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The same driver is used in some of the other larger Beovox models, where it plays the role
of woofer, like Beovox S120 / M150 / M150.2 / MC 120.2 / MS150 so I suggest you find a
good used original to replace the damaged one and then send them all
in for refoam'ing.
There's nothing like the original woofers and matching all the Thiele/Small parameters with
modern drivers will be very difficult.
I seem to remember that a Beoworld member had one of these for sale about a year or so ago.

If you decide to buy new woofers, I would be interested in buying the old
original ones with the bad foam surround.

Martin

I definitely thought about that and agree that would be the best route to take.  3 of the drivers (both 10's and one 8) just need to be refoamed (surround replaced).  Getting an 8" that has everything intact but may just need a surround will be very tough and I imagine not cheap (cost is an issue).  I do have the basket and magnet for the 8" though, but again, I imagine it would be very difficult to get the cone/spider/coil assembly for a 25 year old driver.  Maybe someone will see this post and I'll get lucky...

I even contacted Bang & Olufsen directly and they had no information on the crossover or Thiele/Small of the drivers.

I have a pair of MS150's that I've had to reconstruct, thanks to UPS ruining them in shipping.

Believe me, the 8" midbass is a very unique driver. You won't find a proper replacement for it. Go original.

I've never tried anything by Goldwood, so I guess I shouldn't say they are junk, but that would be my first inclination toward them.

The Dayton drivers you have linked are so-so budget drivers, but not really all that great either. Definitely not befitting B&O's (arguably) best passive loudspeaker.

That 8" driver has a nice 3" voice coil, and a full length copper sleeve over the pole piece. Very reminiscent of a Dynaudio or Scan-Speak driver with a big VC. Really, the only thing it lacks is venting under the spider, but it's movement is limited by the cardboard tube enclosure and the 1st order electrical high pass X-over network, so I don't think it'd be much of an issue.

I used these for replacing the 10" "sub"woofers:

link

B&O states the MS150 enclosure volume as 64 liters, so I modeled for 55 liters to account for the volume taken up by the drivers, tube, and mid/high enclosure and X-over, and then tuned to 33Hz (I decided to use a 3" flared port in lieu of the OEM port, which you will have to do anyway if you use this driver, as the magnet structure is just deep enough to not clear the original 3 3/4" toilet paper roll port).

With the X-over network, this gave a response just about as stated by B&O, -8dB at 30Hz, and -4dB at 48Hz.

As far as the X-over goes, don't believe what Beocentral says. There were significant changes between original and ".2" models. I believe the midbass and subwoofers stayed the same, however, the midrange drivers definitely changed from a clear polymer to a coated fabric type, and I believe the tweeters changed from a SEAS unit, to a Vifa D25 unit.

Also, you can see that the baffle surrounding the midrange driver is moulded differently in the ".2" models. I theorize that B&O lowered the X-over point a bit, widening the passband of the filler driver (dome mid), and changed the shape of the short horn to accommodate that. 

For the MS150, I believe the electrical slopes are 2nd order on all the drivers except the high-pass for 8" midbass, which is 1st order, and the X-over points are 150, 800, and 3000 Hz, respectively. I'm going on memory when I say this, so hopefully I'm remembering correctly.

If you are a silver or gold member, you can get access to service manuals for free, I think.

In short, the 8" midbass drivers are going to be virtually impossible to replace. Refoam the one you have and look for another. I have one I can sell to you if you'd like. It needs to be reCONEed, as the magnet has gotten off-center in shipping. Partsexpress already told me they could do this, but I haven't needed it or gotten around to it as of yet. I believe they wanted around $50-60, plus shipping.

Martin probably wouldn't agree with me, but I think the Peerless drivers I linked to replace the OEM's just fine. They sound a tad cleaner to me as well. BUT, if all your 10"'s need is refoaming, and not reconing, then do that. Don't bother buying anything else.

Hope that helps.😁

Jon

Thanks for all the great information...My 10's only need new surrounds so I will just do that.  Does anybody have a link to get new surrounds?  Every now and then Ebay will have kits for the MS150 drivers but not currently.

