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Quality Power - Page 6

post #151 of 637
Quote:
Originally Posted by OllieS View Post
 
Quote:
Originally Posted by Kbarnes701 
Other than for academic reasons, do you have a purpose in pursuing this?

It is purely for academic reasons. I've been led to believe something for so long which is why I've been having troubles understanding your explanation.

 

Fair enough. I understand how difficult it can be to overturn long-held beliefs, even if those beliefs are based on myths. The audio world is full of such myths - about amplifiers that 'sound' better than others (clue: good amplifiers don't 'sound' at all - they reproduce the input at the output unchanged, except for amplitude); about 'magic speaker cables' (clue: 14 AWG wire is invariably as good as anyone needs and passes all the signal cleanly); about blind ABX tests (clue: in such tests, scientifically conducted, the results always speak for themselves); about 'analogue' being better than digital (clue: pretty much everything you hear these days has been recorded digitally, so analogue playback achieves what, exactly); about DAC 1 being 'better' than DAC 2 (clue: DACs have long since passed the point where any differences they have can actually be heard by human beings); about HDMI cable 1, which costs $200, being audibly superior to HDMI cable 2, which costs $10 (clue: it's 1s and 0s. Either they are passed or they are not and if they are, then you can't have 'better' than 100%); about 'magic power cables' that 'clean up the power to your amp etc (clue: you electricity has travelled 100s, even 1000s of miles along regular, cheap wire, often aluminum, so what difference is the last 2 yards going to make?); and so on and on and on.

 

Like I said, we can very easily prove that clipping doesn't destroy speakers - go to a gig where an electric guitar is being played. You will hear absolutely humungous levels of clipping. But the speakers keep working don't they?  And they will, so long as they are not destroyed by too much power. 

post #152 of 637
Quote:
Originally Posted by OllieS View Post

Please help me to understand this better. If an amplifier delivers more than rated power then the tweeter has an equally high chance of burning out compared to an amplifier that is weaker, but clips and exceeds the speakers capabilities? I've always assumed that clipping had high frequency harmonics that would cause damage to a tweeter. Delivering clean undistorted power wouldn't, so hence there would be less likely chance.

Which is why I'm having difficulty wrapping my brain around the idea that an amp driven into clipping wouldn't result in fried tweeters more so than an amp with too much power. I fully expect an amp too powerful to deliver more power than the tweeter can handle, but a clipped signal to the tweeters is far worse.

power kills speakers. including tweeters. of course, the crossover in the speaker keeps low frequencies out of the tweeter, or it would blow basically immediately when you first use a speaker. so to blow the tweeter you need too much power at high enough frequencies to get into the tweeter. The tweeter doesn't know whether the frequencies it is receiving are as a result of distortion from the amp, or just in the recorded material. (The signal out of a guitar distortion box that is audibly distorting the signal will be over 10 percent distortion, and could itself be part of the "clean" signal . . . .) But the tweeter has never heard the program material, and just sees an electrical signal. It really doesn't care where the spectral content came from. It's just the signal.

Once the power getting to the tweeter gets high enough (for long enough) it'll blow. Clean or not. Now, distortion adds high frequency components and it seems clear that those added harmonics might contribute to tweeter death. But be aware that the tweeter is likely specified for something like 25 percent of the power that the woofer is, and at the "typical" threshold of clipping that I see in Stereophile, for example, (1 percent distortion) the total of all the distortion products is 40 dB below the clean signal. http://www.sengpielaudio.com/calculator-thd.htm. That means that at "clipping" the total power in the new harmonics is 1/10 of 1/10 of 1/10 of 1/10 (each 10 dB being a tenth power) or one ten thousandth of the total power in the clean part of the signal. At ten percent distortion, the spurious harmonics are 20 dB below the clean signal, or 1/100 of the power in the clean signal. Of course if you want to call the knee of the THD vs power curve the onset of clipping then your total power in the spurious harmonics is going to be maybe one one hundred thousandth of total power in the signal.

