4. Rubber or foam surrounds? Why?

4. I prefer rubber surrounds while original foam surrounds were mounted(?)

We have rubber surrounds, but they are less in demand compared to foam surrounds. A hanging surrounds is an essential part of the speaker unit and it could sound completely different with a rubber surrounds rim instead of a foam (-rubber) surrounds. The advantage of rubber is that it does not decompose. This is partially true; however, rubber may dry out and/or harden. The foam rubber surround rims we offer are made of top-quality polyether and are extremely durable. The following text is a direct quote from the Dutch edition of the book ‘The Loudspeaker Design Cookbook‘ by Vance Dickason. This is not just any book, but a Bible among books used by designers of loudspeakers:

'For this reason the surround is an essential part of the cone construction, and also a part that in an important way is reponsible for the frequency-charateristics.'  

'The surround can dampen membrane vibrations and refractions to the center of the membrane, affecting both the amplitude and the phase of resonance modes'.

Furthermore, when the speaker is designed, the mechanical mass MD is also determined by the weight of the surround. Rubber surrounds are a lot heavier than foam surrounds. In the calculation, the MD includes half the weight of the surround. For example, by another MD, the Fs = resonant frequency and other parameters also change, so that the original design can be lost.

If you want rubber edges that are as close as possible to the original, Audiolab is the specialist in the professional repair and placing appropriate rubber surrounds.