Hi

I'm new to this forum. I got a pair of white Beovox mc120.2's, and there is a huge lack of bass in both speakers. The original drivers have been replaced with cheap 8 inch woofers (ohm), but i also got the original ones (with foam roat). I replaced the driver in one of the speakers with an old one, but there is still a lack of bass. None of the drivers are blown. Tried them on 3 different amps (2 Nads and a Tandberg), but it seems to be a speakerproblem. Has anyone experienced this with such speakers and/or got a possible solution?

I do also need re-foaming kit if anyone knows where i could get one.

PS sorry for my bad english

best regards

I have a pair of MC120.2's too and find them wonderful speakers. Obviously the incorrect woofers will be doing you no favours. Either refoam the originals (not too difficult) or you can buy new peerless drivers for them (800667 or something similar - have a search on here for the correct peerless number). I would recommend changing the capacitors in the cross over as that will make a difference too.

When working well they are superb speakers.

That was what i thought too, my plan is to refoam the originals. Do you know where i can find such a set for re-foaming and the capacitors i need? Looking forward to test them!

Even if the foam are rotten on the original drivers, and even if i try other 8-inch drivers in the speakers, there should be some amount of bass. I wonder if the crossovers are faulty. Anyone who has experienced something like this on similar speakers and solved it with a change of capacitors?

johansens:

Even if the foam are rotten on the original drivers, and even if i try other 8-inch drivers in the speakers, there should be some amount of bass. I wonder if the crossovers are faulty. Anyone who has experienced something like this on similar speakers and solved it with a change of capacitors?

Caps won't do that much either way for bass, since they are mostly involved in the mid and treble networks. However, there's a remote possibility that both of the crossovers have a blown coil or resistor. Do the bass drivers move at all, this should be obvious to see/feel even at low volume?

Ok. The bass drivers do move, and it increases with the volume. Problem is that mid/treble are very dominant compared to the bass. Both type of bassdrivers are acting the same way. I have to set bass-settings to max on all the different amp's i've tried, just to aquire a somewhat balanced output from the 3 drivers. Mid/treble seems to be working well. From what i have read on this forum, these speakers should be more than powerful enough in the bass-range.

The service manual is sadly lacking from the site (or I just cannot find it), so I don't know how the crossover looks like. However, I guess you could just take a look at them; if there are burnt resistors, those should be pretty obvious.

There is also the possibility that the "new" drivers are totally unsuitable for the job and therefore sound weak. And if the surrounds have rotted through on the original ones, they will not sound good either, as the bass frequencies will just short circuit round the cone as if they weren't installed in an enclosure at all (and you may damage the voice coils trying to play them too loud).

In short, you can't really say much about the speakers with incorrect or broken drivers!

tournedos:

In short, you can't really say much about the speakers with incorrect or broken drivers!

Absolutely!

Refoam the originals and put them back in.

Also, take a look over here.

P.S. Welcome to BeoWorld!

The service manual for the S120 is on site - look under the MS150. I don't think I have the MC120.2 and don't know the changes.

Oh yes, I suppose those would be quite similar. In S120, there's only one coil in series with the woofer (and an RC network in parallel, but a fault in there would probably only make the bass louder). So if that coil had burned, there would be no signal at all to the bass driver.

So - if the overload protector has been reset (pressed in) and it is not oxidized - there can't really be much else of a problem than the drivers themselves. And I stress that if the originals have a lot of holes in the surrounds, they simply cannot create much sound pressure at low frequencies!

I suspect the cheap drivers to be unsuitable for the job and therefore sound weak, but I expect somewhat difference in volume compared to the original ones.

To me, nothing seems to be damaged on the crossovers. Overload protector is pressed in, can't see any oxide on it. 

One thing I could mention is that I'm not testing this with a B&O amp, I do do only have some old nad-amps and maybe the bass would be better with suitable B&O equipment?  

As you can see, the foaming is completely damaged, so I'm not expecting any good bass out of them before re-foamed. 

