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FE3T
08-31-2011, 04:11 PM
Just received a pair of 030 mid domes wich should be identical to the 095 used in the XPL A serie.

Testing them revealed that one of them was very low on volume compared to the other one. searching for the cause revealed lots of corrosion, both on the magnet system and the connection betwin the voice coil leads and the small connectors which the internal x-over was connected too. (the 095 does probably have just wires from the connectors on the rear chamber to these) I was able to clean up the worst and resolder the connection, but another problem was also discovered.

On the magnet system there is a foam ring pretty close to the voicecoil gap, the diamond patterned surround on the dome rests on this foam ring, wich probably provide some damping to the moving assembly. some may already have guessed what the problem with this foam ring is. it falls apart, its rotten, crumbles into sticky dust if touched. :banghead:

I just reassembled the parts without messing with the foam, its mostly intact, and this dome now have the same output level as the other, but i fear that this rotten foam has some impact on the specs, and migh even end up as dust in the gap.

IF the 093 and 095 domes have this foam ring, and i belive they have, this means that most XPL owners sooner or later will have the same problem.

So if anyone have a solution or know for sure if this foam ring can be removed without negative impact, please speak out.

Don C
08-31-2011, 09:23 PM
Mine had the same foam rings, and yes, mine were coming apart too. I think that they are used to cut down on the out of band resonance that's visible in the 093 frequency response plots. But this foam ring shouldn't be too difficult to replicate. You would just need to find a sheet of foam that's very soft and thin, and cut out rings. I see similar foam used as packaging material sometimes. It probably wouldn't take too long to find a jar lid or two to use as a pattern to trim a ring of the right size.
In my case, I had another member here coat the inside of my domes with aquaplas. That gave me a huge improvement, the mod is highly recommended. The aquaplas applied to my domes didn't cover the diamond pattern surround, where the foam is located. But I've seen other domes where that aquaplas covers everything, including the surround. The LSR32 tweeter is an example, all of those tweeters are completely covered with the aquaplas, even the surround. I think that's a good alternate solution, it will give you s midrange that's better than the original instead of just doing a repair.



Just received a pair of 030 mid domes wich should be identical to the 095 used in the XPL A serie.

Testing them revealed that one of them was very low on volume compared to the other one. searching for the cause revealed lots of corrosion, both on the magnet system and the connection betwin the voice coil leads and the small connectors which the internal x-over was connected too. (the 095 does probably have just wires from the connectors on the rear chamber to these) I was able to clean up the worst and resolder the connection, but another problem was also discovered.

On the magnet system there is a foam ring pretty close to the voicecoil gap, the diamond patterned surround on the dome rests on this foam ring, wich probably provide some damping to the moving assembly. some may already have guessed what the problem with this foam ring is. it falls apart, its rotten, crumbles into sticky dust if touched. :banghead:

I just reassembled the parts without messing with the foam, its mostly intact, and this dome now have the same output level as the other, but i fear that this rotten foam has some impact on the specs, and migh even end up as dust in the gap.

IF the 093 and 095 domes have this foam ring, and i belive they have, this means that most XPL owners sooner or later will have the same problem.

So if anyone have a solution or know for sure if this foam ring can be removed without negative impact, please speak out.

DavidF
09-01-2011, 04:46 PM
"...Mine had the same foam rings, and yes, mine were coming apart too. I think that they are used to cut down on the out of band resonance that's visible in the 093 frequency response plots. But this foam ring shouldn't be too difficult to replicate. You would just need to find a sheet of foam that's very soft and thin, and cut out rings..."

When I had mine apart I thought that the foam looked and felt very much like some window weather stripping foam I had on hand. About the same size- 1/4" or 6mm height and width going by memory. Never tried installing because the foam was still intact on mine but thought that someday I would need to revisit the idea.

pos
09-02-2011, 05:03 AM
That would be nice to find a replacement that does not rott.
035Ti tweeters have the same problem.
But at least these HF units can disassembled and the rotted foam removed (even in the gap or on the voice coil), whereas thing are more difficult with woofers...

Do you know in LE5 mids also have a foam pad behind the dustcap?

ratitifb
09-02-2011, 07:53 AM
Do you know in LE5 mids also have a foam pad behind the dustcap?:scold:

and it would probably be useless :hmm: in mid frequency range if this foam pad is really present in the tweet to shape the upper frequency response

pos
09-02-2011, 08:57 AM
Yes you should be right.
It is present in most woofers, albeit for another reason: to protect the vent (and le5 have no vent...). In this application I find it is better to replace it by a piece of cloth (rotten foam in a woofer voice coil aint no fun...)

Don C
09-03-2011, 08:34 AM
I have disassembled 035ti and I didn't find foam inside. 044Ti does have foam behind the dome.

pos
09-03-2011, 10:04 AM
035TiA are supposed to have a foam pad.
I have reconed one recently, and it had a (rotten) foam pad, and the recone kit from JBL also includes one (as well as a small rubber pad that I don't know what I am supposed to do with :blink:)

jhal
11-13-2011, 03:58 PM
Proud XPL-200A owner here for the last 3 years or so. My mid domes have this rotten foam. When I got these, one of the mids was smashed in, so I was lucky to find a good used one at a decent price to replace it.

Anyway, here's a pic of the smashed dome taken apart to reveal the problem. I have not noticed any ringing or buzzing from any of my other titanium drivers, so I guess I will leave them be. Although it is obviously rotten, I am not going to "fix" something that seems to be working fine. My luck, I would mis-align the voice coil upon re-assembly and ruin a good driver.

jhal
11-13-2011, 04:01 PM
Sorry for the large pic size, can a mod please help me? I am not sure how to reduce their size, as they are already resized to fit the file size requirement.