JBL 4348 - Horns 435AI repair info needed

[oldbrowndog]

Hi All, i really could use some help finding the right avenue to go down regarding a dead 435AI driver in my 4348 monitors, showing 0 resistance & no sound.
Who in the world is the best speaker driver repairer for JBL ? For this kind of rare driver i need the best, please recommend where it could be sent.

[Ian Mackenzie]

Pm sent for local options

[rusty jefferson]

Just saw your other post. That is a drag. I'm sure you're disappointed. Good luck getting it straight. :)

[Robh3606]

Keep us posted!

Rob :)

[oldbrowndog]

yessir! Will do, still in motion..



Keep us posted!

Rob :)

[oldbrowndog]

Hi all, im having difficulty with the repair option.. So ive started to investigate the option of replacing with a similar spec JBL driver. I have tried the JBL 2435HPL in its place which seemed to have very similar specs, but the sound was muted and very low. I suspect the 4348 crossover doesnt suit them.. I did try manipulatiing the crossover pot for the mid horn on the front of the 4348, but yeh no joy.. it sound dull & very low compared to the 4348 with the one working 435AL driver i have.

So i am back to the beginning, short of finding a replacement 435AL driver I need a solution and I wonder if anyone here can tell me does the 435Be have the same specs as the 435AL? It looks exactly the same so i wonder if the Be is just a retagged version of the Al (or vice versa), if so it would be the perfect choice..?

[Ian Mackenzie]

Referring to the attachments below a guesstimate is to transpose the SE9800 horn filter schematic and try your 2435HPL. Some adjustments to the capacitor value at the input of the filter may be required.

You can buy the parts from Wes Components or Speaker Bug in Aust then build out the schematic and bypass the 4348 horn filter. Layout the construction just like the schematic and it will work fine. Hot melt the parts to a strip of 12 mm ply or mdf. Hot melt gun from Jaycar.

Without detailed measurements this is a good starting point.

To reach an advanced level of response flatness with the 4348 horn and baffle location/ dimensions consider Downloading REW software and buying one of the recommended mics with calibration software. You can objectively dial in the measurements empirically just like JBL do with all their commercial loudspeakers. This ultimately is the preferred approach to so called simulation software that attempts to predict the response prior to building out the crossover. The SE9800 HF filter is a good starting point and accounts for the impedance magnitude and phase of the driver. Some variations are to be expected on the 4348 HF horn.

The voltage drives are for reference only as they are used on different horns but they are both CD horns. You can see the 4348 filter provides more attenuation of the lower frequencies than the SE9800 schematic and this is mostly likely why your 2435HPL sounds muffled.

Give it a try and take it from there.

I am off the tools ⚒️ in far north QLD for a little while so l can’t give you more specific assistance.

[Earl K]

Hi all, im having difficulty with the repair option.. So ive started to investigate the option of replacing with a similar spec JBL driver. I have tried the JBL 2435HPL in its place which seemed to have very similar specs, but the sound was muted and very low. I suspect the 4348 crossover doesnt suit them.. I did try manipulatiing the crossover pot for the mid horn on the front of the 4348, but yeh no joy.. it sound dull & very low compared to the 4348 with the one working 435AL driver i have.

So i am back to the beginning, short of finding a replacement 435AL driver I need a solution and I wonder if anyone here can tell me does the 435Be have the same specs as the 435AL? It looks exactly the same so i wonder if the Be is just a retagged version of the Al (or vice versa), if so it would be the perfect choice..?

Really, your experience is just the opposite of what I would expect to encounter from a properly working 2435h driver ( substituted for a 2431h ).

This "Be" driver is noted to be a bit louder and clearer sounding than the aluminum diaphragmed 2431h ( 435Al ) .

I suspect its ( 2435h ) diaphragm is either after-market Chi.Com junk or there's something wrong with the OEM diaphragm presently in it ( +/or, the ferrofluid in the gap has dried-out and is locking the voice-coil within a mucky death-grip ).

You should follow Ian's directions and download REW and run some tests on that driver ( build the recommended impedance jig and capture a raw impedance curve for that 2435h ).
- It should look something like this;

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=7503&stc=1&d=1116001274
Used 2435h drivers of unknown provenance need extra attention paid to them to make sure they are performing ( at least close ) to spec.

Additionally, I would ( if mine ) open it up and remove all the old ferrofluid within the gap ( using thin card-stock and something absorbent wiped/pushed around the gap ) .

