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JBL 2441 compression driver


richieb

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I have a line on a pair of professional 2441 drivers, a close cousin of the fabled JBL 375's. Alnico magnet structure, 4 inch voice coils, 23 lb., 2 inch throat. My KPT 904 Frankensteins have the B&C 750 drivers attached to a EAW 2 inch horn. Crites did the networks like the Klipsch 904 with the 510 horn. The JBL is 16 ohm, the B&C is eight. I've investigated the 2441 and believe it crosses at 800hz like the BC but its gets a bit technical for me and I have no way do run any type of analytics or frequency sweeps. Am I asking for trouble just swapping the BC for JBL? Will the 8 vs. 16 ohm be a factor? Or is it much more complicated than that? The JBLs aren't cheap and I would hate to damage not only them but the speaker in general. 

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Someone else will be able to answer your questions.

How close a cousin?  Are they the pro version of the 375?

 

All I know:

  • The 375s were startlingly clear sounding in the JBL "scoops," the Hartzfield, the Paragon, The S8s, and evidently some theater speakers
  • They rolled off above 11K Hz, so, in later years were used with a supertweeter
  • When mated with long horns, or the big horn lens, they were often crossed over at 500 Hz, perhaps at 12 dB/octave.  The 800 Hz crossover came in when they were mated with shorter horns, like those used in the S8 and S8R series

 

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22 hours ago, richieb said:

I have a line on a pair of professional 2441 drivers, a close cousin of the fabled JBL 375's. Alnico magnet structure, 4 inch voice coils, 23 lb., 2 inch throat. My KPT 904 Frankensteins have the B&C 750 drivers attached to a EAW 2 inch horn. Crites did the networks like the Klipsch 904 with the 510 horn. The JBL is 16 ohm, the B&C is eight. I've investigated the 2441 and believe it crosses at 800hz like the BC but its gets a bit technical for me and I have no way do run any type of analytics or frequency sweeps. Am I asking for trouble just swapping the BC for JBL? Will the 8 vs. 16 ohm be a factor? Or is it much more complicated than that? The JBLs aren't cheap and I would hate to damage not only them but the speaker in general. 

 

On ‎7‎/‎26‎/‎2016 at 11:12 AM, richieb said:

I now have two Frankensteins as my KHorns have Dave Harris Elliptrac horns and ALK extreme slopes. My only comparison to a stock KHorn was in the listening room at Hope where I had a very poor seating position and the electronics were mid- grade at best. I found those very forward and a bit harsh.

My KHorns are really smooth, very well blended top to bottom. As you see in the photo for comparison the EAW horn atop the KP is much larger than the Elliptrac, the RB75 you see next to it will fit lengthways in the horn opening. It's much bigger than a 510, much smaller than a 402. A happy medium I guess. And the two inch B&C driver is much bigger than the stock K55 with the Elliptrac.

 

 

I remembered reading the quote above that your KHorn loudspeakers have the Elliptrac midrange horns and ALK extreme slope crossovers.  If this is still the case, since the Elliptrac has a 2 inch entry, I believe that the JBL 2441 would be a better match in a 3-way system.  Without some type of high frequency boost, and as garyrc alluded to with the 375's, and can be visualized in the JBL 2441 response curve below, the JBL 2441 tends to roll off above 8 KHz and is essentially done by 11 or 12 KHz.

 

JBL 2441 coupled to a JBL 2350 radial horn response curve

 

large.586fb321b37e0_JBL2441compressiondricverresponsecurve.jpg

 

B&C DE750 coupled to a B&C ME 75 "constant directivity" horn response curve

 

large.586fbc5306720_BCde750-responsecurvenarrow.jpg

 

 

An important aspect to keep in mind is that the horn has a lot to do with the frequency response curve of a compression driver.  If measurements are provided, they tend to be a compression driver on a specific horn from that company.  Although the same compression driver might be used, a different type of horn could give a significantly different frequency response curve.  One problem that I have is that it is becoming very difficult to find compression driver frequency response curves measured on a plane-wave tube, for which I find that plane-wave tube response curves can be helpful, when comparing what compression drivers can actually do, without actually owning the compression drivers and having your own test equipment.  

