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post #1 of 514 Old 01-03-2007, 02:30 PM - Thread Starter
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I'm in the process of building my home theater, and I think I found the receiver I want (Yamaha HTR-5930SL). It's 110W/channel, but the speakers I currently have are 100 W for the front L&R, and ~33 W apiece for the center and rears. It's an old Aiwa shelf system.

Anyway, will this receiver work with my existing speakers? If I have to get new ones, then so be it, but I'd rather not replace everything all at once if I don't have to.

Is there anything else I should be concerned with?
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post #2 of 514 Old 01-03-2007, 03:03 PM
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You should be fine, its better to have an overpowered reciever than an undepowered one. Secondly, I wouldnt worry about it putting out 110wpc, its probably more like 70wpc, yamahas have been known to be pretty generous with their specs. I would just really watch for distortion at moderate/higher volumes.
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post #3 of 514 Old 01-04-2007, 09:54 AM - Thread Starter
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So as long as I don't turn up the volume too high, I probably won't risk blowing any of my speakers?
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post #4 of 514 Old 01-04-2007, 10:26 AM
 
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Quote:
Originally Posted by bphisig View Post

So as long as I don't turn up the volume too high, I probably won't risk blowing any of my speakers?

Correct.

There is no such thing as "too much power" capability. You can always blow your speakers by turning them up too loud. And turning up the volume too loud is MORE dangerous with an underpowered amplifier than a capable or "overpowered" amp.
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post #5 of 514 Old 01-04-2007, 10:33 AM
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Eh, i beg to differ . A good receiver will make those little shelf system speakers sound GREAT ... until you reach their maximum, and then that center channel is going to blow.

If your careful, and dont turn it up too loud you wil be fine though. Even if you blow them, that will give you a great reason to upgrade
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post #6 of 514 Old 01-04-2007, 11:39 AM - Thread Starter
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Good point John, it will make it much easier to explain to the wife that way!
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post #7 of 514 Old 01-04-2007, 02:54 PM
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If it makes you feel better my speakers are rated up to 150 watts per channel (8 ohm) and I use a power amplifier that is conservatively rated at 300 watts per channel into 8 ohms. Been running with this setup for years.

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post #8 of 514 Old 01-04-2007, 03:09 PM
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I have a noobish question - what about the opposite of the TC? The receiver I'm looking at (Onkyo TX-SR604) only does 90 watts per channel, and the speakers I'm looking at (HTD Level 2 Bookshelfs, Center) do 100 and 120 watts respectively. Will this be a problem? I most likely won't be turning the volume up that high though.
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post #9 of 514 Old 01-04-2007, 03:56 PM
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Originally Posted by epsilon72 View Post

I have a noobish question - what about the opposite of the TC? The receiver I'm looking at (Onkyo TX-SR604) only does 90 watts per channel, and the speakers I'm looking at (HTD Level 2 Bookshelfs, Center) do 100 and 120 watts respectively. Will this be a problem? I most likely won't be turning the volume up that high though.

You will be fine too. Most likely the loudest you will go is about 60% on the volume scale. Anything more will be too loud for most people (and drive them out of the room ... )
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post #10 of 514 Old 01-04-2007, 04:19 PM
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Epsilon this isnt a "volume" issue, its a "reserve power" issue. A transient spike in a movie soundtrack will use all the power of that receiver, even at moderate volumes. Its not so much the wattage, as it is the size of the single transformer that provides DC voltage to the amp sections.

I had a 21 pound, 500 series Onkyo reciever that gasped when running my (87dB efficiency) Rocket speakers. So I immediately ran out and bought a used Yamaha RXV-995, a 35 pound used receiver with good amps. All the sudden my Rockets came to life.

With the 600 series Onkyo, your in better shape than I was; and it likely will sound fine. BUT keep in mind that those HTD level 2s are relatively inefficient speakers (87dB) too, so a bigger receiver, with more reserve power, will sound better.
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post #11 of 514 Old 01-04-2007, 04:23 PM
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I concur with what others have said here.

Something useful to know is that it takes double the wattage to produce a 3dB rise in output level. It generally takes a 10dB rise for a person to judge output as being twice as loud, demanding over 8x the initial wattage! This makes the comparison of 70 vs 100 watts much easier. I just ignore it until there is at least a doubling of power and consider those close in wattage to be of little of no useful difference.

