Refoam or replace???

[Zero Cool]

I recently purchased a pair of Duntech Crown prince speakers that have been in storage for many years. the foam on the woofers is just at that point where the foam is rotten. they haven't fallen apart yet but you can tell one good bass note and they are toast!

SO, I have 2 options.

1- refoam. Now I can have Bill Watkins do the refoam work. he has some sort of special method to align the voice coils in the gap electrically without having to cut the dustcaps off. Dynaudio woofers don't have dustcaps anyway. I did some research and found a place that supposedly has the correct foam surround kits imported from germany. I believe this to be a good way to repair the 24W75 woofers as they are no longer available from Dynaudio.

However.

2- I did contact Duntech and Dynaudio will sell them custom replacement woofers with rubber surrounds instead of the foam. this is a more expensive option but in the long run they will never rot out again.



So those are my two options. There are advantages to both. 1- the stock woofers are matched and voiced to those cabinets. granted changing the foam surround may alter the drivers characteristics slightly? and the spiders could be weak anyway.

Going with new woofers has the advantage of rubber surrounds and possibly be a more advanced driver with better specs i don't know. But will they be as matched to the cabs and each other as the stock woofers?


Thoughts?


Zc

[flyingtele]

If all that is wrong with the drivers are the outer cone suspensions, no need to replace them. Personally I would either replace with the correct type foam suspensions, they might rot out again but most aftermarket replacement foam rings will last around 20 years or so depending on conditions.
Or another alternative is to use a replacement rubber surround, if its replacing a foam surround just make sure that it is thin and very flexible, and in most cases you will notice an improvement. Foam surrounds are in general more flexible, but the rubber has better energy storage characteristics.
Unless the magnet gap is very tight, there is no need to remove the dustcap. In most cases the cone will self align, and passing a low level signal anywhere between 10-30 Hz can be useful for hearing if its buzzing.
There are plenty of websites that sell both foam and rubber replacement rings for cheap, and I would advise this to be your best option. Provided your repair person does a good job, there is no reason it can't perform as new (depending on the condition of other components of course).

If you decide to replace the woofers then send me a PM as I would be happy to buy your old ones and pay for shipping

[fatmarley]

I wouldn't replace foam with rubber. Foam tends to be lighter than rubber and has better dampening properties.

[sreten]

Hi,

Foam vs. rubber I would say is not an real issue for 3 way bass units,
especially if the bass units have relatively heavy cones for their size
and relatively stiff spiders (high Mms, low Vas for the Fs.)

In a two way cone termination will affect the midrange response,
so you should always replace like with like, but 3 ways not so much.

http://www.gattiweb.com/images/dynaudio/24w75.pdf

Hmmm..... Qts of 0.84 before its even put in a cabinet
and Vas of 88L with a 33Hz Fs ..... Mms 18g ..... Tricky .....

I'd go with rubber, even though there might be differences,
rubber tends to be more lossy than foam in the bass end.

rgds, sreten.

[Original Burnedfingers]

The speakers were designed for drivers with foam suspension. The properties are not the same if changed with rubber surround speakers thus they will not perform/sound the same.

Change the foam surrounds

[Zero Cool]

Let me clarify that Duntech/DYNAUDIO has an updated version of the 24W75 driver with Rubber surrounds that i can buy. I am not just shopping parts express and choosing another driver, or just replacing the foam surround with rubber surrounds. I would be buying an upgraded version of the stock driver.

and consider this. the foam kit is an aftermarket foam kit the seller CLAIMS is the factory correct foam...but is it? Dynaudio does not sell foam kits nor do they refoam woofers. SO...it MIGHT be the same foam?? but who knows? it may not have the same properties.

And consider that the stock woofers are now 15-20 years old. the spiders could be weak at this age?? New woofers would be fresh!

So the choice is not so easy.

Zc

[Michael Chua]

If the cost of the foam kit and labor exceeds 1/3 of the updated 24W75, I would rather buy a new driver. With the old drivers, there's an inherent risk that other issues may need attention besides re-foaming.

[930Slant]

Zc,

I am in the same boat and was wondering which way you went. I was hoping to find a larger driver that would fit this application.

Thanks

[pdul]

Do some of you guys know where to buy 12 inch rubber surrounds/kits for wofers?

[lduarte1973]

see if this fits :

2 JBL 12" (12 inch) Foam Surround Kit | eBay