Here's a picture example of why I don't trust the longevity of Poly speakers...

As you can see the cracks are starting to form near the voice coil. .
I trust Good Old Paper pulp and treated paper pulp because there are speakers still in existence over 70 years of age made with paper..
Infinities polydome is another example of failure with Poly..

What are your thoughts?.. fellow members

 

Do we know the history of those systems? I can see a few hundred watts causing
a little damage. Reminds me of the HPM graphite woofers...

 

Looks like results from Rap music

 

I don't disagree with this opinion. There are many different formulations of 'poly' however. My RS2b use poly cone woofers with the phase plug bullets, They are 40 years old and still pliable and strong with no evidence of any form of oxidation.

My Kappas all were in need of severe maintenance, as regards the polydomes. Either the thickness, or the formulation was no bueno long term.
The IMG cones are nearly indestructable, afaik. I'v never never damaged one, anyway, and I've had IMG cone drivers since 1993.

 

This ^^^^ x2...

Cuz honestly it looks to me like those were "punched in" vs. being "busted up" by normal usage.
It may be that with those flat poly dustcaps the cone took all the damage instead of the dustcaps themselves.

FWIW

Bret P.

 

Norman Labs. Opaque white poly woofs, still working. No problemo

 

Paper would probably be in shreds with the same trauma.

 

Or could have softened from being flexed, whether a crease is visible or just internal. Cones of all materials whether titanium, carbon-fiber, graphite-filled poly, mineral-filled poly, ceramic, pulp, pulp/aquaplas, ... all have their yield point beyond which they will have irreversible damage.

I hate to stereotype here, but the only CV! speakers I own are a permanent part of my test bench. It has been my experience (in days gone by) that most CV! buyers buy them as party speakers, and they get abused.

 

Are these in the back window of a car in Arizona?

 

https://www.facebook.com/marketplace/item/386887902073344/

It's a center Channel on Facebook marketplace for sale

 

Rap is music?

 

I have a couple dozen Infinity poly coned drivers, all 35 years old roughly.
No signs of the actual poly cone degrading.

 

I've owned many speakers with poly cones and found them quite rugged.

My current speakers employ aluminum cones, or titanium domes, or ceramic-coated aluminum/magnesium alloy cones and domes. As someone posted above, any material can be damaged by abuse.

 

Yea - I agree with others that there must be tons of different formulations of poly cones.

All the older KEFs I have seen have been fine - including mine.

I think a lot can be said about rigidity of the cone - or lack of - I think the latter could lead to less stress on the cone, and eventually, damage like the type you have shown.

Plus, isnt the (informal) motto of Cerwin Vega "SLAM IT HARRRRRRD BRUR!!!!!!" - Im not sure, I could be making that part up.....

 

Ten Infinity woofers, ten midranges, and a pair of KEF 104/2 and they are all fine.

Add a pair of IMG that were accidentally torture tested last night. BTW, don't hook up your CD player to the second pair of outputs on your preamp

Although I also have paper-cone/cloth surround speakers that are 63 years old and doing fine.

 

Well I have plenty of speakers with poly cones that seem to be getting along just fine.

That being said, I did run into a problem with a set of midrange drivers ( Elac 4/200 from IMF Supercompact II) that I discovered when doing a refoam. At first it appeared that the edge of the poly cone was brittle, but as I inspected further I found the poly cone was cracked near the voice coil. Seems the entire poly cone got brittle over time.

I see some have suggested yours having been overdriven or hundreds of watts poured into them. Maybe , maybe not, but certainly my midrange drivers did not have the problem of high wattages hitting them or massive amounts of excursion causing the cracking.

 

Yeah, it is. You know, it’s been around now, what, 25-30 years? Time to accept it or at least stop bitching about it.

 

They are not mine, I came across this on market place

 

Why should someone accept something they obviously don't like? To please you?

Perhaps you should accept that some people don't like rap , and are entitled to their opinions about it. Just sayin'....

 

True