as an 8" which simply doesn't move the air like a 10" or 12" while the listener was trying to get more SPL out of it....

Just my $0.02...

 

[PENG]

Don't mix the apples & oranges..
Comparing an audio system with @ least 30-50 Watts/channel is very different vs a ghetto blaster having 3-5 Watts/channel.. I don't have any data or experience for loudspeaker failure for ghetto blasters but I do for audio products/amplifiers...
However having brand marketing profit $ responsibility for a couple of the more popular audio brands field failure rate for all components including loudspeakers was under constant review for warranty purposes.. Also I may add that in many of the field failures for loudspeakers it was apparent the listener had no clue he was driving the loudspeaker into distortion until it started rattling and/or sounding distorted... Common reasons for the failure was using a source component of high THD such as an analog tape cassette and/or simply jacking up the tone & loudness controls.. Another major reason for the failure was the system was using a smaller woofer such as an 8" which simply doesn't move the air like a 10" or 12" while the listener was trying to get more SPL out of it....

Just my $0.02...

IMO 3-5W is in fact a good example to show low power amps, even if clipping, may or may not destroy more speakers than higher power amps might. It is not mixing apples and oranges at all. Until someone can show some credible statistics, I am not going to choose side, but would simply say we don't really know. As I said before, everything else I agreed with you. Even on this point, there is no disagreement, other than I don't believe we can make such "claim" as "facts" (not saying you did..), but it could be interpreted as such.

 

[M Code]

IMO 3-5W is in fact a good example to show low power amps, even if clipping, may or may not destroy more speakers than higher power amps might. It is not mixing apples and oranges at all. Until someone can show some credible statistics, I am not going to choose side, but would simply say we don't really know. As I said before, everything else I agreed with you. Even on this point, there is no disagreement, other than I don't believe we can make such "claim" as "facts" (not saying you did..), but it could be interpreted as such.

Ghetto blasters were made to reproduce distortion...
Even if a loudspeaker driver was blown its doubtful the listener would even notice..
Unless it went completely dead..

Just my $0.02...

 

[PENG]

Ghetto blasters were made to reproduce distortion...
Even if a loudspeaker driver was blown its doubtful the listener would even notice..
Unless it went completely dead..

Just my $0.02...

Haha, that could be, they also don't have real tweeters so less prone to the potentially damaging hf resulted from clipping.

 

[CB22]

Not gonna lie, even on the second re-read of the loudspeakers & Power Ratings article a bit of the Testing section went a bit over my head. But the main take away was... "Peaks of very short duration can serve to destroy a loudspeaker even though they are of such a short duration, they are not able to heat up the speaker significantly. Frequency content and Peak to RMS ratio (crest factor) are critical in determining the potential for loudspeaker destruction of a test signal. The loudspeakers impedance magnitude gives us clues as to the potential harm from a signal based on the variation of impedance with frequency.

High frequencies are NOT DANGEROUS to the typical woofer, and the notion that clipped signals of a given RMS value are more dangerous to a woofer than unclipped signals is not necessarily correct. Clipped signals do put a higher percentage of amplifier power into the tweeter or high frequency device, and are therefore more dangerous to multi driver systems or high frequency units. Low frequency drivers (woofers) have very high impedances at high frequencies and are therefore not able to easily draw power from the amplifier at the highest frequencies. Without specifying the frequency content and crest factor of the test signal used, the POWER HANDLING NUMBER IS MEANINGLESS!" Low frequency drivers (woofers) have very high impedances at high frequencies and are therefore not able to easily draw power from the amplifier at the highest frequencies.


Hopefully, this does not sound like a bunch of mumbo jumbo. Sorry in advance if it does.

A quick recap: The point of having a powerful amp it to give more head room so your speakers don't clip. With that being said, if you have a very large room, naturally your speakers will need more amplification to achieve the same SPL. I understand this just fine.

So Lets take my Klipsch 280's for example. The speakers have an impedance of 8ohms. Klipsch's specs they say, "POWER HANDLING (CONT/PEAK) 150/600" & let's pretend that I have a 2000w amplifier into 8ohms.

- Assuming the specs are true they continuous power rating of 150 watts:
Using a test signal of 17,000Hz, it's fair to say that 150 watts of amplification could be put into the speakers without damaging the speakers tweeters?

