Tweaking the FE206ES-R

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Please receive my greetings from Paris, France and my best wishes for the new decade.

I currently use Fostex FE206ES-R in nagaoka style of enclosures (fostex recommended enclosures). Very happy with them although it took me a while before I could get the proper damping, filtering, placement of the T90 tweeter, attenatuor…

I have left this pair untouched (no phase plug) except covering the rear magnet with a “felt sock” that can be removed if need be and treating the frame members with felt as well. I did not try to apply some marine latex sealant or duct seal putty between the (motor) magnet and the (chassis) frame as the thing looked very sturdy and did not seem to need something to reduce vibration of the speaker chassis : Modifications and Tweaks - Fostex FE206E and FE206En Fullrange Driver

I have come across a paid of FE206ES-R which have been sitting unused for 10+ years in someone’s inventory. They are brand new but they have suffered from being stored in their shipping boxes, in a environment without heating and probably some dampness.

Everything looks OK, especially the diaphragm and the surround. No tear or deformation / warp of the diaphragm. I have left them “drying out” in my office for a couple of weeks and they look fine. They sound OK as well since I have tested them, although they are just being broken in.

Only the diaphragm is dirty from storage and the whizzer cone edges look a tiny bit “uncrisp” and since I want to build a second paid of FR speakers for my son and may be try out the sachiko build, this is the occasion to get some advice and feedback from the forum and may be tweak this pair of speakers a little more than my original pair.

1) I am thinking to give the diaphragm and the whizzer cone a crispier look and apply a new colour like what Dave from Planet10 has done on numerous speakers. This would remove the grayness of the diaphragm and whizzer and protect them for the future.

I have read many posts and there seem to be some consensus on puzzlecoat (modpodge) or thinned PVA glue to the consistency of a milky solution all mixed with some water based ink we find in Art store. Can’t find the puzzlecoat in Europe so something else needs to be done, liike diluted PVA.

2) I have read that you apply two coats on both the fronts of the diaphragm and the whizzer. The edge of the whizzer at the back should also receive some treatment but not the full back of the whizzer.

3) In some other posts : I read that the back of the diaphragm (BTW, is the diaphragm what you call “cone” in US ?) can be treated as well. Does this apply to the FE206 ?

4) How many coats do you apply of this thinned PVA glue ? Just two or more ? what is the correct dilution if we start with

5) Other finish to apply after the puzzlecoat treatment ? water based acrylic paint, water based varnish ?

6) Other improvements and recipes that could be shared with me ? There are not many tweaked FE206ES-R around I think.

7) I would still do the “felt sock” treatment as it helped me a lot with finding the right amount of damping. Very little was then needed except some felt behind the speaker and some polyfill.

I will leave the phase plug for another post. From what I have read insofar, this is probably what will bring the most noticeable improvement but I am concerned to cut through an expensive and rare speaker which cannot be found anymore…

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