calling all RS2 owners- what about the rear foam?

[jonemw]

I just got a very nice set of RS2 2 weeks ago. Listening tests and impressions have been great and fun. I got these because all parts were intact. Front grills with emblems, rear grills and drivers original and in fine shape. Even the rear precision cut foam is there in fine shape.
My question is this rear foam. how many RS2 owners have this or use it? Obviously Infinity designed the foam to be there, yet I expect many have crumbled to dust long ago. Would appreciate thought and comments on use without, or sonic effects plus or minus. I know many folks run without rear grills also, and see open backs in pics, but the foam is original????, and I am a nut for originality.
Also, will post pics of them when I get a chance, and now have a very nice clean set of RS3A for sale....

 

[AZDean]

I bought a pair earlier this year. They didn't have the foam. I have mine so that the mid/high panels are about 4 ft from the wall behind them. I'm not such a stickler for original condition, because I think some tweaks can make them sound better than original. See my other posts for what I did. If mine had the foam I would listen both ways and let the sound and placement tell me if I should use it. I would think if your forced to keep them closer to the back well, you would use the foam. I wouldn't be surprised if Infinity added the foam in the middle of the production run.

 

[tubed]

The foam is original to my RSII so I use it as is.
Plus it sounds superb.

 

[slimpikkins]

Sad to say my foam is long gone. Is it close cell foam? Any chance for a pic with a coin on it for cell size comparison? Maybe they can be made if the right foam can be sourced.

 

[srb02]

I too, just got my speakers 2 weeks ago. Yes, the rear grills and foam is intact. Tonight I would be happy to remove one and post some pics w/ a ruler for size comparisons.
Mine are right at the "crumble" stage, so a replacement is on my radar. I would probably start at "the foam factory", they helped me get the foam for my RSIIIa's.
and yes Slim, I believe it's closed cell.
I spent the weekend getting acquainted w/ them, what amp they like, placement in the cave, so forth, and this much I can say: TUBES....!!!!!

Stu

 

[goodolpg]

I am confused but that's nothing new.
What RS 2 are you talking about?
Or is it RS II or RS IIa/b?

I have RS II's and I never knew about any foam on the back and only one picture shows up on Google images and it appears to be a DIY application.

Could someone post pics of the RS 2 (II?) in question with pics of the foam?
Thanks.

 

[srb02]

The one down-fall of Infinity, reusing model names and designations.
Reference Standard ii's.
( http://www.audiokarma.org/forums/index.php?threads/reference-standard-ii.735836)

On the rear of the top section there is a fitted foam piece, around the magnets, under the little grill cover.
I''l post pics tonight.

Stu

 

[tubed]

 

[srb02]

here we go:
I think they are open cell, after all, but a high cell count. Real dense.
Stu

 

[goodolpg]

Thanks for the pictures tubed and srb02.
Same model I have and mine do have the rear grilles but no foam. I never knew they were made with foam on the back side and pictures of it seem rare if nonexistent.
Seems like it would affect the dipole dispersion of the midranges but maybe that was Infinitys intent?
I assume those are factory foams you both posted? I ask because they look like they were factory made/punched because of the perfect circle cutouts.
I tried making some round foam plugs for a pair of Marantz HD 66 that had the missing vari-q plugs and my attempt at cutting perfect circles in foam ended up not even close.

 

[jonemw]

^ This was exactly my reason for this thread. I always thought Dipole operation was designed for both Mids and the emit. however, I had seen and knew about the factory foam insert in the back, and was trying to get a handle on Infinity's design intent. The emit on the back clear from the foam as there is a cut around it. I think the foam is closed cell, one side of it is definitely solid in appearance. Pouring water on it will tell. This thread applies only to the original RS2 , not the 2 A or B

 

[goodolpg]

This is certainly interesting.
Here's part of an Infinity RS II brochure (from Klaus' Infinity classics website) http://www.infinity-classics.de/mod...6/Reference-Standard-II/RS_II_Brochure_02.jpg

No foam shown in the rear view, and it specifically states "The three five inch midrange drivers are dipoled by leaving their backs open, allowing the back wave to complete the point source radiation pattern."

 

[tubed]

The foam is factory, open cell but rather dense with an embossed rather closed cell back, at least that's how it looks.
The dipole effect is not eliminated by any means though probably altered for desired effect.
My bet, the foam was left off the back for photogenic display purpose on the brochures.

 

[slimpikkins]

Thanks for the pics and info guys. That foam looks like the same they used around the emims and emits on the rs2.5 and 4.5. Maybe an insert could be made that fits n the rear grill. That way it could be removed if the speakers are way out from the wall in a nice big room.
Jim

 

[srb02]

i'll try several thing tonight. Mine currently are placed w/ their backs to the garage door, about 5 foot out. W/ the foams in place, already sound good, I'll try with out foam, and see how much bounce-back/echo I get.
the other thing I can try is: I still have 1/2 sheet of the foam I fixed my RSIIIa's front baffles with. I will cut several pieces and just tuck into the grill as Slim suggested, as a substitute maybe.

Stu

 

[goodolpg]

I've learned something from this thread, never knew about that foam.
That's why I like this place, helpful people and a good source for information.

 

[jonemw]

Glad we could all be of service, I think the discussion allowed everybody to learn something at least....

 

[srb02]

When moved back within three feet of the door (hard surface), without the foams in place they (upper ranges) get muddy, soundstage disappears, and there is a pronounced echo/cathedral effect. obviously the echo has messed w/ our sound.
Conversely, when they are removed at 6 feet away, WOW that adds another dimension, mids are fuller, rounder, more complete.

Trouble w/ these speakers: no Wife Acceptance Factor. They'll never make it into the house.

"THE CAVE", so you can get an idea, and my placement where they sound the best.
I have Sears equipment dollies I am ultimately setting them in so they can be wheeled out to use, and back to a corner when not used.


my two cents Stu

 

[jtucker]

I had RS IIs bought new. They did not have any foam like you show. Just a back grill cover.

 

[Seppo]

I bought mine from the original owner. No foams, and he did not mention them missing. I got an impression from some earlier threads here on AK that the foam was introduced a bit later in the production.

Anyways, I like mine a lot in any case...