Using a test signal of 35Hz, it's fair to say that 150 watts of amplification into the woofer could very easily destroy the woolfer?

So how does crest factor play into the example above?


- A peak at 600w :
1 signal of any amplitude at 600 watts would clip the speakers and destroy the speakers. Correct?


Bear with me and help me dumb this down a bit: What I still don't really understand is crest factor and how this plays into the test signal used. Google say, "It's defined as the level difference between the RMS and the peak value of the waveform." So crest factor has something do do with the ratio between the peek current and the RMS current.

Here's my understanding of crest factor so far:
=================
Crest factor consists of two things - 1. Peek + 2. Is RMS.

Peek current is the point of amplitude where clipping will occur in my example 600watts

RMS is average voltage level of electrical signals

So as the RMS increases -> the RMS comes closer to 600w and the ratio narrows down.

Once the ratio gets to 1:1 that's the loudest possible amplitude the wave form can be played at.

So at ratio of 1:1 the speakers would be clipped and destroyed, correct?
=================

After watching this, I was just like ohhh goddd.

 

[highfigh]

Oh I agree, everything dies eventually. I thought it was obvious that I exaggerated things to the nth degree to make a point. It is however, a fact that I have seen some ghetto blasters survived after playing for hours with absolute signs of clipping and I had no idea at what point they died. To me that confirms my thinking that the so called too little power killed more speakers is likely overrated, key word is "more", sorry about nitpicking though.

I had a customer who bought a Pioneer SX-780 and Jamo J-101, which are the same model I had (and still use at my bench in the basement, mainly because I have too many speakers and I don't feel like carrying them two floors). He came in with the speakers one day and said they had problems. Checked them out and found that the mids and tweets were toast, which is a pretty good trick since they have polyswitches, to protect them. I called back and told him that I'd like him to bring the receiver in, because we had never seen a pair of their speakers blown so badly. He did, we checked it out and IIRC, it was OK. The problem was that speaker manufacturers usually don't honor warranties when two or more drivers are blown, and we explained that to him. His dad came back to argue about it and said "My kid doesn't crank the stereo that loud!", to which I answered "Are you at home all day, every day". He quietly said "Can you call when they're done?" and we did. The thing that we also did, as a lesson, was to honor the warranty- we were Jamo's 2nd dealer in the US, so there wasn't much chance they would dispute it since we sold so many of their speakers.

Must have been 30 years later, I went to see Rush at an outdoor venue and I felt a tap on my shoulder. I turned and the guy behind me asked if I was Jim, from a particular stereo store. I said I was and he told me his name. He looked familiar, but I couldn't place him until he said "You told me I blew my Jamo speakers in a way you had never seen and at that point I said, "Oh, I remember you!". He just hung his head.

 

[highfigh]

Haha, that could be, they also don't have real tweeters so less prone to the potentially damaging hf resulted from clipping.

Typically, they had piezoelectric tweeters- nasty sounding things, but they could handle a lot if the right things were done to protect them.

 

[PENG]

Not gonna lie, even on the second re-read of the loudspeakers & Power Ratings article a bit of the Testing section went a bit over my head. But the main take away was... "Peaks of very short duration can serve to destroy a loudspeaker even though they are of such a short duration, they are not able to heat up the speaker significantly. Frequency content and Peak to RMS ratio (crest factor) are critical in determining the potential for loudspeaker destruction of a test signal. The loudspeakers impedance magnitude gives us clues as to the potential harm from a signal based on the variation of impedance with frequency.

High frequencies are NOT DANGEROUS to the typical woofer, and the notion that clipped signals of a given RMS value are more dangerous to a woofer than unclipped signals is not necessarily correct. Clipped signals do put a higher percentage of amplifier power into the tweeter or high frequency device, and are therefore more dangerous to multi driver systems or high frequency units. Low frequency drivers (woofers) have very high impedances at high frequencies and are therefore not able to easily draw power from the amplifier at the highest frequencies. Without specifying the frequency content and crest factor of the test signal used, the POWER HANDLING NUMBER IS MEANINGLESS!" Low frequency drivers (woofers) have very high impedances at high frequencies and are therefore not able to easily draw power from the amplifier at the highest frequencies.