How much would you want for the 8" and do you think the voice coil is ruined when the magnet shifted and pinched it?  Even so, my concern is if it need to be reconed it will not match the one I currently have.  I assume they would re-use the voice coil and just put a new cone on it?  My 8" magnet is perfectly centered, I wonder if I could use my basket and magnet and just use your voice coil and cone?

I believe the vendor on Ebay is "Good Hifi". I've bought surrounds for the 8" drivers from him, and they fit perfectly. I didn't find it necessary to remove the dust cap and use shims. No scraping at all through the voice coil's range of travel on either.

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Sorry - quick camera phone pics.

A damaged voice coil is definitely possible, although I really don't think so. If you were to buy it, I would refund your money if the VC were damaged.

However, you raise a good point about both drivers matching. I'm not sure how Partsexpress goes about their recones, and I know there's no specific kit for this driver, so they'd have to use the closest parts they could match to. Depending on how close they were, it might make enough difference in the frequency response or sensitivity to be audibly different from the one you have.

Probably your best bet is just what Martin said - to find a pair of speakers (maybe really beat up ones with known good drivers) that use these drivers, and salvage the woofers out of them. Then just refoam them. When I was going through all this, Martin had one good one that he was going to sell to me, and then I happened to stumble on a good pair of them, so maybe he still has one he'd sell to you?? Not sure. Anyway, if you can't find a known good one, I have one (actually two) that, as I said, need reconing. I wouldn't ask alot for them, but I don't want to sit here and try to sell you something on the forum, so if you decide you want it, PM me and we'll talk. But yeah, if you find a good one, or a good pair, that would be the easier route.

Jon

I also meant (and forgot) to say that you could just find his store on Ebay and Email him about the 10" surrounds. I'd bet that he has some, even though he may not have any listed.

Jon

P.S. - Haha, I typed a whole other original reply, but got a "pending moderator" message when I clicked "post", even though this afterthought message posted right away! Weird. Anyway, I have another reply, but it will be delayed.😂

You're right.
I don't agree on neither the fit of the surrounds (as I wrote in details elsewhere I got two different 10-inch surrounds that both were guaranteed
to fit but none of them did) nor the skipping of aligning and re-shim'ing.
It is important that everything is aligned, especially for powerful drivers like these.
But that's just the opinion and experience of a grumpy old man, that was looking at a pair of large Bose (stage-) woofers yesterday
that were not aligned when refoam'ed by the DIY-owner and now one of them has the outer 2-inch portion of the entire cone
circumference broken clean off due to uneven load to the cone material. That makes two sets of failed DIY-attempts ending up here
this week. The other set being four RL140's where one woofer is now frozen solid and it's mate has turned quiet - and it's only tuesday morning...

Martin

Well Martin, I may not agree completely with you, but you know I bow to you as the B&O master. And in my experience, grumpy old men who've done something for years and years usually know best when it comes to that thing.😕

Anyway, maybe I've just lucked out on the drivers I've refoamed so far, but it's never been an issue for me.😛 Tested with a 20 cycle tone and no high pass filter, my 8"'ers don't make any scraping noise. I made sure before I installed them.

Good Hifi's surrounds fit perfectly for me. But I've never tried their 10" surrounds, so you would be the one to know on that one.

Jon

Just to add my twopenneth worth to the debate here:

A couple of years ago I was given some cosmetically mint MC120.2s, but both woofers needed refoaming and one of the voice coils was dead. I was faced with the choice of tracking down another woofer to refoam along with my 'good' one, or simply replacing the woofers with brand new Peerless replacements. I heard from Beoworld member Peter that he had taken his S120s (I think) to a respectable recone centre here in the UK, and they had swapped in some new Peerless units. With that kind of endorsement I went and got some new 8" Peerless woofers from Wilmslow Audio here in the UK. I have to say that I am delighted with the quality and fit of the woofer and its rubber (i.e. non-perishable in the future surround). Whether the complete MC120.2 package has been degraded by my adding in newer components in neither here not there as far as I am concerned, as to my ears at least, they sound great :)