I need to replace the HF diaphrams in a pair of BMS 4594ND coaxial drivers.
I have a gig tomorrow morning, so this is obviously critical.
The old diaphragms' outer aluminum rings are kind of "stuck on" to the driver body, and there is a fine, white, powdery-but solidified substance all over the front face of the driver body. I can rub it off with a little effort, and it feels slippery, something like graphite.
Is this some kind of ferrofluid? (No one at EAW or the reatialer who sold me the new diaphrams mentioned this, nor can I find any mention of it on the BMS website.)
If it IS ferrofluid, why did it get all over the place, and what do I do now?
If it's NOT ferrofluid, then what the heck is it?
I have a gig tomorrow morning, so this is obviously critical.
The old diaphragms' outer aluminum rings are kind of "stuck on" to the driver body, and there is a fine, white, powdery-but solidified substance all over the front face of the driver body. I can rub it off with a little effort, and it feels slippery, something like graphite.
Is this some kind of ferrofluid? (No one at EAW or the reatialer who sold me the new diaphrams mentioned this, nor can I find any mention of it on the BMS website.)
If it IS ferrofluid, why did it get all over the place, and what do I do now?
If it's NOT ferrofluid, then what the heck is it?
Here's a pic:
Dropbox - BMS HF DRIVER - RESIDUE.jpg - Simplify your life
(I can't get it to post, but hopefully you can click on it & then see it.)
Dropbox - BMS HF DRIVER - RESIDUE.jpg - Simplify your life
(I can't get it to post, but hopefully you can click on it & then see it.)
Is the cover made from aluminium ? Then it is probably just thermal compound like the one used for mounting transistors (and other power semiconductors) to heatsinks.
Ferrofluid does definitely not look like that.
Regards
Charles
Ferrofluid does definitely not look like that.
Regards
Charles
Yeah, now that it's been mentioned, I'm 100% sure it's thermal compound.
So, is this to be expected on a BMS coaxial?
I called EAW, but they weren't sure. The tech there had never heard of this, but then again diaphragm failure isn't too common if processing s set up right. He's going to try to find out from BMS, but that may take a while.
FWIW, this stuff seems to have been applied only to the mating ring, where the HF unit touches the MF unit. It might make sense to have it, since the cooling fins are on the MF unit only.
However, the stuff obviously leaked out and all over the external ring. Plus, there seems to be a very light coating of a clear, thin fluid INSIDE, where the actual diaphragm is. Maybe just a little seeped into the coil gap, (I'm not sure) so perhaps this compound was added by the previous owner? (I bought the KF394's second-hand)
------------------
Does anyone know for sure?
Does BMS use thermal compound in their coaxial drivers?
So, is this to be expected on a BMS coaxial?
I called EAW, but they weren't sure. The tech there had never heard of this, but then again diaphragm failure isn't too common if processing s set up right. He's going to try to find out from BMS, but that may take a while.
FWIW, this stuff seems to have been applied only to the mating ring, where the HF unit touches the MF unit. It might make sense to have it, since the cooling fins are on the MF unit only.
However, the stuff obviously leaked out and all over the external ring. Plus, there seems to be a very light coating of a clear, thin fluid INSIDE, where the actual diaphragm is. Maybe just a little seeped into the coil gap, (I'm not sure) so perhaps this compound was added by the previous owner? (I bought the KF394's second-hand)
------------------
Does anyone know for sure?
Does BMS use thermal compound in their coaxial drivers?
Well, I FINALLY GOT MY ANSWER:
(In case anyone has this same issue in the future.)
BMS does, in fact use thermal grease in-between the HF and MF components of their coaxial drivers.
I wasn't able to get a response directly from BMS, but a tech at EAW was kind enough (and quite curious himself) to take a new one apart. Sure enough ....
------------
But I question BMS's quality control, as my units had the white stuff all over the exposed outside areas. One would think there's a danger of heated compoud getting into the voice coil gaps, and in fact, I did find some yellowish residue in my HF gaps. After cleaning that out, the speakers definiteyl sounded better. (Less harsh.)
So .....
(In case anyone has this same issue in the future.)
BMS does, in fact use thermal grease in-between the HF and MF components of their coaxial drivers.
I wasn't able to get a response directly from BMS, but a tech at EAW was kind enough (and quite curious himself) to take a new one apart. Sure enough ....
------------
But I question BMS's quality control, as my units had the white stuff all over the exposed outside areas. One would think there's a danger of heated compoud getting into the voice coil gaps, and in fact, I did find some yellowish residue in my HF gaps. After cleaning that out, the speakers definiteyl sounded better. (Less harsh.)
So .....
- Status
- Not open for further replies.