4365 has quality problems

[martin_wu99]

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?

[martin_wu99]

more pixes

[Robh3606]

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:)

[JeffW]

I've never seen one cracked open, seems strange that they would Aquaplas a Mg 'phragm.

[sebackman]

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

[sebackman]

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

[Earl K]

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.

[martin_wu99]

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:)
Only the edge is rusty,this stucked diaphragm and make SPL reduced.almost every 4365 has this problem.
If you have 4365,please check it

[martin_wu99]

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
It is a authentic product purchased from local JBL dealer,not smuggled goods.

[Earl K]

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

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.



http://www.hifishock.org/galleries/speakers/jbl/k2-s9900-4-jbl.jpg
http://www.geocities.jp/sound_sonata/img/photo/IMG_s9900_17.jpg



:)

[bubbleboy76]

Both my 476Mg were heavily corroded on the diaphragm. They were cleaned, and measured like new. But still looks like shit.
I have picture somewhere.
So this is a general problem. I will contact my service guys.

[martin_wu99]

Both my 476Mg were heavily corroded. They were cleaned, and measured like new. But still looks like shit.
I have picture somewhere.
So this is a general problem. I will contact my service guys.
Thank you for telling the truth.
Not occasional one person told me,as i know at least 4 pairs of 4365 have these problem.they said every 4365 have these problems.

[Earl K]

Both my 476Mg were heavily corroded on the diaphragm. They were cleaned, and measured like new. But still looks like shit.
I have picture somewhere.
So this is a general problem. I will contact my service guys.

Thank you for telling the truth.
Not occasional one person told me,as i know at least 4 pairs of 4365 have these problem.they said every 4365 have these problems.

JBL should make good on the necessary repairs to stabilize the rust problem.

JBL should also make sure the refurbed drivers are performing back up to spec.

All at Harman's cost.

OTOH, if someone wants to make an attempt at stabilizing the rust situation ( on the outer edge of the phase plug ) I recommend treating the problem area with a rust converter product that contains Phosphoric Acid & Tannic Acid ( as the active ingredients ).

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=83188&stc=1&d=1547992265

These rust converter products are pretty common in countries having a real winter and where the use of road salt leads to all sorts of rust problems.

Here's a product available here in Canada for the DIY crowd ( every northern type country should have something comparable ).

https://www.rustcheck.com/wp-content/uploads/2016/04/Rust-Converter-Bottle.jpg (https://www.rustcheck.com/product/rust-converter-2/)


:)

[bubbleboy76]

Pic of one of my 476Mg diaphragm (to the right) after cleaning.

[martin_wu99]

pixes

[Earl K]

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=83200&stc=1&d=1548172177

It appears to these eyes that the metal in the dome of 476Mg is interacting with that of the phase plug ( just a guess ).

Were there loose oxides present in the shape of those 4 concentric rings ( matching the slits in the phase plug )?

:)

[bubbleboy76]

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?

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.

[Earl K]

Here's a relevant thread (hosted over at DIYaudio ) about Corroding Magnesium cones on SEAS drivers! (https://www.diyaudio.com/forums/multi-way/300775-corrosion-seas-magnesium-drivers.html)

https://www.diyaudio.com/forums/attachments/multi-way/586052d1481841394-corrosion-seas-magnesium-drivers-driver1-view-jpg
https://www.diyaudio.com/forums/attachments/multi-way/586043d1481841394-corrosion-seas-magnesium-drivers-driver-1-jpg
https://www.diyaudio.com/forums/attachments/multi-way/652449d1513944552-corrosion-seas-magnesium-drivers-img_2533-jpg


Some ideas within that thread on cone protection.

:)

[bubbleboy76]

Replacing with TrueExtent Be diapraghms would solve the problem, you think? Or are other parts likely damaged/corroded as well?
My service guy told me only diaphragm was affected.

[Robh3606]

Replacing with TrueExtent Be diapraghms would solve the problem, you think?