These drivers don't need any ferrofluid to operate within a home audio environment ( SR is a different story ).

Years back ( almost 20years now ) I bought 16 used 2431h drivers from eBay. Each one that was opened ( for inspection ) has had the ferrofluid ( quite obviously cooked and ) splattered around the inside of the 3" aluminum dome.
- Ferrofluid doesn't easily leave the gap area unless internal temperatures within that gap have climbed to excessive heights.

:)

[Robh3606]

Additionally, I would ( if mine ) open it up and remove all the old ferrofluid within the gap ( using thin card-stock and something absorbent wiped/pushed around the gap ) .These drivers don't need any ferrofluid to operate within a home audio environment ( SR is a different story ).:)

That's not correct. Take a look at Doug Buttons comments in Ian's attachment. Middle paragraph.


Rob :)

[Earl K]

That's not correct. Take a look at Doug Buttons comments in Ian's attachment. Middle paragraph.


Rob :)


I prefer the sound of my 2431h(s) without ferrofluid in the gap ( especially "cooked" ferrofluid ).

So, I'll have to disagree with those who audibly prefer it's presence.

:)

[Ian Mackenzie]

Failing the effort of a new filter simply pop in a replacement diaphragm

https://www.simplyspeakers.com/jbl-replacement-speaker-diaphragm-d8r2431.html

You would need to contact the supply to confirm it will fit.

If you end up replacing the diaphragm try putting a polymer loudspeaker protection component in series with the crossover to future damage from power amplifier clipping. They have a positive temperament coefficient which increases the temperature with signal current above a threshold value and the series dcr.

[Earl K]

Hi all, im having difficulty with the repair option.. So ive started to investigate the option of replacing with a similar spec JBL driver. I have tried the JBL 2435HPL in its place which seemed to have very similar specs, but the sound was muted and very low. I suspect the 4348 crossover doesnt suit them.. I did try manipulatiing the crossover pot for the mid horn on the front of the 4348, but yeh no joy.. it sound dull & very low compared to the 4348 with the one working 435AL driver i have.

So i am back to the beginning, short of finding a replacement 435AL driver I need a solution and I wonder if anyone here can tell me does the 435Be have the same specs as the 435AL? It looks exactly the same so i wonder if the Be is just a retagged version of the Al (or vice versa), if so it would be the perfect choice..?

@oldbrowndog

The current problem might just as easily be that the HF portion of the crossover ( within the bad speaker ) is also cooked .

Whatever event blew-up your bad 435Al could just as easily stressed the network right out of spec ( making the sound of anything now connected to it dull + muted ).

I'd recommend installing your 2435HPL into ( your known ) properly working 4348 ( iow; this "dull" 2435hpl now needs to be checked out on a properly working speaker ).

Next, install the good 435Al into the 4348 that's had all the problems.

Now compare to see which channel has the "Dull + Muted" sound .

This will help determine whether the "bad 4348" also has a properly working crossover.


:)

[Ian Mackenzie]

One of the diaphragms is open circuit.

[Earl K]

One of the diaphragms is open circuit.


The way I read his posts is that he has one working 435Al and one ( iffy//sketchy//unknown quality ) 2435hpl and a open-circuit 435Al ( for a total of 3 HF drivers ) .


Whatever,


To kill a 435Al takes at least 40 watts sustained power ( which a horn driver within a home setting should never ever really see ).

Still. there's a blown driver here and some untoward event has caused it's failure ( implying the driver did in fact see more > than 40 watts ).

So, here's a power dissipation chart for the HF portion of the 4348 network ( with a full 40 watts applied ).

89525

One can see the stress that the 7.5R resistor is operating under ( represented here by the black line in the above chart ).

The initial LC components within this horn circuit form quite a resonate circuit ( peaking at around 2500hz ).
- This resonance ends up drawing more than the applied 40 watts.

89526

I don't think JBL used 50 watt resistors in that location .

:)

[Ian Mackenzie]

We talk about it a month or so ago on pm. The driver is definitely blown. The problem is how to repair the driver or implement new horn crossover filter.

[Robh3606]

I prefer the sound of my 2431h(s) without ferrofluid in the gap ( especially "cooked" ferrofluid ).

So, I'll have to disagree with those who audibly prefer it's presence.

:)

I understand your preference but when the drivers designer says it should be there that's information the OP should have and he can make his own decisions.

Rob:)

[Earl K]

I understand your preference but when the drivers designer says it should be there that's information the OP should have and he can make his own decisions.