Add to this the inaccurate power ratings of many receivers and there is even less power distinction. Another way to compare is to have a look at the rated maximum draw located next to the power cord connection. It's amusing to see how far less that value is compared to the number of channels times the per channel rating. Compounding the issue, you can further reduce the output potential by adjusting the rated draw maximum by an optimistic efficiency factor of say .7 (unless the amp uses one of those high efficiency digital switching designs).

If you need high volume, say 110dB+, out of your speakers, consider buying speakers with high sensitivity ratings. Whatever your sensitivity is, it's pretty easy to figure out just how loud you can get based on the actual wattage pumped into them. Whatever happens, make it a policy not to push an analog volume control past 60% of it's maximum and you should be fine. If it's a digital control, keep it 6+ dB lower than max as a good safety margin. In both cases, this is likely to be very loud, ear damaging loud if exposed for hours, maybe even minutes. Use caution and enjoy!

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post #12 of 514 Old 01-04-2007, 04:34 PM
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Aye but most good speakers aint so efficient
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post #13 of 514 Old 01-04-2007, 05:54 PM
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post #14 of 514 Old 01-04-2007, 07:28 PM
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Thanks for all of the answers to my noobish question. If I can find something slightly more powerful in my price range (but not low budget quality) I'll go for it, otherwise I'll probably just stick with the Onkyo.
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post #15 of 514 Old 01-04-2007, 11:24 PM
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A good rule of thumb for amplifiers is to provide twice the power rating of the speaker (more is always better)... if you can afford it. Granted, there are exceptions - depending on sensitivity, listening levels and distance. The idea is to have enough headroom to give you enough dynamics when the speaker calls for it. Most speakers will have no problem handling much more wattage than it's power rating (sometimes as much as 4x), but only for very short periods of time (<10 seconds). You can certainly blow a driver, but you'll most likely notice the distortion long before this happens, as long as your doing something reasonable (i.e. not playing sine waves at reference levels).
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post #16 of 514 Old 01-05-2007, 12:17 AM
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speakers usualy are being burned because of underpowered amps. this is because of low power amp starts to limit signal at low levels, that way feeding DC into speakers, which burns the coil because of no membrane movement makes no cooling for coil. always use as high power amps as possible.
btw amps actual output power depends on volume u turn. the wattage printed on box just says that you wount get more than 110W without significant distortion.

dont make fun of my english, its 3rd language for me
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post #17 of 514 Old 01-05-2007, 03:58 AM
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Quote:
Originally Posted by ChrisWiggles View Post

You can always blow your speakers by turning them up too loud. And turning up the volume too loud is MORE dangerous with an underpowered amplifier than a capable or "overpowered" amp.

If you are suggesting that underpowered amps are more likely to blow speakers at a certain volume setting than overpowered amps because of clipping, I disagree.

An underpowered amp is more likely to cause clipping at a certain volume setting, but an overpowered amp at the same volume setting will be more likely to blow the speakers due to putting more power into them than the underpowered amp. The overpowered amp will give the extra voltage during the peak of the wave while the underpowered amp won't.

If measuring the maximum voltage coming out of the amp, a clipping amp showing the same maximum voltage as an overpowered one will cause more damage, but only because it is actually putting more power into the speakers. The underpowered amp has a clipped wave, meaning the time when it has that maximum volatage is longer than for the overpowered amp. The only reason this happening that the clipping amp is trying to represent a higher volume level than the overpowered amp. If the overpowered amp were trying to represent the same volume level as the underpowered amp, it would be much more likely to blow the speakers.

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post #18 of 514 Old 01-05-2007, 06:06 AM
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the speakers can be killed in bouth way, that is true.
BUT, in practise its hard to kill for example good 100W speaker with overpowered amp because if u would like to kill it you would need to turn volume to like 500W which will give you a good amount of SPL which your ear probably wount carry.
on other hand, with underpowered amp u can kill the same 100W speaker with like 20W if amp is in saturation, and it wount make a big SPL so your ear wout tell you 'turn it down'.

im new in home audio, but in car audio i got 126dB SPL with 20W on speaker @ 50-70Hz, so i wouldnt care too much about 100W vs 200W, as difference between thos 2 are 3dB SPL

again, sorry for my english

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Originally Posted by greeniguana00 View Post

An underpowered amp is more likely to cause clipping at a certain volume setting, but an overpowered amp at the same volume setting will be more likely to blow the speakers due to putting more power into them..