Probably not the response curves are not identical so trading one problem for another so to speak.

Rob:)

[Robh3606]

Hmm wonder what's going on? How is so much moisture getting inside the drivers?? Could condensation do that?? Cold driver vs damp humid air??

Rob:)

[speakerdave]

Two suggestions for JBL (and Seas): 1) hire a metallurgist; 2) create an upgrade path by re-engineering the crossover with a true extent/JBL Be diaphragm. They have a crack engineering staff that could put that together in good time. Oh, wait . . . .never mind.

[4345]

Could JBL have made the phase plug using a different method or material? Could it be plated metal rather than solid metal? Could it be from a new factory using inferior metals. Maybe they are importing this part and not making it as they did for the last 70 years? I think it said" Designed and Engineered in the USA". Not "MADE IN THE USA".

[baldrick]

Have never opened mine 4365... how do one remove the driver?

476mg is used also in S9900 and DD65000, so this could probably be a quite huge problem for JBL!?

[HCSGuy]

On a whim, I cracked one of mine open - looks pretty clean, though there is a faint shadow on the diaphragm. This is good as I got mine "Sideways" as bare drivers and don't have any warranty recourse against JBL. I also live in the high desert, so very low humidity, which can be a blessing, as nothing rusts, and also a curse, as your sandwich gets stale if you don't eat it in a hurry:) Lastly, I wonder if there is any production change - my drivers are very early production. Here are a few pics:8320683205

[Earl K]

HCSGuy , So coincidentally (??) your non-rusted phase-plugs are mated to a diaphragm with a cleaner glue line ( than the others have displayed above ).

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=83206&d=1548193365

The rust around the edge of the phase-plug perimeter is in quite close proximity to the glue line seen on the inside of the diaphragm.

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=83200&stc=1&d=1548172177

Reactive\\\Corrosive glue maybe ( that's out-gassing ) ?

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=83204&stc=1&d=1548173110

:dont-know:

[Mctwins]

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?

In the first picture where one can see the cable(negative wire) there is a faston connection. Can this be right, I thought it schould be soldered. The tiny cables looks strange as well, compare to some pictures I have seen, more of a flat cable and solder too.

When you are saying "they said thses problems are very common in 4365." who is they?

The trancducers must have been in some moisture enviroment for some time. Just my guess.

[Mctwins]

http://www.hifishock.org/galleries/speakers/jbl/k2-s9900-4-jbl.jpg
http://www.geocities.jp/sound_sonata/img/photo/IMG_s9900_17.jpg



:)

Thanks, great pictures, excactly what I mean about the cables.

[HCSGuy]

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?

There seems to be a miscommunication in this thread - the aquaplas "cladding" is on the side of the diaphragm that is away from the magnetic gap - if it all flakes off, it will fall into the insulated back cover of the driver, but will not go into the magnetic gap, as the diaphragm separates the aquaplas from the gap. However, if there is a problem with flaking rust on the phase plug, this will easily fall into the gap, causing the problems mentioned.

[martin_wu99]

Could JBL have made the phase plug using a different method or material? Could it be plated metal rather than solid metal? Could it be from a new factory using inferior metals. Maybe they are importing this part and not making it as they did for the last 70 years? I think it said" Designed and Engineered in the USA". Not "MADE IN THE USA".
Yes,it is Mexico made.

[martin_wu99]

In the first picture where one can see the cable(negative wire) there is a faston connection. Can this be right, I thought it schould be soldered. The tiny cables looks strange as well, compare to some pictures I have seen, more of a flat cable and solder too.

When you are saying "they said thses problems are very common in 4365." who is they?

The trancducers must have been in some moisture enviroment for some time. Just my guess.
Another 4365 users,many of them live in south of China,relatively hot and humid,but they treat their 4365 very carefully.

[Mctwins]

Another 4365 usres,many of them live in south of China,relatively hot and humid,but they treat their 4365 very carefully.

Ok, understand

What about the wire cable?

