BS Button Posted February 15, 2010 Share Posted February 15, 2010 I have an opportunity to get a pair of these which are blown...any idea on cost to fix and other valuable information would be appreciated... Thanks BS Quote Link to comment Share on other sites More sharing options...
djk Posted February 15, 2010 Share Posted February 15, 2010 Notes on JBL 2441 New D16R2441 are in excess of $200 each. The various titanium models will fit, but don’t sound as good (they ring). There are three different phase-plugs used in the 2441, make sure your pair match. Make sure there are no cracks in the throat (part is no longer available). Make sure the old blown diaphragms have no marks on either the inside of the coil former (grey marks), or on the outside of the coil (light colored marks on the redish-orange voice coil insulation). Marks indicate rubbing, and the driver may have to be returned to JBL to be de-magged, cleaned, aligned, and re-magged. There is a reason clean, good working JBL 2441 bring $600+ Even if you manage to find a pair, they may not survive shipping (been there). Dr Bruce Edgar is very knowledgeable about these, and may be able to help you. 1 Quote Link to comment Share on other sites More sharing options...
BS Button Posted February 15, 2010 Author Share Posted February 15, 2010 DJK, Firstly, thanks for your informative response Secondly, I may be getting the horns, throat, and compression drivers for next to nothing...The horns are huge...guessing 36"x 36" at the opening, which model might those be..? the throat looks like a mini K700 .They are currently sitting upside down, drivers up, in a utility building. I;m to pick them up and haul them off, next week... Quote Link to comment Share on other sites More sharing options...
Marvel Posted February 15, 2010 Share Posted February 15, 2010 If they are square, they could be 2360, 65, 66 horns. Attached is a pdf... Bruce 23606566.pdf 23606566.pdf 23606566.pdf Quote Link to comment Share on other sites More sharing options...
BS Button Posted February 16, 2010 Author Share Posted February 16, 2010 If they are square, they could be 2360, 65, 66 horns. Attached is a pdf... Bruce Great forum, thanks Bruce Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted February 17, 2010 Share Posted February 17, 2010 I own a pair of these drivers that I run with actives in a two way setup. They are super clean/clear sounding and if given the opportunity will absolutely blow your head off without notable distortion. Diaphrams can be sourced from Orange County Speaker as well as other places. These can be awesome drivers. Quote Link to comment Share on other sites More sharing options...
CIGARBUM Posted February 17, 2010 Share Posted February 17, 2010 Are the 2441 a later model of the JBL 2440, I have a pair and haven't thought of an application yet. CB Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted February 17, 2010 Share Posted February 17, 2010 IIRC the 2440 is 8 ohm and the 2441 is 16 ohm. Otherwise the same driver. Quote Link to comment Share on other sites More sharing options...
Blvdre Posted February 17, 2010 Share Posted February 17, 2010 JL and CB, according to the old JBL literature, they are both 16 ohm drivers with aluminum diaphragms, but the 2441 touts the "new diamond surround" (it also handles 70W at 500Hz, as opposed to the 2440's 60W). Quote Link to comment Share on other sites More sharing options...
dkalsi Posted February 17, 2010 Share Posted February 17, 2010 I believe that is incorrect. The "H" and "J" after the 2441 designates whether is is 8oms or 16ohm. Additionally, the 2440 and 2441 have the same body but different diaphragms - I believe the 2441 has higher HF extension. Lastly, if my post above is incorrect, then I apologize for in advance for any confusions I may have caused :-). Quote Link to comment Share on other sites More sharing options...
djk Posted February 18, 2010 Share Posted February 18, 2010 The 2440 and the later 2441 have different phase plugs, and different diaphragms, but are similar otherwise. http://www.jblproservice.com/pdf/Transducers%20Parts%20List/Transducer%20Parts%20List.pdf Both drivers are only available in 16 ohms. The 2440 with its anular half-roll suspension rolls off above 3.5Khz (on a constant directivity horn) and has a peak in the 9Khz region, and rolls off hard above there. The 2441 with its diamond pleat suspension rolls off above 3.5Khz at a 6dB/oct rate (on a constant directivity horn), but is smooth to beyond 16Khz. http://alteclansingunofficial.nlenet.net/publications/techletters/TL_231.pdf Quote Link to comment Share on other sites More sharing options...
