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A simple question:Based on the Wattage rating on your amp and your speakers, is it possible to determine whether or not your speakers are at risk of damage?
For instance, My amp is 70 watts per channel(Marantz 2270). My speakers are 50 Watts (ADS L420). I listen to my system at a moderate level, and sometimes i like to kick it up a bit.
Can anyone appease my concern that I am at risk of doing damage without really cranking it, but just because the amp has a higher output? Thanks.
Follow Ups:
Those basic measurements are useless and should be of no concern. Unless you listening at extremely loud levels or have very inefficient speakers, you are probably listening, on average, to one or two watt maximum- certainly not at anything close to the 50 watt or 70 watt maximum. That being said, music is a very dynamic sound which can take up to 1,000 times the average energy to accurately reproduce a transient for milliseconds. What you should be concerned about is how much distortion is caused by these transients and how well the amplifier can control the drivers in the speakers. Generally, when you blow a driver is when you feed it to much distortion and it reacts asymetrically. Therefore, what you want is an amp that has plenty of reserve power.gjg
This is from Wharfedale:
Burn Out:
"This happens when the amplifier from a high average running level refuses to supply any more power to the loudspeaker. The Cones or diaphrams are then prevented from making a full excursion as required to produce the note or signal they are trying to achieve. The cone becomes an unstable quivering object with no power left to propel it forward or to pull it back, and heat builds up in the voice coil.
[my note as to why receivers sound so crappy with bass heavey material - they're SLOW at controlling the woofers] Normally, this heat is dissapated through vents and by conduction along the former, aided by the motion of the whole assembly through cooler air, and because changes and gaps in the signal level provide a rest offerring some brief respite to allow radiant and conductive cooling. Even a few watts can cause a rapid and damaging build up of heat under these conditions, after all, the wire round the coil is little different from the wire in an electric fire or a bulb. So, a sustained onslaught of even a few distorted watts is always likely to prove fatal.
The message is clear...IF YOU LOSE DETAIL OR YOU HEAR DISTORTION TURN IT DOWN."
"all Wharfedale loudspeakers are designed to accept the full output power capability of a 100 watt amplifier when correctly used. They can withstand momentary or short duration peak signals well in excess of 100 watts [and knowing the Brits they mean WELL inescess]. The can be destroyed or damaged by as little as 10 watts.BY far the commonest cause of loudspeaker failure is damage to the voice coil caused by "amplifier" overload. All loudspeaker manufacturers regularly receive letters from indignant or perplexed customers who have inadvertantly damaged their loudspeakers. Typically, these will state the the volume control was not at maximum at the time, and the speaker is rated at several times the amplifiers power rating..."
RGA
I would say that *MOST* people who run floorstanding speakers(which typically are rated well above 150RMS+ power handling)are running amplifiers WELL WELL below that rating...likely in the 50-100 watt range. I would bet 90% of all speaker owners are in this kind of camp where they are running lower powered amps with high watt rated speakers. Yet they blow tweeters...to say the only way to blow one is to overpower them is nonsense since most people who blow them are clear examples of underpowering them.A basic understanding is that bass drivers request most power and if the amp is in trouble you get high distorion sent to the tweeter...which should make a real irritating sound which should get you to turn it down. When you don't the tweeter can blow.
The cones never stop moving unless you power them with DC from a battery. There is no DC from clipped complex AC waveforms more commonly called "music". Clipped music has no DC components.RGA wrote:
"Yet they blow tweeters...to say the only way to blow one is to overpower them is nonsense since most people who blow them are clear examples of underpowering them."RG responds:
Voice coils ONLY get damaged from too much power input (electricity).
If you disagree with that statement, please stop reading, as
science is NOT your subject. The only question is how much of that electricity can be attributed to clipping harmonics. Of course,
the answer depends on the program content and the tweeter's high pass filter ... but I presented a Rane Corp white paper with a worst case analysis based on a 100 Hz. square wave with continuous severe clipping (assuming an INCREDIBLY LOUD 100 watts power input) that might amount to one watt or less clipping harmonics getting through to a typical home speaker tweeter with a 2000Hz. 12dB/octave
high pass filter.The average power getting to the tweeter from clipping harmonics would be considerably LOWER with the intermittent clipping typical with real music.
Please realize that 100 watts and 100Hz. square waves do not represent real music which typically has intermittent clipping due to kick drum hits, snare drum hits, etc. ... where no drummer could hit his kick drum 100 times per second, for example, to immitate continuous clipping of a 100Hz. sine wave test tone!
Here's a quote from Tom Nousaine who tests speakers for a living:"The speaker never comes to a stop. This idea is a fundamental misunderstanding that comes from that "DC" argument.
I think it stems from the misunderstanding that the analog picture of a sine wave or square wave as it appears on the face of an oscilliscope is actually the 'signal' and the flat top is some kind of DC component.That picture is just an analog idea or representation of the sound or signal. As Mark began by saying (in his white paper on clipping) there is no DC component ... he's right .... and therefore the cone never stops.
Another part of the analysis that tends to get forgotten is that the tweeters impedance will be rising as well and the only important harmonics will occur around the resonance area of the speaker.
All this is not a criticsm of the work. The idea is well taken and right on the money. You won't protect your speakers by using a larger amplifier. It will just burn them out as fast by supplying more power no matter what the condition of the signal. "
TOM NOUSAINE
And I'm not electrical engineer. But it would seem, if i understand you correctly that assuming people use an amp that can overpower a tweeter...say a 50 watt+ amp. That in either case the amp CAN blow a speaker. Or, are you saying there is no way a 50 watt amp can blow a 175 watt speaker even if you crank the volume knob to full circle? I'm not sure I'm following your point.I'm guessing that what your saying is that the 50 watt amp will, generally, distort and clip and thus provide the listener a big warning thatt their tweeter is unhappy. If you used a 300 watt amp with the 175 watt speaker there will not be that *Distorted Sound* and therefore no warning and oops you've fried the speakers.
Again, I may not be a scientist or an electrician...but lots of people blow their speakers using an amp with a lower watt rating than the speaker...and I would bet it happens in the VAST majority of cases where a speaker is blown. If it is impossible to blow a speaker with a lower powered amp...then why does it happen in most cases?
I'm not trying pretend I know more about the issue than you...you obviously know what you're talking about...I just know people and you hear it all the time and even the big speaker companies get their complaints *Wharfedale as an example* where people have blown their tweeter *With* a lower powered amp.
It ould seem to me that UHF says either way for different reasons a speaker will be blown no matter the amp(leaving 3 watt sets aside).
Generally,a speaker with a 175 watt rating means that it can be used with an amp of that power playing unclipped music.The average to peak ratio of music is 10-20 db,so in reality the speaker would only see 1.75-17.5 watts RMS,with the amp at the clipping point. Fortunately,most of that power is in the lower frequencies,so the tweeter will not see very much of it.Anyone care to put a 17.5 watt sine wave into your tweeters? Do so at your own risk,because most will die with that or less power.I think many people would be very dissapointed if they knew how little power their tweeters will handle,despite a large power rating for the system.
If that was a 100Hz. sine wave @ 100 watts input, the clipping harmonics that reached the tweeter through a typical high-pass filter would probably be no more than 1 watt (which was my whole point -- the clipping harmonics are just a small percentage of the total
treble power needed to detroy most modern tweeters). But the woofer
would probably get damaged from 100 watts input/100Hz. sine wave
while the tweeter survived!I like to think of tweeters as modern day "speaker fuses" --
if you ignore the fact that the music is VERY LOUD,
and you fail to notice the clipping distortion,
then the blown tweeters are the final warning
that you are damaging your hearing.