[Mctwins]

In the picture from hifishock posted by Earl k the text on the tranceducer is differen't from martin wu's picture.

[martin_wu99]

Ok, understand

What about the wire cable?
They are original 4365,no one touch the cable.

[martin_wu99]

In the picture from hifishock posted by Earl k the text on the tranceducer is differen't from martin wu's picture.
I noticed that the pixes are of 9900,maybe that's the point!JBL changed something later.
I have no 4365,let Bubbleboy76 give you the details.

[Mctwins]

They are original 4365,no one touch the cable.

Ok, I do belive you, But, that cable can't be made from factory. Looks strange, I would be very suspicious.

[baldrick]

Have anyone removed a driver from 4365, and if so, how is it done?

[Mctwins]

Have anyone removed a driver from 4365, and if so, how is it done?

Remove the back access panel.

Disconnect the wires.

There are two screws on the horn and two on the bottom where the L-shape plate is. Remove this. Take care of the gasket.

Remove all this, L-plate and the tweeter.

Then there are for bolts on the tweeter where the L-plate is attached, remove this and you have the 476mg free to dismantle.

Look for technical manual of 4365.

Hops this helps.

[baldrick]

Thank you Mctwins!

[Ian Mackenzie]

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.

[martin_wu99]

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:crying:

[Ian Mackenzie]

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.

[edgewound]

Another 4365 users,many of them live in south of China,relatively hot and humid,but they treat their 4365 very carefully.

Very moist air is not compatible with compression drivers. The patterns on the phase plug side of the diaphragm is typical of moisture entering the horn throat.

A dehumidifier might help in the room where the speakers live. A piece of open cell foam over the compression driver exit might also help reduce moisture entering the internals of the driver.

[smooth dancer]

Some pics of mine 476mg. The speakers were bought brand new Des 2011. My listening room have a steady temp around 20-22˚celsius.

[smooth dancer]

The sound is as always very very good.

[Earl K]

The sound is as always very very good.

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=83216&stc=1&d=1548275809

Wow, that diaphragm definitely has a Shroud of Turin thing going on.

:blink:

[edgewound]

Some pics of mine 476mg. The speakers were bought brand new Des 2011. My listening room have a steady temp around 20-22˚celsius.

Yes....but the humidity in Oslo today is 86%, and 74% average year round. 8 years of accumulated moisture is going to have an effect, as you can see. Once the moisture goes in, it's not coming out without leaving some residue behind.

[Mctwins]

Some pics of mine 476mg. The speakers were bought brand new Des 2011. My listening room have a steady temp around 20-22˚celsius.

It looks nice and the cables seems to be as Martin wu's picture regarding the faston. My wrong here, Sorry Martin!!

But your cable attaching to the diafragman looks different. Flat wire contra round.

[Mctwins]

I can agree that moisture can be a problem.

[baldrick]

Had to open mine and it was easy without removing the driver.And for me it looks good!? But the voicecoil.... is this OK or could it be damaged?

[baldrick]

Is this damaged?

[Earl K]

Baldrick, your voice-coil looks good-enough ( iow; its not damaged ).
- It's just not the cleanest coil winding job that I've seen.

On a different matter;

In my opinion, you should remove the driver body from the horn before replacing the diaphragm.

Working on the driver ( with the gap vertically oriented ) is all too easy to make a mistake during re-assembly.

IME, it's safer/better to work on drivers when you can walk around them ( 360deg ).

:)

[Mctwins]

Had to open mine and it was easy without removing the driver.And for me it looks good!? But the voicecoil.... is this OK or could it be damaged?

Looks good to me!

[Mctwins]

I am not gonna open mine, don't have any moisture in my room. As long it's sounds fine I am not gonna bother with this issue. Maybe in 10 years:)

[pos]

ignorance is bliss ;)

[bubbleboy76]

Can TrueExtent Be diaphragms be installed in the 476Mg core?