CIGARBUM Posted February 18, 2010 Share Posted February 18, 2010 Well, I haven't heard anything bad about the JBL drivers. I guess I will have to find a use for my 2440. I guess, in general, that the JBL drivers do a pretty good job. I have a pair of 2482 in my DBB with a 225hz wood horn, talk about sweet, and the gentleman who said that if you turn then up, they will take your head off, but what a way to go. cb Quote Link to comment Share on other sites More sharing options...
garyrc Posted February 18, 2010 Share Posted February 18, 2010 Is the 2441 a descendant of the JBL 375 midrange driver used in the '50s in the Hartsfield, and in the late '50s and '60s in the Paragon? The 375 also had a 4" voice coil, and was rated for 60 wts continuous power handling. I believe they were used (with a different non-consumer designating model numbers) in some of the 70mm 6 channel movie systems such as the theaters "4 walled" by Mike Todd for Todd-AO, They rolled off at about 12K, so there was a tendency to add a supertweeter as more and more program material that was relatively undistorted in the top ocatve became available. If the 2441 is indeed an update of the 375, then I must say that the 375s were some of the clearest, most precise midrange units I ever heard, given a good enough horn. In some cases (e.g., The Hartsfield) they overwhelmed the woofer. Perhaps the displayers failed to set the crosssover pot correctly, which is one reason that PWK didn't provide a pot on his crossovers! For premium theater use, I believe the balancing networks had a strapping bar that could be unscrewed and placed in 4 different positions one dB apart by the people setting up the theater. That way there was no pot to tempt people... Quote Link to comment Share on other sites More sharing options...
djk Posted February 18, 2010 Share Posted February 18, 2010 The 375/2440 start rolling at about 3.5Khz on a plane-wave tube (3dB down point). This is called the mass corner, and the roll-off should be about 6dB/oct (red line). The mid-band (500hz) level is about 139dB (10dB/major division) and is down about 10dB in the 7Khz~8Khz region (129dB). We can see that there is about a 6dB peak in the 9Khz region (reference the mass roll-off line), and rapid roll-off beyond (12Khz down over 10dB with respect to the 9Khz peak). The 376/2441 was developed in the late 70s for Paramount. By replacing the annular half-roll suspension with the three-dimensional diamond-pleat suspension the 9Kz peak went away and they were able to get some more output in the 16Khz region. The slots in the phase-plug were moved around twice in search of more 16Khz output (so there are three different phase plugs in the 2441, depending on the vintage). Ultimately, it was found that the depth and symmetry of the three-dimensional diamond-pleats could make a huge difference in the 16Khz output. This finding also applied to the ‘iris’ pattern in the 175/LE85 diaphragms. The LE85 was advertised as having more VHF than the 175 (it has a bigger magnet and a silver-plated top-plate), but the diaphragms for the LE85 were obtained on a selection basis* In use, the alignment and dimensions in the exciter made about 8Khz the practical top-end limits, so the 375/2440 was really all that was needed. Later, the LED exciters with the small slits came out and 16Khz was possible (although most theaters were not up-dated, and seldom properly aligned). High end and horns. In a large room (with a reverberant field) all horns tend to sound like their measurements on a terminated tube. With a constant-directivity (CD) horn this may mean using a bunch of EQ (as much as 20dB at 20Khz). The EQ makes the CD horn flat in the near field, and the far field too. What about exponential and tractrix? The 329A horn shown with the 2440 is a radial horn of exponential type, and as such the directivity greatly increases above 2Khz or so (beaming). This combination of increasing directivity and the mass roll-off makes the driver/horn combo measure flat in the near field, but it still rolls off in the far field. EQ to make it flat in the far field makes it bright enough to shave your eyebrows up close. In an auditorium the audience is in the far field, and so the EQ is used. People in the near field are usually off-axis and don’t get their eyebrows totally shaved. What about a small room? I listen in the near field, do I need to worry about any of this? Maybe. Remember how the drivers tend to sound like their terminated tube response in the far field? The reflections off your walls tend to have the same response as the terminated tube, so a system can sound bright, yet dull at the same time (because the direct sound is flat, and the reflected sound is rolled off). CD horns don’t have this issue, and tend to sound better. The 402 horn looks to be a CD horn in the throat area, with a tractrix mouth, it looks like it should sound good (I haven’t heard one yet). *JBL source = Steve Jennings in QC, and Drew Daniels in engineering. I have dinner with Steve about once a week, so if anyone has any questions I can refer them for you. Quote Link to comment Share on other sites More sharing options...
