Today two local audiophile complained that their 4365s have quality problems after two years using,they said thses problems are very common in 4365.
1.476Mg cladding material is easy to exfoliate,this will block the gap.
2.the magnetic steel is easy to rust.
These problems caused the compression drivers don't have same SPL.
Why?
46 lover
more pixes
That's weird how did the aguaplas end up in the gap?? The diaphragm is a physical barrier and gravity, with the driver mounted in the cabinet, is going to make it fall into the back shell cavity. Sure it not just the corrosion around the edge of the gap? That corrosion is concerning.
Rob
"I could be arguing in my spare time"
I've never seen one cracked open, seems strange that they would Aquaplas a Mg 'phragm.
That looks really odd.
Normally the phase plug never rust from what I have seen. It is the steel outer ring that corrodes and that is not uncommon due to leaking back cover or water coming in from the horn side.
I have never seen an original 4" driver with rust on the phase plug. Corrosion from water yes, but not rust. If it indeed is rust? -And is the phase plug corroded from water the outer steel ring almost always shows some rust. This does not.
Easy to clean up the steel ring but not in the phase plug.
Can it be something from the inside of the dia due to excessive heat? Glue perhaps? Can you post a picture of the phase plug side of the dia.
Is it original JBL dia’s? I have not seen those lead covers on the leads from the WC on any other dia. I don’t have them on my 475Nd dias.
I have not seen Aquaplas coated dias loosing coating like in the picture so that may also indicate heat maybe? On the other hand, I do not have any Mg’s just Ti, Alu and Be.
“Bubbleboy76” and “hlaari” (and probably many more) here on LH are using 476MG and has opened them so they should be able to bring some light on the coating issue.
Kind regards
//RoB
The solution to the problem changes the problem.
-And always remember that all of your equipment was made by the lowest bidder
Not sure those are original dias.... Looks like someone swapped in something else.
I have never seen a JBL dia looking like that with leads trough the dome.
Kind regards
//Rob
The solution to the problem changes the problem.
-And always remember that all of your equipment was made by the lowest bidder
Robh3606 has some 476Mg drivers.
I suppose there's good reason now for everyone with these drivers to check underneath the diaphragm and look for rust.
OTOH, what we are looking at could well be the realized consequences of local counterfeit parts ( or whole systems ).
I'll reserve my indignation till I see world-wide evidence of any wrong-doings on JBL's part .
PS; the dressing of diaphragms lead-in wires is interesting being situated on the dome side of the diaphragm ( a la Altec )
>> typically JBL has tucked those lead-ins under the diamond surround ( going directly to the voice-coil ).
- Mind-you, this is my first look at a 476Mg diaphragm that I can remember.
- What Rob just said.
It is a authentic product purchased from local JBL dealer,not smuggled goods.Originally Posted by sebackman
I need to check out my 476Mg drivers, it does not look good like this
Ari
Only the edge is rusty,this stucked diaphragm and make SPL reduced.almost every 4365 has this problem.That's weird how did the aguaplas end up in the gap?? The diaphragm is a physical barrier and gravity, with the driver mounted in the cabinet, is going to make it fall into the back shell cavity. Sure it not just the corrosion around the edge of the gap? That corrosion is concerning.
Rob
If you have 4365,please check it
pixes
It could be a cleaning solvent residue or a metallurgy problem with the enamel or other coatings, adhesives used on the voice coil or the glues used to bond the voice coil to the diaphragm. If the acquaplas is effected then it could be vapours from adhesives. Sounds like a problem in production (Mexico) if it’s not an isolated case.
I recommend you talk to a JBL consumer or the reseller you acquire the 4365’s from.
One of the 4365 user contact the reseller,the reseller promise to repair,but need the whole speaker to be transported to the store
Of course.
The think is why did the owner not take the loudspeakers into the reseller in the first instance.
Because he had tampered with the loudspeakers it may not be covered under warranty.
It’s like lifting the lid on an amplifier because you think there is a problem with it?
Can he prove a difference in sensitivity and that this is the cause?
I am not sure cynical (miss trust) publicity is appropriate unless the business can confirm what the issue is and if it is the actual cause as alleged.
What was JBL response? Did they get new drivers?
I am waiting on answer.
Seems to me like incompatible metals are used togheter, causing galvanic corrosion.
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