tg989

if you want to pay for shipping I can send you a box of them.

Nobody mentionned that power doesn't kill a speaker, the only point that was put forth was that a low power amplifier can kill a higher powered speaker due to clipping. You keep running off course saying that WELL YOU NEED POWER. obviously you need heat or a shitload of innertia to kill a speaker, both of which require power, but you don't need as much if you're clipping it.

A moving assembly does not respond EXACTLY to the signal, it takes energy to stop innertia, and when that woofer is flying outwards at around 1.5 meters per second it takes more than just a lack in driving force to stop it. Unless you're talking about an extremely high frequency speaker, the delay is measurable, and the larger the speaker, the more noticable it is. Unless the moving assembly weighed nothing, which is impossible, and the suspension weighed nothing, again-impossible, the moving assembly would not respond exactly to the voice voil's signal the instant it is applied.

You've probably never seen one of these before, but this waterfall graph shows you the difference between when the signal is applied to a speaker at various frequencies, and the amount of time it takes the moving assembly to match it. it is NOT instantaneous, and the heavier the moving assembly, the larger the gap.



I was referring to a subwoofer in a trunk in my response, so go and feed your 15" sub a 10,000khz frequency and see how well it resonates it with that heavy moving assembly. Not only this, but also the fact that when the voicecoil is pushed past where it is supposed to be according to its signal, it created feedback, referred to earlier as back emf, which depending on the amplifier, usually causes a shorter wave at the top of that squarewave, this is a higher frequency and usually diminishes before the end of the peak -- enter your grinding sound. Problem is when its on a large woofer that cannot reproduce that higher frequency noise, you simply don't hear it. Anybody can hear when somebody is clipping a midrange or full range speaker, the sound is an audible squeak, it usually sounds a bit like a voice coil grinding, but when you're clipping your sub, and it's in the trunk, and you are in front with a wall of high frequency being thrown at you by your fronts, most people cannot hear their subwoofer making that sound unless you have an ear for it. This leads to 200w amplifiers cooking 400w subs while all the while it 'sounded okay'. This happens at the shop at least once a month and its always a perplexing situation for somebody so I am trying to explain it instead of blurting out "oh you're overpowering it".

I have alot of respect for Regina, they have fought hard since 1999 to keep their spot in the top 5 cities in Canada every year for sexual misconduct and incest per capita!! keep up the great work guys!

I agree with industry experts that you can't blow a speaker without exceeding either its thermal, electrical, or physical limits, what I'm trying to say is that you can do that with a lower powered amplifier than your speakers are rated for, through clipping.

Without explaination, this advice is useless to the average user who doesn't understand clipping, which is why I explained it.


So just to sum it up:
all of these except maybe 3 and 5 (most likely not a clipping case, just generic overpowering) are a case of running better speakers on crappy gear.

Ligeia

iTrader: (1)

This is the point you're missing: it still needs the same average power over a given period of time to damage a speaker thermally, whether it's a clipped signal or not.

The only thing that drives the moving assembly forwards is the voice coil; once the oscillates in the other direction, the damping characteristics of the suspension attempt to stop movement in the forward direction and return to rest. Of course, the voice coil continues in the rearward direction and pulls the assembly past rest anyways; the suspension is only one part of a speaker's ability to dampen movement. In this respect, a clipped signal is no different than a sine wave. There is no magical force that changes the damping characteristics as soon as a clipped signal is applied.

This is comedy at it's finest, but the two easiest points I can make:
1. Yes, I'm quite familiar with what cumulative spectral decay looks like. I've measured a waterfall plot or two before.
2. This is a perfect example of how misinformed you are: mass is not a limiting factor for upper frequency response: inductance is. The real reason that you can't hear 10kHz through your 15" subwoofer is that the coil behaves as a 6dB/octave filter above it's inductive corner frequency, which in a subwoofer is rarely any higher than 200-300 Hz, and quite often substantially lower. This is the real reason you have a hard time hearing clipping with a subwoofer: most of the high frequency artefacts are filtered out by the inductance of your voice coil.

Care to provide statistics to back that up?

And I have never argued otherwise, but the average power over time is still the same.