[Robh3606]

ignorance is bliss ;)

Yes count me in as well not going to open mine either unless a measurement goes funky or an impedance sweep goes awry

Rob:)

[Earl K]

Can TrueExtent Be diaphragms be installed in the 476Mg core?

That's a good question to which I personally don't have an answer.

:)

[hlaari]

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


I need to check out my 476Mg drivers, it does not look good like this:(




Ari

[ivica]

That's a good question to which I personally don't have an answer.

:)

Hi Earl K,

what kind of problem can expected to use Be-Trx diaphragm with 476 core.
I can imagine that Mg diaphragm would produce higher F/R response then Be-Trx one.
Using JBL Be diaphragm, would be different story, I think.....

regards
ivica

[Earl K]

Hi Earl K,

what kind of problem can expected to use Be-Trx diaphragm with 476 core.
I can imagine that Mg diaphragm would produce higher F/R response then Be-Trx one.
Using JBL Be diaphragm, would be different story, I think.....

regards
ivica

Ivica,

I have no idea if older JBL diaphragms will even fit into the 476 driver ( since I don't own any 476 type drivers > therefore can't try out the idea ).

I also don't know if the 476 line of drivers uses JBL's standard sized phase-plug ( ie; using the same curvature and height ).


:)

[Robh3606]

The 476's use a coherent wave phase plug so a 2450+SL/2451 I would think would fit as they are also Neo drivers same phase plug. ???

Rob:)

[Earl K]

The 476's use a coherent wave phase plug so a 2450+SL/2451 I would think would fit as they are also Neo drivers same phase plug. ???

Rob:)

It's the curvature & height of the phase-plug that concerns me most.

:)

[martin_wu99]

I need to check out my 476Mg drivers, it does not look good like this:(




Ari
Hi Ali,

How is everythg going?how about your 4348 clone work?

I konw you like 476Mg very much,please let us konw your comments:D:applaud:

[martin_wu99]

Can TrueExtent Be diaphragms be installed in the 476Mg core?
Very good question,i am anxious to know the answer too,can it be replaced with Be diaphragms directly without any modification of the crossover?:confused:

[bubbleboy76]

Very good question,i am anxious to know the answer too,can it be replaced with Be diaphragms directly without any modification of the crossover?:confused:


I have active crossover, so I do not care about that. I can just remeasure and make new EQ-settings. I meant if the TrueExtent Be dia fits and works technically in the 476-core.

[martin_wu99]

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?
And more,one 4365 user said the components of 4365 crossover is very poor comparing with 4367,is that true?
below is the pix of 4367's crossover

[bubbleboy76]

I think we have had this discussion before, were I claim that 4365 crossover probably was somewhat ”detuned” to not make 4365 sound too good relative K2 and Everest.

[hlaari]

Hi Ali,

How is everythg going?how about your 4348 clone work?

I konw you like 476Mg very much,please let us konw your comments:D:applaud:




476Mg is a great sounding driver, but I hope at my 476Mg in the S9900 project is in good condition, I have not take a look inside them yet:crying:



Ari

[hlaari]

And more,one 4365 user said the components of 4365 crossover is very poor comparing with 4367,is that right?
below is the pix of 4367's crossover


I think at the components in 4365 and 4367 is in similar quality, S9900 and DD67000 have better capacitors and better design crossover
I think at all the networks JBL use in the high end speakers could use better parts (capacitors, resistors and inductors)
I would go for Jantzen capacitors and inductors



Ari

[Earl K]

And more,one 4365 user said the components of 4365 crossover is very poor comparing with 4367,is that right?
below is the pix of 4367's crossover

Lets keep this thread focused about the oxidation problems that some 476Mg drivers have > rather than a general gripe-fest ( or buyers-remorse blog ) about the 4365.

