Clipping or Too Much Power?

[nailer]

Too much power to the woofers, plain and simple. If the volume knob wasn't touched, and a larger amp was used, the same thing would have happened. The only effect clipping had was to REDUCE the heating of the woofers very slightly, by directing about 1% of the amp's power to the tweeter, in the form of harmonics.

It can hurt one's brain, for sure: in this case, the 40 Watt amp might be putting out 100 Watts of square waves. BUT... that is not caused by the clipping, it is simply a matter of the volume setting. Using a big amp that didn't produce square waves would also put out 100W under those conditions and also blow the speakers.

Sheesh, after many, many hours of posting here, I should avoid this topic. I have already explained it generally, mathematically, drawn diagrams, given technical references and experimental setup for people to try. But, a new year, and a new crop of folks need to reconsider the "facts" they learned about small amps and speaker damage.

Smaller amps = safer speakers. Loud music = blown speakers.

-k

And now I know the rest of the story. Thanks Quackman, once again you've saved the day!

Ignorance may be bliss, but knowledge is better.

 

[davidro]

there appears some sort of desire among ppl to ascribe blowing speakers to weak amps. wonder where it's coming from.

 

[89grand]

there appears some sort of desire among ppl to ascribe blowing speakers to weak amps. wonder where it's coming from.

In most cases, I'd have to say it's just parroting what they've heard others say. I say that because I doubt everyone that says that, has blown up speakers with small amps themselves so therefore had first hand experience with this.

I don't think I've ever blown a home driver. I've toasted a few car audio drivers, but never a home audio driver.

 

[ken kantor]

there appears some sort of desire among ppl to ascribe blowing speakers to weak amps. wonder where it's coming from.

In the early-to-mid 70's, the loudspeaker industry experienced a crisis. People had been listening to very loud, sustained music for several years already, but now a bunch of very high power amps and receivers were reaching the market at affordable prices. And tweeters were dying in droves.

There were crisis meetings at individual companies, and at industry conferences. During this time, I had just started working with AR, and was invited to a few meetings in which the engineering department was grilled by management for a solution. Management was told that 3/4" domes were being phased out, and that ferrofluid was being added, (as well as other power handling improvements), but that the changeover would take a year or more to impact the market. So, management needed an interim story to deflect blame away from the speaker, and onto something else.

After much brainstorming amongst the engineers, the "clipping harmonics" theory was floated. It wasn't tested either theoretically or in practice, but it was brilliant on the face of it: deflect the blame onto the amp, but do it in a way that won't cause amp makers to respond, in that they will be selling bigger amps. AR contacted our counterparts at JBL, who were thinking along the same lines. An agreement was reached to set about promoting the theory in the press, in literature and in advertisements. JBL and AR drew up press releases and white papers. Influential pundits in the press were won over, and "knowledgeable audiophiles" were encourage to help spread this "secret truth." And, as a result, you are a generation of audiophiles who has come to believe the "clipping harmonics" theory as an established fact, when, really, it never was tested.

Eventually, people started actually testing the theory, and subjecting it to rigorous analysis. It was found lacking. Unfortunately, the cat was out of the bag, and the lone scientists who questioned the concept never had 1/1000th of the marketing power of those who promoted it.

Now you know the real inside truth from someone who was there.

-k

 

[E-Stat]

In the early-to-mid 70's, the loudspeaker industry experienced a crisis. People had been listening to very loud, sustained music for several years already, but now a bunch of very high power amps and receivers were reaching the market at affordable prices. And tweeters were dying in droves.

You mean like when Harry Pearson drove double Advents with a Phase Linear 700 and fried multiple tweeters? He always has been a power user.

I still have a double pair of New Advents (slightly tweaked) which have the ferro fluid tweeters. I've used them for the annual Halloween party my neighbor holds for his teen daughter. Here the system is driven wide open with a Threshold Stasis 3 (200 watts/channel into that load) using highly compressed MP3 content for hours on end. Last year, one set of woofer surrounds ended up shredding to pieces, but I've never blown any drivers. In fact, in over forty years in this hobby, I've never blown a driver. I have, however, opened up speaker fuses on a pair of Acoustat 2+2s after cranking some uncompressed 12" 45 RPM LP singles of Madonna with a pair of VTL MB450 amps. The fuses were noticeably hot when I replaced them.

