Despite many people don't like the sound of the JBL431x speakers (too rough, too harsh, doesn't sound like other larger JBL monitors.), the achievement of this series of speakers and it's sibling L100 is unquestionable. This series of speakers are being sold for more than 50 years and even today you can still find them in service in a recording studio. It's hard to find a second speaker model that shares this kind of success.

Left to right: 4311, L100A, L100, 4310. Source: the Internet

Let's start the tittle-tattle with the earliest model, the JBL 4310. Back in the 60s Mr. J.B. Lansing left Altec and started this new company bearing his name. JBL had a hard time to penetrate the processional recording market. In that time most recording studios, both in America and in Europe, have Altec 604 series 15" coaxial driver based speakers as their reference. The 604s (604D was the model by that time) were usually installed inside a wall or installed in the Altec 620A enclosure which is quite big. The design goal of the JBL 4310 was to mimic the sound characteristic of the Altec 604s with a much smaller footprint. Despite the efficiency is much lower(90dB/W/M), the 4310 successfully achieved it's design goal. There are also some factors that helped the market penetration of 4310s: The industry started to adopt 8-track recording. It is not practical to install 8 620A in a studio hence alternatives were sought after.  There was also a trend to start small studios with limited space hence a smaller monitor speaker was desired. Also Altec was trying to replace the 604D line with a cheaper 605A which many people believed was a downgrade and turned away. The 4310 successfully won the battle and marked the the start of the JBL professional history. Although Altec learned the mistake they made and introduced 604E to the market. It was already too late.

4310 uses three drivers: 123A-1 as bass, LE5-2 as mid-range and LE20-1 for the high. All drivers were using Alnico magnets. According the the documents found in the Internet, the design of 4310 were majorly done with experiments due to the lack of a complete speaker design theory. The rumor says the designer, Ed May, installed a mid-range driver to mimic the (in)famous mid-range peak of a 604D while the rest is based on the existing model L88. So my dear reader if you don't like the mid-range peak in your 431x speakers maybe you should consider disconnecting the mid-range driver. :)


JBL 4310, Source: the Internet

4311 was introduced in 1974 to replace 4310. The design was pretty much the same. The protruding front panel panel was removed for a simpler enclosure design and the high-frequency driver was replaced by a bigger LE25 which suppose to give a better HF extension. 4311 successfully pick-up the market for 4310 in no time.


4311, Source: the Internet

Following the success in the professional market, JBL introduced the L100 targeting the home market. Generally speaking, the L100 is a 4311 with a less-complex enclosure. The drivers are the same. There are a total of three generations in the history of L100. In the first generation the drivers are all aligned vertically with the tweeter LE25 sitting on top, the midrange LE5-2 in the middle and the bass driver 123A at the bottom. As far as I know JBL didn't sell many L100s in this configuration. The name for this model is L100 Century. the name for the second generation of L100 is L100A Century. The drivers alignment was changed in a way that they are not aligned either vertically or horizontally, similar to the alignment of a 4310. The name of the last generation of L100 is L100A with prefix "Century" removed. 4311 later was changed to 4311B with drivers replaced by ferrite counterparts. The bass driver is 2213H and the midrange is LE5-10.

There are two major differences in appearance between L100 and 4311. The first one is the chocolate foam used in the front cover. The second one is the knobs for frequency adjustment is flush to the front panel for L100. Unlike the protruding knobs found on the 4311s. In the following JBL's catalog you can see the chocolate foam front cover with vivid colors. I am not sure how many of them survived today. To accommodate the chocolate cover, the front of the enclosure is flat with 4 notches on the corner to lock the cover.


The chocolate cover found in the first generation of L100. Source: the Internet


Later generation of L100, Source: the Internet


Approximately in later 80s JBL updated 4311 with 4312. Visually 4312 is like a 4311 with the metal label on the front panel flipped. By design the 4310 and 4311 should be mounted so that the bass driver sits on top of the midrange driver and the tweeter. The 4312 on the other hand should be mounted with the bass driver at the bottom. Except the change of the look the rest of the design of 4312 is the same as 4311. The crossover and the drivers remain the same as 4311B.


The first generation of 4312, Web road map

In the following years 4312 underwent a major change. The high-frequency driver was replaced by a TI-035 with a Titanium diaphragm and the updated model is named 4312A. According to JBL's documents the frequency response of TI-035 extends to 27kHz. I guess this is driven by the introduction of digital sources such as CD. After it doesn't sound so cool for a so-called studio monitor that can only go up to 15kHz. In the following updates 4312 pretty much remained the same. There is no apparent difference between 4312B and 4312A.

Took half those years, 4312 made a major change leather, facelift because 4312A treble veneered Stadium libmysql.lib Wan taixin exactitude diaphragm TI-035 Hao airport can 響 Ying 27kHz, Alto veneered Stadium stub powder magnetic LE5-10 types 104H-3, bass veneered Stadium because magnetic powder 2213H. More falls under the treble unit Stadium reason, guess stub CD digital 訊 popularity by Jian about that source, because dubbing Studios 專 Horn, Frequency 響 Ying to 15kHz is only a little paint. Take on the future both on behalf of 4312 Almost little different in Datong, 4312B see no stub 4312A difference, 4312C sound veneered Stadium-stub configuration fully stub 4312A/B model courses, Re:Torpark libmysql.lib Landmass manufacture.