-so not true. its easy to kill with clipping(if i understand meaning right) and hard to kill with overpower

dont make fun of my english, its 3rd language for me
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post #19 of 514 Old 01-05-2007, 09:39 AM
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Quote:
Originally Posted by greeniguana00 View Post

If you are suggesting that underpowered amps are more likely to blow speakers at a certain volume setting than overpowered amps because of clipping, I disagree.

An underpowered amp is more likely to cause clipping at a certain volume setting, but an overpowered amp at the same volume setting will be more likely to blow the speakers due to putting more power into them than the underpowered amp. The overpowered amp will give the extra voltage during the peak of the wave while the underpowered amp won't.

If measuring the maximum voltage coming out of the amp, a clipping amp showing the same maximum voltage as an overpowered one will cause more damage, but only because it is actually putting more power into the speakers. The underpowered amp has a clipped wave, meaning the time when it has that maximum volatage is longer than for the overpowered amp. The only reason this happening that the clipping amp is trying to represent a higher volume level than the overpowered amp. If the overpowered amp were trying to represent the same volume level as the underpowered amp, it would be much more likely to blow the speakers.

Clipping makes a square wave. After the crossover, much more high frequencies content will be delivered to the tweeter and it will blow sooner. You are likely to blow tweeters more easily using an under-powered receiver, driven to clipping.

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post #20 of 514 Old 01-05-2007, 11:15 AM
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Here is a first class explanation of what kills speakers and the role clipping might play. I am quoting it here with new paragraphing because the original was in one very hard to read chunk.

Average power at too high a level, clipped or not is the culprit. If a speaker can safely disapate 50 watts, then at clipping, an amplifier delivering 50 watts of power as a square wave, will not damage it. An amplifier delivering 100 watts, clean or clipped, will damage it.

The author posits 10dB of headroom in music. That may not be true for many these days. Recent recording practices favor very heavy compression, with a very small difference between average and peak levels. The so called program material that many speaker manufactures refer to in giving power handling specs now has a very high average level; one that approaches clipped.

Clipping and You Amplifier clipping, and it's respective causes and effects, is perhaps one of the most misunderstood concepts amongst audio circles. There is a whirlwind of myths surrounding this topic that seems to exceed all other topics I have come across. ... There are only two ways that a speaker can be damaged, both of which occur from too much input power. : 1. Mechanically 2. Thermally

Every speaker has an excursion limit (often measured in mm), or how far the speaker can move forward or rearward before damage occurs. This is the mechanical limit of the speaker. This limit remains the same regardless of the use of the speaker, but the power required to reach this limit changes dependent on the enclosure. If you exceed this limit, the speaker will suffer mechanical damage, whether it's ripping your spider, bottoming out on the back plate, or any other mechanical damage.

The second type, thermal damage, occurs when you exceed the thermal power handling limits of the voice coil itself. Voice coils are simple pieces of metal that will melt if too much power is applied. This limit is pretty much constant, ie. if a voice coil will be damaged at 1 kw, it will be damaged at 1kw regardless. There are two final myths to cover here.

Despite the tireless efforts of some, there are still many people that believe that underpowering a speaker will damage it or that clipping will damage a speaker. Please remember that these last two thoughts are entirely UNTRUE! And now we will find out why.

Where Does This Power Come From?

Let's first understand the power potential of an amplifier when clipping. The power created is largely determined by the rail voltages. Let's compare two amps, each one connected to a 4 ohm speaker rated at 75 watts rms.

Amp 1: 50 watt amp 50 Watt amp means this amp can cleanly deliver a sinewave of 50watts into a 4 ohm load. This means (Vrms)^2/4 = 50W Vrms = 14.14V Vpeak = Vrms*(1.414) Vpeak = 19.99V The rail voltages of this amp must be a bit higher, to prevent output stage distortion at this power level. In this case, the Rail voltage would have to be +/- 20 Volts.

