Foam vs rubber speaker surrounds question

Kuja

Active Member
Hello everybody,

For a long time I wanted to pair my Acoustic Research AR-90s with their smallest brothers AR-18s.

Unfortunately I coludn't find any for a long time.

I had to settle with a minty pair of AR-17s that I have found couple of weeks ago. :)


On The Classic Speaker Pages forum, I've read many enthusisatic posts describing great bass coming out of small ARs like AR4x, AR7, AR18, etc.

AR-17 have similar drivers (or same as in AR-18), same one cap crossover, but their boxes are larger, so they should have even more bass extension.


When I hooked them up I was kind of dissapointed.
Their sound is quite thin.

Their sound is very transparent and highly detailed, but with some recordings it can get fatiguing.

There is noticeable lack of bass.

When I use switch on the back, tweeter output is reduced but sound gets dull and life is sucked out from the music.

I'm not sure if my expectations were too high for a speaker system of that size, or there is something wrong with them.





I suspect that the problem might be in woofer surrounds.

Original foam surrounds that rotted away due to their age, were replaced with rubber ones by original owner.

Original AR foam surrounds were very thin and soft.

Rubber surrounds that are on my AR17s are much thinner and softer than modern foam surrounds that are available to me locally.
Modern foam is quite thick and it is much harder than the orignal.

Are there some other important properties inheritent to foam surrounds?

Will I get better bass extension if I switch to foam,
no matter if it is thicker and harder than rubber in my present non-original surrounds?




Thanks in advance,

Aleksandar
 
The usage of foam over rubber & vice versa is not a question of cost but what the designer was trying to achieve. Usually a foam rubber surround will contribute to better efficiency of the driver it was mounted to.
 
What environment are they in ? even the best little speakers get lost in a big room. If the rubber is soft and not restricting the cone movement I would not expect much difference with a change to foam.
 
Do what was originally there. The designers did it for a reason.
The usage of foam over rubber & vice versa is not a question of cost but what the designer was trying to achieve. Usually a foam rubber surround will contribute to better efficiency of the driver it was mounted to.

I know this.

If I could buy foam surrounds that are close to originals, it would be no-brainer.

BUT... the rubber surround that I presently have is much thinner and softer than any foam surround that I can get in local stores.

It is made of rubber, but its compliance is much closer to the original than those new thick foam surrounds.

Are there some other important aspects inheritent to foam surrounds that would make them more suitable for sealed boxes than ANY rubber surround, no matter how thin and soft?

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What environment are they in ? even the best little speakers get lost in a big room. If the rubber is soft and not restricting the cone movement I would not expect much difference with a change to foam.

They are in a space that roughly has 3000 cubic feets, but it is very wide and shallow. Speakers are positioned on the longer side of the room.
Distance beetween listening position and speakers is 8-9 feet. They are set with their backs close against the wall as intended by their designers.

Pages from the original brochure:

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