Rob:)


Agreed!

:)

[oldbrowndog]

Thanks all for the input, regarding your post first Ian, that seems like an appropriate solution, but well beyond my capabilities in terms of technical knowledge.. and since we are in heavy lockdown getting anyone in to help is a no go.

For clarity, i have tested the 2435Hpl in both speakers (i have a pair), & both produce the dull muted sound.. (The 2435 return an impedance of 4.0 (both of them).
Ive also tested the one working 435AL & its performing well in both speakers, so its not a blown crossover.

The reason the 435AL that is broken is not working is likely twofold, open circuit diaphragm, but also (according to a JBL tech in japan) the magnets are coated in neodymium and in this particular model the coating is known to not last very well, and peel off the magnet, probably causing the short in the diaphragm. I believe that is the case here (perhaps as these speakers lived in sydney & singapore the weather being a bit humid caused this to happen.. at least to one). So replacing the diaphragm would be a disaster otherwise i would have simply done that before jumping on here to ask questions.

So, since i am not technically able to work with the crossovers to suit the 2435 and more to the point i'd like to keep these as original as possible, i was hoping that the 435Be which looks so similar in design and shape to the 435AL might be the answer for a plug & play solution..
I had hoped this might be the case with the 2435hpl's but it definitely was not, so yes perhaps the pair are also damaged, or perhaps the crossover in the 4348 simply doesnt suit the 2435 (which is my assumption).

Again thanks for all the input.

[Earl K]

Hi oldbrowndog,

Where did you buy those 2435hpl's from ?

FYI;

The "PRO" 2435hpl model more or less equates to the "CONSUMER" 435Be model ( both have Beryllium diaphragms, it's just that the 435 designation also means the diaphragm has a coating of aquaplas )

The 2431h more or less equates to the 435Al ( since both have Aluminum diaphragms , the 435Al has an aquaplas coating on the diaphragm while the 2431 doesn't).

Neodymium (https://en.wikipedia.org/wiki/Neodymium_magnet) is more prone to corrosion effects ( especially if it's the sintered type ) if/when the surface plating breaks and exposes the magnetic slug to air.

Normally, the slug is protected from the elements by encasing the slug in multiple passes of nickel type plating.


If the plating fails the neodymium magnet core will eventually corrode, turning back into a pretty useless powder.

https://upload.wikimedia.org/wikipedia/commons/thumb/a/a9/NdFeB_corrosion.jpg/1280px-NdFeB_corrosion.jpg

All four driver models mentioned here share similar motor/magnetic structures. What I don't know is whether they are of a sintered or bonded magnet type.

Your two 2435hpl motors could also be losing their magnetism > if so, that would certainly explain your sonic impressions of them if the neodymium is degrading/corroding.

Those 2435hpl's really need to be properly tested.

Many of us are in the same boat due to owning many of these variants .

Chris Hagen ( a current speaker designer at Harman ) even made an off-hand comment some years back about returning to designs using ferrite magnet drivers > now that statement has a whole new perspective .

:)

[Ian Mackenzie]

Hi Earl,

Your post was very insightful and explains failures in the 4344mk2 which used a neo driver.

Do you think in your experience the gaps can be cleaned out and a replacement diaphragm and oil installed?

To old browndog,

If you are interested l could put a mock up filter together for you to try out with your 2435s. I can obtain the parts. I could also measure your drivers on one of the horns remotely and match the crossover to suit the 2435s.

The other options of an 0435BE are very expensive and they are incredibly rare. I would not jump to that.

Using an alternative 1.5 inch driver is an option however the driver would need to fit physically in the space and have the same bolt pattern. RCF, B&C snd 18Sound and others make excellent drivers.

I would suggest waiting till Earl responds on cleaning out the gaps before considering your next steps.

Ian

[Earl K]

@oldbrowndog,


The reason the 435AL that is broken is not working is likely twofold, open circuit diaphragm, but also (according to a JBL tech in japan) the magnets are coated in neodymium and in this particular model the coating is known to not last very well, and peel off the magnet, probably causing the short in the diaphragm. I believe that is the case here (perhaps as these speakers lived in sydney & singapore the weather being a bit humid caused this to happen.. at least to one). So replacing the diaphragm would be a disaster otherwise i would have simply done that before jumping on here to ask questions.

- You heard this wrong. The plating///covering surrounds the magnet as a form of environmental protection ( not the other way around ) .

