Tweeter power ratings?

[Artie]

I love reading the articles and projects from Rod Elliott. (http://sound.whsites.net/index2.html)

I recently ran across his article called "Why do tweeters blow? http://sound.whsites.net/tweeters.htm

In that article, he makes this statement:

"Nearly all tweeters are rated to 'system power', and this will usually be quoted relative to a specific crossover frequency. A hypothetical tweeter may be rated at 100W system power when crossed over at 3,000Hz. The power that it can withstand is not 100W! Not at any frequency or for any duration. The actual bandwidth-limited long-term average power for most tweeters is around 10W, but many can't even handle that much without some distress."

I really respect Rod's opinions and knowledge, but I've never heard of this before. So I interpret this as him saying that a 20-watt tweeter is meant to be installed in a 20-watt speaker system. NOT that the tweeter itself can handle 20 watts. Kinda makes sense. Always wondered about those 100-watt tweeters.

Anyone else ever heard of this before?

 

[whoaru99]

Guess I never really thought about it in those terms. But, yeah, if you consider the hair thin wire comprising the typical tweeter voice coil it's clear most can't handle much continuous/average power.

 

[Artie]

I just wish there was more comprehensive info on this subject. Especially from tweeter manufacturers. It sure would help in selecting tweets for your next speaker project.

 

[gdmoore28]

Rod Elliot is exactly right. It'd be hard to expand on what he said.

GeeDeeEmm

 

[Artie]

I agree. But I still think it's strange that no one else seems to have ever touched on this subject.

 

[gdmoore28]

Well, others have explored the topic at various times, and usually in the context of a larger subject at hand. But what Rod says simply makes sense, especially in the way he emphasized "The actual bandwidth-limited long-term average power. . . " idea. Those two italicized words are the key to understanding the prospect of tweeter power handling.

If you'd like to plumb the minds of the real geeks on the subject, simply post the same question on the Parts Express Tech Talk forum. (http://techtalk.parts-express.com/) The folks there are incredibly kind, and talk over my head about 50% of the time, but when I want the real skinny on any audio subject, these are the folks I turn to.

GeeDeeEmm

 

[Artie]

I'll check it out. Thanks for the link.

 

[Pete B]

Most 1" tweeters handle 5- 10W RMS continuous if they employ a metal voice
coil former, less if paper. The classic AR .75" domes had paper formers, the early
Dyna A-25 had paper formers in both the woofer and tweeter. The metal acts as
a heat sink, helping to reduce thermal compression (copper resistance goes up
with temp, you can look up the thermal coeficient) and burn out.
Most typical small woofers with 1" voice coils on metal formers handle 15-30W RMS
continuous. I'd estimate that the Large Advent with a 1.5" VC on a long metal former
will handle 50W RMS continuous perhaps. What helps here is that music is not
continuous rather the average power level is reasonably low even when the peaks
are large.

I used a pair of 8" cheap but good woofers on each side of my first large speaker
design that had 1" paper formers. We would crank the system with something like
200W/ch into the 4 ohm load and would smell something like toast burning for 6months
to a year until the woofers failed with completely burnt and shorted voice coils. The
enamel insulation coating on the wire was completely burnt.

 

[Pete B]

There was an earlier paper in the AES by Mark Gander of JBL - excellent work,
it is probably referenced in this paper:
https://pearl-hifi.com/06_Lit_Archi...s/LS_Heat_Dissipation-Thermal_Compression.pdf

Edit: Here is Mark Gander's AES paper:
http://www.cieri.net/Documenti/JBL/...oudspeakers (Mark R. Gander - JBL) (1984).pdf

 

[CopperWizard]

I just wish there was more comprehensive info on this subject. Especially from tweeter manufacturers. It sure would help in selecting tweets for your next speaker project.

I believe that they actually do their best in this regard. There has to be some sort of average as everyone will have a different amp, different taste in music, tone, volume. It's like the rating on the back of a speaker box saying a similar thing. My dad still thinks his speakers put out 50 watts. Some sort of average has to be set in order to start somewhere in the ballpark.

 

[whoaru99]

...Some sort of average has to be set in order to start somewhere in the ballpark.

There are some standards in this regard, e.g. IEC, but not all adhere.