:)

[martin_wu99]

I think we have had this discussion before, were I claim that 4365 crossover probably was somewhat ”detuned” to not make 4365 sound too good relative K2 and Everest.
I didn't see that post:blink:i just want to know the quality of 4365's crossoever:D
what does detuned mean?:confused:

[martin_wu99]

I think at the components in 4365 and 4367 is in similar quality, S9900 and DD67000 have better capacitors and better design crossover
I think at all the networks JBL use in the high end speakers could use better parts (capacitors, resistors and inductors)
I would go for Jantzen capacitors and inductors



Ari
You are going to upgrade your JBL crossover? sounds good:D
I think 4365's drivers is better than 4367's,so i recommend 4365 to other audiophiles,not 4367,but some 4365 users complained about this.

[martin_wu99]

Lets keep this thread focused about the oxidation problems that some 476Mg drivers have > rather than a general gripe-fest ( or buyers-remorse blog ) about the 4365.

:)
I just want to know why 4365's crossover is not as good as 4367's?:crying:why 4365 have so many quality probelems?:blink:

[ngccglp]

After reading this thread, it reinforced a principle , which is never to outsource critical components or process where you no longer have control of the quality. Many speakers manufacturers are still winding their own voice coils eg ATC.

Hope HK/JBL stop this nonsense of just focusing on production cost.

[bubbleboy76]

4365 might have been manufactured and/or stored in a humid environment.

As far as I know, 4365 and the parts like 476Mg is assembled in Mexico.

Is Mexico humid?

[bubbleboy76]

But I am not at all sure that humidity is the problem causing this.
Might be something else.

[Mctwins]

Ok, I have been thinking.

We have to know for certain that it is the humidity in a room or a warehouse where the speakers are stored that is the culprit to the problem. There must be more speakers that have this problem. K2 uses the same driver.

Or, can it be that it is due to excesive heat produced by to much(or low) power, amplifier goes into clipping. Thinking out loud here.

We need more information from "they" who have problems.

And, we need statement from a engineer from factory quality department to see what they have to say about it.

All I can say is that I have been playing all day long yesterday pretty much at high volume(as usual), sounds great.

It's been a while I have played with these speakers. Some four to six month have they been switch off.

Don't worry, other brands besides JBL had some problems as well, very expensive audiophile loudspeakers.

May the investigation continue...

[Ian Mackenzie]

If you look on Japanese auction website the compression drivers images show actual brown rust on the mounting bolt circle that attaches to the horn. On eBay images of diaphragm terminals often show corrosion where screws attach the wires to the diaphragm. But that type of corrosion takes on the appearance of white oxide. That is moisture either between surfaces or trapped in the rear of the drivers.

That is consistent with the hypothesis of moisture finding its way into the junction of two surfaces. However it could also be that as suggested the glue line or glue that had not full cured made contact with the edge of the phase plug on assembly. The glue has then reacted with phase plug. If it was moisture you would expect corrosion across the surface of the phase plug. But the marks of the corrosion or glue reaction are very defined.

On the subject of humidity its a problem with optics where the lens is cold and is suddenly exposed to moist air. In the situation where the air is moist or humid and the metal is the same temperature you won’t see condensation on the metal. But if you cooled the room down quickly you would expect water in the form of condensation forming on surfaces.

[1audiohack]

Hi All;

My 4365’s perform just fine. I am not going to take them apart. I live in the desert where lack of humididty is a problem.

I will hazard a guess that this is a storage problem, based on an experience I had with some other new JBL’s I bought in the past.

These were stored in their unopened factory boxes in the Northern California bay area for a while and when I brought them home, opened them up and stood them up, water literally ran out of the horn mouths. Drops, not a river but far more than just wet surfaces.

It took me about two hours to scramble together the equipment and get the comp drivers under vacuum in a bell jar and almost 30 minutes each under high vacuum to get them completely dehumidified. Nearly a decade later they are still fine. These are Al drivers.

Most the parts in these drivers are coated or plated with some sort of anticorrosion except the phase plugs which are zinc and fairly corrosion resistant. The aluminum diaphragms are alumaclad 2024 which has a very thin coat of pure aluminum which is very corrosion resistant and Be is corrosion resistant. Magnesium unfortunately is not corrosion resistant by itself.