Hmm,

I've ( also ) conflated and mis-contrued Chris Hagen's words regarding Ferrite vs Neodymium.

I believe this is the video that triggered my mis-direction.


https://youtu.be/BrTQiGiN-ro


Do you think in your experience the gaps can be cleaned out and a replacement diaphragm and oil installed?

Ian, I don't have an informed opinion as to whether or not one can save a neodymium magnet ( once the protective covering has started to break-down and flake off ).

OTOH, my understanding is that there should be a minimum of 2-3 platings ( and hopefully more ) if the magnet is of the sintered type, so losing only the outer-most covering might not be catastrophic ( if dealt with in time before rust sets in ).

If the delamination process stabilizes ( or is stabilized/treated ) after the first layer of covering//plating has dis-integrated > then "YES" , maybe one could simply clean out the gap and install a new diaphragm ( along with ferrofluid ) .
- OTOH, if VC failure was actually due to metallic ( plating ?? ) particles present in the gap shorting the coil then there's little guarantee it won't re-occur.


I think it's worth noting at this point that the "JBL tech-in-Japan" didn't think that re-diaphragming was a viable approach.

OTOH, one can always look to slow down the degradation process by applying some other protective covering ( I'm thinking along the lines of a "Cold Galvanizing Compound" (https://www.google.com/search?q=Cold+Galvanizing+Compound&rlz=1C1CHBD_enCA823CA823&oq=Cold+Galvanizing+Compound&aqs=chrome..69i57&sourceid=chrome&ie=UTF-8) as found in my link ).

89529

I have no idea about the adhesion properties for these sort of products when applied onto any existing zinc plating.

BTW, I just un-boxed 8, 2431h ( used eBay specials ) > that never made it into general use.

3 of 8 now have the outer plating layer letting go ( all in various stages of delamination ). I'll look at the gaps at some point.

Here's the worst example.

8953089531

This actually looks more like silver paint that's giving up the ghost ( perhaps a bit of fraud was perpetuated towards JBL by their magnet supplier of the time ).


All 3 have what appears to be a batch number of "92N-JBF" ( all 3 sport a silver colored plating > rather than the more typical black colored plating ).

If I were to care about saving this example, I would first test it for output characteristics and then try the previously mentioned cold galvanizing treatment onto the remaining plating ( don't hold your breath for this to happen though ).


Important quote ( reality check ) by sebackman ( for those who missed it the first time out ).


Another topic I have not seen mentioned here at LHF is Neodym magnet rot.

The older JBL drivers used Neodym magnet material that also tend to corrode/rot in certain environments.

This materializes as small magnetic fragments in the coil gap and regardless how many times you clean they keep coming back.

This means that the magnet is beyond salvage. I have had this on a few 2450SL/2451 drivers that had to be canned.

I have also had it on a few older Neodym woofers like the 1400PRO (currently 3 dead basked in the shop). JBL knows of the problem and has also replaced a bunch back when.

:):(:)

[Robh3606]

Thanks all for the input, regarding your post first Ian, that seems like an appropriate solution, but well beyond my capabilities in terms of technical knowledge.. and since we are in heavy lockdown getting anyone in to help is a no go.For clarity, i have tested the 2435Hpl in both speakers (i have a pair), & both produce the dull muted sound.. (The 2435 return an impedance of 4.0 (both of them).Ive also tested the one working 435AL & its performing well in both speakers, so its not a blown crossover. The reason the 435AL that is broken is not working is likely twofold, open circuit diaphragm, but also (according to a JBL tech in japan) the magnets are coated in neodymium and in this particular model the coating is known to not last very well, and peel off the magnet, probably causing the short in the diaphragm. I believe that is the case here (perhaps as these speakers lived in sydney & singapore the weather being a bit humid caused this to happen.. at least to one). So replacing the diaphragm would be a disaster otherwise i would have simply done that before jumping on here to ask questions.So, since i am not technically able to work with the crossovers to suit the 2435 and more to the point i'd like to keep these as original as possible, i was hoping that the 435Be which looks so similar in design and shape to the 435AL might be the answer for a plug & play solution.. I had hoped this might be the case with the 2435hpl's but it definitely was not, so yes perhaps the pair are also damaged, or perhaps the crossover in the 4348 simply doesnt suit the 2435 (which is my assumption).Again thanks for all the input.


