No this isnt a kinky question...
Is there a major reason why some companies still use foam surrounds around the driver rather than change ro rubber? What are the advantages or disadavantages between the two? I know the last set of home made boomers I made had foam around the cones (25 watt 8 inchers) and i blew the cone right out of the basket. It was funny. But...any thoughts?

Most likely it's a cost factor. Foam is cheap.

My thoughts exactly. Of course, there may be some purists out there who swear by foam. Who knows...

Rubber is much more durable; foam will deteriorate. This may be especially true in humid climates. Many years ago I owned a cheap pair of speakers with foam surrounds. The surrounds deteriorated in about ten years time. I own a pair of speakers with rubber surrounds that are about 16 years old, and I've had no problems with those.

A friend of mine has a pair of old speakers with nearly completely missing foam surrounds. They still sound pretty good though. Is there an acoustical reason for them?

They're not supposed to add any sound, if that's what you mean, but they help the speaker cone maintain linear excursion (i.e. prevent any side-to-side motion which would color the sound).

I guess sealing the gap between cone and frame is also a good thing, particularly for air suspension speakers where the compressed air in the cabinet is used to control cone excursion at resonance rather than "back pressure" from a tuned port.

I had 80's vintage Large Advents until last year. The foam disinigrated after the first ten years. I bought new woofers. Last year the foam started to separate from the cones so I got out the rubber cement and fixed them...then dumped them and bought Athena AS-F2s.

thanks for the replies, I was just always wondering why :0

how do you like the F2s? I bought a pair of AS -B2's at futureshop on boxing day for 200$, they arent as great as all the people on epinions.com and audioreview.com say but they are very good for the price. Some people compared them to mission and tannoy - which I dont understand at ALL (I also disagree lol)

I bought my AR9's back in 1981 and the foam surrounds failed on all four bass drivers and the two larger midranges just last year. I replaced them all and the distributor said that the newer foam is immune to deterioration. If he's wrong I really don't care if they only last another 23 years. If you're unfamiliar with the AR9's they were a fantastic speaker and very highly reviewed (still sought after, in fact). The only problem with them is the size at five feet tall and weighing 120 pounds. Price had nothing to do with AR's use of foam since these giants are beautifully built and cost $1,800 the pair (back in '81.

By the way, without the foam surrounds the cones rattle against the frames during excursion since the foam is there to align the cones properly. Hearing the rattling in the background was the only way I knew the surrounds were bad. Broke my heart to pull the grills off and see that rotten foam.

In reply to:

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By the way, without the foam surrounds the cones rattle against the frames during excursion since the foam is there to align the cones properly. Hearing the rattling in the background was the only way I knew the surrounds were bad. Broke my heart to pull the grills off and see that rotten foam.

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Likewise with my Snell Acoustics Type K/II's. My heart hit the floor when I removed the grills and saw that deteriorated mess.

But they're all fixed up and good as new again now though.