Amp 2: 75 watt amp (Vrms)^2/4 = 75W Vrms = 17.32V Vpeak = Vrms*(1.414) Vpeak = 24.49V

In the example, the 75 watt amp is delivering 75 watts as it is not distorting at all. The 50 watt amp is in hard clipping, as and such, is delivering a fair bit more power. P = Vrms^2/R = (19.99V)^2/4 ohm = 100 watts.

It is quite obvious that there is potential for an amplifier that is clipping to deliver substantially more power than you would expect. Keep in mind that this is only a way to determine peak voltage potential.

Average Power Now we can get into how a speaker really gets hurt. The key issue is average power over time. Let's get to the nitty gritty. The first key is understanding Crest Factor. "Crest Factor" is the difference between the average level of the signal and its peak level. A pure sine wave has a "crest factor" of 3dB, meaning that it's peak level is 3dB higher than its average level. We all know that 3dB represents a difference in power by a factor of 2. Another way to look at it is that the peak power of the signal is twice that of its average level. If we were to play a sine wave on our 50 watt amplifier, just below its clipping level, the average power over time the speaker would need to dissipate is 25 watts.

On the other hand, a square wave has a crest factor of 0dB. In other words, it's average power and peak power levels are equal. Our same 50 watt amplifier playing a square wave into our speaker requires the speaker to dissipate 50 watts. Keep in mind that this refers to sine and square waves only.

Music has a much higher crest factor. Most widely available recordings have a crest factor of approximately 10dB. Looking at this in terms of power, the peak power is 10 times greater than the average power. If we were to play one of these recordings with our 50 watt amplifier when not clipping, the speaker needs to dissipate a mere 5 watts of average power over time. When the amplifier begins clipping, the peak level/power does not increase. BUT, the average power DOES increase.

If we were to turn the volume up 6dB higher than the clipping level of our recording, we have reduced our crest factor to 4dB. Guess what? We are now needing the speaker to dissipate 20watts. This is four times the average power and four times the heat when measured over time. As you can see here, it is not the distortion or the waveform or anything along those lines that is killing your speaker; there is simply more average power over time. However, if the average power of time is still below what your speaker can handle, it doesn't matter if it's clipping or not. At higher power levels, the fact that a clipped signal carries more average power over time can result in damage.

DC in clipping One of the most famous myths regarding clipping is that it produces DC. The assumption is made because of the flat tops and bottoms to a square wave. It's incorrect to think of a squarewave as made up of positive and negative dc components. The only way for a it to be DC would be if there was a non-zero average value over long periods of time. If the polarity changes at all within the time frame that you are looking at, it is simply not DC.

What are these flat portions of the signal? It is simply a combination of the fundamental frequency and all of it?s higher order harmonics in sine wave form. For example, if you were to play a 20hz tone while clipping, there would be the fundamental frequency (ie. 20hz) and the second (40hz), third (80hz), and 4th (160hz) order harmonics. The sum of these frequencies creates what appears as a squarewave.

There are two ways to test this for yourself; one is quite easy, the other is a little more advanced. The first way is simple if you have a variable crossover and an oscilloscope handy. Pass a low frequency square wave. You will notice the square shape on the oscilloscope. Now turn your crossover?s low pass filter on. Slowly lower the setting as you approach the fundamental frequency. You will notice the waveform on your oscilloscope slowly rounding off into a typical sinewave. Once you have reached the fundamental frequency, your oscilloscope will show a perfect sinewave. The second way is for your math guys (or for those who like to use Matlab). If you look in the frequency domain using a Fast Fourier Transform, you will see the fundamental frequency and it's higher order harmonics only. There will be absolutely no DC present.

Clipping and the still voice coil The final myth is that of the still voice coil. It is perhaps the most believed myth regarding clipping. The idea is that because of the square wave, the coil is not moving during the flat portions of the signal. This is simply not true for a variety of reasons. The speaker does exhibit mechanical damping and remains in constant motion. Assuming the same voltage and excursion xmax, the cooling at any given frequency will remain the same, whether the signal is clipped or unclipped. Here is a great article to read on the cooling effects and how a driver fails under various waveforms: http://forum.carstereos.org/f-car-au...-results-47441 Summary To provide a final review of all that we have discussed on this topic, there are only two ways to damage a speaker: Mechanically and Thermally. The only way to do this is by applying too much input power in a given enclosure (mechanically) or too much average power over time (thermally). There is no DC in a clipped signal; the coil does not stand still; air passing over the coil (and thus cooling) is the same regardless of the waveform; and clipping is acceptable provided that the average power over time is lower than the speaker's limits. The next time you hear those famed words "your speakers died because of clipping", remember what you have learned, and above all, keep searching for the truth?.It's out there somewhere.

