Crossover caps are bipolar (non polarized), dont buy any expensive film, foil or polypropylene caps just normal bipolar electrolytic caps, like

Søren Mexico wrote:

As for the frequencies you can check that with a good digital multimeter

I believe OP wants to know which cap belongs to which driver network in the crossover filter.

This is obvious in the schematic (see attached) as the crossovers are relatively simple. The plastic foil caps indeed do not suffer from aging, and the only caps that might benefit from refreshing are the electrolytics. Tired electrolytics usually manifest themselves in muddy treble due to increased ESR in high frequencies.

But, looking at the schematic, you can see that the treble network doesn't contain any electrolytics, they are all in the bass / mid region. Replacing them with fresh caps certainly won't make anything worse, but don't expect a dramatic improvement either, unless the old caps are downright broken.

For these reasons, I haven't bothered rebuilding the speaker parts of my Beolab 5000, but will probably do so if I ever take them down from the wall again - it's just two caps per speaker after all.

Hi all

That's great thanks!

I was looking or a schematic but was unable to locate one - so seeing this is great. I will replace them anyway now seeing as I am in the process of refurbishing them. I can purchase some polypropylene film caps for crossover use fairly cheaply from a manufacturer in the UK.

I notice on the schematic the second woofer is fed by an inductor - and indeed there is a large square transformer like inductor inside the speakers. I always thought the woofers shared the same frequency output from the crossovers, but having seen the inductor & the schematic it would appear the second woofer is supplied with a lower frequency range than the first?

Thanks again 🙂

machineage wrote:

I always thought the woofers shared the same frequency output from the crossovers, but having seen the inductor & the schematic it would appear the second woofer is supplied with a lower frequency range than the first?

Yes, the second woofer & coil are only present in Beovox/Lab 5000; the smaller 3000/4500 only has one woofer. At the lowest frequencies, both woofers are working and the "extra" woofer is gradually attenuated as the frequency gets higher.

If you decide to buy film caps to replace the electrolytics, keep an eye on their physical dimensions so that they will actually fit. Film caps are usually much larger, and there isn't that much space in the flat speaker cabinets.