Watts and peak?

[SuBXeRo]

This is the easiest way i could think of explaining this without going into too much depth:

1. Your amplifier has the capability of putting out "X" number of watts into a speaker. It is just that, capability....
2. Music/Movie media is dynamic which means the power requirements to reproduce the sound is dynamic which means power output will vary based on dynamic signal being amplified.
3. The power capability of an amplifier is rarely the full amount of power that is fed into a speaker consistently. Most klipsch owners use just a few watts of power because of their high efficiency. Other brands may use more or less power consistently depending on design. Like i said though, media is dynamic, so it's nice to have extra power for when it is needed.
4. RMS is the max wattage a speaker can handle consistently for a given period without destroying itself.
5. PEAK is the max wattage a speaker can handle for an extremely short period (like an explosion in a movie).
6. You can have a million watt amp and put it on a 5 watt speaker without blowing it up...until you exceed the wattage with which the driver can handle...
7. Headroom is great to have with a solidstate amplifier. Rule of thumb is to have RMS output power of an amp exceed the RMS output of the speaker. This also depends greatly on the type of speaker, how power hungry the speaker is, the capabilities of the speaker and how loud you like to listen. Again, this is rule of thumb. I have 125 watts to each of my RF-7's and they work great and can go to ear splitting and uncomfortable levels.
8. There are benefits to extra power, usually in a quality amplifier you will gain some accuracy and bass depth. This is highly debatable but a trend I have noticed between the various pieces of equipment i have had.

Now, lets apply this to your Denon AVR-X1000. It has a max output of 175 watts per channel which is most likely a split second peak output. Then it says 120 watts per channel but its bandwidth is only from 1,000hz upwards which is great if your sound was only 1,000hz and up but its not. The more realistic output number is the 20hz and up which is 80 watts. Taking this a step further, we know that manufacturers like to legally "fluff" their numbers as a method of advertising and when benched, most receivers show a drop off of power from what the manufacturer has specified. This drop is usually somewhere in the 20%-40%. Without actually seeing bench test results I can't tell you what you can really expect. My guess is you are getting power output somewhere in the 50-60 watt range but that could more or less and in a given frequency test range.

Now that we have that out of the way. Let us apply it to your scenario. Yes, you will drive your speakers fine! Klipsch is efficient and you are also talking about surround speakers which typically get used to a lesser extent than you center and left/right. You pretty much have the RMS power of the surrounds so there isn't anything to worry about unless you are planning to crank the hell out of it and push it to its limits.

Many of us go to class D driven receivers or outboard class A, A/B, D, or G, H power amplifiers because the power is easier to get and is usually better quality. Receivers are an all-in-one unit and have trade off's because of this. For the majority of the population, receivers are excellent solutions and most don't ever move beyond that. I feel that they have their place in the market but over the years, I have come to find that I am tinkerer and I like tons of options which makes having separate power amps beneficial for me.

Most importantly, Enjoy!!

Edited January 17, 2014 by SuBXeRo

[CECAA850]

without going into too much depth

I'd hate to read the in depth post, LOL!!

[psg]

For example, a 100 w amp push to severe clipping is really pushing close to 200 watts. The cooling of the voice coil is ineffective under these circumstances because the traveling of the coil is not proportionate to the power and heat build up. A 200 w amp can push the voice coil 40% further which results in better air flow aroun the voice coil. The heat build up in the 100 watt amp fries the voice coil.

This explains how to blow a woofer (because clipping usually occurs at woofer frequencies) but not the tweeter. But I guess I didn't specify that in my myth title phrase.

The speaker/tweeter survives with the 200 watt amp.

No, it would be worse, because the 200W would also be into severe clipping (and outputting 400W).

i.e. you can't get to extreme clipping in the first place by raising the volume control by 3 dB over maximum whereby the 200W would still be fine. You probably raised it by 10 or 20 dB to make a square wave (that has double the power of a sine wave).

[derrickdj1]

This explains how to blow a woofer (because clipping usually occurs at woofer frequencies) but not the tweeter. But I guess I didn't specify that in my myth title phrase.

In the Klipsch speakers, the passive xo help protect the tweeter. Unless and extremely high power amp is used and the tweeter is not rated for that extreme power, then you can blow a tweeter. If the tweeter is rated to handle significantly more power than the amp, even clipping will not damage it in most instances. I agree with you psg, the different varibles depending on the amp, and speakers make this topic not simple to answer.

