[cbarth]

Hi guys,

I bought a pair of old Dali AXS8000 some time ago. They are fitted with Vifa C20WJ-66-08 woofers with foam surround. The foam surrounds looks to be original and in very good condition.

The problem is the bass, which is really really bad. I have Dali 104 and Qln 929 speakers using Vifa C17, and they are lightyears ahead of them in the bass department.

I had a suspicion that the woofers were out of spec, and got them measured. They are all consistent with a Qts of 0,9 – 1.0 and fs 58 – 60 Hz.

I just shook my head and stuffed the speakers far away in the back of my garage, thinking both the Vifa engineers and Dali engineers must have had a real drinking party while designing this speaker.

I would have thought they would have fs 35-40Hz and Qts 0,3-0,4.
But then while surfing the net I came to read this:

"I recently refoamed a Model EIII (Vifa M21WN-07) woofer with foam from Audio Note (AN) in the UK.
WT2 testing of the recent refoam compared to a prior refoam with one of my 'standard' 8 inch foams showed the AN foam's results very close to original compared to st'd foam which were not.

The AN foams are very expensive at 15 lbs sterling each plus shipping. However, I don't know of another source of similar quality foam, let alone a lower price. The standard foam resonant frequency (Fs) was 39 hz vs 26 for the AN foam that was yet to be broken in. Qts for AN = 0.23 vs 0.53 for st'd foam.

The roll measures 11/16 wide on top which is quite wide for an 8 inch foam. The general feel of the foam is quite supple. It's easy to tell it will yield a very low resonant frequency for its size.

IMO, the bottom line is if you want to maintain the performance of your Snell speaker which utilizes the Vifa woofer, you should consider the AN foams. Visit their web site's support page for contact information.

Also IMO, the Snell Model E speakers are very worthy of the AN foams."

And then it hit me, that maybe the foam surrounds could be out of spec. Do you guys have any experience with this kind of problem before?

I know that the speakers had been stored and not used for several years when I bought them...

Cbarth

[Hank]

I can't help you with those drivers, but I did re-foam my Original Advent woofers a few years ago.  Inexpensive foam (forgot the source), easy to do and worked perfectly.
Good luck to you.

[SteveFord]

I can't be of much help other than to suggest a kit from Parts-Express.  I did some JBLs years ago and it was easy enough to do.

[Doublej]

Rub your fingers lightly on the foam surround. If bits of foam start coming off you definitely need to replace the surrounds.

Depending upon where you live there may be a repair shop that can do it for you if you don't want to do it yourself. You can send them off to be done but the shipping can be a expensive for four eight inch woofers.

[dB Cooper]

I did a friend's pair of original Advents years back with a Parts Express kit. The instructions called for removing the dust cap in order to immobilize the voice coil while replacing the surround, and replacing it with a significantly larger dust cap which was supplied with the kit. It seems to me that this can't help but change the 'voicing' of the speaker, which may or may not be a good thing. Maybe Hank would know more about this.

The butyl rubber surrounds on my 40+ yo Dynaco A25's are still in working condition FWIW.