Strikes me that the added harmonics aren't the issue. It's the added power in general.
post #153 of 637
Quote:
Originally Posted by OllieS View Post
 
Quote:
Originally Posted by kbarnes701 
They are tiny little delicate things compared with a mid range driver or woofer. Thus they are much more easily overdriven. And they only consume relatively small amounts of power. Stuff masses of watts into them and they will fry more or less instantly. At least with a woofer you get some indication that you are torturing the driver and the chance to turn it down. But the chances are, by the time you notice the distortion in the tweeter, it is already dead.

Please help me to understand this better. If an amplifier delivers more than rated power then the tweeter has an equally high chance of burning out 

 

It isn't the power that the amplifier delivers that causes the problem. It's that the speaker/tweeter cannot handle that amount of power. That is why it gets damaged. It makes no difference if that amount of power is clean or clipped: if the speaker is not designed to handle it, it will get damaged. Similarly, if the speaker can handle all the power output by the amp, it will not get damaged, even if the amp is clipping like *&%$.

 

I think that despite all we've said, you are still always starting from the point that clipping damages speakers. 

 

Quote:
 compared to an amplifier that is weaker, but clips and exceeds the speakers capabilities? I've always assumed that clipping had high frequency harmonics that would cause damage to a tweeter. Delivering clean undistorted power wouldn't, so hence there would be less likely chance.

 

The excess power is what damages the speaker. You can't just pour limitless amounts of power, even clean power, into a speaker. The speaker has a design capability of handling so much power. Exceed that - even with the cleanest power imaginable - and the speaker will be damaged. If you do not exceed the power handling capability of the speaker, you will not damage it, even if you feed it a clipped signal. (Simplification alert there).

 

 

Quote:
 Which is why I'm having difficulty wrapping my brain around the idea that an amp driven into clipping wouldn't result in fried tweeters more so than an amp with too much power. I fully expect an amp too powerful to deliver more power than the tweeter can handle, but a clipped signal to the tweeters is far worse.

 

No it isn't. I am going to give up now and let someone else have a go if they fancy it. I have exhausted the number of ways I know of to explain it...

post #154 of 637
Quote:
Originally Posted by JHAz View Post
 
Quote:
Originally Posted by OllieS View Post

Please help me to understand this better. If an amplifier delivers more than rated power then the tweeter has an equally high chance of burning out compared to an amplifier that is weaker, but clips and exceeds the speakers capabilities? I've always assumed that clipping had high frequency harmonics that would cause damage to a tweeter. Delivering clean undistorted power wouldn't, so hence there would be less likely chance.

Which is why I'm having difficulty wrapping my brain around the idea that an amp driven into clipping wouldn't result in fried tweeters more so than an amp with too much power. I fully expect an amp too powerful to deliver more power than the tweeter can handle, but a clipped signal to the tweeters is far worse.

power kills speakers. including tweeters. of course, the crossover in the speaker keeps low frequencies out of the tweeter, or it would blow basically immediately when you first use a speaker. so to blow the tweeter you need too much power at high enough frequencies to get into the tweeter. The tweeter doesn't know whether the frequencies it is receiving are as a result of distortion from the amp, or just in the recorded material. (The signal out of a guitar distortion box that is audibly distorting the signal will be over 10 percent distortion, and could itself be part of the "clean" signal . . . .) But the tweeter has never heard the program material, and just sees an electrical signal. It really doesn't care where the spectral content came from. It's just the signal.

Once the power getting to the tweeter gets high enough (for long enough) it'll blow. Clean or not. Now, distortion adds high frequency components and it seems clear that those added harmonics might contribute to tweeter death. But be aware that the tweeter is likely specified for something like 25 percent of the power that the woofer is, and at the "typical" threshold of clipping that I see in Stereophile, for example, (1 percent distortion) the total of all the distortion products is 40 dB below the clean signal. http://www.sengpielaudio.com/calculator-thd.htm. That means that at "clipping" the total power in the new harmonics is 1/10 of 1/10 of 1/10 of 1/10 (each 10 dB being a tenth power) or one ten thousandth of the total power in the clean part of the signal. At ten percent distortion, the spurious harmonics are 20 dB below the clean signal, or 1/100 of the power in the clean signal. Of course if you want to call the knee of the THD vs power curve the onset of clipping then your total power in the spurious harmonics is going to be maybe one one hundred thousandth of total power in the signal.