I was referring to music played up to the clip point,but not actually clipping,and the actual power being 10 to 100 times less,and the fact that even without clipping,you can fry a tweeter due to the fact that many tweeters just can't handle even that much power.And yes,a 100 watt sine wave would probably do much harm to most woofers,along with your hearing...
For instance my speakers are around 10 years old rated 175watts(95db sensitive)8ohms. The tweeter is a horn with ferro-fluid cooling.My Sugden is ~70watts per. I have cranked it to the 2 o'clock position and I get incredible and very clear volume levels(yes the neighbors complained and the windows and floor rattled) but I only did for a couple of minutes to see. It did not distort but I didn't want to get insane but I'm pretty sure I Could have pushed it further. I also don't think the Sugden has a frequency limiter as the review of it was babbling about that(to the non engineer like me it may as well be Star Trek techno-babble).
I was wondering about horns because it seems most clubs(well all the clubs I've seen) use horns to get the high volume levels...so, in general do they take more of a beating than a soft dome or ribbon...or is it just the voice coil and the rest doesn't matter.
The only tweeter I damaged in 37 years as an audiophile was a horn tweeter back in the 1960's. A horn would increase tweeter efficiency so you wouldn't have to input so much power to obtain loud treble = less heat build-up.Ferrofluid really helps with power handling.
Clipping harmonics were much more important in the old days
of paper cone tweeters and low-power-handling domes with no
ferrofluid. That's when "clipping kills tweeters" started.
One extra watt of clipping harmonics would be a burden on a
tweeter that could only handle 5 watts. Not to mention the
inefficient acoustic suspension speakers and very low power
transistor amps common 30-40 years ago clipped too often.
Now you can rarely find amplifiers less than 50wpc ...
and the amp power ratings are honest now (except maybe
sound receivers) -- there was a lot of BS 30-40 years ago.The voice coil wire diameter and the diameter of the voice coil are most important ... but so is the driver's efficiency and the protection from the high-pass filter circuit in the crossover.
The first speakers I built in 1971 used pro-style compression drivers for 800Hz and up. These compression horns are very efficient (perhaps 110dB efficiency versus 90dB for a typical 1" dome tweeter
today) and use voice coils that are 2" or 3" in diameter versus only 3/4" or 1" for dome tweeters. So they play very loud w/o much power input and the voice coils have lots of copper to absorb heat.
NT
Just so you don't get on me Richard LOL. I also agree with you 100% that damage will result from opverpowering a speaker...which seems to make a lot of sense. In effect this is PUSHING a tweeter, say, too hard and well beyond its limits. However, most people I know who have blown speakers tend to blow tweeters with underpower and blow woofers with overpower...just observation no stats just things I've noticed.Gerard Rejskind, "The World of High Fidelity", p132
"There is scarcely a manufacturer that doesn't publish a suggested amplifier power figure for its speakers. Indeed, it may publish two figures: Minimum power of 35 watts, and a maximum of 200 watts, say. Reading those is largely a waste of time...time that would be better spent going over the warranty with a magnifying glass.
Most speaker warranties aren't worth the paper they're written on. That's because they don't apply if you overload the speaker, or if you drive it with an amplifier that is too small. Who determines if the you've done that? The manufacturer does.
And not too many apply the warranty liberally. Obviously, you can't win. Use a large amplifier and you'll be told that you turned it up too loud and blew the speaker. Use a small one, and you'll be told it probably overloaded enough to produce large amounts of harmonic distortion whcih burned the tweeters...that 35 watt minimum figure doesn't mean a thing, since only you know what your room is like and how loud you like to listen. The 200 watt figure doesn't mean much either. If you feed a 200 watt white noise signal to the speaker and wait for a while, you'll see smoke. In a typical system with such a rating, the woofer will accept 200 watts for 20 seconds at a time, with a ten minute cooling period before you do it again. The tweeter will do the same thing with ten watts. And the crossover network will behave fairly well at an input of 100 watts, but will not necessarily meet its specs beyond that. So what does that 200 watts mean? Everything as long as the speaker doesn't burn out, not much if it does.
My Advice: Learn what distortion sounds like, and turn down the volume when you hear it...and at your New Year's paty, arrange to run out of liquor before anyone gets too loaded."
From the paragraph:
"My Advice: Learn what distortion sounds like, and turn down the volume when you hear it...and at your New Year's party, arrange to run out of liquor before anyone gets too loaded."RG adds:
You can even be happy there are harsh sounding clipping harmonics to warn you the speakers are playing VERY LOUD ... because you can blow tweeters just a fast with a powerful amplifier playing VERY LOUD clean sounding treble -- the problem is always VERY LOUD treble ... and any amplifier can play VERY LOUD treble when the volume control is turned too far clockwise. Well maybe not a 3wpc SET amp at full output indefinitely -- so maybe everyone should buy 3wpc SET amps and protect their tweeters!
"so maybe everyone should buy 3wpc SET amps and protect their tweeters!"Well that would be the SET lover's wet dream... A world of SET amps everywhere.
If it sounds too loud, then it is. If it sounds distorted or increasing bright and hard, then you're probably over driving the speakers. In addition to risking hearing damage, too much volume can blow your tweeters. It's all a matter of time. Doing it for 5 minutes is probably ok, then turn it down. Voice coil take time to heat up and then they blow.With the 2270, IME, anything over about 2 o'clock on the dial is about the limit of the useable clean power. I wouldn't play it over 11 o'clock or 12 for extended periods and that's probably way too loud for your ears anyway.
Beware of volume creep though. It's better to turn it up for a song you like and then turn it down and readjust than to just turn it up a little and a little more. You'll get used to the high volume and just want more, not noticing as much how louder it really is. Ruichard has some good advice, invest in a meter. Anything over 80db or so for extended periods will result in some level of hearing damage.
Oooohhh. "Anything over 80db or so for extended periods will result in some level of hearing damage". Damn! I'll do an hour or so at a time at a nominal out of 95 db. That's within OSHA standards, I thought.Along the lines of "let your ears be the guide"... I don't have experience blowing tweeters, which seems to be what everybody in this thread is talking about. The only thing I've heard of there is that any DC offset problem not protected against will surely blow a tweeter.
-------------------------
What about woofer damage? I have seen an underpowered woofer (home-made sub) tear right off the magnet. It only had a 70 watt Amber amp driving it, but going to my Carver PM1.5 (450 wpc), I couldn't blow a darned $8 radio shack driver to save my life, unless turning it up to the point where it would hurt my ears to listen, perhaps. Now all this was some 15 or 20 years ago...Now getting closer and closer to the point. With the speakers I presently have, I have 8" woofers. If the amp is not powerful enough, esp. in the right places, then those woofers will start to go really nonlinear in their travel. Wiggling in an awful way. That has to be bad, right?
But with a more powerful amp, and I would say more power (and speed?) for stability in the lower frequencies, the woofer travel stays linear with the same source - same SPL. And I'm thinking that's a good thing for the life of the driver, yes?
I couldn't remember the exact numbers, but I thought it was around 80db. According to OSHA, it's a little higher, at 85db they suggest ear plugs:d)(1) When information indicates that any employee's exposure may equal or exceed an 8-hour time-weighted average of 85 decibels, the employer shall develop and implement a monitoring program.
TABLE G-16 - PERMISSIBLE NOISE EXPOSURES (1)
______________________________________________________________
|
Duration per day, hours | Sound level dBA slow response
____________________________|_________________________________
|
8...........................| 90
6...........................| 92
4...........................| 95
3...........................| 97
2...........................| 100
1 1/2 ......................| 102
1...........................| 105
1/2 ........................| 110
1/4 or less................| 115
What you have to realize is that these are the levels and durations where damage is guaranteed. According to OSHA, you're ok for an hour at 95db. But listening that loud begs for more volume and you'd have to go to 100-105 to sense much increase and the safe time limits get increasingly small.