First step: Fix original woofers! Where do i buy the re-foaming set?

Thanks in advance

For example Good Hifi from the Netherlands can sell you the surrounds (I see they have just opened a proper webshop). Or, if you have never done that work before, these may not be the best pair to practise on - you might want to send the drivers to Denmark to Martin (Dillen on site) for a guaranteed good job.

I can't see anything obviously wrong with the crossovers either. Those look like a very nice pair of speakers, well worth getting back to spec!

Welcome to Beoworld Oyvind
Your 120s look lovely in white, thanks for the photo's.
I refoamed mine recently, and am extremely pleased with the result, and use them daily.
Good Hifi has a good name, so I would agree with getting foams from him.
HERE is a photo'thread I made showing my first attempt at refoaming my 120s.

Andy T.

My Beovox S120 are also white. This is very rare so keep them original and in as good condition as you can.

Foam rot yes so Dillen did the service and they sound wonderfull.

Its a complex job if you have no experience doing it before.

If you send them to Dillen they will be perfect when you recive them.

Thanks for all feedback!

Unbelievable, cabinets are still like new.

Jandyt, your thread was exciting to read! I'm considering doing this job myself, mostly because I'm on low budget, but also because it had been fun to re-foam a set of speakers myself. Only question is where to get a set of new dust-caps, if I bother changing them. Do i need any special shims made for these woofers to center them, or could i use something from my own garage?

Eventually, who is Dillen and how do I get in touch with him?

I acquired a pair of MC120.2s with both woofers rotten, and one of the voice coils fried. I wasn't willing to look for a spare unit and then go to the hassle of refoaming, so I went and found some new Peerless woofers that matched the specs of the originals. You might find this thread interesting. I can certainly vouch for the replacement units - a straight swap and very good build quality.

johansens:

Eventually, who is Dillen and how do I get in touch with him?

 

Dillen is a user and moderator on this forum. He lives in Denmark  and is an invaluable source of advice, service and spare parts for vintage B&O.

You can contact him by sending him a personal message on this site.

The thought has crossed my mind, but I'm keen on fixing the original ones since the voice coil seems to be ok on both.

Peerless drivers are also a bit expensive, those cost around 100 euro here i norway (for one). I'm on a low budget and if I'm ending up spending a bit of money on these speakers, I think I will be re-foaming the originals with help from a pro.

Yep - my new Peerless units were £50 each, so that sounds about right at 100 Euros.

The speakers were given to me for free, so I saw it as a good investment, as two new rings plus glue was approx £20 anyway...

I understand your choice of solution, especially because the burned voice-coil. Your result do look (and probably sound) very delicate.

I also consider to do this job myself, in an amature way, just ordering what i need from the Netherlands. I had to pay 800nkr for mine, roughly around 100 euro.

Woofers are now refoamed and installed properly in the speakers. Tested them today and the lack of bass is still prominent. Looks like the drivers did not affect the result.  I have to set bass-settings to max to aquire a somewhat balanced output from the 3 drivers. From what i have read on this forum, these speakers should have more than enough bass. I have been testing them with a couple of old amps/receivers (Nad 3100PE and a Beomaster 4400), but the change of amp did not affect the results.

Anyone got any suggestions on what the problem could be? 

Thanks in advance!

I have no experince on these speakers nor have I studied the schematics of the crossover but this resistor in one of your photos looks a bit strange (like it had some sort of foam on it); perhaps worth checking further?

Does anyone know if this looks like a broken resistor? Both speakers are playing bass in the accurate same way. Those with similar speakers out there, are yours a bit lean in the bass-tones? 

That stuff on the resistor looks more like foamed & dried protective lacquer to me, and that would've been there from the factory.

I don't know what your personal perception of "lean bass" means or if I would hear it the same, but the newly refoamed drivers will need some playing before they will sound right. Give them a little use and see how they develop.

Also, have you tried themwith a different Beomaster?  Maybe the fault is not in the speakers.
Mine don't lack bass. I have them connected to a Beomaster 7000.