Strikes me that the added harmonics aren't the issue. It's the added power in general.

 

Hooray!  

 

I've just given up JHAz, as you ride to the rescue. I can't explain it any more simply or in any more ways, so maybe Ollie will get more from your reply, even though you and I are saying the same thing.

post #155 of 637
Quote:
Originally Posted by kbarnes701 View Post

If the speakers could handle, say 1000 watts, and you have a 50 watt amp and you wind it so far up that it clips like **£% and delivers 200 watts, the speakers will not be damaged because they can handle the 200 watts. This proves that it is not the clipping that has damaged the speakers. If clipping damaged speakers, every speaker ever used by any modern guitarist would be damaged as soon as the gig started wouldn't it?

FWIW, understanding the example aspect, FTR, I believe the max an amp could do driven to full square wave would be 2x rated power. Assuming, of course, the rated power isn't some hugely sandbagged number or already including some amount of clipping.
post #156 of 637
Thread Starter 
So would I be correct in saying this, that a more powerful amplifier is easier to damage a speaker than a less powerful amplifier because the distortion levels will be lower at a given power, so even if the amp exceeds the speakers thermal limits, by the time you notice this it's too late, whereas with a lower power amplifier, because the distortion will be considerably higher due to clipping, you'll know about it because the distortion will very audible so you can somehow preempt speaker failure by knowing when to turn it down.

Am I sort of in the ballpark?
Quote:
Originally Posted by kbarnes701 
I can't explain it any more simply or in any more ways, so maybe Ollie will get more from your reply, even though you and I are saying the same thing.

I'm sorry if I'm a slow learner. I guess that's just the way I am.
post #157 of 637
^^ Hows this for simple: if you are a sane, sober adult with reasonably functioning ears and have a general desire not to break your gear, then you are unlikely to damage reasonable speakers in use with any amp.
post #158 of 637
Another way to look at this is that tweeters fail when their ability to dissipate excessive heat is reached. The signal of an amplifier driven into excessive clipping begins to resemble a square wave, which will have twice the average power of a sine wave. So a 50 watt amplifier, in heavy clipping, may actually be delivering 100 watts of non musical average power. By comparison a 100 watt amplifier would still be producing a musical signal with perhaps only 10 watts of average power.

As the average power goes up, so will the amount of heat present in the voice coil. Musical transients allow time for the structure of the voice coil to cool before the next transient. Highly clipped, or highly compressed music, do not provide an opportunity for the voice coil to cool leading to eventual failure.

As for a the higher power amplifier being safer, not necessarily. Remember that a tweeter is rated at a much lower wattage than the speaker in its entirety. A 250 watt speaker may have tweeters only rated for 15 watts. The 100 watt amplifier is more than powerful enough to deliver excessive power to your tweeters.
post #159 of 637
Quote:
Originally Posted by Trendy View Post

The signal of an amplifier driven into excessive clipping begins to resemble a square wave, which will have twice the average power of a sine wave. So a 50 watt amplifier, in heavy clipping, may actually be delivering 100 watts of non musical average power.
This is true for a sine wave in testing, but due to the highly dynamic nature of program material, this may only be a small fraction of the time, and therefore the heating power applied to the coil will be commensurately small. Stating it as you have may lead some readers to conclude that any clipping will immediately apply a long term doubling of power (and it will seldom ever be that much) to the VC, when it will typically be transitory in nature.
post #160 of 637
Quote:
Originally Posted by A9X-308 View Post

^^ Hows this for simple: if you are a sane, sober adult with reasonably functioning ears and have a general desire not to break your gear, then you are unlikely to damage reasonable speakers in use with any amp.