I don't know about woofers. Over execusion is typically a problem AFAIK.
Sometimes we have so much fun arguing with each other that we fail to provide concise answers to any questions.QUESTION:
"Based on the Wattage rating on your amp and your speakers, is it possible to determine whether or not your speakers are at risk of damage?"ANSWER:
No.More information:
Damage correlates best with how loud your speakers are played.
Play speakers too loud for too long and the tweeters will be damaged. Almost every amplifier available is capable of damaging tweeters if the music is played too LOUD for too long, whether 20wpc or 200wpc or 2,000wpc.
.
.
.
QUESTION:
"Can anyone appease my concern that I am at risk of doing damage without really cranking it, but just because the amp has a higher output?"ANSWER:
Calm down -- the amp's output directly correlates with how loud the speakers are playing. If playing REALLY LOUD, you'd probably have an average output of only 10-20wpc.More information:
The 70 wpc power output you mention is the maximum power output at a given rate of distortion. At higher rates of distortion, your amp could probably output 140 wpc, if you're interested.In normal listening you will almost always generate less than 10-20 watts per channel ... with 1-2wpc being typical. However if you turn up the volume incredibly LOUD you WILL be able to damage the tweeters ... and your hearing.
My sister-in-law, for example, blew both tweeters in the ADS L410 speakers I gave her as a gift by trying to fill her large house with music during a party. The Sony amplifier I gave her was somewhere in the range of 30 to 60wpc. I provided replacement tweeters for free and there's been no damage again since the early 1980's so far.
So just use common sense with the volume control and you'll be okay --but beware of alcohol & parties -- the leading causes of speaker damage!Even though I've been an audiophile since the mid-1960's, and have been building DIY speakers since 1971, the ONLY definitive statement I could make about speaker damage is to describe the one thing I always hear before the damage is done:
****The music was VERY LOUD***
Based on the Wattage rating on your amp and your speakers, is it For instance, My amp is 70 watts per channel(Marantz 2270). My speakers are 50 Watts (ADS L420). I listen to my system at a moderate level, and sometimes i like to kick it up a bit.
Can anyone appease my concern that I am at risk of doing damage without really cranking it, but just because the amp has a higher output? Thanks.
It is not possible to know ehether
The cause of damaged speakers is almost always the person who last touched the volume control. The good news is damaged speakers can be replaced ... the bad news is damaged hearing can't be fixed.
That means if speakers are being damaged by being played too loud, there's a good chance your hearing is being permanently damaged too.If the owner of a receiver or amplifier turns up his volume control high enough, for long enough, his speakers will be damaged unless they are fused in some way, which few are, or are some unusual pro speakers that can handle a huge amount of power.
Most likely the tweeters will be damaged first. It matters little whether your amplifier is clipping or not. Some people think buying a more powerful amplifier that never clips will "save" your tweeters but they know little about electricity. Tweeters use lightweight wire voice coils that can't handle much power -- even a 20 or 30wpc amplifier played at or near full volume will damage most tweeters.
Too loud for too long = damaged tweeters. Buying a 200 or 300wpc that never clips won't protect the tweeters.The ONLY common situation before a non-defective speaker is damaged by too much power (that's the ONLY way to damage speakers) will be VERY LOUD music. Usually loud enough to damage your ears too.
Radio Shack sells a $35 sound meter.
Buy it and measure the average volume (SPL) using A-weighting and slow response. If the average is 80dBA or lower you'll never hurt your ears ... but if 90dBA or higher, you will probably damage your hearing in the long run ... for which there is no cure.
As one who has occasional tinnitus, said to be caused by exposure to loud sound over a period of time, I know that one's ears are precious.In my experience, listening at levels that has the Rat Shack meter kicking around 80 to 85 dB is plenty loud.
In my one experience with frying speakers (courtesy of my daughter), the mid-woofer of my small two-way died before the tweeter (which survived). But, as they say, YMMV.
Remember that the Rat Shack meter is an average reading. It will not pick up short-term transients of brief duration that are louder, assuming that your system is capable of reproducing them.
Just got one. I am going to bring it to work. Will be interesting to measure what 12000 HP. worth of machinery measures. I wear hearing protection but some guys don't. Bet they will when I tell them how load our plant is.
The power rating on a speaker references the amount of current a particular driver or speaker's voice coil can handle continuously before melting down. If your speakers are rated @ 50 watts then I would not power beyond that. Using a 70 wpc or higher amplifier is fine in that it gives you headroom and the ability to provide a clean 50 wpc without distortion that would likely be introduced from a 50 wpc amp wide open. A 40 wpc amp wide open and distorting would kill your speakers (allthough underpowered) just as quick as more than 50 wpc of clean power would.
Keep your ears open. If all sounds fine than all probabally is. If you hear the cones starting to bottom out or hear alot of distortion than obviously cut it back a little. It doesn't take much to ruin a pair of speakers.
Hope this helps!-Johnny
"A 40 wpc amp wide open and distorting would kill your speakers (allthough underpowered) just as quick as more than 50 wpc of clean power would."RG
Sorry, but your statement is not even close to correct.A 50wpc amplifier could play about 1dB louder than a 40wpc amplifier.
Most people would not even notice a 1dB increase
while listening to music.50wpc "wide open" would probably damage the tweeters a
fraction of a second faster than 40wpc "wide open".
"A 40 wpc amp wide open and distorting would kill your speakers (allthough underpowered) just as quick as MORE than 50 wpc of clean power would."Sorry for the confusion, if a speaker is rated at 50 wpc rms and your feeding it > 50 wpc rms (as stated previously)than would this not damage your speaker?? I realize that in order to get +3db you roughly double the output power. Maybe my statement of "just as quick" is a little off, but both cases will cause damage, is this not true?? That was my point.
I really don't believe my statement is that far off. If it is please correct me so I understand a little better.
Thanks,
--Johnny
There are pro standards for power handling detailed in a white paper at www.JBLpro.com:IEC standard 268-5
Pink Noise
6dB crest factor
12dB/octave high-pass filter at 40Hz.
12dB/octave low-pass filter at 5kHz.I have no idea what other speaker companies do.
Many tweeters in catalogs I have claim 50wpc or more power handling but never reveal what kind of protection (high-pass filter) is specified to make those claims ... which seem inflated to me.
Moot point though -- an average power output of 50 wpc would be TOO LOUD for you to stay in the room with most speakers.
Then you won't hurt a thing. As the previous poster mentioned, more damage is done from underpowering the speakers, especially tweeters. What kind of speakers are you using?
The small amount of clipping harmonics that reach a tweeter even when there is continuous clipping of a 100 Hz. sine wave (much more energy than typical music) will rarely account for one watt of power.
No tweeter will blow from one watt of clipping harmonics.Please define what you mean by "underpowered".
Are you suggesting that a 1 wpc amplifier would be 'extremely dangerous' for tweeters while a 1,000 wpc would be 'safe' for tweeters?
I've seen too many tweeters go out with under-powered amplification. In contrast, I do not recall a tweeter ever going out with sufficient power. (With the exception of a speaker that had a poorly-designed series crossover.) Now woofers are a different story...Some speaker manufacturers even print warnings in their instruction manuals stating that using under-powered amplifiers will take out tweeters. (And use of such amplifiers would "void" the warranty.) Have you wondered why just about every decent speaker out there has a *minimum* power rating? If clipping did not take out tweeters, there would be no *need* for a "minimum" power rating.