Bubbleboy mentioned the possibility of galvanic corossion where two types of metal react and while my experience with this is where these materials are in contact with each other like a bare steel part pressed into or threaded into aluminum there may be the possibility of electolytic effect if the zinc plating of the pole piece is connected with water to the magnesium.

Short story with a disclaimer first: I have the utmost respect for Jerry Morro. I don’t know him well but liked him a lot.

I had the privilege of speaking with him for a couple of hours at the Nothridge facility one day and he showed me a box of large format experimental diaphragms. Many lightweight metal aloys with many types of coatings. Of particular interest was a hard anodized aluminum diaphragm. This is where a coating of aluminum oxide is grown into and on the surface that is nearly diamond hard and actually reduces the weight of the part slightly. He said that they performed very well but failed quickly from fatigue at the bending area of the surround so it was one of the experiments that was abandoned.

The one in my hand was completely anodized so I asked what I thought was the obvious question, “were they all like this or did you mask the surround on any?” (This would leave the surround still flexible)

I could not tell from the look I got if it was either, of course you idiot, or damn, we didn’t think of that. But the look was enough fo me and I dropped it, and he didn’t answer. Pondering that on the drive home I didn’t think I remembered seeing any where the surround had been masked.

In the end, nobody knows everything and maybe this corrosion thing was a possibility no one recognized or planned for.

I haven’t done much with mag in a long time besides weld it. Are there corrosion inhibitors for it now? I guess we ought to look into it now that we have a reason. Magnesium is about to come into its renaissance in automotive production and this will have to be solved if it has not been already.

On the is TJ humid? Depends where you are and which way the wind blows. It’s a big city by the coast.

My best.
Barry.

[Earl K]

Thank-You for your thoughts Barry on how this likely occurred ( it makes sense to me ).

I've had compression drivers ( 2426's or 2425's ) get their gaps completely filled with water ( & to my horror ) haven't discovered this fact till a couple of months later ( the joys of using general cargo hauling across Canada ) .

Needless to say the diaphragm coil-formers were ruined and the gaps were starting to rust very badly ( the zinc plating can only do so much to prevent rust when it's under water ).

I saved my drivers by flushing the gaps out with penetrating oil ( WD40 ), then getting rid of all the rust and then re-immersing the gap for some time in oil ( before cleaning it all out /drying & finally installing new diaphragms ). This effort saved my drivers.


Most the parts in these drivers are coated or plated with some sort of anticorrosion except the phase plugs which are zinc and fairly corrosion resistant. The aluminum diaphragms are alumaclad 2024 which has a very thin coat of pure aluminum which is very corrosion resistant and Be is corrosion resistant. Magnesium unfortunately is not corrosion resistant by itself.

So ( in your 4365's ) you've swapped out the original Mg types for Al diaphragms ?


:)

[1audiohack]

Hello Earl;

The hydro event was not with my 4365’s. They are still virtuous in their assembly.

I too have bought “working” drivers that were badly water damaged. Like you I cleaned them up and then relegated them to general low expectation duty like shop stereo.

It seems that to some people “working” means that the law of gravity still applies to it. If I only wanted a door stop...

Barry.

[martin_wu99]

After reading this thread, it reinforced a principle , which is never to outsource critical components or process where you no longer have control of the quality. Many speakers manufacturers are still winding their own voice coils eg ATC.

Hope HK/JBL stop this nonsense of just focusing on production cost.
QC is always a big problem for those companies which have oversea factories.

[martin_wu99]

4365 might have been manufactured and/or stored in a humid environment.

As far as I know, 4365 and the parts like 476Mg is assembled in Mexico.

