Good morning, I ask you for help to restore to the best of JBL K2, unfortunately they have decentralized 435BE drivers and in my opinion they are useless, even the diaphragms are badly put only one diaphragm is recoverable, the other is gone. I am thinking of replacing Driver and Diaphragm with a new pair but being the 435Be not found I have to settle for mounting either 435Al-1 or alternatively 2435HPL. I ask if replacement is possible, do they mount on the horn?
Welcome to the forum, I saw your other thread and it sounds like you have a nice JBL collection.
Unfortunately the JBL of today is pretty poor at supporting their products. You used to be able to buy repair parts to support 50 year old JBLs, today it can be difficult to even get them repaired under warranty. I am not sure if there are any current JBLs that use the 435Be. I don’t think they are still producing that driver and I don’t think they ever supplied replacement diaphragms for them.
Obviously swapping out both 435Be drivers would be your best course of action, but if that is not possible and you can get the 435AL drivers they will bolt right in and will sound close to the same. A network modification will be required.
Anecdotally, there have been 2435s with widely varying performance. This is likely due to someone dumping factory rejects or partially blown drivers from PA systems. Personally I would avoid those drivers unless you had proof that they were new “A” stock drivers.
Widget
I thank the whole forum and especially Mr. Widget for the contribution i was given by telling me where to take the cue for this repair.
Can’t accept the credit. Earl pointed you to Rob’s thread... But I must say, I am impressed.Originally Posted by Paul001
Well done!
Widget
the Special Editions have the same filter but use solen mkp instead of the electrolytic of the normal version.
It is a very easy modification, if you want to be picky you can also easily adjust the coil of the 435BE L4 by 0.1 mH
http://www.audioheritage.org/vbullet...pecial-Edition
Yes, >> I know if I owned those networks I'd swap out all the yellow caps for 250Volt MKP Solens ( as used by JBL ) .
I regularly listen to 400Volt MKP Solens ( dc-biased ) > BUT I do so at a drastically lower bias voltage ( compared to the STANDARD 9Volt DC Bias >> it's typically less than 1 Volt DC ).
Considering that you've stated that like what you hear ( due to swapping out the Elytones ) you would do yourself a ( educational ) favor by measuring your existing DC voltage ( from the center of any pair of caps to ground > using a multimeter ) to see what your voltage is at today.
- Remember that GT evolved the DC biased networks to being biased through a diodic "tap" taken from the LF drivers input voltage ( for when/if biamping is being used ).
- That form of variable biasing can result in a much lower dc voltage if ones normal listening habits are well controlled.
- It may turn out that you too prefer the sound of a lower bias voltage.
It takes a while for the caps to charge up to a full 9 volts after they've been discharged ( the charging slowness is due to the 2.2 meg resistor ).
- If your networks discharged when you were working on them // they might ( currently ) be only partially charged >> hence a lower bias voltage possibly being a contributing factor to a "different//preferred sound".
It's worth checking just to get a snap-shot ( reality-check ) to create a marker that's connected to your current satisfaction level.
Thanks for the reply, I would buy the new drivers I had thought of both the 435AL-1 (acquaplas), and the 2435hpl which have the beryllium diaphragm, also I could use my rear cover of the 435Be to transform the 2435hpl to something very close to the 435Be.
What do you think about it?
I think that back cap will fit the 2435, but I personally would not open these drivers. As I recall, the back cap holds the diaphragm in place. If the diaphragm moves slightly the performance will be affected. Also as I stated, based on numerous posts by members on this forum, quite a few 2435 drivers that were sourced through various means were not satisfactory.
I do not think the beautifully made 435AL/435Be back caps provide a performance upgrade over the smaller back cap of the Pro series of 3" drivers. I think it is an aesthetic change... though there has been some debate on that.
Do you have factory built K2-S9800s? If yes, have you tried to have these repaired through contacting Harman in Europe?
Widget
I bought the k2s knowing of a defect in the 435be drivers and paying for them relatively little. I thought it was the diaphragm instead inside the driver was decentralized, it should be unglued and centered well however the beryllium / aquaplas membranes are nowhere to be found as spare parts.
I think I can easily live with a new 435AL - 1 driver at this point if you think it will snap into my h9800 horn.
Physically the two drivers are identical so yes, you can easily bolt them in, but you must replace both so that they match.
Have you tried to contact Harman to see if they would sell you the correct drivers? It might be expensive but it will make your speakers worth an order of magnitude more than without them. Furthermore if they are available today it’s very likely they will not be available soon.
Widget
RobH3606 fixed one of his eBay bought 2431H drivers where the internal pole piece had broken loose from the magnet after he dropped it.
This sounds like what might have happened to the OP's 435Be.
The diaphragm's voice-coil is plastic protected and wrapped ( in teflon tape ?? ) ( meaning, even though the OP's diaphragm might appear to be bad <> it might just be "captured tight within the gap" & needing an extra careful release ( to be saved ) .
See Rob's How to Ruin Your Day thread to review his Best Save of the Decade.
A preview :
He was good, very good.
I think for now I will take two 435Al-1 I am quite convinced that it will sound very good too, at the limit through the resistive network already present in the crossover I will change the attenuation .... I expect that the aluminum is less lively than the beryllium .... for the rest I think the engine is the same.
I have already asked Harman for no spare parts unfortunately.
For the rest the speakers are very nice, in my opinion it is a more than acceptable solution
He was good, very good.
I think for now I will take two 435Al-1 I am quite convinced that it will sound very good too, at the limit through the resistive network already present in the crossover I will change the attenuation .... I expect that the aluminum is less lively than the beryllium .... for the rest I think the engine is the same.
I have already asked Harman for non spare parts unfortunately.
For the rest the speakers are very nice, in my opinion it is a more than acceptable solution
Questo è il mio preferito...
unfortunately the 435AL-1 is not available as a spare .....
At this point I have to take either a pair of 2430s or a pair of 2431s.
Which one do you recommend to insert in place of the 435AL-1 and that it attaches to my horn 9800?
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