I've always thought the minimum rating was the manufacturer saying "use at least this much if you want to ENJOY the sound of this speaker. You simply won't have enough power to get decent volume and transient response on music with less".To support this view, I note that quite a few manufacturers offer a set of recommended minimums based on room size. The only reason room size can make a difference is listening distance and the way sound pressure level falls off with increasing distance.
My feeling is that the minimum recommendation is based on some expectation of what the average listening level will be at the listening position plus an allowance for the power required to respond to whatever the manufacturer regards as a good figure for transient peaks above the listening level.
David Aiken
Not that it matters.Please define "underpowered amplification" and
"sufficient power" in a way that could help fellow audiophiles
convert those terms into specific rms watts per channel
for their speakers.Did it ever occur to you that "minimum power recommendations"
may have more do do with the sound quality provided by the speakers?
You are speculating on what the words in the owner's manual really mean. The fact is clipping harmonics from music can only account for a very small perentage of the rms power needed to damage voice coil wires/adhesives. It's just a coil of copper wires glued to a cylindrical former -- so in plain English, only too much electricity can do damage ... and clipping harmonics are just a very small percentage of the electricity, so they should receive only a very small percentage of the blame.Nationally known speaker tester Tom Nousaine on "underpowered amplifiers" from a use net post (see link):
"You won't protect your speakers by using a larger amplifier.
It will just burn them out as fast by supplying more power no matter what the condition of the signal." TOM NOUSAINE
According to the Rane article, under powered amps are more likely to blow tweeters. The answer is not because of clipping, it's due to compression according to their research. Because the amp compresses the low end signal, the user doesn't notice the volume increase as much, but rather should notice an increasing brightness. In any case, the volume can be continued to be applied until the amp clips at 100 watts on the high end easily over powering and burning out the tweeter."If you overdrive the amplifier by 10 dB, the high frequency
amplitude goes up by 10 dB. This goes on dB for dB
as you turn up the volume, until the high frequency reaches
the 100 watt level. Meanwhile the peak level of the low
frequency portion can not increase above 100 watts (See
Figure 4). This now represents nearly 100% compression (no
difference between HF amplitude and LF amplitude).
vol. 38, pp.34-39 (Jan-Feb, 1990)"Their solution was to build in limiting. So, volume is the culprit, but using an under powered amp would be more likely to encourage the listener to abuse the speaker because of compression. This of course excludes people like my brother that blow tweeters because they just want to see how loud it will go before it breaks.
Do you really think I'm so dumb as to post a link that contradicts what I posted?
Don't answer that!What the link explains is that even if bass transients are clipped,
the treble is not and will get louder and louder as you turn the volume control clockwise so eventually the tweeter will fail.But the same thing will happen if you turn the volume control clockwise with an amplifier that never clips at all.
The only difference is the clipping harmonics that make the treble slightly louder and much more harsh sounding without you touching the volume control ... but only when there is clipping ... which is almost always intermittent when playing music.
A small quantity of clipping harmonics gets through the high pass filter to the tweeter -- the article calculated 1.4 watts for a severely clipped 100 Hz. sine wave which they represented by a 100Hz. square wave. And further, they assumed a 1000Hz. turnover frequency. For home speakers playing real music, not sine waves, and a typical 2000Hz or higher turnover frequency for the tweeter, the clipping harmonics are likley to be much less than 1.4 watts -- I was being very conservative in estimating one watt.
In plain English the article says treble too loud for too long = tweeter damage. The article speculates on what listeners would notice ... in a way that promotes sales of Rane limiters.
It's my opinion that the "warning effect" of an audiophile hearing
harsh clipping harmonics and then wanting to turn down the volume or at least not make it any louder ... at least offsets the slight danger of one watt of intermittent clipping harmonics. With no clipping at all, the treble sounds better ... but the tweeters are still damaged if they play too loud for too long.At least clipping gives some warning that the music is much too loud and speaker damage is possible. Of course if everyone is drunk at a party, no one would notice.
I can read just fine Richard.What the article states quite clearly it that when an amp compresses, it tend to damage the tweeter because it continues to supply power to the higher frequncies. What you're denying is that this is more common with under powered amps. If you're familiar with amps that clip nicely and compress when over driven, then you'd know that the user doesn't get the perception that the music is getting that much louder. Even if druck at a party, if the amp can deliver the power to sound louder, then it's less likely to get over driven into compression or clipping to the point of over driving the tweeter.
I've repeatedly stated that clipping harmonics can make lower power amps slightly more dangerous to tweeters than higher power amps.Assuming the listener plays the treble at exactly the same volume, the clipping amp will produce slightly more treble output from the clipping harmonics of bass and mid-range transients without one touching the volume control -- with real music this is likely to amount to 1/2 to 1 watt of intermittent clipping harmonics, which would be only a small percentage of the power required to damage even a cheap tweeter.
So I assigned 5-10% of the blame for tweeter damage to clipping harmonics.
But the typical "buy a more powerful amp" advice given to someone who has blown tweeters does not work. Some people do get conned into spending a lot of money on more powerful amplifiers. And maybe they will never damage tweeters again. But let's not be so fast to credit the new amplifier -- people who damage tweeters learn from their mistake and usually are more careful about playing LOUD music in the future (I had a tweeter-blowing experience as a teenager in the 1960's and have been much more careful since then = no tweeter damage in the following 35 years).
The reason this "buy a more powerful amplifier advice" does not work is because the new amplifier (assuming it NEVER clips which is probably not true) can only play the treble slightly louder than a clipping amp before the replacement tweeters will be damaged!
(No clipping at all but the tweeters will still be damaged ... although the "good" news is the treble will sound better ...
before the tweeters are damaged this time!"When voltage peaks of bass transients or lower midrange transients are clipped, the average power increases. The music is somewhat compressed ... and just like a compressed dynamic range TV commercial, the music sounds LOUDER. True that the kick drum hits can't reach higher dB's as you turn the volume control clockwise if the voltage peaks are being clipped ... but the guitars and cymbals and everything else can continue to get louder (as the average power increases).
Our perception of loudness is based mainly on the average dB's (power level) -- haven't you ever noticed how LOUD compressed TV commercials can sound -- that's from the high average dB (power) level.
The danger to tweeters from clipping harmonics coming from a clipping amplifier is comparable to turning up the volume slightly with a
non-clipping amplifier. That's why a "more powerful amplifier" accomplishes little -- it doesn't address the root cause of tweeter damage = treble played TOO LOUD for too long!
I have learned about underpowered amps taking tweeters out the "hard" way- in my *own* system... Several times, in fact...When it happened to me the first couple times, I did not realize an underpowered amp was causing the problem. Then Rudy Stoklos, head of Saras of America, found out I was using a 30-watt receiver to drive his speakers, he went on a verbal rant about under-powered amps clipping and taking out tweeters. I then went to a 70-watt Amber Series 70 amplifier, and I never blew out a Saras tweeter again.
All I am doing is attempting to save people the grief in making this mistake. If you think that's "wrong," oh well...
There are a lot of people I respect in regard to audio advice, but Tom Nousaine is *not* one of them... (I know him very well from rec.audio.)
Anecdotal evidence is not a very scientific analysis of the relationship between maximum amplifier power output and speaker damage. There are far too many variable involved.
For one example, did it ever occur to you that after damaging tweeters you became more careful about playing music at high volumes in the future? And had you simply stayed with the 30wpc amplifier and been more careful with the volume control, your tweeters would have remained intact in the future too?When I was a teenager in the 1960's I blew out a University horn tweeter from excessive volume and it cost $50 to replace, which is equivalent to about $250 in 2003 dollars ... so I learned my lesson and never blew a tweeter in the following 35+ years.
So what does that prove about amps and tweeters?