Is Mexico humid?
Do you have any pictures of your 4365 crossover? please post out to show the difference between 4367:applaud:

[martin_wu99]

And more,one 4365 user said the components of 4365 crossover is very poor comparing with 4367,is that true?
below is the pix of 4367's crossover
4367 crossover

[JeffW]

What exactly is the problem with the 4365 crossover? "Very poor" is not a very good description of the perceived problem.

There's a photo of the 4365 crossover in this pdf. It's large enough to be zoomed in quite a bit, enough to see that on the upper crossover section, all the capacitors are poly caps, no electrolytics. The inductors on both sections are air core, no iron core inductors.

They look like nice units to me.

https://www.jblsynthesis.com/tl_files/catalog//jblsynthesis/4365/SC_JBL_093_JBL_4365_STUDIO_MONITOR.pdf

[bubbleboy76]

There are fine components in 4365-crossover, as far as I know.
The problem, to me, is that the HF part has no lowpass-filter. This causes HF to play the same register as UHF all the way up to 20KHz. This causes comb-filtering. 476Mg HF-driver does not roll off on its own.
There is no proper acoustic crossover between HF and UHF.
This makes 4365 sound and measure too bright for my taste. Listen on high volume and ears get fatigue after a while.

But if this particular discussion should continue, do it in a new thread.

[martin_wu99]

What exactly is the problem with the 4365 crossover? "Very poor" is not a very good description of the perceived problem.

There's a photo of the 4365 crossover in this pdf. It's large enough to be zoomed in quite a bit, enough to see that on the upper crossover section, all the capacitors are poly caps, no electrolytics. The inductors on both sections are air core, no iron core inductors.

They look like nice units to me.

https://www.jblsynthesis.com/tl_files/catalog//jblsynthesis/4365/SC_JBL_093_JBL_4365_STUDIO_MONITOR.pdf
Thanks,a 4365 user complain that 4365's crossover is not as good as 4367's,so i want to know the truth.

[martin_wu99]

There are fine components in 4365-crossover, as far as I know.
The problem, to me, is that the HF part has no lowpass-filter. This causes HF to play the same register as UHF all the way up to 20KHz. This causes comb-filtering. 476Mg HF-driver does not roll off on its own.
There is no proper acoustic crossover between HF and UHF.
This makes 4365 sound and measure too bright for my taste. Listen on high volume and ears get fatigue after a while.

But if this particular discussion should continue, do it in a new thread.
Is that so?that may be a problem,please post a new thread

[baldrick]

4365 MF/HF filter.

i really can’t understand that JBL did make a poor x-over design. Maybe they did not use absolute high END parts to svar Money. Are there LF filter on K2 or E2?

[martin_wu99]

4365 MF/HF filter.

i really can’t understand that JBL did make a poor x-over design. Maybe they did not use absolute high END parts to svar Money. Are there LF filter on K2 or E2?
Thank you,i am looking for 4365' crossover pixes these days, it is true that 4365' crossover is not as good as 4367,not to mention K2 or E2,why?

[baldrick]

The picture I attached is 4365 crossover.

Have no idea how it’s compared to 4367. It’s very normal components, nothing fancy... but that is probably the case for most crossovers.

[JeffW]

it is true that 4365' crossover is not as good as 4367,not to mention K2 or E2,why?

You are the one who keeps saying the 4365 crossover is not any good, yet have yet to articulate what the perceived problem with the crossover is.

Point blank: What is the issue with the quality of the 4365 crossover? And I don't want a reply of "it's not good", give specific points relating to the issues with the crossover.

[martin_wu99]

You are the one who keeps saying the 4365 crossover is not any good, yet have yet to articulate what the perceived problem with the crossover is.

Point blank: What is the issue with the quality of the 4365 crossover? And I don't want a reply of "it's not good", give specific points relating to the issues with the crossover.

Some 4365 users complained that 4365's crossover is not as good as 4367's,i don't believe it,JBL should have same QC standard ,that is the whole thing.:blink::confused:

[baldrick]

There are fine components in 4365-crossover, as far as I know.
The problem, to me, is that the HF part has no lowpass-filter. This causes HF to play the same register as UHF all the way up to 20KHz. This causes comb-filtering. 476Mg HF-driver does not roll off on its own.
There is no proper acoustic crossover between HF and UHF.
This makes 4365 sound and measure too bright for my taste. Listen on high volume and ears get fatigue after a while.