Hello Oldbrowndog

There is a measureable difference between the two drivers and when I built my Array 1400 DIY I used the beryllium drivers and had to make a value change in one of the inductors from the stock schematic. The Be puts out more energy from say 2-10k and rolls off faster above 10K. There is also a bit of gain sensitivity wise. So it should not sound muted.

What the tech said?? They are not coated in Neo they are neo magnets. They have a paint or epoxy coating which has been know to shed. The voice coil is completely encapsulated in the kapton surround so the coil cannot be shorted by loose material. Another possible issue is that the magnet pole piece shifted either from a bonding failure or shock as in it was dropped. This is certainly possible with the 2435's as I actually dropped one and it jammed the VC in the gap so really muted output. I was able to fix it and there is another recent thread that could help if this is the case. I would send them back if you could.

Have you opened the dead 435Al?? You should be able to get a replacement 2431 diaphragm. It won't be coated but it as close as you are likely to get. If it is jammed because of a shifted pole piece when you get the screws out it will not lift out.

Normally when you open the drivers the clips that make the connection to the terminal push pins hold the diaphragm in the cover and you have to carefully pry the diaphragm free of the clips. The back cap should come right up in the dead 435Al as long as it's just an open VC .

If it's jammed you can order a new 2431 from them as well as long as they will ship to you.

Rob :)

https://reconingspeakers.com/product/jbl-2431-d8r2431-diaphragm/

[Earl K]

Here's a good web-page on the various coatings // platings applied to sintered Neodymium magnets.

Magnet Plating and Coating Options (https://www.amazingmagnets.com/t-plating_options.aspx)

Here's an example pic//chart.

8953289533

I'm hoping that the "good" 2431h's that I have use one of the two black coatings seen above.

I'm also assuming that the "bad" 2431h's that I just displayed pics of have the most common ( cheapest ) Nickel cladding ( Ni-Cu-Ni ).
- The flakes shown in my pic are attracted to the internal magnet ( so that rules out the flakes being zinc plating ).

89534

Conclusion ??

One wants to own neodymium drivers having black epoxy enclosed magnets ( like the example seen in the left foreground might imply ).

89535



:)

PS; Rob's 2435h repair thread ( click the first pic );

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=16911&stc=1&d=1153262338 (http://www.audioheritage.org/vbulletin/showthread.php?11490-How-to-ruin-your-day)http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=16909&stc=1&d=1153262280

[Earl K]

Hey Rob,


I tried an epoxy, got the shim out and just watched the top plate creep over to the pole in slow motion. I took a chance and used medium viscosity super glue. It worked like a charm.

Regarding your successful repair ;

Which epoxy didn't work for you ??

Was it the 30 minute type ?

Did you let it fully cure before removing that ( great looking ) shim ?

Did you clean off this failed epoxy glue before the successful supergluing ?

Thanks :)

[Robh3606]

Hello Earl

Hmm that was a while ago. This may not be exact from what I can remember I used a 5 minute epoxy and removed it before using the supper glue. The pole piece shifted before it was fully cured so I was able to get it apart and basically clean it up. The epoxy was very thick and viscous probably used too much in comparison to the super glue gel. I pulled the shim when it was hardening up and not fully cured. I was concerned the shim could become jammed. With the super glue gel it was just a thin line and it bonded almost instantly. I followed the original glue line scar on the magnet.

Hello Oldbrowndog

Here are the measured differences between the 2431 vs 2435 of the Array 1400 horn. Red is the 2431 the other two are the 2435's I used in the build. You can see where the differences are in sensitivity and areas where the outputs are different.

Rob :)

[Earl K]

Hello Earl

Hmm that was a while ago. This may not be exact from what I can remember I used a 5 minute epoxy and removed it before using the supper glue. The pole piece shifted before it was fully cured so I was able to get it apart and basically clean it up. The epoxy was very thick and viscous probably used too much in comparison to the super glue gel. I pulled the shim when it was hardening up and not fully cured. I was concerned the shim could become jammed. With the super glue gel it was just a thin line and it bonded almost instantly. I followed the original glue line scar on the magnet.

Hello Oldbrowndog

Here are the measured differences between the 2431 vs 2435 of the Array 1400 horn. Red is the 2431 the other two are the 2435's I used in the build. You can see where the differences are in sensitivity and areas where the outputs are different.

Rob :)


Thanks for the update Rob ( it's much appreciated ! ).

Yes, great to see your comparison of the 2435H vs the 2431H ( I've been hammering away at this audible discrepancy since getting involved in this thread ).