The best protection for all audio gear is a little common sense when using it.

[thelittleone]

Thanks or all the answer guys….

[Scrappydue]

Jeeze sorry I asked.

[psg]

Why is that?

[etc6849]

Your explanation is interesting. While at first it seemed counter intuitive to me, I think you have a valid point after thinking about the science involved. I'd like to further discuss this topic though; to be sure I understand.

Assume that you have two sinusoidal waveforms you are playing, one is a low frequency wave, the other a high frequency wave riding on the lower frequency wave as shown in figure 2 below (figures taken from: http://sound.westhost.com/bi-amp.htm as I'm too lazy to make my own figures).

If that's the case and we think of clipping as exceeding the peak voltage an amplifier can provide, the high frequency waveform will be clipped, as it rides on the low frequency waveform. What seems interesting is you'd think this clipping would only impact the high frequencies as it appears information is lost. What seems very deceiving about thinking about the issue in the time domain is that it appears low frequency information is unaffected and that the woofer and the sound being produced from it will be unchanged... What seems at first crazy is this is not the truth!?!

Low frequency information will be more affected than the high frequency information as shown in the next image of what's occurring in the frequency domain. As PSG stated, clipping a waveform will add some harmonics similar to that of a square wave, and this will mean the lower frequency of these new harmonics will have more energy compared to the newer higher harmonics that were added (due to the Fourier transform of a square wave being a sync function). This is demonstrated by figure 3C copied below (although not explained in the article at the URL above). Ideally, one would expected to see only two peaks at 200 hz and 2kz, but this is not the case due to the clipping. This looks pretty nasty, more so for the lower harmonics.

Is this your point then that there will be more low frequency energy imparted on the woofer due to the extra lower frequency harmonics from the clipping? Or is there some other nuance I'm not seeing?

Thanks in advance

Why is that?

Edited January 19, 2014 by etc6849

[psg]

If you have a low frequency wave, the high frequency wave will ride on it as shown in figure 2 (figures taken from: http://sound.westhost.com/bi-amp.htm as I'm too lazy to make my own figures).

If that's the case and we think of clipping as exceeding the peak voltage an amplifier can provide, the high frequency waveform will be clipped, as it rides on the low frequency waveform. What seems interesting is you'd think this clipping would only impact the high frequencies as it appears information is lost. What seems very deceiving about thinking about the issue in the time domain is that it appears low frequency information is unaffected and that the woofer and the sound being produced from it will be unchanged...

However, I agree that clipping a waveform will add some harmonics similar to that of a square wave, and this will mean the lower frequency of these new harmonics will have more energy compared to the newer higher harmonics that were added (due to the Fourier transform of a square wave being a sync function). I think this is demonstrated by figure 3C copied below (although not explained in the article at the URL above). Is this your point then that there will be more low frequency energy imparted on the woofer due to the extra lower frequency harmonics from the clipping? Or is there some other nuance I'm not seeing?

Yes for the high frequency riding on top.

Thus, yes, clipping affects high frequencies drastically during the clipped part of the low signal. Whether this creates more high frequencies to kill tweeters, or perhaps less high frequency is a good question, since sometimes there's no voltage headroom left to add them at all (leading to less HF signal).

Correct also that higher frequencies are generated by the clipping itself as in a Fourier Expansion of the square(ish) wave. This generates harmonic distortion, some of which may reach the tweeter past the crossover frequency, but most of which will affect the woofer as distortion.

Thanks for posting the figures! They make it easier for people to understand.

[etc6849]

PSG, thanks for confirming this. I haven't used my EE degree in a while, so I hope the figures help others. This may very well explain why when I added a real 200W x 7 channel amp to my previous RF-83 setup, the lower frequencies sounded more real to me.

