Very Newbie Question - Is this a electrolytic capacitor?

[zBuff]

Hi guys, I just taking apart some (around 1970s) old speakers I have and decided to replace the capacitors.

These are what I found that were currently inside of them. I assume that they put non-polar on them must be they are electrolytic capacitors? Are unicon any good? does it matter too much what a replace them with? The speakers themselves I don't believe are that high quality they have Plessey drivers.

So how can I normally tell if a cap is an electrolytic type or not?

Also in taking apart the said speakers and looking at the crossovers I noticed the 2 inductors in the circuit are parallel with one another would it make much different changing the axis of one of them so the magnetic fields don't affect each other?

Please excuse me for my complete noobness

[imperfectcircle]

Yes those are electolytics, there is no sure fire way to tell if a cap is an electrolytic other than expereince, but most of the time if it says Bi-polar on it it means its an electrlytic because film caps are all bipolar so they arent labeled as such.

As far as if they are good or not, you want to stay away from electrolytics as much as possible in xovers when possible. Sometimes you have so choise as films arent made much larger than 50-100uf and sizes like that are huge, think soda can sized and expensive $$25+ each. Film caps almost always sound better than an electrolytic in Xovers. Since yours apeear to be 4uf your best bet is to replace them with a film cap. A few companies that make good but inexpensive poly fim caps are Panasonic, Bennic, Solen and Wima.
Good luck with your speakers and happy listening!

Frank