Original at http://www.radoforum.com/showthread.php?t=57

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post #21 of 514 Old 01-05-2007, 11:32 AM
 
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Originally Posted by greeniguana00 View Post

If you are suggesting that underpowered amps are more likely to blow speakers at a certain volume setting than overpowered amps because of clipping, I disagree.

An underpowered amp is more likely to cause clipping at a certain volume setting, but an overpowered amp at the same volume setting will be more likely to blow the speakers due to putting more power into them than the underpowered amp. The overpowered amp will give the extra voltage during the peak of the wave while the underpowered amp won't.

If measuring the maximum voltage coming out of the amp, a clipping amp showing the same maximum voltage as an overpowered one will cause more damage, but only because it is actually putting more power into the speakers. The underpowered amp has a clipped wave, meaning the time when it has that maximum volatage is longer than for the overpowered amp. The only reason this happening that the clipping amp is trying to represent a higher volume level than the overpowered amp. If the overpowered amp were trying to represent the same volume level as the underpowered amp, it would be much more likely to blow the speakers.

No, the lower powered amp is pushing much higher wattages of high-frequency components which are very likely to blow tweeters. This happens all the time.

A higher powered amp will maintain a clean signal and can overdrive the woofers usually, but generally speaking woofers are pretty resiliant at handling being overdriven and you can more easily tell when they are being overdriven. This is why it's almost always the tweeters that get blown, usually because the speakers are being underpowered and the amp is driven to clipping. Ask any service guy and he'll quickly tell you that the vast majority of speaker damage occurs to the tweeters, and this is largely why.
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post #22 of 514 Old 01-05-2007, 11:42 AM - Thread Starter
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So my 33 W speakers have a pretty good chance of being damaged by a 110 W/ch amp? I'm a total noob when it comes to audio.
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post #23 of 514 Old 01-05-2007, 11:45 AM
 
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Originally Posted by bphisig View Post

So my 33 W speakers have a pretty good chance of being damaged by a 110 W/ch amp? I'm a total noob when it comes to audio.

No, not unless you turn it up loud. And again, you're more likely to damage those speakers with a 10W amp than a 100W amp, despite errant claims to the contrary.
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post #24 of 514 Old 01-05-2007, 12:52 PM
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Originally Posted by ChrisWiggles View Post

No, the lower powered amp is pushing much higher wattages of high-frequency components which are very likely to blow tweeters. This happens all the time.

A higher powered amp will maintain a clean signal and can overdrive the woofers usually, but generally speaking woofers are pretty resiliant at handling being overdriven and you can more easily tell when they are being overdriven. This is why it's almost always the tweeters that get blown, usually because the speakers are being underpowered and the amp is driven to clipping. Ask any service guy and he'll quickly tell you that the vast majority of speaker damage occurs to the tweeters, and this is largely why.

Could you explain why an amp not being able to draw enough power causes more voltage to get to the tweeters?

Say you just took the power supply out of the amp you are using now, and replaced it with one capable of only 30 watts. How would that cause high frequency sounds to be any more damaging to the tweeters than they already are with the orignal power supply?

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post #25 of 514 Old 01-05-2007, 01:23 PM
 
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Could you explain why an amp not being able to draw enough power causes more voltage to get to the tweeters?

Say you just took the power supply out of the amp you are using now, and replaced it with one capable of only 30 watts. How would that cause high frequency sounds to be any more damaging to the tweeters than they already are with the orignal power supply?