I agree. It comes down to knowing your gear and what you elude to...if it sounds bad it probably is bad, and generally in the tone of this thread means turn it down.
post #161 of 637
Quote:
Originally Posted by OllieS View Post

So would I be correct in saying this, that a more powerful amplifier is easier to damage a speaker than a less powerful amplifier because the distortion levels will be lower at a given power, so even if the amp exceeds the speakers thermal limits, by the time you notice this it's too late, whereas with a lower power amplifier, because the distortion will be considerably higher due to clipping, you'll know about it because the distortion will very audible so you can somehow preempt speaker failure by knowing when to turn it down.

Am I sort of in the ballpark?


Sorta.

In my experience with big amps and home speakers you typically run into the mechanical limits of the woofer (making clunking/clanking or popping noises as it bottoms out) before you run into concerns about thermal overload of the drivers. A caution here is if you're running a high pass filter before the speakers then you can dump quite a lot of power into them without getting that clue from the woofer(s). The possibility to thermal overload with those big amps becomes a greater concern in that case..
post #162 of 637
Quote:
 
Originally Posted by kbarnes701 
I can't explain it any more simply or in any more ways, so maybe Ollie will get more from your reply, even though you and I are saying the same thing.

I'm sorry if I'm a slow learner. I guess that's just the way I am.

 

I wasn't dissing you in any way, or even showing any frustration - it's exactly what I said - I have run out of ways to explain it. It will be as much my inability to explain it as your understanding of it - so I figured someone else might have a go and it might suddenly 'click' with you. Apologies if you felt I was somehow impugning your intelligence or anything - I wasn't. In fact, I thank you for an even-tempered and adult discussion.

post #163 of 637
I'll take a stab and relate how I understand speaker demise:

As I remember my physics, does one give major consideration the magnitude of current the voice coil is seeing? Power and clean or unclean signals only matter in relation to the current seen at the voice coil. An amp delivering two-hundred watts of unclipped power will be sending only AC to the load, whereas a clipped amp is effectively sending DC during the time it is clipped. This DC will be higher at a given power level than the AC due to the higher impedance seen by the AC from reactive componets, as compared to almost pure resistance seen by the DC. So it would seem to follow a speaker will handle a higher power clean signal than a same power clipped signal.

Send enough clean power to a speaker and eventually too much current will burn up the voice coil. This same current level is likely to be reached at a lower power level when sending clipped signals.

Kind regards,
dbrown
post #164 of 637
Quote:
Originally Posted by dbrown3611 View Post

whereas a clipped amp is effectively sending DC during the time it is clipped.
No. It Is NOT DC. It's still a periodic waveform and therefore AC. Ever heard of a guy called Fourier?
post #165 of 637
Quote:
Originally Posted by OllieS View Post

Quote:
Originally Posted by kbarnes701 
All that clipping does is allow the amp to deliver more than its rated power.

Okay, I understand that now. But then I still don't get what the point would be of more powerful amplifiers. If you clip a lesser amplifier it will deliver more than rated output.

Unfortunately, an amplifier that is actually clipping at the moment sounds bad. Clipped music is distorted music.

You've changed the basic topic of discussion. You were talking about damaging speakers, and now we are talking about sound quality.
Quote:
But if you had an amplifier with additional headroom it's still going to fry the speakers. So what does the additional headroom allow for?

We havn't gotten into headroom yet. We are just talking about amplifiers with enough power so that they don't clip or distort the music.
Quote:
What I'm confused with is the point of having an amplifier that exceeds it's rated output and one that delivers it cleanly.

We call the amplifier that delivers additional output cleanly "a more powerful amplifier".
Quote:
What's the point then of the amp that can deliver it cleanly if it's still the same result?

It isn't the same result. The more powerful amplifier can produce more output that is unclipped. However, as others have correctly pointed out, the extra power means nothing unless you actually need it.


Bringing this back into the real world, The typical approximately 100 wpc amplifier in AVRs is usually enough to drive average speakers in an average room to reference levels and beyond, particularly if the system has a subwoofer.
post #166 of 637
Quote:
Originally Posted by A9X-308 View Post

Quote:
Originally Posted by dbrown3611 View Post

whereas a clipped amp is effectively sending DC during the time it is clipped.
No. It Is NOT DC. It's still a periodic waveform and therefore AC. Ever heard of a guy called Fourier?