From the respective spec sheets (excerpted below), the JBL 2441 16 ohm driver handles 70 watts continuous program at 500 Hz (also note that 500 Hz is the recommended low-end crossover point for a pro application), 12 dB/octave slope with no problem at all; and looks to be about 2.5 to 3 dB hotter when coupled to a JBL 2350 radial Horn vs the B&C DE750 8 ohm driver coupled to a B&C ME 75 "constant directivity" horn (gleaned from the respective rated sensitivities).  In all actuality, in a home environment, each of these compression drivers should not have a difficult time crossing over in a KHorn at 400 Hz on an appropriate horn.

One reason why I suggest using the JBL 2441 in a 3-way KHorn system, is that I have a much better understanding of the aftermarket tractrix horns being used (direct experience with both the 1 inch and 2 inch ALK Trachorns that were made by Martinelli, Greg Roberts 2 inch tractrix horn, and a pair of Fastlane Audio 2 inch Elliptrac horns I picked up on the secondary market), whereas it tends to be difficult for me to speculate how the specifications for each driver measured on different horns translate to your EAW 2 inch horns (I don’t know the EAW horn model number to see if there are even any horn specs out there), especially, if you don’t have the ability to add a little boost at the high frequency range.  At least the ALK extreme slope crossovers provide for midrange attenuation, if necessary; and the JBL 2441 performs very nice in the 400 Hz through 6,000 Hz KHorn midrange band.

Specs for JBL 2441 on left and B&C DE750 on right..

 

large.586fba03555a0_JBL2441compressiondricverspecsnarrow.jpglarge.586fb9f818e70_BCde750-specsonlynarrow.jpg

 

Overall, I view the JBL 2441 as a very nice compression driver if there is life remaining in the aluminum diaphragm and the Alnico magnet is still magnetized.  Also, I find that there is still a very large contingency of people that will choose aluminum diaphragms over titanium diaphragms for the home environment.  :ph34r:

In addition, I believe that you can still find a fairly large contingency of people that “just say no” to ceramic magnets :P, and believe that there is nothing better in sound reproduction than “flux density” in a compression driver (or woofer driver for that matter) being modulated by an Alnico magnet structure using a signal coming from a tube amplifier. B)

While I currently have my Klipschorn loudspeakers set up with TAD TD-4001 2 inch throat exit compression drivers with the Alnico magnets and Beryllium diaphragms coupled to a pair of the Greg Roberts 2 inch entry tractrix horns (along with TAD ET-703 tweeters), I have used several of the JBL 2 inch throat exit compression drivers, including the Alnico magnet JBL 2440 and the Alnico magnet JBL 2482 in different top hat combinations.  Tweeters used with these mid-drivers were the EV T350 model (much better performance, but still retains some of the old K77V flavor) where my crossover points were at 400 Hz and 6,000 Hz when using the JBL 2440, then crossover points of 300 Hz and 4,000 Hz when using the JBL 2482.

Note that all three JBL drivers have Alnico magnets; however, the JBL 2482 has a phenolic diaphragm while the JBL 2440 and JBL 2441 have aluminum diaphragms.  FWIW, at that point in time when I was experimenting with JBL 2 inch throat exit compression drivers, similar to my reason for selecting the EV T350 tweeters in respect to the K77V, I selected the phenolic diaphragm JBL 2482 since I wanted to experiment with the 300 Hz crossover point and the K55V used phenolic diaphragms.

 

 

 

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From what I have read the only difference is diaphragm material, the 2441 using aluminum. The 375 uses titanium I believe and for whatever reason commands more $$$ in the marketplace. The 2441 seems to be the choice in a two way install and for what reason? I am not sure? But I am very hesitant to spend the $$$ if I cannot be sure of its compatibility with the KP450,EAW, Crites combination. And even with the insight of those on the Forum I'm not sure anyone will have the sure-fire answer I am looking for. 

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2 hours ago, djk said:

" both the JBL 2440 "

 

 

2440 is aluminum, same as the 375.