As the signal clips, the distortion at the corners is all high frequency components. All that goes right to the tweeter. That's why tweeters are usually what get blown, rather than woofers. You can absolutely blow a speaker with too much clean power, but much more often people are blowing tweeters and this is why. Blowing a woofer is relatively much rarer, but it certainly happens too. Overpowering a speaker is harder to do than many people think. It's overwhelmingly underpowering a speaker and turning the volume up too loud. Especially because as the amp goes into clipping, it doesn't get any louder, so people keep trying to turn it up. This is a doomed proposition because it will never get any louder, but it certainly will grow ever more dangerous to your speakers the further into clipping you go.
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post #26 of 514 Old 01-05-2007, 02:35 PM
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So, I probably won't be turning my receiver's volume up much more than half (small room), definitely not more than 2/3. Do you think I'll still be getting clipping, hurting the tweeter? (90x7 receiver, 100w speakers)
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post #27 of 514 Old 01-05-2007, 02:41 PM
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Originally Posted by ChrisWiggles View Post

Especially because as the amp goes into clipping, it doesn't get any louder, so people keep trying to turn it up. This is a doomed proposition because it will never get any louder, but it certainly will grow ever more dangerous to your speakers the further into clipping you go.

Now that's a very interesting observation.

From it, I take it that the overpowered speaker *may* not also be producing audible distortion? If so, look out; it will thermally fail in short order.

However, I expect most speakers near their power limits to also be approaching excursion limits which result in audible distortions as the first warning. I suppose if the average power is moderate but an extended transient from a source with limited compression is then encountered, it will be too late to react to the potentially short lived signs of stress!

I think damage would be a lot easier to avoid if it were always clear to the user what the peak sustained power level is for any given attenuation setting...perhaps a maximal output wattage reading...but I've never seen such a thing on consumer products. It could even be programmed into a modern receiver on a per channel basis, preventing the possibility of damage. I believe some powered speakers, mainly subs, do this on their own.

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post #28 of 514 Old 01-05-2007, 02:45 PM
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trekguy, good find.
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post #29 of 514 Old 01-05-2007, 02:50 PM
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Oh, here we go. Thanks trekguy. I don't think I'll ever turn my receiver up loud enough so that I hear clipping.

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Originally Posted by trekguy View Post

Despite the tireless efforts of some, there are still many people that believe that underpowering a speaker will damage it or that clipping will damage a speaker. Please remember that these last two thoughts are entirely UNTRUE! And now we will find out why.

Where Does This Power Come From?

Let's first understand the power potential of an amplifier when clipping. The power created is largely determined by the rail voltages. Let's compare two amps, each one connected to a 4 ohm speaker rated at 75 watts rms.

Amp 1: 50 watt amp 50 Watt amp means this amp can cleanly deliver a sinewave of 50watts into a 4 ohm load. This means (Vrms)^2/4 = 50W Vrms = 14.14V Vpeak = Vrms*(1.414) Vpeak = 19.99V The rail voltages of this amp must be a bit higher, to prevent output stage distortion at this power level. In this case, the Rail voltage would have to be +/- 20 Volts.

Amp 2: 75 watt amp (Vrms)^2/4 = 75W Vrms = 17.32V Vpeak = Vrms*(1.414) Vpeak = 24.49V

In the example, the 75 watt amp is delivering 75 watts as it is not distorting at all. The 50 watt amp is in hard clipping, as and such, is delivering a fair bit more power. P = Vrms^2/R = (19.99V)^2/4 ohm = 100 watts.

It is quite obvious that there is potential for an amplifier that is clipping to deliver substantially more power than you would expect. Keep in mind that this is only a way to determine peak voltage potential.

Another NOOBISH QUESTION!

If a receiver is 90w x 7ch, would it be 126w each channel for 5 channels?
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post #30 of 514 Old 01-05-2007, 04:30 PM
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Quote:
Originally Posted by epsilon72 View Post

So, I probably won't be turning my receiver's volume up much more than half (small room), definitely not more than 2/3. Do you think I'll still be getting clipping, hurting the tweeter? (90x7 receiver, 100w speakers)

The position of the volume dial means little. Half way doesnèt mean half power. In fact, half power is pretty close on the dial to max volume (which can occur way before turning it up as far as it will go).

A more meaningful (but not foolproof) is the dB scale on volume dials. A reading of 0 dB indicates max output given a maxed-out input (e.g. the highest recorded passage on a CD). A reading of -3dB is already at half power.

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