Nothing!I did say that clipping harmonics account for roughly 5-10% of the power reaching tweeter so did not imply they have no danger.
In my mind is a typical 12dB/octave 2000Hz. or higher crossover frequency. The danger to tweeters would increase if the tweeter couldn't handle much power, used only a 6dB/octave crossover slope and had a relatively low turnover frequency. But rms power would still be the primary cause of damage by far - not clipping harmonics.All other things equal, if you had massive clipping, let's say 10dB, using a 30wpc amplifier, then you'd still have 6dB clipping using a
70 wpc amplifier. That's not a big difference.Taking your popular but wrong "clipping is dangerous" theory to the extreme:
-- Would you say if eveyone used a 1000wpc amplifier that never clipped, we would never have damaged tweeters again ... and if everyone used a 1wpc amplifier that clipped heavily all the time, we'd hear horror stories of blown tweeter's every hour?
I think you two might be arguing two different points, actually. And it seems like at one point you were confusing talking about power to a speaker as a system as opposed to using the term speaker to refer to a driver....... Anyway, read the link for a good primer, which pertains to all speakers, not just the brand and type in the article.
Speakers consist of one or more drivers.
The term "speaker" communicates better than the
term "driver" to most people.My link provides data, rather than speculation.
I know you're thinking: "YOU know more than JBL?"
Well folks, the "Don't use an underpowered amplifier"
warning has been used for many decades to help sell expensive
powerful amplifiers! And it works too!When that article was written a long time ago when JBL did sell amplifiers (they may not anymore). Did you ever consider that back then JBL had a financial interest in selling more powerful pro amplifiers ... not to mention that pro usage is not comparable to home audio. Today, pro sound production companies can monitor speakers and amplifiers real time via computer links to built-in sensors in the equipment, not to mention using limiters that immediately cut power to prevent clipping. They take no chances.
Of course clipping distortion sounds bad, so who wants to listen to that?
And even a small amount of clipping harmonics reaching a tweeter can be bad news in very-high-SPL-close-to-the-edge pro situation where reliability is absolutely the top priority, not sound quality -- so why take even a little more risk? If the speakers break, the audience is liable to turn on the sound engineers and beat them up!
Even the Rane article in my link is slanted toward convincing readers to buy Rane Limiters (rather than providing the common sense advice "just turn down the volume", which I wish they would do more often in pro sound reinforcement) but at least there is useful data provided, while the ancient JBL article does not provide any data at all to support it's conclusions.
"... not to mention that pro usage is not comparable to home audio"Sorry, I flatly reject that; in fact, besides that all the physics are the same, the longer I am at this the less distinction (and need for distinction) I see.
As for the JBL article, no, I don't believe by any stretch that they wrote it to sell higher power amps; they wrote it to lower warranty costs, as did Klipsch, etc.
"Today, pro sound production companies can monitor speakers and amplifiers real time via computer links to built-in sensors in the equipment, not to mention using limiters that immediately cut power to prevent clipping. They take no chances."Yes, I know that, and I know that that pro sound people still know the value of sufficient power.
Anyway, here is another newer doc that describes recommended power based on speakers input rating. But then again, maybe they are just trying to sell something..........
I've read dozens of the articles on the JBLPro site over the years -- I especially like the one at the last link you provided because it explains how JBL rates woofers' power handling using a 40Hz. 12dB/octave high-pass filter to protect the drivers, which is fine for pro sound usage ... but many people up until a few years ago bought JBL 2235 and 2245 drivers for ported home DIY subwoofers
and used no high-pass filter protection at all because they wanted to hear/feel 20Hz. from their subs. So the JBL power ratings intended for pro use had low correlation with home usage as subwoofer drivers w/o high-pass filter protection. That's just one more example of differences between home and pro usage.For home usage, a 100 wpc amp with massive 10dB clipping oif bass transients could be replaced by a 200wpc amplifier ... and then there would only be 7dB clipping with the same input voltage, all other things equal. That would make little difference to the tweeter.
And the data in the above paragraph has no meaning at all for pro use
where limiters are always used.
Yeah, I HAVE ported JBL 2245 for home sub use, with a few caveats; I have never blown a single driver/system in my life, always had a pretty good sense how hard/loud I was pushing it; I don't run anything NEAR the rated input into most drivers; the sub is tuned to 28.8 and I don't try to get 20 hz; and I often use an amp with built in variable high pass, usually set to 30hz. Thanks for the reply.
MBB
The 2235's and to a lesser extent the 2245's in ported enclosures or infinite baffles could suffer overexcursion damage when one misunderstood the JBL power handling ratings. Very popular drivers for Michigan DIY subwoofer builders, especially infinite baffles.
The 2245 is a classic subwoofer driver -- not until recent years did the 18" Aura / North Creek Leviathan surpass it (for only about $800 each!!!)
Yes, I have been insisting that some of us are arguing different points, and certainly not answering the poster's question. Your link is a good one.
For the question that the original post asks, there is absolutely no danger whatsoever.
I owned ADS 410 speakers for about six months in the early 1980's.
Gave them as a gift to my sister-in-law. One time a few years later during a party she cranked up those little speakers very loud for a party in their large house which eventually blew both tweeters.
The Sony integrated amplifier I had also given her was either 40
or 50 or 60wpc -- I can't remember over 20 years later.Well since I'm such as nice guy, I bought two exact replacement
Audax dome tweeters for something like $30 each as a gift and installed them with the warning:
"Too LOUD for too long = goodbye tweeters ...
and I'm not paying for the next pair".Well the sister-in-law was a lot more careful after that incident and the ADS 410's were never damaged again and are still in use today.
And still sound pretty good too.Now the ADS 420's may be completely different than those ADS 410's which used a 7.5" Audax woofer and 1" dome Audax tweeter ... but the lesson is still the same -- almost any receiver can take out a tweeter if the volume control is turned too far clockwise.
To say there is absolutely no danger at all is not true.
If the receiver was only 3wpc there would probably be no danger.
nt
speakers results from underpowering them. This is news to you?
bwkendall:
This is not intended as an insult.
You may be a very intelligent person in general ...
but just not on the subject of speakers and amplifier clipping:There are many beliefs about audio that are wrong.
Clipping as an extremely dangerous speaker killer is one myth.
Of course there is a little truth behind this myth -- clipping harmonics are not completely harmless to tweeters."Underpowered amps" are dangerous to tweeters,
but other amplifiers are safe, is another urban myth.Do some research and learn more about speakers and clipping.
I offer one link that describes how clipping may limit the SPL of some bass transient voltages, but if one keeps turning the volume control clockwise, the treble keeps getting louder until the tweeter is damaged. To blame clipping for too much volume is to ignore the primary (90-95%) cause of speaker damage -- the person who last touched the volume control.But even if you were right about "underpowered amplifiers",
I challenge you to make a definitive "ruling" on whether or not a 70wpc receiver is "underpowered" relative to ADS 420 speakers rated
for 50 watts rms.I make this challenge because 99% of the time the (95% incorrect) advice "your amplifier was underpowered" comes AFTER a speaker is damaged.
Advice too late to do any good.
Note that the paper at the Rane Corp link is from a pro speaker point of view -- the test tone used to calculate clipping harmonics (100Hz. square wave) would represent a heavily clipped 100 Hz. sine wave test tone and the 1,000Hz. crossover frequency to the tweeter is at least an octave lower than crossovers in home speakers
The typical intermittent clipping of real music and 2,000Hz. or higher crossover frequencies for home speakers would be much less damaging to tweeters ... and yet the Rane Corp engineer calculated only 1.4 watts clipping harmonics from their worst case analysis
with a 1000Hz. crossover frequency to the tweeter.
