I have a pair of BeoVox MS 150.2 speakers that I found on a city clean up day when I was 15 or so. The cabinets, crossover, mid and tweeter are all in great shape.  They are also missing the stands (was going to make my own out of welded square aluminum tubing) and they have no grills.  Both woofers is each cabinet also need replacing (surrounds are gone on 3 of the drivers, the 4th driver, an 8", is missing the cone, voice coil, and spider). I was just going to replace the drivers but want it to be as close to original as possible.

These were the two that I was looking at for the 8"...

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=290-314

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-310

and these are the two I was looking at for the 10"...

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=290-324

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-315

All of the above drivers would fit, however, after some researching it seems that Bang & Olufsen used the 8" as more of a mid-bass which means the Goldwood would probably be better since it goes to 7 kHz.  I was planning on using an oscilloscope and a full frequency signal to find out what the crossovers are set for, that way I can more appropriately choose a woofer.

Any advice or tips would be appreciated.

Thanks

Welcome to Beoworld !

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:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-1110

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.

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 :)

I have been searching for such a long time and these drivers are just so rare and hard to find.  I got these cabinets when I was 15, searched for months, coudn't find any replacements and gave up.  I'm now 25 and have been thinking about these things sitting for 10 years now and just got an area to put them in my house.

Also, my 8" driver that still has the cone isn't perfect either, the cone has a crease in it from getting bent (it's not really bad but still bothers me).

Jon, your cabinets look great, very impressive.

I'm still unsure of what I should do.  It would be so easy to just throw some new drivers in there but if the original does have that much of a "special sound" as you guys say then I don't want to do that either.  There is a very reputable speaker repair place a few cities away.  I was going to attempt this myself but if it is as low tolerance as Dillen says then I may not.  I'm sure if I bring the 10's they would resurround them and they could probably do something with my 8, Jon's and my spare basket.

Jon, I will PM you.

I agree that it's the owners speakers and they can do with them what they please, I'm not that grumpy.
You may have good skills and hands for refoam'ing or maybe, like me, just a good portion of luck, either or both is good, but I can assure
you that's far from common and I say that based on the things that are dropped off at my door.
Hardly a week goes by without some failed DIY-attempt in dire straits and I would always prefer to do a refoam job
rather than a repair to a failed refoam job. It's not that costly to get it done by an experienced guy and you will have someone to blame
if it doesn't go as planned.
I recently had a woofer on the bench where the alignment and surround was all fine but the owner had dropped old foam debris down
the inside of the coil and it had rubbed up and down.
The cone had become more or less stuck and it had made a complete mess. The owner then, in a desperate
attempt to smoothen things up a bit, added a little engine oil...
That one took some time and I politely told him that if he was looking to save money, he took a wrong turn.

Peerless make some wonderful woofers and I've used some myself where the originals could no longer be rescued or had been
replaced with some el-cheapo stuff.
Anyway we face it, if the owner is happy with the way the speakers sound, we can't ask for more.

Martin

Haha about adding engine oil, was that his attempt at a ferrofluid woofer?

The reputable speaker repair place located near me (mentioned in my last post) charges $40 a driver for surround replacement.  If I end up buying Jon's "locked" 8" (assuming they can even fix it) and have them transfer it to my 8" basket I would venture to bet it would be $100 at least.  After taxes I would probably be approaching $300 for the transfer and 4 surround replacements.  Also, if I buy aluminum or stainless square tubing and weld some stands that would be another $50 roughly.  The speakers would still be missing the grills and $350 + what Jon charges is a ton of money for me right now which brings up a question...how good do the MS150's sound?  I spose I should explain what I plan on doing with these.  I have an area in my basement where I want to set up a listening spot to sit back, relax and enjoy music.  It would just be the two MS150s with a powerful stereo amp (shooting for ~150W RMS at 8 ohms).

