Rebuilding 435be, sourcing correct ferrofluid and in need of O-ring

I have three 435be drivers and two of them need a little work. With the diaphragms removed I saw that there was what looked to be a little metal specks in the coil gap. I cleaned the coil gap quite well and now need to replace the ferrofluid. What should I be purchasing? Also I am in need of one of the O-rings that goes around the diaphragm and holds it in the back chamber. I hope that makes sense. Attachment 90429Attachment 90430Attachment 90431

Here are some photos of the O-ring and you can see it installed with the diaphragm in the back chamber.


Thank you,
Dan

Here is the Ferro

Both compression drivers have 100 ul of APGS38N ferrofluid in the gap. The ferrofluid provides some damping and seals off cavity resonances. Without the ferrofluid the curve gets rougher and it is audible. - Courtesy of Doug Button - JBL


The O ring you should be able to get at a hardware/plumbing supply.

Rob :)

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Originally Posted by Robh3606

Here is the Ferro

Both compression drivers have 100 ul of APGS38N ferrofluid in the gap. The ferrofluid provides some damping and seals off cavity resonances. Without the ferrofluid the curve gets rougher and it is audible. - Courtesy of Doug Button - JBL


The O ring you should be able to get at a hardware/plumbing supply.

Rob :)

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Awesome, thank you so much Rob! Wasn’t sure if it was a special type of O-ring, but I can run down to the hardware store today for that. As for the ferrofluid, 100uL is wayyy less than I thought it would have been, I’ve used that much for small dome tweeters! Any hope of being able to purchase this APGS38N fluid? I can only seem to find APG L11. I’d really like to be able to use what JBL used.

I also have 3 045Be drivers which I’m guessing have ferrofluid in them as well? I’ll have to research that, but for the moment I’m not touching them. I remember Greg Timbers saying that they have incredibly delicate diaphragms, much more so than the 435s. But it would be good to grab APGS38N for them as well while it’s available. I’ve replaced a lot of dried up fluid, so i know it won’t last forever. If it’s not then never mind.

Thank you again,
Dan

In my experience the orange colored o-ring material is a high temp silicone.


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Any hope of being able to purchase this APGS38N fluid? I can only seem to find APG L11. I’d really like to be able to use what JBL used.

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Yes I purchased some years ago just go here:

https://ferrofluid.ferrotec.com/prod...pg-s/apg-s38n/

I was able to purchase it in both bulk and in individual recharge packets specifically for the 435 drivers. The 045 does not use Ferro and Yes don't open them.

Rob :)

Quote:

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Originally Posted by Robh3606

Yes I purchased some years ago just go here:

https://ferrofluid.ferrotec.com/prod...pg-s/apg-s38n/

I was able to purchase it in both bulk and in individual recharge packets specifically for the 435 drivers. The 045 does not use Ferro and Yes don't open them.

Rob :)

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I wanted to thank you for the link, I thought I had done that, very rude of me. Thank you for pointing out where to grab some. May I ask, how long should it take for them to get back to me? I made an inquiry about 1-1/2 to 2 weeks ago and still haven’t received an email back. I’m just wondering if I need to reach out again.

Thank you,
Dan

Hello Dan

If I remember correctly I called them on the phone. That was a while ago, I would just try again.

Rob