Agreed. The waveform usually satisfies additional criteria such as being approximately symmetrical, and is typically fairly symmetrical and relatively free of any large DC component.

There have been poorly-behaved amplifiers that did not work this well in the past (1960s and 1970s), but they are from the old days. There seems to be this phenomena where old-timers see an amp doing something weird, and then they suspect every amp they ever work with again of doing the same thing.

One of the big technological changes in SS amps that happened early on is that they changed from having a single power supply and a large DC blocking capacitor in series with the speaker, to having symmetrical plus and minus supply and forget the blocking capacitor. This is both a more economical way to build amplifiers and it also avoids certain technical diffculties. This technological change was pretty well completed by the early 1970s.

Modern power amps can fail into a mode where one or the other power supplies is shorted to the output terminals through damaged output transformers. This can cause a steady DC voltage to appear on the speaker terminals. Most well-designed amplifiers have some way, usually a relay, to disconnect the speaker when this happens. If your power amp clicks when it is powered on, then you are usually hearing this relay activate.
post #167 of 637
Quote:
Originally Posted by arnyk View Post

... damaged output transformers. ...

Typo in this discussion context, presumably, but important clarification.
post #168 of 637
Quote:
Originally Posted by ärnyk" 
It isn't the same result. The more powerful amplifier can produce more output that is unclipped. However, as others have correctly pointed out, the extra power means nothing unless you actually need it.

Yes, but if an amplifier is damaged due to too much power delivered due to a clipped underpowered amplifier then having additional clean power won't provide any additional benefit as the speaker would still be damaged past that point. The only benefit I can see is that the speaker would sound cleaner before the onset of failure and because it's cleaner, the possibility of damage is greater as you won't know it until it's too late.
post #169 of 637
Here is a question... Since I do not know what a "clipped" signal to the speakers sound like, how do you know when you're clipping? How do you know you have enough power? Sorry for being ignorant, I just don't know what it sounds like if you are under powered.

This is a good read, as I was prepared to buy a much larger external amplifier than whats included in my Denon 4520. I sometimes like to listen to my Salk Veracity ST's loud, but I don't know if I'm doing harm to them or not, which makes me scared to crank them up. (Rated 4ohm, 88db sensitivity, 250watts at 4/ohms)

Can someone lay this down in "layman's terms" for me? Kbarnes?

I appreciate the help and "watt honesty" here.. this is what makes AV SCIENCE different than the other forums that talk more is better.

Thanks!

Mike
post #170 of 637
Quote:
Originally Posted by Cvetan1 View Post

Here is a question... Since I do not know what a "clipped" signal to the speakers sound like, how do you know when you're clipping? How do you know you have enough power? Sorry for being ignorant, I just don't know what it sounds like if you are under powered.

This is a good read, as I was prepared to buy a much larger external amplifier than whats included in my Denon 4520. I sometimes like to listen to my Salk Veracity ST's loud, but I don't know if I'm doing harm to them or not, which makes me scared to crank them up. (Rated 4ohm, 88db sensitivity, 250watts at 4/ohms)

Can someone lay this down in "layman's terms" for me? Kbarnes?

I appreciate the help and "watt honesty" here.. this is what makes AV SCIENCE different than the other forums that talk more is better.

Thanks!

Mike

 

Hey Mike,

 

Clipping has a technical description and I think this has been covered in this thread - the bits that describe the waveform having a 'flat top' etc. You can see this on a 'scope. But what you are after is a 'lay' description of what it sounds like, so I will have a go.

 

If you push your amp into clipping it will have a progressively deteriorating sound quality. It will start by just sounding 'uncomfortably loud'. After a short while you will have the overwhelming feeling that you need to turn the volume down. It is hard to describe this stage but you will know it if you have ever experienced it. It doesn't sound like 'something is wrong' yet - just that it is 'very, very loud'. Human ears regard distorted sound as 'loud sound'. Many people call this 'listener fatigue' because the listener gets 'tired' of the sound after a short while and turns it down or stops listening. 