 

As usual, Dennis is correct.  JBL 2440/375 and JBL 2441/376 all have aluminum with the difference in diaphragms being that the JBL 2440/375 aluminum diaphragm has more of a half roll type of outer suspension, whereas the JBL 2441/376 aluminum diaphragm has a diamond pleated pattern outer suspension.

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4 hours ago, JL Sargent said:

Isn't the 2441 same thing as 375? I have a pair of the 2241s in 16 ohm. I can't hear above 13K or so. Using mine in a 2 way setup.

 

Not really. The JBL 2441 is technically the same driver as the JBL 376, whereas the JBL 2440 is technically the same driver as the JBL 375. The JBL 2440 and the JBL 2441 have different outer suspensions on the aluminum diaphragms and I believe somewhat different phase plugs.

 

JBL 2440 spec sheet

http://www.jblpro.com/pub/obsolete/2440.pdf

JBL 2441 spec sheet

http://www.jblpro.com/pub/obsolete/2441.pdf

 

 

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2 hours ago, richieb said:

From what I have read the only difference is diaphragm material, the 2441 using aluminum. The 375 uses titanium I believe and for whatever reason commands more $$$ in the marketplace. The 2441 seems to be the choice in a two way install and for what reason? I am not sure? But I am very hesitant to spend the $$$ if I cannot be sure of its compatibility with the KP450,EAW, Crites combination. And even with the insight of those on the Forum I'm not sure anyone will have the sure-fire answer I am looking for. 

 

The JBL 375 typically sells for a higher price due to the desirability among "collectors" where the JBL 375s with the factory red seals still intact tend to go for the highest amount.

 

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FJD's posts are correct. For those interested in deep background on the JBL 2440/375 2441/376 drivers, here's a link to the appropriate thread in the Lansing Heritage forum: http://www.audioheritage.org/vbulletin/showthread.php?910-JBL-375-vs-2441.

 

Even though I'm a true Klipsch fanatic I spent several years working at Harman International (wrote user manuals and other tech stuff for JBL, HK, Revel and Infinity). They had some outstanding engineers. Fun times, indeed.

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2441 diaphragms are very, very expensive.

 

Make sure the pair of drivers have the same phase plugs, there were three different ones over the years (check the serial numbers for being close).

 

Make sure that throats have not cracked (from rough handling), the part is NLA.

 

Personally, while I love the 2441, I would get the Altec 288G with new diaphragms.

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On 1/6/2017 at 7:52 AM, Fjd said:

 

 

 

I remembered reading the quote above that your KHorn loudspeakers have the Elliptrac midrange horns and ALK extreme slope crossovers.  If this is still the case, since the Elliptrac has a 2 inch entry, I believe that the JBL 2441 would be a better match in a 3-way system.  Without some type of high frequency boost, and as garyrc alluded to with the 375's, and can be visualized in the JBL 2441 response curve below, the JBL 2441 tends to roll off above 8 KHz and is essentially done by 11 or 12 KHz.

 

JBL 2441 coupled to a JBL 2350 radial horn response curve

 

large.586fb321b37e0_JBL2441compressiondricverresponsecurve.jpg

 

B&C DE750 coupled to a B&C ME 75 "constant directivity" horn response curve

 

large.586fbc5306720_BCde750-responsecurvenarrow.jpg

 

 

An important aspect to keep in mind is that the horn has a lot to do with the frequency response curve of a compression driver.  If measurements are provided, they tend to be a compression driver on a specific horn from that company.  Although the same compression driver might be used, a different type of horn could give a significantly different frequency response curve.  One problem that I have is that it is becoming very difficult to find compression driver frequency response curves measured on a plane-wave tube, for which I find that plane-wave tube response curves can be helpful, when comparing what compression drivers can actually do, without actually owning the compression drivers and having your own test equipment.  