Just to help with locating the costs either way here:

My replacement 8" Peerless woofers were approx £100 inc. shipping here in the UK. They really are lovely units too :)

EDIT: BTW - that 150w amp you're looking for should be a Beomaster 8000 (the original partner for the MS150.2s)!

j0hnbarker:

EDIT: BTW - that 150w amp you're looking for should be a Beomaster 8000 (the original partner for the MS150.2s)!

I was waiting for that from you, j0hn!

burantek:

j0hnbarker:

EDIT: BTW - that 150w amp you're looking for should be a Beomaster 8000 (the original partner for the MS150.2s)!

I was waiting for that from you, j0hn!

You know I love this amp Jeff!! :)

Just wanted to give everyone an update…

I am going to re-surround both of my 10’s.  I noticed that the gap is very tight in these and if the cone is the slightest amount off the coil rubs.  Therefore, I am going to take these to a local reputable speaker repair shop and have them do it.  They will do both for $75 parts and labor.

Jon has been great and I am purchasing an 8” with a good surround but the magnet shifted and is pinching the voice coil (hopefully it is not damaged).  He is also going to send me an 8” cone/voice coil/spider assembly with some minimal spider damage.  To reiterate what I have for 8’s…I have one that just needs to be re-surrounded, cosmetically the cone has two creases in it but functionality is good.  My other 8” only has the basket and magnet.  I am planning on having the same speaker repair company use one of Jon’s cones/voice coil/spider assemblies and mount it in my good basket.

Sounds like a good plan !

Martin

Are the MS150's pretty power hungery?  I'm looking at a Rotel RA972 for powering them, it only does 60WPC but has a large toroidal transformer.  You can dowload the maual here for more information...

http://www.audiocircuit.com/Home-Audio/Rotel/RA-972

DKAudio:

Are the MS150's pretty power hungery?  I'm looking at a Rotel RA972 for powering them, it only does 60WPC but has a large toroidal transformer.  You can dowload the maual here for more information...

Yes.

You need one of these instead.

Despite what most people think, the smaller the amplifier, the greater the
risk of distortion and burned tweeters.
The MS150s are a bit hungry though not extremely so, and they will probably work
fine with a 60W amplifier and as long as you keep the sound clean, you will
not destroy anything.
Actually most speakers will handle a lot more power than their specs suggest as
long as the distortion is kept low.
Distortion contains a huge amount of power in harmonics and that is the dangerous
content in the signal.

Martin

Beovox MS150 has - like the other speakers in this serie - an effective overload protection if they get "to much", - so dont worry.

With these loudspeakers I would go for the Beomaster 6000 with 2 x 75 W (IHF). In different test at the time in 1981/82 it was in many ways better than Beomaster 8000.

arned:

Beovox MS150 has - like the other speakers in this serie - an effective overload protection if they get "to much", - so dont worry.

With these loudspeakers I would go for the Beomaster 6000 with 2 x 75 W (IHF). In different test at the time in 1981/82 it was in many ways better than Beomaster 8000.

I disagree. I've had both (still do, but my 6000 is non-operational for the time being...), and the 8000 is the far superior product. Much more dynamic and powerful.

Jon

Just to clarify, I used Peerless drivers in my S120 before I knew of Recone (who are not active at present sadly) - given what I know now, I would have had the originals reconed. The Peerless drivers were however very good.

Jon:

arned:

Beovox MS150 has - like the other speakers in this serie - an effective overload protection if they get "to much", - so dont worry.

With these loudspeakers I would go for the Beomaster 6000 with 2 x 75 W (IHF). In different test at the time in 1981/82 it was in many ways better than Beomaster 8000.

I disagree. I've had both (still do, but my 6000 is non-operational for the time being...), and the 8000 is the far superior product. Much more dynamic and powerful.

Jon

I've had both too. The 6000 is a great little amp that is very nice to listen to, but if you want to listen to music at serious volume in a big room, then you need a Beomaster 8000 and either some MS150.2s or some Beovox Pentas!