 

If you don't turn the volume down at this point (although most people would) and instead you decide to push the amp even further, you will notice a clear distortion to the sound - like you may have experienced when you have turned your small transistor, or car radio or boom box up too much. It will be rough and harsh and screeching and so on.

 

You may hear thumps and bumps from your mid-range or woofer drivers as they bottom out and generally show signs of distress (not really to do with clipping but still caused by feeding too much power to the drivers, so this may accompany the other tell-tale signs I mention). I honestly doubt whether most normal people would push this hard - the sound will be so rough and unpleasant your ears will almost force you to back off.  The bottom line is that if your Salks don't sound distressed or harsh then you are not harming them in any way. 

 

Clean power sounds effortless. Advancing the volume control doesn't cause any deterioration in the quality of the sound, it just gets louder. But it doesn’t necessarily sound 'loud' when it is clean. You may have noticed when listening with a friend that you have wanted to say something to the other person but when you speak, not only can your buddy not hear you, but you can’t even hear yourself speak!  Yet the sound, until that moment, didn't seem overly 'loud'. That is a sign of nice, clean power. I have experienced this numerous times when watching movies - sometimes I have reached for my SPL meter and measured the loudness in the room - amazed to see I am peaking at 103dB.

 

Usual caveat here: do not feed masses of power into your speakers unless the speakers can handle it (although as I say above, your ears will tell you before you damage the speakers in almost all cases). Any speaker can be blown up by overdriving, clean power or not. 

 

EDIT: PS. This is a good thread isn't it?  One of the few on this sort of topic that hasn't descended into a pi&&ing contest or been overtaken by trolls.


Edited by kbarnes701 - 9/9/13 at 4:31am
post #171 of 637
Kbarnes-

Thanks for the explanation! Yes, this thread is great and I've learned something very valuable here today. I can actually thank you, for not having me spend $$$ on external amps. biggrin.gif I applaud members such as you.

I actually think my Denon does a damn good job and its doing exactly as you describe. I've had my system reaching levels of 125 db on my ratshack, at around 2 meters, and my speakers sounded sweet to me ears.

Thanks again!!

Mike smile.gif
post #172 of 637
Quote:
Originally Posted by OllieS View Post

Quote:
Originally Posted by arnyk 
Speakers are damaged by having too much power applied to them, which is obviously more likely with a more powerful amplifier..

Okay, so you had an underpowered amplifier clipping like crazy and a high powered amplifier that could deliver power cleanly without clipping, you're saying that the underpowered amplifier would be the safer bet. confused.gif

Which amplifier has the potential to provide more power - the less powerful one or the more powerful one? This is not a trick question!

We have a human being who is operating a volume control. He turns the gain up on both the small amp and the large amp.

The smaller amp reaches its limit and starts clipping. The music sounds distorted. The distortion is feedback to the user to stop turning up the volume. A logical user stops turning up the volume. The power being delivered to the speaker stops increasing. The speaker receives less power and is therefore less likely to be damaged by excess power.

The larger amp has not reached its limits and the music simply sounds louder. The user receives no feedback to stop turning up the volume. The user continues to turn up the volume and the speakers receive more and more power. As the speakers receive more and more power, they are more likely to be damaged.
Quote:
That goes contrary to every known source I've ever read. Forgive me for being more than a little skeptical about your claims.

If you can't follow the above simple logic, how do you know that you have a correct understanding of everything else that you have read?
post #173 of 637
Quote:
Originally Posted by Cvetan1 View Post

Kbarnes-

Thanks for the explanation! Yes, this thread is great and I've learned something very valuable here today. I can actually thank you, for not having me spend $$$ on external amps. biggrin.gif I applaud members such as you.

I actually think my Denon does a damn good job and its doing exactly as you describe. I've had my system reaching levels of 125 db on my ratshack, at around 2 meters, and my speakers sounded sweet to me ears.

Thanks again!!