>> Again, a simple swap using the 2435H vs 435Al should have resulted in a reaction that was just the opposite of what oldbrowndog reported.

His used pair of 2435H need some serious testing done on them to determine their relative health.


:)

[Robh3606]

Hello Earl

Your welcome! I am thinking that they were damaged in shipping and the pole pieces shifted pinning the voice coil. That would account for the muted response. Just a guess on my part though.

Rob:)



Thanks for the update Rob ( it's much appreciated ! ).

Yes, great to see your comparison of the 2435H vs the 2431H ( I've been hammering away at this audible discrepancy since getting involved in this thread ).

>> Again, a simple swap using the 2435H vs 435Al should have resulted in a reaction that was just the opposite of what oldbrowndog reported.

His used pair of 2435H need some serious testing done on them to determine their relative health.


:)

[oldbrowndog]

At this point its probably best to insert some photos of both the 2435 & the 435AL (which i have opened up).

Ian, when you are back in town (assuming we will then be out of lockdown) and assuming i havent found a fix for this I would be very appreciative to take up your offer and happy to pay for your time.

These are pictures of the 2435 which as mentioned has an impedance of 4.0 (the pair are matched).. i havent opened these up as yet.
89541
89542


& these are pictures of the non-working 435AL ( i have not opened the working one..). Note: I will need to include 2 more pictures in the next post as 5 is the max per post.
The impedance measures 0, the short on the diaphragm is very hard to spot, so hard that i cant see anything that indicates damage.. The magnet as you can see is peeling.
If it simply were that i could recoat the magnet and buy a replacement 2431 diaphragm, that would be a fantastic solution..
89543
89544
89545

According to the technician I spoke with in Japan there were a few possibilities with the repair of this non functional 435AL.
In all instances the quote for repair did seem high, but then the Japanese also usually do fantastic work, but i include this information below to show you what the insights were.
At the worst case i could box up & send both 435AL to them for repair/inspection/matching, and the first 2 quote dollar amounts would be borderline worth it if i can get both in working condition again.. but if its the 3rd option thats a tad to expensive for my taste.

The technician did intimate that the magnet coating being in the condition it was (via my pictures) that it may be the 3rd option.. hence my reluctance to send them as yet.

Japan Tech Quotes
[ In case possible to repair the disconnection point ]
1 x 25,000 JPY

[ In case impossible to repair the diaphragm ]
2 x 39,800 JPY = 79,600 JPY

[ In case there are issues on the Neodymium magnet coating and rust exists ]
Either of above + 2 x 185,000 JPY (demagnetizing 40,000 JPY, making
new magnets 90,000 JPY, remagnetizing 40,000 JPY, Voice coil gap
adjustment 15,000 JPY)

[oldbrowndog]

2 more pictures as mentioned of the diaphragm connection points on the malfunctioning 435AL
89546
89547

[Robh3606]

Are those tinsel leads touching the ring? That could short them they don't look like they are coated there.

Rob:)

[oldbrowndog]

Are those tinsel leads touching the ring? That could short them they don't look like they are coated there.

Rob:)

No they are not touching, i should have taken a shot from above, but no they are about 2-3mm away from the ring.

[Earl K]

@oldbrowndog,

Thanks for the pics.

All 3 magnets you've pictured are badly rusting ( the 2, 2435H are the worst and beyond help IMHO ).

The Japanese pricing is typical ( for them ). IOW, prices that are much higher than the rest of us would entertain paying.

Personally, I would simply buy a new pair of 2431H ( from the link that RobH previously provided ) , then install the larger ( interchangeable ) backcaps ( of your existing 435Al drivers ) and call it a day .

Click this pic for the link;

https://reconingspeakers.com/wp-content/uploads/2011/11/2431H-3.jpg (https://reconingspeakers.com/product/jbl-2431h-driver/)

:(

PS 1; Again, I feel these 2435H magnets are beyond redemption ( the Be diaphragms may well be salvageable////re-useable in a pair of new magnets >> maybe this is a job for Ian ) .
- This example's magnet has been rusting for a while .

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=89542&d=1631504066

PS 2; The "bad" 435Al might also possibly be salvageable >> if the gap can be cleaned of any debris in it and then possibly a new protective layer of thin epoxy laid into the bottom of the gap ( as a barrier to further migration of the magnet's cladding into the gap area ) .
- This would be a major "Science Experiment" ( due to the previous existence of ferrofluid there ) with the whole exercise possibly amounting to nothing more than a futile pain in the arse (with no real long term benefit ).