My statement, pure and simple, is that the Marantz 70 wpc amp will work fine with the ADS speakers rated at 50 wpc rms. Especially at moderate listening levels, which I would define as never taking the amp beyond "high noon" on the volume knob. I am always happy to learn new tricks, so I will spend some time reviewing the two links you have included in your posts. I suspect that those links contain comparisons of equipment that are much more extreme than what we are talking about here.
Thanks for the speedy replies! My speakers are A/D/s L420's . Any other input is relished.
-Dave
but if you aren't turning your volume up beyond the 12:00 position, it shouldn't be a problem. Did something happen that prompted you to ask the question?
No, nothing happened that was unusual. In fact, the system sounds great. I had just been wondering what the relationship between these was all about. And just a wee bit concerned for my new speakers.
Thanks.
nt
Way more speakers get damaged by underpowered amps than with amps capable of prodigious power. All within reason, of course. If an amp is forced into hard clipping all manner of nasty things occur (way more distortion) and it is those nasty things that kill the drivers or x-over components. The difference between 50 and 70 watts is not that great so you should not experience any problems if you don't force your amp into clipping. You should know that it is clipping by the audible levels of distortion and stress heard. Unfortunately, sometimes it is too late for the speaker components and something will have died in the process (usually the tweeter, but not always). What is more important is the efficiency of the speaker and the load it presents to the power amp. The amp and speakers should always be thought of as one system.
My "all within reason" in my initial reply to me meant that you can kill any part of a speaker if you overdrive it and, obviously, a powerful amp can overdrive a speaker with clean power. In fact, I guess I was merely repeating what is so often said about clipping. My only experience has been with quite powerful amps: Mitsubishi D-15 or whatever it was at 150 wpc, VSP Gold Edition at 180 wpc, Adcom 565 at 300 wpc and Bryston 7B-STs at 500 watts per channel (will the next one be a kilo? I don't think so). Failures have been two blown tweeters in two different speaker models; at different times, many blown midranges, a blown tweeter and blown x-over components (the smoke in the room was thick and acrid) with a pair of well-respected speakers (in this case all repaired by the manufacturer even after many years of service); and a blown midrange in my most recent speakers. So, all in all, yes, indeed, big power can be quite deadly. I am now listening at saner levels. To get back to the original question: no, you should not have any problems if you don't overcook things.
Voice coils are damaged from too much heat.
The cause is too much rms power.
Clipping harmonics might add 0.5 to 1.0 watts to the treble output -- not even close to the rms power needed for damage -- and these clipping harmonics would be intermittent added treble output unless the clipping was continuous, which is rare for home audio equipment.In my opinion, the harsh sound of clipping harmonics serves as a warning to turn down the volume ... offsetting the slightly increased power output due to the clipping harmonics themselves.
A more powerful amp might sound LOUD and clean before a tweeter is damaged ... while a clipping amplifier will sound LOUD and harsh,
but the result is the same -- the tweeter is damaged.
taking different routes. You obviously fall into the power listener category. In that regard, you are right. You wind up with the same problems as the underpowered listener. So? What we are talking about here is a guy with a 70wpc amp who claims to stay within reasonable volume levels, who also owns a pair of speakers rated at 50wpc. If they are rated at 50 wpc, that can't be peak power, so in this case the poster should be just fine. What point are you trying to get at?
Hey, you know, I'm wondering if it's possible, when using a 70 watt amp, to produce 50 watts all that often, when listening to music?Is a speaker rated at 50 watts good for a 50 watt amp, or is it good for 50 watts continuous?
The only exception would be an extremely low power amplifier that simply can't provide enough voltage to damage a voice coil.
Perhaps 5 wpc or less could not damage any tweeter I've ever used in my DIY speakers.In my teenage years a friend and I actually did an experiment with a 1-2 wpc amplifier originally from a TV set used to drive an EPI 100 speaker -- extemely LOUD and DISTORTED -- lots of clipping -- we had to leave the room the sound was so distorted --- but the amp could not damage the speaker at all.
While your explanation makes excellent sense in the abstract it does not jive with my experience. I worked in high end audio retail for a major shop for a cumulative period of about seven (not all consecutive) years. We sold considerable numbers of fairly robust amps: big ARCs, Brystons, Levinsons, etc. The cooked tweeters we saw were very, very rarely connected to those amps and quite commonly from systems using receivers, integrated amps, or relatively inexpensive separate amps with comparatively lightweight power supplies. I can think of specific examples where the customer repeatedly fried tweeters and the problem went away when they moved up to a more powerful amp. I realize that this is anecdotal evidence and not a statistically meaningful data set, however, if you must have statistically solid data sets you might consider picking another field rather than high end audio. My trust in my ears and my experience has limits but in this case I'll go with them over your data.
I did not claim clipping harmonics have no danger at all -- but they are just a small percentage of the power needed to damage a typical tweeter.So an amplifier that never clips is theoretically "slightly safer" for tweeters ... but then it's also more likely to cause overexcursion damage to mid-range and bass drivers!
So you can't win.In the past few decades tweeters have been gradually improved to be able to handle more and more power --- ferro fluid in the voice coils really helped. In the early days of transistor amps when only 30wpc was typical and people used low-power handling paper cone tweeters -- clipping harmonics were then a considerably higher percentage of the power needed to damage the tweeters. One watt of clipping harmonics is a big deal for a tweeter than can only handle 5 watts continuous power.
Did it ever occur to you that people who have enough intelligence to make enough money to afford your high-end equipment might have learned from their experience damaging tweeters (by the time you were done with them they probably spent a small fortune buying a more powerful amp!) and as a result, they were much more careful in the future and rarely, if ever, damaged tweeters again!
Interesting note, Richard, about the less capable tweeters of yesteryear. I have never blown a tweeter. I wonder what the sound has to get like to do it. ?
So an amplifier that never clips is ... more likely to cause overexcursion damage to mid-range and bass drivers!Slight touche' there. A more powerful amp typically provides greater electrical damping. More powerful amplifiers typically need a little more SPL to blow a woofer, as compared to less power, less damping.
That's my experience. I can push a woofer to compression, which is not over-excursion; that can't come into play until the driver is out of control. I've seen over-excursion come about specifically as a result of not enough amplifier!
Along the same lines, I think also a reason why folks say that more powerful amps don't blow drivers as much is because there is typically less distortion at the same SPL. As a result of this, typically it's going to take more db to get it to tear itself up or experience over-excursion, when using a more powerful amp.
And also please don't take any of this out of context - I make no mention of melting coils here. I'm guessing that's what all the talk about tweeters is about - melting voice coils?
With woofers more powerful amplifiers are more dangerous.
Clipping harmonics would add to a mid-range driver's workload or a tweeter's workload but would have little effect on true bass drivers.Many modern subwoofer drivers, for example, could be driven at full volume with a 30wpc amplifier indefinitely with no damage ... but almost all could be damaged by a 300wpc amplifier (which should be able to produce 600wpc at high distortion levels).
Here is a cut and paste of an e-mail I received from Adire Audio whose Temmpest driver I use in one of my DIY subwoofers ... about the "danger" of driving their 15" sub driver with an often clipping 30wpc receiver:
"Richard,
Thanks for the e-mail! A 30WPC channel amp won't damage a Tempest at all, regardless of clipping. On the other hand, a 300W amp clipped heavily could cook a Tempest quite easily. Clipping is a problem in that it can double the effective power delivered to the driver, and do it with a much more damaging spectrum. However, I think the 30WPC concern is a bit overzealous."
Thanks again,
Adire Tech Support
-----Original Message-----
From: Greene, Richard (R.K.) [mailto:rgreene2@ford.com]
Sent: Tuesday, August 05, 2003 8:37 AM
To: 'techsupport@Adireaudio.com'
Subject: Clipping dangerous to Tempest driver?