Mike smile.gif

 

 

I would be surprised if your Denon lacked the power you need. If you are able to hit the SPLs you desire, cleanly, then additional amp power would be superfluous. Power left on the table is exactly that. Your Denon is a powerful AVR and likely to be all you will ever need.

 

It's terrific when someone realises that spending hundreds or thousands of dollars on bigger amps is more often than not just a waste of money - it means they can spend those dollars elsewhere, on things that do make a big difference to SQ, such as speakers, subs and room treatments. Or just on Blurays and CDs - the reason we have these systems in the first place!

post #174 of 637
Quote:
Originally Posted by Cvetan1 View Post

Here is a question... Since I do not know what a "clipped" signal to the speakers sound like, how do you know when you're clipping?

As has been pointed out, the quality and clarity of music starts degrading rapidly when clipping commences. Kbarnes clearly has plenty of experience with very clean powerful systems. As the music gets louder with them, the music simply gets somewhat louder, without any changes to its basic character.

If you could play computer files I could provide you with downloadable files with and without clipping. You could play them at lower levels and hear what clipping sounds like in total safety.

What I feel compelled to add is that clipping is not the only reason why there are changes in sound quality as you turn your audio system up.

Your speakers have limits that are similar to amplifiers. However, there is less consistency. For example, subwoofers in particular are prone to have audible distortion due to running out of something called Xmax or linear travel. Usually this barrier to loud clean sound is less sudden than clipping in power amplifiers. It can actually happen with woofers, midrange speakers, and tweeters as well. Because it is less sudden and less sharply defined, it is not as obvious. However it also causes the sound quality to change as opposed to simply becoming louder.

While not a nonlinear effect like clipping and running out of Xmax, room acoustics can cause a perceived change in sound quality as loudness increases. Rooms that have too many reflections can seemingly "load up" and become unpleasant to listen in at high volumes.

Finally the human ear itself has well-defined limits. The ear is most effective at resolving different sounds around 85 dB SPL. Below 85 dB SPL sounds tend to disappear into audible thresholds. Above 85 dB the mechanical components of the ear become can become quite nonlinear. Above about 105 dB at midrange frequencies, the ear may be damaged, either short term or long term. The ear has far more tolerance for loud sounds at low frequencies. For example at 70 mph the SPL of wind buffeting inside a car at low frequencies can exceed 120 dB SPL.
Quote:
How do you know you have enough power?

To be absolutely sure that you have enough power, you set up a means to view a graphical representation of the voltage across your speaker's terminals, and examine the graphical representation of the voltage across the speaker terminals for clipping.

Here are some examples of clipped music:



The areas where there is flat-topping near the top and bottom of the picture above represents clipping.



The above picture (annotated Fig 1) shows a number of areas where there is clipping, some labelled "peak clipping", and others notable because the signal reaches maximum Y or minimum Y.

Quote:
This is a good read, as I was prepared to buy a much larger external amplifier than whats included in my Denon 4520. I sometimes like to listen to my Salk Veracity ST's loud, but I don't know if I'm doing harm to them or not, which makes me scared to crank them up. (Rated 4ohm, 88db sensitivity, 250watts at 4/ohms)

4250 spec: 150 W + 150 W (8 Ω, 20 Hz – 20 kHz with 0.05 % T.H.D.)

From a ratings standpoint, I don't find http://www.salksound.com/veracity%20st%20-%20specifications.htm to be particularly helpful. The system contains 2 Seas E0049-04S W16NX001 type speakers that have a long term rating of 80 watts. http://www.seas.no/index.php?option=com_content&task=view&id=66&Itemid=90 So 150 watts could be pretty safe. The ratings on the RAAL 70-20XR midrange tweeter are proprietary so what they can do is questionable.

Depending on how you use them, they are probably safe with your AVR, but may not be safe with significantly more powerful amplifiers. This comment is contingent on use with a good subwoofer crossed over in the 60-80 Hz range.
Edited by arnyk - 9/9/13 at 5:51am
post #175 of 637
Thanks Arny!

Yes, I have the Salk's crossed at 80hz as well. My dual JTR S1's take care of the rest. I would expect to maybe run into issues at loud db's running full-range.