PS 3; In case it hasn't translated yet, all 4 models ( 435Be, 435Al, 2431h, + 2435h ) use a single type of interchangeable magnet. So that opens up your replacement options.

[oldbrowndog]

@oldbrowndog,

Thanks for the pics.

All 3 magnets you've pictured are badly rusting ( the 2, 2435H are the worst and beyond help IMHO ).

The Japanese pricing is typical ( for them ). IOW, prices that are much higher than the rest of us would entertain paying.

Personally, I would simply buy a new pair of 2431H ( from the link that RobH previously provided ) , then install the larger ( interchangeable ) backcaps ( of your existing 435Al drivers ) and call it a day .

PS 2; The "bad" 435Al might also possibly be salvageable >> if the gap can be cleaned of any debris in it and then possibly a new protective layer of thin epoxy laid into the bottom of the gap ( as a barrier to further migration of the magnet's cladding into the gap area ) .
- This would be a major "Science Experiment" ( due to the previous existence of ferrofluid there ) with the whole exercise possibly amounting to nothing more than a futile pain in the arse (with no real long term benefit ).

PS 3; In case it hasn't translated yet, all 4 models ( 435Be, 435Al, 2431h, + 2435h ) use a single type of interchangeable magnet. So that opens up your replacement options.

Thanks Earl, great and very useful info, seems like a feasible option to buy the 2431 and use that in its place, assuming you are 100% that this is the correct option for the 435AL?
I want to be doubly sure as this thread mentions the matching model is actually the 2430, but it could be incorrect?
The post is from 'vintage tubes' about 2/3 down the page & regarding the 4348 speaker, reads:

The bass driver is the new 1500Fe which uses the same basket as the 1500AL with a ferrite motor. Midbass is handled by the 10" pro 2251J which uses a differential drive motor. The midrange compression driver is the 435AL which is a consumer conversion of the 2430. This is the same motor as the 2435/435Be but uses an aluminum diaphragm instead of beryllium. The acoustic lens is gone, replaced by a small biradial horn. The UHF is the same 045Be from the S9800."

https://www.audioaficionado.org/archive/index.php/t-5637.html

Just want to be extra sure as if i go down this path and get the wrong driver im back to square one..

Assuming one of them is the correct model i would also assume:
1. no modifications to the crossover needed whatsoever?
2. how do u think the sound might differ from the 435AL?

[Earl K]

Sorry oldbrowndog :( .

I'm not 100% sure of anything ( regarding the "Plug-And-Play" substitution of 2431h drivers for your 435Al ).

It's really all just best guess since I don't own any variants of the 435 series ( 435Be or 435Al ) .

You'll need to continue to research this ( and hopefully others who have had those 435 drivers will offer-up their opinions and experiences so that you can move forward ).

:)

[oldbrowndog]

Sorry oldbrowndog :( .

I'm not 100% sure of anything ( regarding the "Plug-And-Play" substitution of 2431h drivers for your 435Al ).

It's really all just best guess since I don't own any variants of the 435 series ( 435Be or 435Al ) .

You'll need to continue to research this ( and hopefully others who have had those 435 drivers will offer-up their opinions and experiences so that you can move forward ).

:)

Ahh ok great good to know.
Yes its a bit of a mystery the old 4348.
I had hoped to simply buy another 435AL and not need to worry about all this but that hasn't proved easy, so its onto this search for info.
Many thanks for your input so far.

[Robh3606]

Are there any JBL Synthesis dealers in Australia?? The SAMHF is still current on the US site. The 435AL is used in that system. Maybe they could get you a spare driver?

Rob :)


https://www.jblsynthesis.com/products/loudspeakers/type/lcr-oudspeakers/

[Ian Mackenzie]

Yes.

Generally they only support product sold under warranty in Australia.

However it’s worth a shot.

PS. The problem is not selling it but obtaining the product. The installer market is quite strong here. For a while JBL weren’t able to supply…like 2 years so dealers went to other brands.

[oldbrowndog]

Are there any JBL Synthesis dealers in Australia?? The SAMHF is still current on the US site. The 435AL is used in that system. Maybe they could get you a spare driver?

Rob :)


https://www.jblsynthesis.com/products/loudspeakers/type/lcr-oudspeakers/

Wow, now thats a good lead, i had no idea they were still in production, you'd think they'd be able to spare one if that were the case for such a great speaker like the 4348.
but then..... anyway let you know thanks.