But if this particular discussion should continue, do it in a new thread.

I'm no expert understanding passive XO, but doesn't it seem like DD66000 is designed the same way without no LP on MF driver?


83318

I can't imagine that GT did create a bad designed crossover for these speakers.

[JeffW]

Some 4365 users complained that 4365's crossover is not as good as 4367's,i don't believe it,JBL should have same QC standard ,that is the whole thing.:blink::confused:

What exactly is the issue? Again, "not as good" is not a very detailed description. What's "not as good" about it?

[Ian Mackenzie]

My understanding is the uhf device has an acoustic crossover point of about 15 khertz.

If your over 50 you will be lucky to hear that. The uhf driver is to please the Japanese market. That is why the horn is run all the way out.

As for the comb filter effects it’s subjectively not an issue at these frequencies.

[smooth dancer]

What exactly is the issue? Again, "not as good" is not a very detailed description. What's "not as good" about it?



I think the original crossover is good as it is. I have replaced some resistors and caps as you can see on the pics, and I feel that it maybe was a small upgrade. Just after the modification I was convinced it was a step forward, but after a while I’m not so shure. Maybe because I’m getting used to it ?

( I think that Valhalla internal and external speaker cables, was a bigger upgrade)

[martin_wu99]

I think the original crossover is good as it is. I have replaced some resistors and caps as you can see on the pics, and I feel that it maybe was a small upgrade. Just after the modification I was convinced it was a step forward, but after a while I’m not so shure. Maybe because I’m getting used to it ?

( I think that Valhalla internal and external speaker cables, was a bigger upgrade)
Looks good,many persons upgraded their crossover this way.

[tom1040]

I have no complaints with my pair of 4365's......:dont-know:

[martin_wu99]

I have no complaints with my pair of 4365's......:dont-know:
That's great,just enjoy it,if you replace its 045Ti with 045Be,it will be S9900

[tom1040]

That's great,just enjoy it,if you replace its 045Ti with 045Be,it will be S9900


I good with them as they are-thanks.

[Ian Mackenzie]

There are fine components in 4365-crossover, as far as I know.
The problem, to me, is that the HF part has no lowpass-filter. This causes HF to play the same register as UHF all the way up to 20KHz. This causes comb-filtering. 476Mg HF-driver does not roll off on its own.
There is no proper acoustic crossover between HF and UHF.
This makes 4365 sound and measure too bright for my taste. Listen on high volume and ears get fatigue after a while.

But if this particular discussion should continue, do it in a new thread.

Can you elaborate on your listening environment and your listening position.
I raise this as the acoustics can contribute to the perception of brightness.

If in fact you feel the measured and subjective concerns correlate then consider some EQ. If you have a digital signal path this is not too difficult. This assumes modifications to the room acoustics or changing the loudspeakers position is not an option.

No one loudspeaker is going to satisfy all tastes all the time. Try disconnecting the uhf device.

Lastly it’s possible that the loudspeakers are analytical to the point they are exhibiting the characteristics of other components in your system such as your power amplifiers. Cables can also have an impact on the voicing of a system overall.

I bring these points up because sometimes there are one or more contributing factors.

[Ian Mackenzie]

I have listened to the 4365 although not for an extended period.

On the crossover parts in a system at this level the parts are selected for the system as whole to function and perform to deliver the end result. In the diy space you have flexibility to change out parts for alternatives. The results maybe different but not necessarily better. Unfortunately more transparent parts show up more deficiencies in the signal path and recordings.

If you were involved in the development of the loudspeaker and you were familiar with the acoustics and amplifiers and other components used and you continued to use the system under these conditions then it’s unlikely you will have any concerns.