advise wanted on switch from titanium to phenolic diaphrams on 2440's please

[L-Bone]

hi everyone,
I have been collecting jbl stuffs for several years now and I have been running a pair of heavily modified c50 Olympus speakers for some time. over the past while I have been slowly tweaking the setup and have know gotten it to the point where I am pretty happy with it but am still not completely happy with the mid range on these.

A bit of background on them. I bought them from the original owners family who bought them new in 1969. the original owner tweaked them over the years including double layering the cabinets (very tastefully still maintained the original look), made custom ports that replaced the passive radiator with a much improved sound difference, added top mounted 2440's with 2397 horns and 2405's for uhf and custom crossovers designed and built in the U.S that I was told had cost over 3k.

From what i have read the titanium diapragms come from the 2445 and have extended highs with a roll of about 10 db at 10 k to about 20k where as the phenolics drop hard at about 9k. JBL states that the 2405 should be run over 7k and I am wondering if most crossover designers would roll it in at that point and if a 2k slope between the 2 drivers would be good? I really don't have any specs on the crossover and I guess the only thing I could do would be run a signal generator though my ipad to see where they roll off and in but am not really sure if I trust this method.

I am looking for input on phenolic vs aluminum vs titanium and opinions on if crossover reworking will be necessary to get a smoother, warmer more detailed mid range.
thanks!

[Earl K]

Hi,

JBL phenolic diaphragms ( aka, used in the 2482 model ) won't fit properly into your 2440 drivers .

If you want the phenolic sound, then you'll need to buy used 2482 drivers ( or a comparable driver model from JBL/Selenium ) .

Aluminum diaphragms are noted to be smoother sounding ( dynamically ) when compared directly to titanium .

You could look for used 2440 diaphragms ( though that might take years to scare up a pair here in Canada ) or buy new 2441 diaphragms from ? or purchase a pair of Radian 1245-16 diaphragms from Q-Components located in Kitchener ) .

[L-Bone]

Thanks for the reply, I thought I remembered reading somewhere that the early 375's came with phenolic and didn't read more thoroughly on it after that.

Hi,

JBL phenolic diaphragms ( aka, used in the 2482 model ) won't fit properly into your 2440 drivers .

If you want the phenolic sound, then you'll need to buy used 2482 drivers ( or a comparable driver model from JBL/Selenium ) .

Aluminum diaphragms are noted to be smoother sounding ( dynamically ) when compared directly to titanium .

You could look for used 2440 diaphragms ( though that might take years to scare up a pair here in Canada ) or buy new 2441 diaphragms from ? or purchase a pair of Radian 1245-16 diaphragms from Q-Components located in Kitchener ) .

[/QUOTE]

[Earl K]

You can see from this pic that the 2482 barely makes it past 5K ( one wants to cross a 2405 quite a bit higher than that ).

[L-Bone]

Thanks for the input I appreciate it! I think I have a line on some aluminum diaphragms will try them out

You can see from this pic that the 2482 barely makes it past 5K ( one wants to cross a 2405 quite a bit higher than that ).

[Mr. Widget]

JBL has been blowing out the 2441 diaphragms which are currently available from Speaker Exchange for $145 ea. This may seem expensive, but it is really a deal if you have high quality cores. I have no insider knowledge, but based on recent experience my guess is that these will go and then they will all be gone.

http://reconingspeakers.com/product/...441-diaphragm/


Widget

[ivica]

JBL has been blowing out the 2441 diaphragms which are currently available from Speaker Exchange for $145 ea. This may seem expensive, but it is really a deal if you have high quality cores. I have no insider knowledge, but based on recent experience my guess is that these will go and then they will all be gone.

http://reconingspeakers.com/product/...441-diaphragm/


Widget

Hi Widget,

I have to agree with You that 2441 Aluminum diaphragms are the best , especially using in two-way speakers, but if 2405 would be applied too, then may be cheaper solution like D16R2451SL ("dusted" Ti diaphragm)

http://reconingspeakers.com/product/...1sl-diaphragm/

can be used too, as it works fine up to about over 10kHz, so a kind of proper crossover (round 9~10kHz) would be possible solution.

regards
ivica

[1audiohack]

Current stock:

D16R2440 13 ea.
D16R2441 6 ea.
D16R2482 42 ea.

As a note, I twice bought all the D16R2441's they had and they have been coming back so the end is not yet?

Even though on paper the 2405 will reach down to the 2482, this is far from ideal.

With a D16R2440 / 375 diaphragm you can just let it run out and bring in the 2405 just above 9kHz.

Barry.