Definitely, I don't need the amps full power now that I'm running 4 La Scala II's due to the horn loaded woofer. However, I put a balanced voltage divider between my preamp (Marantz AV8801) and my amp (ATI AT2007), so I believe my La Scala's are protected even if someone turns the preamp up all the way. Of course, this doesn't protect them if someone unplugs and plugs the amps inputs and causes a voltage spike, but lets hope that never happens

However, I'd recommend to the OP that he/she run multiple matched subs (either two or four) and keep the AVR. Then, use the AVR's crossover setting to lower the load on the AVR's internal amp. Multiple subs will add a world of difference wrt room modes (e.g. low freq peaks caused by the room). It will be an immediately noticeable improvement. It was for me anyways. Horn loaded subs are nice too if you can fit two. I can't, so I've been using two Klipsch RT-12d subs (120db output @ 30hz) and they sound excellent in my setup.

Edited January 19, 2014 by etc6849

[psg]

This linked document from Rane was brought up on another forum. I think the author rounded a few corners but he agrees with what I said above in the end:

http://www.adx.co.nz/techinfo/audio/note128.pdf

[tigerwoodKhorns]

To the OP, nothing to worry about. They are now rating receivers at "peak power" which is meaningless. a continuous rating from 20 to 20 at a reasonable THD gives a much more meaningful number, though still not completely informative.

As to clean power will not destroy a speaker, not true. A friend had 300 wpc tube monoblocks (forget the brand, they are huge). He was driving a pair of Thiels. He tried a pair of Classe CAM 350 monoblocks (clean 700 wpc at 4 ohms) and damaged the woofers.

He did not push his system very hard, but the woofer cones actually distorted and crinkled and he had to replace them. The motors still worked, but he did do some damage. An expensive lesson.

[derrickdj1]

With that much power he over drove the woofer.

[etc6849]

What the article says seems like it could happen, depending on the signal. However, it does seem opposite of what we were talking about before in that the tweeter is damaged before the woofer...

What I think the article is saying is the low frequency gets clipped, but you won't notice, so you turn the volume up even louder so the tweeter is damaged first (and presumably the woofer can take the abuse). Seems plausible on a signal type as shown that contains mostly HF information, and only LF information for a few cycles.

Luckily, I've never blown a speaker, so I haven't had to experience this...

[etc6849]

Did he not turn off the amp when hooking it up? This would surely cause damage.

It seems to me that if you were very careful with the volume knob, the woofers should never get damaged (am I missing something?!?). Amplifiers work by amplifying voltage. This is called gain and expressed in dB. The dB difference from 300 watts -> 700 watts sounds like it'd be big, but it'd only be about 4dB. Thus, if you lower the voltage input by 4dB (from the max value that you normally set it at), it should be the same level of voltage coming out of the 700 watt amp when compared to the 300 watt amp. This assumes input sensitivities are the same between the two though.

To the OP, nothing to worry about. They are now rating receivers at "peak power" which is meaningless. a continuous rating from 20 to 20 at a reasonable THD gives a much more meaningful number, though still not completely informative.

As to clean power will not destroy a speaker, not true. A friend had 300 wpc tube monoblocks (forget the brand, they are huge). He was driving a pair of Thiels. He tried a pair of Classe CAM 350 monoblocks (clean 700 wpc at 4 ohms) and damaged the woofers.

He did not push his system very hard, but the woofer cones actually distorted and crinkled and he had to replace them. The motors still worked, but he did do some damage. An expensive lesson.

Edited February 1, 2014 by etc6849

[tigerwoodKhorns]

I know all of the basics and so does he. Regardless of the db (which is over twice as loud - log scale) it is over two times the electrical power.

This really did happen, mechanical damage to the cones by using too powerful of an amp. You would think the tweeters would have gone first. The motors on the woofers also were fine if I remember right, just con damage.

[etc6849]

Everything you said is correct. Definitely, the folks on here, including yourself, are very intelligent.

I didn't mean any disrespect by stating some basic theory, but just wanted to better understand what caused the woofers to blow. Clearly, there's some other mechanism going on that is beyond the electronics design stuff I learned in college, I just want to better understand it.

Maybe there's a design issue with the amp, and it has a voltage spike when you turn it on, lacking a soft start feature that many amps have? Maybe there was a large difference in input sensitivities between the two amps and this caught your friend off guard?

I know all of the basics and so does he. Regardless of the db (which is over twice as loud - log scale) it is over two times the electrical power.

This really did happen, mechanical damage to the cones by using too powerful of an amp. You would think the tweeters would have gone first. The motors on the woofers also were fine if I remember right, just con damage.