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In Reply to: Re: That would make you wrong too posted by Todd Krieger on August 25, 2003 at 14:44:25:
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?
Follow Ups:
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.
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