From the respective spec sheets (excerpted below), the JBL 2441 16 ohm driver handles 70 watts continuous program at 500 Hz (also note that 500 Hz is the recommended low-end crossover point for a pro application), 12 dB/octave slope with no problem at all; and looks to be about 2.5 to 3 dB hotter when coupled to a JBL 2350 radial Horn vs the B&C DE750 8 ohm driver coupled to a B&C ME 75 "constant directivity" horn (gleaned from the respective rated sensitivities).  In all actuality, in a home environment, each of these compression drivers should not have a difficult time crossing over in a KHorn at 400 Hz on an appropriate horn.

One reason why I suggest using the JBL 2441 in a 3-way KHorn system, is that I have a much better understanding of the aftermarket tractrix horns being used (direct experience with both the 1 inch and 2 inch ALK Trachorns that were made by Martinelli, Greg Roberts 2 inch tractrix horn, and a pair of Fastlane Audio 2 inch Elliptrac horns I picked up on the secondary market), whereas it tends to be difficult for me to speculate how the specifications for each driver measured on different horns translate to your EAW 2 inch horns (I don’t know the EAW horn model number to see if there are even any horn specs out there), especially, if you don’t have the ability to add a little boost at the high frequency range.  At least the ALK extreme slope crossovers provide for midrange attenuation, if necessary; and the JBL 2441 performs very nice in the 400 Hz through 6,000 Hz KHorn midrange band.

Specs for JBL 2441 on left and B&C DE750 on right..

 

large.586fba03555a0_JBL2441compressiondricverspecsnarrow.jpglarge.586fb9f818e70_BCde750-specsonlynarrow.jpg

 

Overall, I view the JBL 2441 as a very nice compression driver if there is life remaining in the aluminum diaphragm and the Alnico magnet is still magnetized.  Also, I find that there is still a very large contingency of people that will choose aluminum diaphragms over titanium diaphragms for the home environment.  :ph34r:

In addition, I believe that you can still find a fairly large contingency of people that “just say no” to ceramic magnets :P, and believe that there is nothing better in sound reproduction than “flux density” in a compression driver (or woofer driver for that matter) being modulated by an Alnico magnet structure using a signal coming from a tube amplifier. B)

While I currently have my Klipschorn loudspeakers set up with TAD TD-4001 2 inch throat exit compression drivers with the Alnico magnets and Beryllium diaphragms coupled to a pair of the Greg Roberts 2 inch entry tractrix horns (along with TAD ET-703 tweeters), I have used several of the JBL 2 inch throat exit compression drivers, including the Alnico magnet JBL 2440 and the Alnico magnet JBL 2482 in different top hat combinations.  Tweeters used with these mid-drivers were the EV T350 model (much better performance, but still retains some of the old K77V flavor) where my crossover points were at 400 Hz and 6,000 Hz when using the JBL 2440, then crossover points of 300 Hz and 4,000 Hz when using the JBL 2482.

Note that all three JBL drivers have Alnico magnets; however, the JBL 2482 has a phenolic diaphragm while the JBL 2440 and JBL 2441 have aluminum diaphragms.  FWIW, at that point in time when I was experimenting with JBL 2 inch throat exit compression drivers, similar to my reason for selecting the EV T350 tweeters in respect to the K77V, I selected the phenolic diaphragm JBL 2482 since I wanted to experiment with the 300 Hz crossover point and the K55V used phenolic diaphragms.

 

 

 

You never told me you had the ET-703's....now Green with envy. Sure do miss my TD-4001's!

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  • 1 year later...

One difference between the 2440 and the 2441 is that the 2440 (375) dropped like a rock above about 10 or 11K.

 

But, they sounded unbelievably great, effortless and clear in one 70 mm theater we frequented.  A group of 6 of us, even with our young ears (approx. 13 through 18 years old, all but one of us playing in an orchestra) agreed that the sound in that theater was better than that we heard in the yearly Hi Fi fairs.  We didn't even realize that the top octave or so was missing, and we could all hear to 20K.. 

image.png.1c593c981c54e096d65defc6d9bee122.pngimage.png.fd5cceecdc75f25ecd5be52f4f126b17.png

image.png.b206602b0faf3a47b80404de928776c0.png

 

image.png

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