It seems like you have a good understanding of those articles.

So Lets take my Klipsch 280's for example. The speakers have an impedance of 8ohms. Klipsch's specs they say, "POWER HANDLING (CONT/PEAK) 150/600" & let's pretend that I have a 2000w amplifier into 8ohms.

- Assuming the specs are true they continuous power rating of 150 watts:
Using a test signal of 17,000Hz, it's fair to say that 150 watts of amplification could be put into the speakers without damaging the speakers tweeters?

Using a test signal of 35Hz, it's fair to say that 150 watts of amplification into the woofer could very easily destroy the woolfer?

So how does crest factor play into the example above?

We don't know the basis of Klipsch's claim of 150W continuous, so we don't know the answer to your question for sure. My educated guess is that, if the amp delivers 150W average to the woofer of the "150W cont" rated Klipsch 280, it would fail mechanically if the signal has a much higher crest factor than sine wave's.

- A peak at 600w :
1 signal of any amplitude at 600 watts would clip the speakers and destroy the speakers. Correct?

If Klipsch's 600 W peak rating is real, and is calculated by squaring the voltage peak of the signal divided by 8 ohms (P=V^2/R, if the load is a resistor) then no, it shouldn't destroy the speaker. You really need to ask Klipsch that question, but only if you can get it directly from their design team, not the customer service that typically are of the marketing type.

Bear with me and help me dumb this down a bit: What I still don't really understand is crest factor and how this plays into the test signal used. Google say, "It's defined as the level difference between the RMS and the peak value of the waveform." So crest factor has something do do with the ratio between the peek current and the RMS current.

Did you mean to say:

"Crest factor is defined as the ratio of peak value to rms value of a current waveform: The crest factor for a sinusoidal current waveform, such as that which a pure resistive load would draw, is 1.414 since the peak of a true sinusoid is 1.414 times the rms value."

You can substitute "current" with "voltage" as well.

Here's my understanding of crest factor so far:

Peek current is the point of amplitude where clipping will occur in my example 600watts

RMS is average voltage level of electrical signals

Sorry, incorrect on both counts. It has nothing to do with clipping, though if the signal clips, the waveform as well as the crest factor obviously will change too.

So as the RMS increases -> the RMS comes closer to 600w and the ratio narrows down.

Once the ratio gets to 1:1 that's the loudest possible amplitude the wave form can be played at.

So at ratio of 1:1 the speakers would be clipped and destroyed, correct?

Not really, for a given waveform, if you increase the magnitude such as by putting it through a linear amplifier, both RMS and Peak values should increase in proportion, and the crest factor (ratio of Peak/RMS) will remain the same, unless and until the signal is distorted, such as when the amplifier starts to clip.

 

[CB22]

It seems like you have a good understanding of those articles.



We don't know the basis of Klipsch's claim of 150W continuous, so we don't know the answer to your question for sure. My educated guess is that, if the amp delivers 150W average to the woofer of the "150W cont" rated Klipsch 280, it would fail mechanically if the signal has a much higher crest factor than sine wave's.



If Klipsch's 600 W peak rating is real, and is calculated by squaring the voltage peak of the signal divided by 8 ohms (P=V^2/R, if the load is a resistor) then no, it shouldn't destroy the speaker. You really need to ask Klipsch that question, but only if you can get it directly from their design team, not the customer service that typically are of the marketing type.



Did you mean to say:

"Crest factor is defined as the ratio of peak value to rms value of a current waveform: The crest factor for a sinusoidal current waveform, such as that which a pure resistive load would draw, is 1.414 since the peak of a true sinusoid is 1.414 times the rms value."

You can substitute "current" with "voltage" as well.



Sorry, incorrect on both counts. It has nothing to do with clipping, though if the signal clips, the waveform as well as the crest factor obviously will change too.



Not really, for a given waveform, if you increase the magnitude such as by putting it through a linear amplifier, both RMS and Peak values should increase in proportion, and the crest factor (ratio of Peak/RMS) will remain the same, unless and until the signal is distorted, such as when the amplifier starts to clip.

Thanks for the reply, this does make a bit more sense but I still think I need to go take a class in the science of sound to really get this down.