[Mr. Widget]

Are there any JBL Synthesis dealers in Australia?? The SAMHF is still current on the US site. The 435AL is used in that system. Maybe they could get you a spare driver? Yes, the SAMHF still shows up on my dealer list... and if JBL were like any quality business who cared about their customers I'd say they must have stock for repairs. But, JBL has shown us over the years that they have chosen to take a different path.

It is certainly worth a shot though.


Widget

[oldbrowndog]

Yes, the SAMHF still shows up on my dealer list... and if JBL were like any quality business who cared about their customers I'd say they must have stock for repairs. But, JBL has shown us over the years that they have chosen to take a different path.

It is certainly worth a shot though.


Widget

Well your right about them not being very helpful.. Tried contacting them to no avail.
I did notice the model in the SAM1HF seems to be a 435AL-1 which may well differ from the 435AL?
Which puts me back in a similar position to finding a correct match for the 4348 in any case.

[Ian Mackenzie]

Just in

From a LHS member in Europe:

“Greg Timbers told me for few years ago at you can use 435Al-1 instead of 435Al in 4348 and 4338. 435Al-1 are smoother than 435Al because of the Aquaplas coated diaphragm.
435Al and 2431 have the same diaphgram only different back cap.@

[Earl K]

Just in

From a LHS member in Europe:

“Greg Timbers told me for few years ago at you can use 435Al-1 instead of 435Al in 4348 and 4338. 435Al-1 are smoother than 435Al because of the Aquaplas coated diaphragm.
435Al and 2431 have the same diaphgram only different back cap.@

@Ian,

That's interesting.

Who's words are you quoting ?

So the 435Al doesn't have an aquaplased diaphragm ? I assumed it did.

Oldbrowndog ought to remove his non-working one to confirm the lack of aquaplas.

:)

[Robh3606]

Well that is certainly good news as the 2431's diaphragms are readily available. Looking back at the pictures I don't see aguaplas on the dead diaphragm. It should look flat dark grey almost flat black. That means he can just order a 2431 and switch back caps.

Rob:)

[oldbrowndog]

Just in

From a LHS member in Europe:

“Greg Timbers told me for few years ago at you can use 435Al-1 instead of 435Al in 4348 and 4338. 435Al-1 are smoother than 435Al because of the Aquaplas coated diaphragm.
435Al and 2431 have the same diaphgram only different back cap.@

Thanks Ian, well if Greg said it was so i think thats good enough verification. The question then remains do i search out 2 x 435AL-1 from JBL synthesis for matching mid horns.. Or just buy the 2431 & use it alongside the working 435AL i have... (I inferred that both the magnet & diaphragm in the 2431 exactly match the 435AL?)

What do you think would be the best solution?

[Ian Mackenzie]

I will see if l can get hold of a Greg and ask him.

Will email you when l have an update.

I should have done that in the first place rather than see it turn into a soap opera..Lol

[oldbrowndog]

I will see if l can get hold of a Greg and ask him.

Will email you when l have an update.

I should have done that in the first place rather than see it turn into a soap opera..Lol

That is much appreciated kind sir, and i don't mind starting a bit of a 435 dynasty series..;)

[Ian Mackenzie]

That is much appreciated kind sir, and i don't mind starting a bit of a 435 dynasty series..;)


“Ian,

Ari is correct, you can substitute the 435Al-1. There will be a small difference in response above maybe 6 kHz with the Al-1 being smoother and a little lower in output.

I am surprised the magnet shedding would cause no output. It can cause massive buzzing, but there may be something else wrong with the diaphragm.

Regards,

Greg”

[oldbrowndog]

“Ian,

Ari is correct, you can substitute the 435Al-1. There will be a small difference in response above maybe 6 kHz with the Al-1 being smoother and a little lower in output.

I am surprised the magnet shedding would cause no output. It can cause massive buzzing, but there may be something else wrong with the diaphragm.

Regards,

Greg”

Thanks Ian, really appreciate that.. Now to either find some 435AL-1 ... or repair that diaphragm.
If i thought it wouldn't potentially damage the working diaphragm i have in the other 435AL i'd take it out and test it on the non working one & thereby confirm the magnet is still ok..
I did note that there is some mention of repairing the diaphragm in this blog so that may be a worthy cause as finding a replacement is far from likely.
http://blog.kenricksound.com/2021/02/jbl-project-k2-s9800se-jbl-435be.html