 

[Zonker92]

Now you know the real inside truth from someone who was there.

Nice! :thmbsp:

 

[davidro]

Now you know the real inside truth from someone who was there.

-k

And I hear those who were at the meeting were Freemasons.

 

[nailer]

And libations were drawn from a cask of amontillado.

 

[ofajen]

Smaller amps = safer speakers. Loud music = blown speakers.

If I may ask, Ken, would you mention how NHT decided recommended minimum and maximum amp power ratings, such as the 15W minimum and 100W maximum listed on my SuperZeroes? I power mine with a 100W/ch Hafler amp and they sound marvelous. Of course, I'm careful not to play them too loudly, which is easy to accomplish since I listen at 3 feet or just a tad further away and don't run average levels above 80 dB.

Otto

 

[SoundOfSound]

In the early-to-mid 70's, the loudspeaker industry experienced a crisis. People had been listening to very loud, sustained music for several years already, but now a bunch of very high power amps and receivers were reaching the market at affordable prices. And tweeters were dying in droves.

There were crisis meetings at individual companies, and at industry conferences. During this time, I had just started working with AR, and was invited to a few meetings in which the engineering department was grilled by management for a solution. Management was told that 3/4" domes were being phased out, and that ferrofluid was being added, (as well as other power handling improvements), but that the changeover would take a year or more to impact the market. So, management needed an interim story to deflect blame away from the speaker, and onto something else.

After much brainstorming amongst the engineers, the "clipping harmonics" theory was floated. It wasn't tested either theoretically or in practice, but it was brilliant on the face of it: deflect the blame onto the amp, but do it in a way that won't cause amp makers to respond, in that they will be selling bigger amps. AR contacted our counterparts at JBL, who were thinking along the same lines. An agreement was reached to set about promoting the theory in the press, in literature and in advertisements. JBL and AR drew up press releases and white papers. Influential pundits in the press were won over, and "knowledgeable audiophiles" were encourage to help spread this "secret truth." And, as a result, you are a generation of audiophiles who has come to believe the "clipping harmonics" theory as an established fact, when, really, it never was tested.

Eventually, people started actually testing the theory, and subjecting it to rigorous analysis. It was found lacking. Unfortunately, the cat was out of the bag, and the lone scientists who questioned the concept never had 1/1000th of the marketing power of those who promoted it.

Now you know the real inside truth from someone who was there.

-k

We would like to have a word with you Mr. Kantor.

 

[ken kantor]

Mom! Dad! Wow, gosh, what are >you< guys doing here??

 

[sqlsavior]

Not trying to make any enemies here, but I think that a generation of audiophiles learned the truth, that clipping can overheat and blow tweeters, notwithstanding conspiracy theories to the contrary. I think jluvda has it exactly right, and ken_kantor is wrong, about the clipping not causing it part, at least.

Of course, too much power IS what blows the tweeter, but the REASON it is getting too much power is that the clipped waveform has disproportionately higher energy going to the tweeter due to the high-frequency content of a clipped waveform.

Google "square wave fourier transform" and click on Images to see illustrations of this mathematical truth.

If guitar amps had 1" silk dome tweeters, they would get blown ALL THE TIME. On the other hand, those flower-shaped black plastic piezo-electric tweeters can actually be plugged into a 120v, 60 Hz wall outlet without damage...

I believe the old wisdom, that "Too much power will burn out woofers (and maybe midrange drivers and tweeters too), clipping (can and does) destroy tweeters ..."

Nevertheless, I would like to read the Rane paper. Ken, can you supply a link? Thanks.

 

[jazzmans]

In the early-to-mid 70's, the loudspeaker industry experienced a crisis. People had been listening to very loud, sustained music for several years already, but now a bunch of very high power amps and receivers were reaching the market at affordable prices. And tweeters were dying in droves.

There were crisis meetings at individual companies, and at industry conferences. During this time, I had just started working with AR, and was invited to a few meetings in which the engineering department was grilled by management for a solution. Management was told that 3/4" domes were being phased out, and that ferrofluid was being added, (as well as other power handling improvements), but that the changeover would take a year or more to impact the market. So, management needed an interim story to deflect blame away from the speaker, and onto something else.

