Fostex FE167 cone problem, any solution?

Sounds interesting. Now when i see how you do that,it dosent look so dificult.
Im sure gona try with some cheep drivers just to see what diference can i messure and hear.
Can i use E6000 glue for this?
What glue did you use?
 
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If the "greasy" rim is glue coming undone, especially wrong glue applied by a previous fixer, the effect would be like a leaky drum. Loss of SPL, no "Puck" when tapped, and scraping due to uneven force.

While playing (preferably a low tone sine wave), run finger(s) along the greasy rim very edge, with a bit of pressure to detect/close an air leak if present.
 
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Without being able to measure them, hard to say exactly what's going on. The marks on the cone appear to be moisture (or some kind of airborne oil / grease) damage. What you can see on the surface alone isn't likely to cause major differences in SPL however.
FWIW, my 'knee jerk' thought WRT the discoloration is that the cones are separating from the surround, which could explain the loss of SPL and if the doping is the water based latex like used in the USA nowadays it could be the cause of the discoloration and also explain why its surround looks so 'dry' compared to the other one, though of course it could just be the lighting/angle, so wchang's leak testing seems a good place to start.

Regardless, recommend repair/doping both with https://www.parts-express.com/Speaker-Repair-Glue-1-oz.-Bottle-340-076?quantity=1
 
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Sounds favourite to me. 🙂 Certainly worth trying! It's a whole lot cheaper than replacing the drivers...

I've dug out a pair of horrible old Eagle 5 1/4in units I bought from a local electronics shop about 20 years ago -will see if I can give the foil modifications a try, since if my usual ham-fisted self makes a mistake, no harm done. 😉 One of those I've been meaning to look at properly for years ever since you first told me about it, & never got around to.
 
If the "greasy" rim is glue coming undone, especially wrong glue applied by a previous fixer, the effect would be like a leaky drum. Loss of SPL, no "Puck" when tapped, and scraping due to uneven force.

While playing (preferably a low tone sine wave), run finger(s) along the greasy rim very edge, with a bit of pressure to detect/close an air leak if present.
I try play 50-40Hz sine sweep,and there is no air leaking oraund,both of them are great.I push them near to max,cone was making 6,7 mm in/out movment.So no air around. I evdn lick my finger to be sure😊
But,now i realize what that cener hole can make. Omg,what a sound. And air is blowing out from this hole like its fan inside,i can feel 10cm(4") from speaker how is blowing. This central cap goes down sure an soon. That must be big improvment to driver.
 
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FWIW, my 'knee jerk' thought WRT the discoloration is that the cones are separating from the surround, which could explain the loss of SPL and if the doping is the water based latex like used in the USA nowadays it could be the cause of the discoloration and also explain why its surround looks so 'dry' compared to the other one, though of course it could just be the lighting/angle, so wchang's leak testing seems a good place to start.

Regardless, recommend repair/doping both with https://www.parts-express.com/Speaker-Repair-Glue-1-oz.-Bottle-340-076?quantity=1
Yes,you are right,its not the lightning angle.
Right(bad) one,suspension looks dry and have big discoloration on cone,like some oil is there.
The left(good) one,suspension looks wet and is little sticki to finger when i try it,and cone have almost no "oil" stains on cone.
So it could be that it needs to be glued again.
Do i need to clean somehow cone before glueing?
 
If the "greasy" rim is glue coming undone

Wrong colour for that. I have seen lots of leaked glue on the large number of FE103A i have had pass thru here, it is more brownish and looks like a stain. This looks like mold. I’d try a q-tip with some isopropanel and se eif it comes off before treating th econes.

dave
 
But,now i realize what that cener hole can make. Omg,what a sound. And air is blowing out from this hole like its fan inside

Why i recommend removing them and putting phase plugs in. The oil can resonance under the cap is being forced out the hole. With the hole filled with a phase plug there is no space for the resonance to form. But the short circuiting of the side-to-side waves in the whizzer is the larger benefit/

dave
 
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ZIG 2-way glue. You usd to be able to get it at Micheal’s (no online hit) last batch i got was from Scrap’n Stamp on-line. They don’t see any there now.

I might have an unopened one that i am never going to use.

FExxx and FFxxx should have 2 coats on the back side where the cone interfaces with the surround. This helps kill some of the resonance sthat travel up the cone.

dave
 
It's easy to do, I do it right now
 

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Finished, I fix it with my finger nails

As Barlow said, the composed material is much better than paper or metal alone.

As it is a paper diaphragm the damping is better than combining metal with polystyrene like Barlow did it. So this driver is a fullrange driver going up to 12khz.
 

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