While a more powerful amplifier is being repaired, would it be dangerous for me to use a cheap ($98) Japanese 30wpc receiver to drive a DIY Tempest ported Sonotube subwoofer? I expect with only 30wpc there will be amplifier clipping but I did not believe such a low power receiver could damage a Tempest driver ... until I read what a pro audio speaker expert posted on the internet
-- his post suggests to me that a 30wpc receiver could be a
"Tempest killer" even though the Tempest is rated at 750 watts power handling. Could you provide any comments on his warning below:"99.999999999% of amplifiers driving subs have feedback.
When the amplifier clips this can destroy the woofer.
It has to do with the time constants in the power supply and feedback loop of the amplifier. Watch the motion of the subwoofer cone at clipping, it will generally have a 1~2 hz component to it.It is this 1~2 hz component at rail-to-rail output (clipping)
that causes the destruction of the driver."
Thank you;
Richard Greene
A 30WPC channel amp won't damage a Tempest at all, regardless of clipping. On the other hand, a 300W amp clipped heavily could cook a Tempest quite easily. Clipping is a problem in that it can double the effective power delivered to the driver, and do it with a much more damaging spectrum. However, I think the 30WPC concern is a bit overzealous."Richard;
As it says, a 30 wpc amp just isn't powerful enough to do it. Try asking the same company about the difference between one amp powerful enough to blow it, and then another amp twice as powerful as that one. According to the above quoted text, I think you will find the less powerful of the two to more likely blow the driver.And I'll quote it again...
Clipping is a problem in that it can double the effective power delivered to the driver, and do it with a much more damaging spectrum.Man, I've really seen this - I've seen a lack of power cause clipping where a more powerful amp would not have clipped, and therefore having blown the driver!
I think it's interesting to consider the idea of using an amp that just isn't powerful enough, even when clipping, to blow a driver. I hadn't even considered it before. I'll keep it in mind. Meanwhile, do you feel like dashing off another note to Adire about what's being said here?
You speculations are wrong.
With all drivers too much power causes the damage and a small
percentage of that power could be clipping harmonics. With a subwoofer driver, however, the clipping harmonics are likely to be miniscule because fundamental tones in the 40-80Hz. octave such as bass guitar and kick drums would have clipping harmonics above the subwoofer's pass band (it would be protected by the usual 24db/octave low-pass filter).Sometimes one can point out faulty logic by extrapolating it to the extreme sduch as a 1wpc amp versus a 1000wpc amp!
One could burn out any driver I've ever used in 32 years of building DIY speakers and the other could not damage any drivers. Now you guess which is which ... because I don't have the energy to type much more on this subject, so I'll just quote someone else:From speaker tester Tom Nousaine's usenet post:
"I regularly test speakers near the burn-out point. What fries tweeters is an amplfier that has too much power. A smaller amplifier even driven into clipping is safer than a larger amplifier that delivers more power. Often a somewhat smaller amplifier is still too much but a bigger one never fixes the problem clipping or not."
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From another Tom Nousaine usenet post:
From: Nousaine (nousaine@aol.com)
Subject: Re: xmax
Date: 1998/08/14
Steve notes:
"Don't go into extremes. A severely clipped signal of 1 Watt or so will of course not damage a tweeter."
TN: That's because the tweeter is working within its power limits.
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"When an amplifier clips, most of it power goes into higher order
harmonics."TN: That's not true. Why should that be so? The fundamental is still the same frequency. True there is more power put into harmonics but not "most" of it.
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"Let's presume that in a standard 3 way system, the tweeter typically receives about 10 to 15% of the total power. When the amp clips, sending maybe 70% of it's output to the tweeter, it'll burn out."TN: No. That's not so unless the signal was 10 kHz or something. The reason the tweeter burns out because it just gets too much power. Clipping isn't the issue. Power delivery is.
But we do not need to argue this point. Tweeters are the lowest power handling devie in your speaker line-up. Therefore they are the most damaged device. The main reason that tweeters get gobbled up these days is synthesizer music. Acousttic instruments do not have any power needs at high frequencies. Synthesizers, on the other hand, can deliver full power signals at 20 kHz.
In the final analysis you are just noting that you can fry a tweeter with a 25-watt amplifier. You can also fry it just as easily with a 100-watt amplifier. Or a 1000-watt amplifier. Too much power is too much power.
People want to tell us that a 100-watt amplifier is "safer " for your tweeter than a 25-watter. It's not true. If you want to preserve your tweeter get a 10-watt amplifier. The issue is power delivery NOT clipping.
If the issue was simply clipping my original 'far out' example would still apply. I only used it to illustrate the point that the power delivered to your tweeter is the main concern. And that tweeters have low power handling capacity compared to the other drivers in your system.
I want to point out that when you are frying tweeters getting a bigger
amplifier will not solve your problem."
You speculations are wrong.I don't appreciate the apparently very egotistical presumption on your part. Here is something that has happened right in front of my eyes, and others that I have associated with in audio as well.
------------------------
I have seen a 70 watt amp driving a 12" woofer clip very hard, causing the woofer to separate into two physically distinct pieces.It goes something like this. Some detail provided for general readership. The amp is providing a sine wave acting as a carrier, and the height of that wave equates to amplitude. The motor of the driver coorespondingly travels in and out - excursion. In this case, the amp had enough power to begin to recreate the blast of a canon in the 1812 Overture, however; having completed the introduction of a sharp amplitude and a quick excursion, the amp was then exhausted. There wasn't, for a moment, any power left to continue to provide electrical damping to return the driver along it's natural sine curve. The capacity for the driver to physically provide mechanical damping was not sufficient to prevent the launching of the driver on that excursion from continuing to the point of physically separating from the remainder of the driver assembly - leaving the cone forever floating - torn and separated from the rest of the assembly.
It is not necessary for the coil to be electrically overloaded for the above type of a blown woofer to occur. Some might say this is caused by bad driver design, or perhaps one might say that amp just got a really good start. The important note is this. The driver was not electrically overloaded.
If I irritated you I apologize whether you deserved it or not.
Oops ... I just irritated you again.
I would like to irritate you for a third time by pointing out that
observing a speaker being damaged does not guarantee that one knows
exactly why it was damaged or how to prevent damage in the future ...
but if you guessed the cause was "too much power input" you'd almost always be right. True that too much power input can cause overexcursion damage before any voice coil overheating occurs.
This is especially a risk with ported speakers with high input at frequencies below the port tuning frequency.Woofer overexcursion damage is rare although overexcursion damage is a common problem for the "boombox car" guys -- that's why they often don't care about their driver's XMAX or DUMAX -- all they are interested in is XMECH = maximum excursion before overexcursion damage becomes likely.
Every woofer has an XMECH spec beyond which overexcursion damage is likely. The more powerful the amplifier, of course, the easier it will be to cause overexcursion damage. Clipping is not the cause although it is related in one way -- under conditions that cause a lot of clipping (compression of the complex A/C waveform also known as music) an amplifier's average power output will be roughly double the rated power output. Therefore, a speaker that can absorb 100 watts continuously could be damaged by a severely clipping amplifier rated at over 50wpc (producing over 100 watts continuous output).
If that was the Telarc 1812 overture with output under 10Hz.,
that is definitely one the best CDs for causing overexcursion
damage.Unless you are listening to sine waves the amp is not
"providing a sine wave".
Richard;
My God man, you certainly do type too much. You're way off topic and back onto tweeters again, and the relatively inconsequential amount of power added to the high pass when clipping the amp on the lower.I think you missed your yoga class this morning. Your points are all very well and good, but your apparent desire to avoid a point contrary to your own seems quite unbecoming to me.