After much brainstorming amongst the engineers, the "clipping harmonics" theory was floated. It wasn't tested either theoretically or in practice, but it was brilliant on the face of it: deflect the blame onto the amp, but do it in a way that won't cause amp makers to respond, in that they will be selling bigger amps. AR contacted our counterparts at JBL, who were thinking along the same lines. An agreement was reached to set about promoting the theory in the press, in literature and in advertisements. JBL and AR drew up press releases and white papers. Influential pundits in the press were won over, and "knowledgeable audiophiles" were encourage to help spread this "secret truth." And, as a result, you are a generation of audiophiles who has come to believe the "clipping harmonics" theory as an established fact, when, really, it never was tested.

Eventually, people started actually testing the theory, and subjecting it to rigorous analysis. It was found lacking. Unfortunately, the cat was out of the bag, and the lone scientists who questioned the concept never had 1/1000th of the marketing power of those who promoted it.

Now you know the real inside truth from someone who was there.

-k

That's awesome, thanks for sharing Ken, (quackman)

jaz

 

[mikeybc]

In the early-to-mid 70's, the loudspeaker industry experienced a crisis. People had been listening to very loud, sustained music for several years already, but now a bunch of very high power amps and receivers were reaching the market at affordable prices. And tweeters were dying in droves.

There were crisis meetings at individual companies, and at industry conferences. During this time, I had just started working with AR, and was invited to a few meetings in which the engineering department was grilled by management for a solution. Management was told that 3/4" domes were being phased out, and that ferrofluid was being added, (as well as other power handling improvements), but that the changeover would take a year or more to impact the market. So, management needed an interim story to deflect blame away from the speaker, and onto something else.

After much brainstorming amongst the engineers, the "clipping harmonics" theory was floated. It wasn't tested either theoretically or in practice, but it was brilliant on the face of it: deflect the blame onto the amp, but do it in a way that won't cause amp makers to respond, in that they will be selling bigger amps. AR contacted our counterparts at JBL, who were thinking along the same lines. An agreement was reached to set about promoting the theory in the press, in literature and in advertisements. JBL and AR drew up press releases and white papers. Influential pundits in the press were won over, and "knowledgeable audiophiles" were encourage to help spread this "secret truth." And, as a result, you are a generation of audiophiles who has come to believe the "clipping harmonics" theory as an established fact, when, really, it never was tested.

Eventually, people started actually testing the theory, and subjecting it to rigorous analysis. It was found lacking. Unfortunately, the cat was out of the bag, and the lone scientists who questioned the concept never had 1/1000th of the marketing power of those who promoted it.

Now you know the real inside truth from someone who was there.

-k

Another mystery of the universe unlocked. :thmbsp:

 

[ken kantor]

http://sound.westhost.com/tweeters.htm

http://www.4shared.com/web/preview/doc/gy3rbUMF



If you >actually do< the Fourier transform of clipped waveforms, instead of just blabbing about them, you will find that >very little< energy is actually sent to the tweeters from clipping.

I bet you believe in a lot of conspiracies!

-k

Not trying to make any enemies here, but I think that a generation of audiophiles learned the truth, that clipping can overheat and blow tweeters, notwithstanding conspiracy theories to the contrary. I think jluvda has it exactly right, and ken_kantor is wrong, about the clipping not causing it part, at least.

Of course, too much power IS what blows the tweeter, but the REASON it is getting too much power is that the clipped waveform has disproportionately higher energy going to the tweeter due to the high-frequency content of a clipped waveform.

Google "square wave fourier transform" and click on Images to see illustrations of this mathematical truth.

If guitar amps had 1" silk dome tweeters, they would get blown ALL THE TIME. On the other hand, those flower-shaped black plastic piezo-electric tweeters can actually be plugged into a 120v, 60 Hz wall outlet without damage...

I believe the old wisdom, that "Too much power will burn out woofers (and maybe midrange drivers and tweeters too), clipping (can and does) destroy tweeters ..."

Nevertheless, I would like to read the Rane paper. Ken, can you supply a link? Thanks.

