The usual C/CX foam vs rubber question…

20 replies
matador
Offline
matador
BronzeModerator
Posted July 22, 2021 at 17:11 GMT
#2157508

Hi alls,

You may find my title a little bit ironic, no offense intended: I know they are many threads on the topic but I've honestly not found a clear answer, not to mention most threads are olds.

I'm in the process of refoaming a pair of C30 speakers. So after looking around for surrounds It seems that two brands raise interest from beoworlders: Goodhifi and Audiofriends. There is an old thread on the Archived Forum where good hifi is pointed as being better, up to the point of the guy from Audiofriend did chime in.
But there is also a recent thread where people is wondering about AF being still in business with answer from a respected member of the forum comforting the OP. Prices are the same more or less.

Then there is the Foam or Rubber point. The answer I've found are or passionate (it was foam then it must be foam) or size dependent. I've also recently come across a thread where a woofer of a C30 or C40 was shown with a surround that did look like rubber to me and was told as original legit by Dillen. To be honest I believe that a speaker refoamed (by me) will loose part of his qualities, I expect that. So if changes will be marginal I would go with the easier to install and longer to last. 

Then I could cross the question like AF Foam vs GHiFi Foam.

Right now and wouldn't talk about shimming or not. one step at the time…

Thanks to everyone helping.

Location: Paris France

DI
Offline
Dillen
BronzeModeratorFounder
Posted July 22, 2021 at 18:23 GMT
#2157509

C and CX models use different drivers with different surrounds.
The C surrounds look a little like rubber, but are in fact a kind of coated foam. They tend to last longer than foam, - but not forever.

For CX50/CX100 I would always use foam.
After losening up a little, the new foam surrounds will end up performing very close to the original surrounds,
whereas the T/S parameters if using rubber surrounds will remain far away.

I would also use foam for the C models.

Martin

matador
Offline
matador
BronzeModerator
Posted July 22, 2021 at 18:35 GMT
#2157510

Thank you Martin, will do with foam then.
Any supplier you would recommend, between those two or others? 

Dillen wrote:
The C surrounds look a little like rubber, but are in fact a kind of coated foam. They tend to last longer than foam, - but not forever.

When decomposing they do look like foam again!

 

Location: Paris France

Beobuddy
Offline
Beobuddy
BronzeFounder
Posted July 23, 2021 at 09:23 GMT
#2157511

Audiofriends is still in business. Very knowledgeable man. 

Always trying to reproduce surrounds as close as possible to the original, when it comes to dimensions, material, thickness of it and response.

Location: Utrecht

Quite a challenge to achieve "Less is More" while having the Beovirus.
matador
Offline
matador
BronzeModerator
Posted August 9, 2021 at 15:55 GMT
#2157512

Hi guys,

Refoaming completed! I would not say it was difficult but I would not say it was easy either. It's always tricky to manipulate those things when you think the precision you believe it's involve in their crafting. Honestly, I did it because it was a small driver and that was try or trash, but I think I would not do it on a bigger driver.

Original driver.
 

Work in progress.
 

Ready to re-foam.
 

Kit delivered.
 

Half glued.
 

Ready to go!
 

 

Unfortunately I find them sounding quite average. Maybe a poor repair, maybe by design (I believe they're different design than C40 and obviously CX's) or maybe just because they're competing with a pair of S45-2 as front. 

But they're beautiful!

Location: Paris France

matador
Offline
matador
BronzeModerator
Posted August 11, 2021 at 13:35 GMT
#2157513

Hi,

Don't wanna do any bad taste sorcery but I wonder if "theoretically", sealing the backside port could improve the bass rendition?

I dont understand acoustics and this why I ask. Also seeing that following installment of that speaker were sealed.

Thank you.

 

Location: Paris France

DI
Offline
Dillen
BronzeModeratorFounder
Posted August 11, 2021 at 14:23 GMT
#2157514

The woofer has a ventilated magnet on purpose.

In Beovox CX100 the woofer is ventilated and the midrange is closed (they are not two identical drivers, as many people seem to think).

Martin

matador
Offline
matador
BronzeModerator
Posted August 11, 2021 at 14:39 GMT
#2157515

Dillen wrote:
they are not two identical drivers

Yes distinguished by the hole in the back right,

Thank you Martin, I will not touch them then and carry on with their "flat" rendering.

Location: Paris France

KE
Offline
keepitcomplicated
Bronze
Posted August 12, 2021 at 15:30 GMT
#2157516

Isn't the hole on the back just to wall mount them?

noahwmack
Offline
noahwmack
Bronze
Posted August 12, 2021 at 15:41 GMT
#2157517

I think they are talking about ventilation on the back of the driver, not the speaker cabinet. There are 2 holes on the back of the cabinet, one for the din input and one for wall mounting. 

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