time to retire the 044Ti....or what else to use in a 250Ti ?

[jblnut]

Hi All,

I have come - slowly - to the inescapable conclusion that the foam rot on the "damper" used in my 044Ti's is causing them to get less pleasant to listen to over time. I have been using the bus bars to diminish their output but this only goes so far. I have tried using all manner of expensive and well regarded tube equipment upstream but that too has stopped paying dividends.

So, seeing as I love the rest of the speaker, I am wondering a few things:

1) Does anyone out there "refoam" these? I've seen some DIY posts in that regard but I don't think I'm going to risk destroying mine personally. I would be willing to pay a pro to do it though, providing they have experience in this area.

2) What have other people used on their 250Ti clones or rebuilds ? I am leaning towards a nice textile dome for a slightly softer high-end and there are tons of choices out there. Just curious if anyone has some good first hand experience.

I'm really sad that this day has come, but I think I've been expecting it for some time. I can't keep dulling down my electronics to make up for an underdamped titanium diaphragm.

Thanks for any insight !

jblnut

[Robh3606]

Well why not get a pair of 052ti's and drop them in. Not so simple but at least it's a "close" replacement. I used 050ti golds in my clones. They sound great but I am sure sooner or later I may be in the same boat when their foam dampenng pad melts.

Rob

[rdgrimes]

Isn't it fairly straightforward to open them up and replace the foam?

035ti was used in some of the LE models weren't they?

[Robh3606]

035ti was used in some of the LE models weren't they?

Yes but I think they are now prohibitively expensive if you wanted to get a new pair. The 052 is supposed to be the replacement for the 035 and is much more resonably priced and avialable from JBL Pro in the current Transducer List.

http://www.jblproservice.com/pdf/Tra...cer%20List.pdf


Rob

[SEAWOLF97]

Isn't it fairly straightforward to open them up and replace the foam?

035ti was used in some of the LE models weren't they?

I got some 18Ti's (a good donor for 044Ti's) ..one had a crushed dome ....I was afraid of opening it up, but in hindsight, it wasn't really so hard ...grumpy had good suggestions on replacement foam

http://www.audioheritage.org/vbullet...ighlight=044ti

Yes but I think they are now prohibitively expensive if you wanted to get a new pair. The 052 is supposed to be the replacement for the 035 and is much more resonably priced and avialable from JBL Pro in the current Transducer List.

http://www.jblproservice.com/pdf/Tra...ducer List.pdf


Rob

around here you can get used 035Ti's for $100 a pair anyday. But then same old decaying foam problem again.

[Robh3606]

around here you can get used 035Ti's for $100 a pair anyday. But then same old decaying foam problem again.

Yeah me too but like you say you are going to end up with the same issue eventually. It's too bad we can't come up with an alterative material that won't shed and melt. Hell even a cotton ball might work. I can't measure out far enough to see the ultrasonic resonance you need a set-up that will go out to 30K or so. My CLIO set-up hits the wall at 22K.

Rob

[rdgrimes]

FWIW, "Cotton balls" are made from Dacron these days. The same material used to make the domes of the 033, 034, 066, 040. Can't say if it has appropriate damping qualities, but it lasts forever.

[rusty jefferson]

...2) What have other people used on their 250Ti clones or rebuilds ? I am leaning towards a nice textile dome for a slightly softer high-end and there are tons of choices out there. Just curious if anyone has some good first hand experience.

jblnut

Is the OP asking about other brands? I haven't DIYed any speakers (yet), but Seas makes great tweeters. They may have a model that would be a good replacement.

http://www.seas.no/index.php?option=com_content&view=frontpage&Itemid =1

[4313B]

You can use a little dot of felt glued to the pole piece instead of the foam and aquaplas damps the dome. There is no reason to use the foam anymore.

[jblnut]

You can use a little dot of felt glued to the pole piece instead of the foam and aquaplas damps the dome. There is no reason to use the foam anymore.

Are you saying the domes are aquaplas treated ? They don't look like it, but maybe I'm not sure exactly what it looks like (is it a clear coating) ? I'm more confused my the "there is no reason to use foam any more" statement. If the aquaplas coating was on there from the beginining, why did JBL use foam at all ? Didn't the foam initially make contact with the dome from the back and damp it somewhat ? If not, what was the purpose ?

Thanks a lot for all your responses everyone !

jblnut

[4313B]

The 035Ti and 044Ti were not aquaplased. I don't think JBL thought about the aquaplas solution until the LSR series.

[jblnut]

I'm not following you....if they don't have aquaplas then the foam is needed, right ?

My ears tell me they need it, as they have somehow gotten "brigher" over the past 10 years despite deliberate "softening" of the front-end eelctronics and a lowering of the bus bar levels.

I guess I need to man up and get out the putty knife....


jblnut

[4313B]

I'm not following you....if they don't have aquaplas then the foam is needed, right ?

My ears tell me they need it, as they have somehow gotten "brigher" over the past 10 years despite deliberate "softening" of the front-end eelctronics and a lowering of the bus bar levels.

I guess I need to man up and get out the putty knife....


jblnut

Given that you have to take them apart anyway you might as well just aquaplas them. I'll even send you a little bit of it. The foam should never have been used in the first place. It can be considered a manufacturing defect in the same spirit as lans-a-loy. JBL didn't fully understand the long term ramifications. Remember, all this crap was supposed to be built like a fine musical instrument lasting a lifetime. Human lifetime, not dog lifetime. If the aquaplas on the front bothers you, you can apply it on the back like I do. There is no phasing plug and millionths of millimeters of tolerance to worry about. You then take a little felt dot, like people place under chair legs to keep from scruffing up wood floors and glue that to the pole piece.

[4313B]

Here is what a proper Ti dome is supposed to look like. Greg was right in that "if it moves, coat it".

[berf]

Would the optimal size felt pad be the smaller 7/16" or the medium 3/4" from this set? They appear to be 1/8-3/16" thick. Would a poor quality light felt be preferable to a quality heavy felt? If you're only going to so this once per tweet to make them last forever you might as well use the right material.