 

[1TUFSS]

Of course, too much power IS what blows the tweeter, but the REASON it is getting too much power is that the clipped waveform has disproportionately higher energy going to the tweeter due to the high-frequency content of a clipped waveform.

It's because tweeters handle disproportionately less power than woofers and midranges. The average tweeter can be blown with as little as five watts of clean power (and yes, I've been there & done that - had a cassette deck go out to lunch on me).

To sum it up: people can't tell their amps are clipping, so they keep on cranking it up, all while their amp's using most of its muscle on the lower frequencies - as the volume's turned up, it can only deliver more power in the high-frequency region. And... boom.

 

[davidro]

it looks like this thread is almost about to make a 'go to that link' thread on this subject!

 

[Pandovski]

I remember when I bought my HK6900, it was recycled junk brought from Germany here in Macedonia by "vintage" dealers. It was still set at 240V AC / 60Hz, which is the standard for Germany and I kept using it unaware, played it loud in Macedonia where we have 220V AC/50Hz.

When I turned it up louder I experienced what Steve (89grand) described. The HF and MF drivers went up louder and louder but the LF didn't. The upper range was clean and loud, so I thought the amp isn't clipping, what the hell is going on. HK + AR = no bass?

Then I accidentally discovered the switch on the back of the amp was set for 240V and I changed it to 220V and voila. BASS!

 

[Gang-Twanger]

I remember when I bought my HK6900, it was recycled junk brought from Germany here in Macedonia by "vintage" dealers. It was still set at 240V AC / 60Hz, which is the standard for Germany and I kept using it unaware, played it loud in Macedonia where we have 220V AC/50Hz.

When I turned it up louder I experienced what Steve (89grand) described. The HF and MF drivers went up louder and louder but the LF didn't. The upper range was clean and loud, so I thought the amp isn't clipping, what the hell is going on. HK + AR = no bass?

Then I accidentally discovered the switch on the back of the amp was set for 240V and I changed it to 220V and voila. BASS!

It's comments like this that have me second-guessing myself all the time (And that's a good thing, don't get me wrong). You guys scare me into double-checking for things like voltage-selector switches and that sort of thing (My 800C doesn't have one, thankfully, although it does have a kind of impedance-selector section on the rear panel, but I think that's more of a speaker-optimization selector rather than an absolute, "Don't do this or it'll blow up" sort of thing).

I don't really turn my music up that loud 99% of the time, just background listening, so I don't really have to worry about clipping, although I do occasionally get an opportunity to goose the volume here and there (like this weekend for example... Having a good, ol' time... No neighbors around... Whoo!), but usually I just like it at background level. Because of the size/output of my W90's, it only takes a couple watts to push them beyond "background-listening" levels, so I can understand why some people like speakers that are a bit power-hungry. With a 30wpc tube receiver, I'm barely-cracking the thing most of the time, but that's why I look for amps/receivers that sound great at low volumes, but I'm sure I'll be experimenting with less-efficient speakers here and there. One thing I've learned over the past 4 years is that hi-fi is definitely a constantly-ongoing learning process.

At some point, I want to try a 3ch stereo setup, which I think the 800C allows, but even then, I don't think I'll ever run into any clipping dangers with the speakers I usually run.

 

[Pandovski]

It's comments like this that have me second-guessing myself all the time (And that's a good thing, don't get me wrong). You guys scare me into double-checking for things like voltage-selector switches and that sort of thing (My 800C doesn't have one, thankfully, although it does have a kind of impedance-selector section on the rear panel, but I think that's more of a speaker-optimization selector rather than an absolute, "Don't do this or it'll blow up" sort of thing).

In the period of 15 days while I listened to the amp with wrong voltage selected, at one point started oscillating, went in protection and one channel started frying itself.

Immediately before major damage happened I took it a a service tech, he changed the stock driver transistors with much better heavy duty ones (HM transistors).

So I take it back home and I listen to it, play it loud and heavy on my difficult AR's. And after 90 days still the amp is set with wrong voltage and I am unaware of it. I just notice that the sound is good but lacking LF.

Accidentally I see the wrong setting and finally change it to the right setting. The sound opened up, it became punchy, big, fast, vicious, meaty.

Paranoia is evolutionarily acquired skill for survival.