High Temp Speakers: 3-4in Diam 300-400F

[Jason03]

I have been looking for information on or for a company that produces speakers that can withstand temperatures up to around 300-400 degrees F. The speakers would be 3-4 inches in diameter. Anyone with ideas or knowledge in this area would be greatly appreciated. The speakers are for a design project that will be automotive related.

 

[berkeman]

I have been looking for information on or for a company that produces speakers that can withstand temperatures up to around 300-400 degrees F. The speakers would be 3-4 inches in diameter. Anyone with ideas or knowledge in this area would be greatly appreciated. The speakers are for a design project that will be automotive related.

Yikes. You might have to end up building your own. What's the Curie temperature for common magnets (I'm too lazy to look it up at the moment).

And, um, who is going to be listening to these speakers at that temperature? Is it really audio speakers that you want, or just the electromagnetic drive capability in the audio frequency range?

 

[berkeman]

Looks like you're okay on Tc anyway:

768°C for iron

 

[Pumblechook]

Some are made of mylar.

 

[Jason03]

We are working with noise cancelation at these temperatures...and we are considering making our own...but not sure yet...

 

[Proton Soup]

under hood noise cancellation? interesting...

 

[Emreth]

what about piezo speakers?

 

[Emreth]

i mean i found these
http://www.buy.com/retail/product.asp?sku=208033850&listingid=29752846&dcaid=17902
i don't know if they work at 400F, probably they do. I think the freq range is off for your application tho, works for high frequencies.

 

[Jason03]

Yea we are looking at the frequency range of at least 100hz and higher...mostly low frequency becasue we are working with the exhuast...which we used a spectrum analysis to find the range of...so a speaker with low frequency and higher power...similar to a sub woofer...but in a compact size...hard to find I am sure...

 

[Emreth]

can you directly mount a piezo element on the exhaust itself and drive it for destructive interference?
i couldn't find low freq piezo systems. maybe you can put the speaker away and channel it there with a waveguide(pipe) or something.

 

[Jason03]

we have a piezo element further down the exhuast to determine the frequency so that the speaker can provide destructive interference...The speaker is off the exhuast at a 45 degree angle...which has been tested to provide the best destructive interference...But the problem is getting a speaker to operate at such a low frequency at the high temperatures...

 

[berkeman]

Just a thought -- can you use something like the Bose speaker radios use? With a folded audio resonant path, so that you can use a reasonable-size exciter element, and get reasonably low resonant frequencies from the audio path in the speaker, and not from the driving element itself?...

 

[Jason03]

what do the bose radios use?

 

[berkeman]

what do the bose radios use?

I don't know that much about them, but I believe their claim to fame is using a folded acoustical path to get lower resonant frequencies out of a small-ish speaker package. I'm sure they talk about it at their website. Not sure if it will help on your problem, but just a thought for something to check out in case it gives you some ideas...