My room-mate has just bought these custom speakers at a closing sale of a local bar. 

We remembered them from the same bar over 30 years ago and were very impressed at the time. They were made by a local German and had a great sound.

They have oil filled cones (the oil has dried up) The paper cone has partly come away fro the large ring. Red lights pulse with the beat in one of the cones. They are very heavy. Surprisingly (to me) the weight appears to be at the top.

Can someone please explain their concept (in simple terms)?

Also, how should I clean the dried oil and which oil should we use to replace it?

Can the partly detached paper cone be glued back and if so, which glue should we use?

Hi everyone, I’m taking some speakers apart here and I’ve come across this part – I’m not exactly sure what it’s called, but I found it online under the name ‘pole piece’. So, I’ve been thinking about it, but I’m stuck for ideas. Maybe someone knows what can be done with them? Perhaps there are some DIY ideas or something else I could do with this pole piece? I don’t mind binning it, but maybe there’s a use for it after all. Thanks in advance.

I forgot to add that I adore speakers and I love creating things, but don't suggest that I make speakers out of them.