Also, those ratings above are at 8 ohms and Im sure 2-channel. I would assume we are reaching somewhere near 250 w/channel at 2 channel at 4 ohms, which the Salk's are rated.
post #176 of 637
Quote:
Originally Posted by whoaru99 View Post

Quote:
Originally Posted by arnyk View Post

... damaged output transformers. ...

Typo in this discussion context, presumably, but important clarification.

The quoted text does not appear to be present in the linked post. I'm mystified.
post #177 of 637
Thread Starter 
Quote:
Originally Posted by kbarnes701 
I wasn't dissing you in any way, or even showing any frustration - it's exactly what I said - I have run out of ways to explain it. It will be as much my inability to explain it as your understanding of it - so I figured someone else might have a go and it might suddenly 'click' with you. Apologies if you felt I was somehow impugning your intelligence or anything - I wasn't. In fact, I thank you for an even-tempered and adult discussion.

No problem! Thanks to you as well.
post #178 of 637
Thread Starter 
Quote:
Originally Posted by kbarnes701 
If you push your amp into clipping it will have a progressively deteriorating sound quality. It will start by just sounding 'uncomfortably loud'. After a short while you will have the overwhelming feeling that you need to turn the volume down.

If the symptoms of a clipping amplifier are uncomfortably loud sound then I'm sure one could use the same symptoms and misdiagnose the problem for something else entirely. Like say the room acoustics. Perhaps the reflections in the room at a given volume are so harsh that it sounds too loud at that setting, so instead of addressing the acoustics in the room, they decide to buy a bigger amplifier.

I guess what I'm trying to say is that you could probably have more than one symptom that may also reach similar conclusions - re uncomfortably loud. I'm not a technical guy, but I imagine you would probably need switching gear that could toggle between two amplifiers, one a lesser amp and a more powerful model otherwise it may just be my brain playing tricks on me. biggrin.gif Either that or some way of measuring the signal at that volume, as arny described.

I don't know, what do you think? Thanks again for your explanations in the thread, I'm glad we could all have a civil discussion about this.
Edited by OllieS - 9/9/13 at 5:48am
post #179 of 637
Quote:
Originally Posted by OllieS View Post

Quote:
Originally Posted by kbarnes701 
If you push your amp into clipping it will have a progressively deteriorating sound quality. It will start by just sounding 'uncomfortably loud'. After a short while you will have the overwhelming feeling that you need to turn the volume down.

If the symptoms of a clipping amplifier are uncomfortably loud sound then I'm sure one could use the same symptoms and misdiagnose the problem for something else entirely. Like say the room acoustics. Perhaps the reflections in the room at a given volume are so harsh that it sounds too loud at that setting, so instead of addressing the acoustics in the room, they decide to buy a bigger amplifier.

I guess what I'm trying to say is that you could probably have more than one symptom that may also reach similar conclusions - re uncomfortably loud. I'm not a technical guy, but I imagine you would probably need switching gear that could toggle between two amplifiers, one a lesser amp and a more powerful model. Either that or some way of measuring the signal at that volume.

I don't know, what do you think?

The most feasible way to reliably determine whether your amp is powerful enough has already been given:

"To be absolutely sure that you have enough power, you set up a means to view a graphical representation of the voltage across your speaker's terminals, and examine the graphical representation of the voltage across the speaker terminals for clipping."

This is far more reliable and sensitive than listening tests and requires no second amplifier for comparison.

A PC's built in audio interface can be used for this purpose with simple shareware audio visualization/editing software (Audacity) and an attenuator for cutting speaker voltages down to audio interface voltages.
post #180 of 637
Thread Starter 
Quote:
Originally Posted by arnyk 
A PC's built in audio interface can be used for this purpose with simple shareware audio visualization/editing software (Audacity) and an attenuator for cutting speaker voltages down to audio interface voltages.

Unless someone describes this in a step by step fashion, I'll probably never be able to do it. redface.gif I would love to be able to for peace of mind, don't get me wrong, but I'm not a technical whizz kid. biggrin.gif
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