Perhaps I should not have been so brief, but I was still technically more accurate than saying that clipping killed the speakers.

tg989

You might as well have said "blowing your speakers kills your speakers" as your post provided 0 insight as to why his speakers were blown. The next question was going to be "how can I blow my 80w components with my 50w deck!?!??!!?!?".

JBL uses the same motor assembly for some of its cinema subwoofers as they do their car audio woofers, difference being the lighter moving assembly on the latter and an extended operating range to the tune of +200hz, if you'll pardon the pun. A heavy moving assembly will require more power to reverse the direction of the assembly which is needed 100 times more often at 10,000hz than at 100, and this increased requirement for power will cause the voice coil to ultimately heat up and fail or short across itself instead of travelling through the coil. replace that moving assembly with one that weights nothing and suddely your coil can move it back and forth 10,000 times per second with appropriate wattage -- limiting factor: mass of moving assembly not voicecoil inductance.

Ligeia

iTrader: (1)

IIRC, the pro sound drivers to which you're referring have a slightly shorter voice coil and copper in the motor, but I can't remember unfortunately.

edit: I see you've edited your post. I honestly don't have the patience to explain well documented concepts anymore (maybe read through some JAES for a while?) so I'll leave you to your own journey of self discovery. Feel free to check out my contributions on audiojunkies.com and pm me anytime if you're willing to discuss audio on, perhaps, a more professional and adult manner instead of calling people names and behaving like an infant.

tg989

Thanks for the helpful contribution to the thread. Hope next time you tell somebody they're overpowering their speakers with their underpowered amp, you'll have the common sense to get off your high horse and tell them why.

But seriously, have fun with your 700,000+ rank website, best of luck.

MR2NR

iTrader: (66)

Hmmm, I can send a fully clipped signal into a speaker all day long. PROVIDED that speakers thermal or mechanical barrier is not breached, it will not fail.

Heat kills speakers regardless of it being a clipped signal or overpowered signal. Breach the thermal barrier in either case and the speaker will blow.

For the record though guys, leave the petty argueing aside, you are not painting a pretty picture of yourselves at all. This is a site with some credibility on it from all walks of life. If your credibility lay in slandering other people or cultures, you have zero right to be on this site. This is my view on that part of your discussion from a outside perspective. I am embarrassed for the site to read what I just did.

Ligeia

iTrader: (1)

And for that, I apologize. There are only so many times I can be called a moron and incestuous when I feel I'm correct before I retaliate in some form.

tg989

Nobody has gone so far as to even ask this guy what specific gear he was running so they could determine whether he is overpowering his speakers with too much amplifier, or clipping them with an underpowered amplifier.

Provide him with a proper answer or ask the proper question, then talk to me about credibility.

Haunz

iTrader: (3)

To the 1st poster... you could have overpowered the aformentioned speakers/subs.. there could have been manufacturing defects, and maybe a few other possibilities.... but pushing on the cone of a speaker is not always a good test to see if a coil is rubbing since it can be difficult to know if you are applying the pressure strait down, especially if there is a tight gap.......



As far as clipping blowing speakers... its nonsense IMO... your average power amp only has the current capacity to provide about 20% more power then they are rated for at nominal load; and when you exceed that limit THD skyrockets with little or no gain in output....

In practice clipping a power amp will not damage a speaker any more then a longer listening session then normal...... (road trips must blow speakers too )

Starterwiz

I've never blown a speaker by testing it with a 9V battery, which is essentailly a "clipped" signal.
Perhaps it's time to re-ban the member that thinks he knows it all, and gets insulting when other, wiser members try to correct his mis-information.

There is really no such thing as a "square" wave. There are only sine waves.
A "square' wave is simply the combination of the original note and all the harmonics of that note, at the same amplitude. That's why tweeters burn out from clipping. During normal listening, a tweeter will handle around 10% of the power given to the speaker.
That means that on a 100 watt speaker, the tweeter will handle 10 watts or less.
Feed that speaker a "clipped" signal from a 20 watt deck, and a full 20 watts will burn the tweeter.
The only way a 100 watt speaker will blow with a "clipped" 50 watt amp, is if the speaker is really not 100 watts, or the mechanical limits are exceeded.

Nice try tho tg989....now go away and study some more...or better yet, just go away.