Just a quick followup on this post;

If you're based in the US, foam surrounds of the correct size are stocked here - http://www.simplyspeakers.com - my 'already refoamed' set of these had their product in and it works well, perfect fit. The numbers quoted on their website are correct for the ITT midrange drivers in the Pentas.

Admittedly they don't manufacture, they're resellers, and the prices quoted are high at $24.95 per pair of foam rings with glue (clear not white) and shipping. I rang, explained that I'd need four kits per pair (and two of them); they proposed I'd probably not need eight tubes of glue, and produced a price that was honestly comparable with eBay prices - plus I got to speak with a real person over a phone call. I'm cautiously happy, if it all works I'll post follow up feedback here too.

So call them if you've needs for your Pentas. Ask for Tom.

I've just finished refoaming 16 Penta drivers with foamrings from GoodHifi and I don't have any problems with these. But to be honest, they could be a bit larger! Will tell them next time... 

My GoodHifi units were 4mm too small on the inside, 1.5mm too small on the outside, and the roll is 1.5mm too thick. They probably fit a 3" driver not an 8cm driver, which admittedly is close, and they're certainly not a fit for these ITT 8cm drivers. These are small dimensions but they count.

Could I have 'made' them fit? Sure, though the inner dimension already is a bit of an issue as gluing it down means going over the original glue line, meaning that the next refoam will involve tearing cone material - not ideal. The roll thickness and 'too small' size mean that if everything is glued down properly, there's pre-stress on the cone. Also not ideal, I want electric charge to move these cones, and not any stress in the cone to contribute. Any misalignment and there's a good chance of missing the keyway in the basket (the bit that's 'cutout'), then the driver won't seal and the cabinet design is compromised.

Appreciably it's a cheap component (the foam) though it contributes much.

They're lovely speakers, the Penta (not the most detailed in the midrange but lovely nonetheless) - poor-fitting foams will sound better than rotting foams, good foams will sound better than poor-fitting foams, 'older' electrical components in the signal path will limit things too... a game of perfection, no?

Simply speakers, thats what they do, I think Rich is buying there too, and you are right about not putting the small ones, stress on the surround must give distortion and less lifetime on the surrounds.

BTW put your location in your profile.

Updated! Thank you, Søren.

Søren Mexico wrote:

Simply speakers, thats what they do, I think Rich is buying there too, and you are right about not putting the small ones, stress on the surround must give distortion and less lifetime on the surrounds.

BTW put your location in your profile.

I've only ever used Woofer Repair.

OK, the SimplySpeakers stuff arrived today. There are some significant differences.

The SimplySpeakers foam is on the left, the GoodHifi foam on the right.

The roll on the GoodHifi foam is too large and the inner diameter too much. This creates a slight pre-stress on the cone and means you're gluing over the factory glue line - looks fine today, in 10 years when they're up for replacement these will tear the cone.

It's hard to see in this photo but the outer diameter of the SimplySpeakers kit is a touch bigger. It's a better fit in the basket.

Login to view imageHere are another two photos of the foams, placed on a Penta midrange (please excuse the poor edge colour deletion - essentially the SimplySpeakers foam, to the left, covers the original glue line on the cone and nothing more, and the roll starts just beyond it):

Login to view image

Glues in the kits are also different. The GoodHifi includes what looks like PVA but may not be. The glue in the SimplySpeakers kit is clear and somewhat flexible when dried. I had thought the application required more of a caulking compound, something that dries quite hard. Probably this requires more investigation as to which is better; I suspect neither are optimal though hopefully we've forum members that can help here.

The SimplySpeakers stuff is also a little 'thinner', feels more flexible. Likely we've no idea which are closer to the original foam though given the cone mass on these drivers is significant for their size, it's probably not going to make a great difference either.

I'll be installing the SimplySpeakers kit on one pair and seeing how it goes, then I'll decide on the rest. If someone local wants to buy what's left (foam rings), I'll sell.

I used Good Hifi to re-foam my Pentas, and it went great, however I used the rubber rings, not the foam ones.

Maybe there is a slight difference in both dimensions, or could it be that they simply sent you the wrong rings ?

Christophe wrote:

I used Good Hifi to re-foam my Pentas, and it went great, however I used the rubber rings, not the foam ones.

Maybe there is a slight difference in both dimensions, or could it be that they simply sent you the wrong rings ?

Not sure. I did explain the issues I had to the GoodHifi staff and they seemed OK with the dimensions. I didn't, I've ordered something else, I'm happier. I should stress that short of sending a reworked set of rings, they did do everything possible. When the initial order was lost in the mail, they send a second at no charge. The only issue I've got is fitment. Customer service has been good.

I'd have been reluctant to refoam with rubber - this said I've never heard Pentas with rubber rings. Have you been able to compare the sound to a pair with foam rings? You'll probably have the last laugh in 10 years when these need to be redone again!