garyrc Posted February 19, 2010 Share Posted February 19, 2010 Wow, what a great post! "...because the direct sound is flat, and the reflected sound is rolled off ..." Is there any way around this in a room about 17 x 25? Would diffusors help by delaying the reflected sound to the degree that the brain considers it "the room" not the original sound? It sounds like you are, or were, a movie industry insider. Can you comment on the following? In my lifetime the biggest change in movie sound in the theater was the transition from optical soundtracks (dull as can be) to stereo magnetic in the early 1950's. The magnetic soundtracks sounded like they had ample energy above 8 K (I could hear to 20K or above back then) ... they sounded brighter and more shimmering than AM radio through a "full range" sound system in the home (mine was JBL), and a lot more like FM radio, Lps, and reel to reel tape, but the movies often were considerably more dynamic. Perhaps the illusion of full range sound was the effect of the massive EQ you mentioned, even though the mag theater curve allowed the highs to droop when measured from the listeners' seats, i.e., without the EQ, they might have drooped even more. Much magnetic theater sound (in SanFrancisco, Oakland, and Berkeley) was pretty good, and the 70mm Todd-AO tracks seemed to be wonderfully well balanced, especially Around the World in 80 Days (1956) which the members of our high school orchestra noted sounded "just like" our (big) orchestra. Then there was a change. In about 1964, much theater sound got very bright. Mary Poppins (1964) was extraordinally bright -- but in an enjoyable way -- and so were The Unsinkable Molly Brown and Circus World, to name a few. They (especially Poppins) didn't have what I would call a natural balance, but they sounded great. Did new and different speaker systems get installed about 1964, or was there a change in standard industry EQ, or were the mixers on these pictures just pusihing the envelope? There was another change. Starting in about 1977, a number of soundtracks began to sound harsh. Not all, but some. With Star Wars, I thought it might have been partly style. We saw it in the same theater we had seen the well balanced Ben-Hur and many others, as well as the perfectly balanced 80 Days (not to be confused with the horrible optical versions of the same movie, or the compressed VHS/DVD versions). Some of my friends blamed digital mastering, but I'm not sure when that started. Was there a change in theater speaker systems ablut then? Quote Link to comment Share on other sites More sharing options...
BS Button Posted February 19, 2010 Author Share Posted February 19, 2010 Drivers and horns in the house... 2 - 2365H Horns 2 - 2365T Throat/s? 2 - 2441 Compression drivers...serial numbers 33959, 33961 Based upon the serial numbers can anybody elaborate on the drivers? Pictures forthcoming...I'm about to open them up, they have a pathetic physical appearance, the drivers do, anyway...Can they be refinished? There are no dents or gouges or anything, just paint mainly (crinkle finish). The back covers are off, black foam just crumbled to dust on the slightest of touch...more later BS Quote Link to comment Share on other sites More sharing options...
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