Advice for Beovox MS-150

Good evening everyone,

a short question... In the next days I'm going to replace the foam suspension on the woofers in my "new" Beovox MS-150. Of course I'll need to open them... How much should I worry about aging capacitors in the crossover? I don't like the idea of changing all of them "just to be sure". Can I check them on the circuit (without desoldering them) with the traditional multimeter method (resistance moving)? Or should I get an ESR Meter for that? Or can I be optimistic and hope that the will be still in good shape? :)

Thanks for your advice!

Marco

My advice would be to replace them all if you think you will replace any. The reason is that unlike resistors and inductors, capacitors have a limited lifespan. They degrade over time and need to be replaced to bring the circuit back to design spec. A reasonable estimate could be 15 years of age. I believe capacitors will even degrade on the shelf - they don't have to be in operation.

Hi,

Yes that's sound advice. I'd do that too! Enjoy your MS-150!

What are you driving them with?

If I have to change surrounds I always change the caps, its a 1/2 hour job, and as your speakers are old you will have to change them soon anyway 

Søren Mexico:

If I have to change surrounds I always change the caps, its a 1/2 hour job, and as your speakers are old you will have to change them soon anyway 

I have mixed feelings.

Generally, I'd say replace them.  But having spent way more time than a half an hour on refurbishing the crossover network of one pair of M70s, I have to say a second pair of M70s that I didn't refurbish sound the same.

On the other hand, replacing the capacitors in a pair of S45-2s fixed what I thought originally was a faulty midrange (phase link).

So..."let your ears decide" has become my mantra.

Does the MS-150 have any drivers that need the epoxy bead around the magnet?

Thanks for the advice! I'll be driving the MS-150 with a Beomaster 8000. (It works, but there is somoe slight noise on the speaker outputs and it tends to get quite hot - it definitely needs some recapping, as probably the Beogram 8000 also needs).

I must say, I am very tempted by a conservative approach - only changing things that are really out of specs by now. But maybe it doesn't make any sense to wait... But I'll nee some capacitor-checking-device for the Beomaster, so why not getting it right now and using it on the crossovers too...? Well, I should decide something! :)

Could you suggest me some good-quality capacitors that I may use for the crossovers and for the Beomaster? I have no idea of the "good" brands in this field, and I have no idea of a good on-line shop (in Europe, I live in Switzerland but I can get things delivered cheaply to Germany...).

Thanks, have a nice evening!

I went through a complete MS-150 restoration earlier this year.  It is documented on the forum here (on page 7).  You will find some pictures of the crossover and my recap.  I decided to stay with electrolytic caps on the recapping.  I bought the replacement set from Dillen (here on the forum).  The result came out quite well in my opinion, although I did not hear the MS-150 speakers prior to the recap (because the speakers needed so much work).  I also have a pair of S55 Beovox speakers that I refoamed.  On that pair I did use them for a while after a refoam before I recapped them. I actually recapped just one speaker first, then tried it together with the non-recapped speaker.   I can't say for certain that I could really tell a difference. So it if makes you feel better to recap while you have it apart then I would say do it.  The MS-150 is a big cabinet to take apart again.

-sonavor

Hello everyone!

So... I decided to do small steps and in the last days I refoamed both subwoofers in the MS150. I used the parts from GoodHifi and everything went quite well - withouth shimming, I managed centering them "by ear". They work great now (I hope no problem will happen in the next days!) and I'm happy that I can listen to these big loudspeakers.

What I hear is... Well, great potential, but something is not there yet. Absolutely wonderful high frequencies (basically the two dome drivers, from about 900 Hz up), ok-mids, well controlled bass but... Too light, it feels like the music is lacking energy in the lowest region. In general, coherence is a bit of a problem, and that makes the music sound a bit artificial (classical music, piano for example - I miss hte clear feeling that it is the same instrument trom top to bottom). I will get better as soon as the new foam plays some more hours, probably.

Of course I should check the crossovers (I'm getting an ESR meter to check the condition of the capacitors), but I would like to know what do you think about the old foam (it's still there and looks good on the 20 cm woofers). The subwoofers were also looking ok with the original foam, but one of them had bad distortion all the time, so I had to refoam both of them. This is ok now with the GoodHifi foam, but I noticed that the original one (or maybe the old-and-worn-out-one?) was much more flexible. So... Are the tno smoller woofers working out of spec because of the old foam still there? They have no distortion problems (checked with test tones). I don't like the idea of fixing something that is working, but maybe I should refoam them too?

Thanks for your help!

Marco

Don't forget that the vents are underneath the speakers! 

And err... we like pictures here!

chartz:

Don't forget that the vents are underneath the speakers! 

And err... we like pictures here!

Hi! The speakers are on the original stands... Is there anything to "tune" there?

I'll post pictures... Now everything is way to chaotic here, I need to organise a bit...

If you are planning to measure ESR on all the capacitors, in other words dismount them all,
you might just as well save the meter and replace the lot.

Martin

Dillen:

If you are planning to measure ESR on all the capacitors, in other words dismount them all,
you might just as well save the meter and replace the lot.

Hi Martin!

I understand what you mean... But I plan to experiment a bit with electronics in the future, and it made sense to buy the ESR meter (not so expensive, anyway - I hope I'll get it soon). It should make possible to know something about a capacitor even without desoldering it, and this would be a fast way to check some old devices. I still have to check if this kind of control will work on the MS-150 crossover, but I hope so... If all the values look good, maybe changing capacitors there will not be my first priority anymore (there is a Beomaster 8000 waiting for a bit of restoration...!). I'll let you know what happens!

Marco