I'm sticking to my story. I can rip a woofer right off the magnet by clipping an amp, and based upon the note from Adire, I am willing to bet that they wholeheartedly agree. The only remaining question, then, is, "would you?" Please, read on...
With all drivers too much power causes the damage
Edited: With all drivers, too much power causes damage. I urge you to find a way for the following statement to exist simultaneously. Clipping produces a nastier, less driver-friendly signal than when not clipping, and clipping begins with a lesser amp earlier than it does with a greater one.The fact that some amps simply do not, even when clipping, have sufficient power to blow a driver, has also been recognized. Please try to keep each point in perspective. All of these things are simultaneously true.
Get a grip!
... and annoy you some more!Most amps these days are 100 to 200 wpc.
If you had a 100wpc amp that clipped once in a while,
then a 200 wpc amp would probably clip once in a while too,
given the same input voltage.Lets start with a 100wpc amp with intermittent 9dB clipping,
-- using a 200wpc amp would only reduce clipping to 6db
-- using a 400 wpc amp would only reduce clipping to 3db
-- An 800wpc amp would be needed to entirely eliminate
9dB of clipping.The true comparison is between a typical 100wpc amp that someone owns, and perhaps a much more expensive 200wpc amp upgrade that some people may claim is "safer" for speakers.
But that "upgrade" would only reduce intermittent clipping by 3db, which probably would not even be audible.
When using a 200wpc amp, however, the probability of woofer overexcursion damage would increase compared with a 100wpc amp.
As I said, you're bearing has struck me as egotistical - just callin 'em like I'm seein 'em. Or maybe you are saving the world. Or maybe I'll just never know - comments about others present a different environment than comments about oneself. I'm just trying to add to the thread, not take your comments away. My point about you is to describe your behavior as adamant and dictatorial, not allowing other points of view in the face of your own. And I may have been unduly argumentative myself - sorry - it wouldn't be the first time! Sometimes I don't adapt at the speed of things in real time.
When using a 200wpc amp, however, the probability of woofer overexcursion damage would increase compared with a 100wpc ampIn my experience, a 70 watt amp blew a 300 watt woofer.
If there isn't enough power to blow a driver, then there generally just isn't enough to do it. In the example I had, however; there wasn't enough electrical power, and the design to some extent could be blamed - driver or system. But I also think this leads to some regard for where the wattage desired by the speaker is not the only thing to be measured. There's been alot of discussion on this. I've added a link to the discussion you previously took part in at DIYSubwoofers (and also quoted from in this thread with the Adire note), since there are comments there where the nature of the signal, and not just the wattage, play a role. This can be, and indeed has been, argued at length in it's variety, importance and effect. My current speaker system is rated at 500 watts into 5 ohms, so the equivalent of 350 to 400 watts into 8. When I get to the point where I want to replace the drivers, I will be able to test blowing them without suffering a loss. I will replace the drivers not when they are blown, but when they have experienced noticeable wear and tear.
Too much power blows a driver. A more powerful amp puts a person into a higher risk category, and in my experience audio salespersons know that and do tend to advise their customers of these risks. But you bring up a great point in the face of what may have developed into thinking by some that more power means drivers do not blow, or some such thing. I think the truth is that within the speaker's power handling capacity, such-n-such an SPL level simply sounds better. Generally, more power offers better control of the drivers within acceptable levels. It's been a learning experience to me to hear you say that wattage is everything on the matter.
I want to bring it all together into a single thought now. The most commonly blown driver is the tweeter, at say, 30 watts there. But my God, man, 30 watts to the tweeter. Either someone went ballistic with an 8K test tone, or the amount of power going to the speaker system is really high. In an overall musical presentation, isn't 80% of the power at 300 Hz or below? And when a person puts that amount of power into it, aren't they either statistically forced to be using either an ungodly huge power plant or an ungodly horrid noise coming out of their speakers? I'm not referring to the wimpier tweeters of yesteryear or of the $3 bin. I will never blow the drivers of my 87.5 db speakers. I'm hitting 105 db peaks as it is (bass) - often enough - isn't that enough? When the linear travel is through, I've still got a little space (beyond the XMAX), but I'm not going to like it, and so I'm not going to do it.
Maybe it's a little rough to say that a person might deserve a blown driver if they push it to that point, maybe a little leeway for folks who have drivers that can't handle much. My roommate has, incidentally, also experienced blown woofers in his Aiwa boom box - by it's own amp and it's own speakers. Geesh. Did he deserve it? I don't know if anyone does. It doesn't happen to me, but some folks don't seem to mind when the sound gets bad. Maybe I have my own protection circuit built in? Maybe I'm also spoiled, because presently 150 wpc has me in heaven with the afforementioed speaks. That Aiwa amp is rated more than twice the wattage as my Odyssey (but I think it's a marketing gimmick based design). Maybe I'm starting to see your position better when I start to think of folks whose speakers don't handle very much power.
I'm done, and I'm happy. Glad to give you the last word at this point, Richard.
You Wrote:
"As I said, you're bearing has struck me as egotistical My point about you is to describe your behavior as adamant and dictatorial, not allowing other points of view in the face of your own."My reply:
Thank you for the complements. I'll put them on my resume.
I believe I accused you of speculating in one of my posts,
so I guess I deserved this outburst of affection.
.
.
.
You wrote:
"In my experience, a 70 watt amp blew a 300 watt woofer."My reply:
Assuming the amplifier was honestly rated at 70wpc, it should
be able to reach roughly 140wpc at high levels of distortion.
Therefore, the woofer was unable to survive roughly 140wpc
due to overexcursion I assume, and most likely was overrated
at "300 Watts" ... or this rating only referred to the voice coil's ability to dissipate heat, and didn't account for overexcursion damage. Not very useful speaker or drivers power handling specs are common in audio.
JBL Pro drivers, for example, are rated for power handling using pink noise with a 6dB crest factor and the protection of a 40Hz. 12dB/octave high-pass filter. Someone I know damaged his JBL 2235 15" subwoofer driver from overexcusion because he he didn't understand how the JBL power handling number was calculated.
He used a very powerful amplifier and had no high-pass filter to protect his ported driver below the port tuning frequency.
I would have suspected that over time the speaker would have beome seriously damaged from the clipping and distortion.
The voice coil wires don't care if the music is distorted or clean sounding -- if there is too much electricity for too long the wires and adhesives of a voice coil will overheat/melt/break. Most amplifiers can actually produce average power 3dB higher than the rated power -- that means a 20wpc amp can usually produce 40wpc ... and 40watts of treble energy can damage almost any tweeter.
So just about any amplifier more than a few watts per channel is capable of damaging most tweeters.When the amplifier is clipping (typically clipping is intermittent during transient sounds such as kick drum hits, snare drum hits, etc.) some high frequency harmonics are generated that reach the tweeter through it's high-pass filter without one touching the volume control. It's just like turning up the volume control slightly.
These clipping harmonics only happen when there is clipping.
They make each snare drum hit, for example, sound harsh.
But since the music is already loud at that point it may take 5dB clipping or more before anyone notices the harshness.Maybe 10dB clipping if listeners are drunk at a loud party before anyone notices.
If the music was already very loud, it's true that an extra watt of clipping harmonics could be the 'straw that broke the tweeters voice coil' but let's not place 100% of the blame on clipping because a more powerful amplifier playing just as loud would also damage the tweeters (although the sound quality would be cleaner just before the damage was done!)
Let's place 90% of the blame on the person who last touched the volume control ... where the blame really belongs ... and buying a more powerful amplifier will do very little to prevent tweeter damage in the future. Too loud for too long with no clipping at all and it's still "goodbye tweeters".!
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