2000 to 後 beauty China original facility put 4312 GUI class in household series, launched a paragraph 4312SX, this paragraph Horn and it of Qian both generation styling poor replacement is big, bass reflection mouth modified because two real, open in bass veneered Stadium following, points sound device also complexity 雜 many, see of out future is because has caters to new generation sound 響 of taste, unfortunately this model courses of styling only Tel Aviv holding has generation, 4312SX of bass veneered stadium used 2213H, Alto modified because gold're part vibration film 904Ti-1, treble veneered Stadium bian Hao leak leak long, Why 336454-001.

4312SX, net road map

Not sure if it is because of poor 4312SX how important do sales, Kimberley JBL 4312 series to promote this disappeared in the net, not over in Japan or 歐 Chau 續 after Hao 4312D, Happy Valley to promote some spider hex signs found air circuit breakers Ying this is Japan design plan, and then back to the United States the original facility ren Zheng. Back to familiar 4312A/B/C 4312D apart from outside view, veneered stadium but sharp begins, bass libmysql.lib 2213Nd cobalt Magnet, Alto veneered Stadium libmysql.lib Traditions Paper Cone diaphragm 105H, treble veneered Stadium to give 054Ti. This facelifted maximum features bass veneered Stadium Magnet into the latest technology of cobalt Magnet, magnetic strength, poor Tri-Tri-tone ring Magnet begins to work, Ting up 驚 people, not over the specifications characteristics seem to just the is close to 2213H. In 2012, the latest generation of 4312E and 4312D seem to be almost, bass-veneered Stadium bian Hao are small change, bass change into 2213Nd-2, Alto veneered Stadium 105H-1, treble veneered Stadium entering into libmysql.lib 054Al-Mg 鎂 aluminum alloy. These two horns I no long Ting over. Japan product can over a small Edition of the JBL 4312M series, why six-inch bass unit Stadium, stadium equivalent product can much voice to stub Frequency 響 ying and his older brother is completely different, not more Userboxes/Time introduction.

Bic Camera in Osaka to see the 4312E, a Mai $75000 幣

4312E, net road map

4312E using the latest generation of veneered Stadium 2213Nd-2 bass, handsome 誇 Zhang

By in this series Horn health production super over 50, so adoption with of veneered Stadium also Diego has update, this some update over of veneered Stadium of bian Hao Club Med with-x future standard shows, number value more big representative is more 後 period of production products, for example Alto veneered Stadium on has LE5-2,LE5-3,LE5-10, good both kind of, basically LE5 series reduce Hao 後 surface small in three of is Alnico magnetic iron. Bass veneered Stadium comparison good differentiation of t, why Alnico,2213 123A series series a plus h because iron powder cores. Do not over the readers do not need too fear worry, this unit features are within close proximity of the stadium, JBL's original facility information material also provides alternative to old driverunit Huai when Hao, an example of JBL L100 series project file built here in Tulsa's popular Council falls under the LE5-10 can't LE5-2 of Tel Aviv.


JBL technical brochure may explain LE5-2 LE5-10 proxy, Web road map

See has this so more generation of 431x Horn, read who not difficult release now both between all of treble veneered Stadium stub Alto veneered Stadium in modified paragraph when are has more begins to over outside views, only keep not change of is that only bass veneered Stadium, cannot theory is which generation, Yong yesterday is a circle a circle of concentric round, this kind of concentric round design total is with future extends high frequency of, description veneered of said is frequency rate more high, Club Med brought begins to of vibration film straight 徑 more small. Vibration film a Guan Tel Aviv holding white, with hand to touch bass veneered Stadium of surface, Club Med has a kind of rustling of 顆 grain sense, this is JBL special don't of surface finish acting, airport because Aquaplas,Aquaplas is a kind of to Silicon sand because main of material, formula when so is secret's, high speed circuit switched data said has Bay Qiao of components, can with effect reduced vibration film of resonance.

View stub out color section, in addition to earlier 4310 gray outside, Almost all the 431x series offer two kind of color scheme Xuan Xiang, a kind of is all black, some box Stadium two bian'll make JBL standard, another kind of entering into is Mu Wen 貼 skin. Not theoretical views how to box stadium is 19mm low density particle board, dubbing studios or home image: choose wood Wen color, black in PA for entering into many projects such as a Pub or small stage. This kind of a black box is a coating of black class resembles the surface of plastics 貼 skin, slight collision could set off future, the whole Stadium Feeling 蠻 low, person Feeling than Mu Wen 貼 skin look good, bad does not know on the voice.

Received Xia future 談 a little real people using Shang of experience, 4310 stub 4311 are is not Yes airport design total, Horn veneered Stadium arranged not in a vertical online Shang, does and no has points around bian, this in DVD sound room uses of Jian Ting Horn is usually, for because DVD sound room is near Gatwick hearing Ting, acting theory Shang as long as put Horn of bearing Corporation Online Yes Qi ear, on no has not Yes airport of question problem. Moreover if it is for use by eight 軌 Sound recording and reproduction, the Director cannot each have special design plan. In addition to these factors, my worth was still one of the major reasons, Jie is cost savings, production does not need standard equipment two kind of boxes, 庫 save less than half. The L100 era, first generation L100 Century Horn arrangement into vertical, not over the last two paragraphs were changed back to no Symmetry, not around bian, begins to stand on the grounds of long is not clear, why not over the net the way lopsided 認 arrangement is the best of the first generation, this little stand long Po 贊. 4310, and 4311 and L100 still has a little than 較 special don't of design total, is it 擺 put when bass veneered Stadium Ying this in most above, on like paper most above of photos a model courses, this model courses design total of reasons is by in 123A/2213 this support veneered Stadium in whole real horn Department system here is when fulfill range Horn in using, so anti-over future 擺 can let bass veneered Stadium Yes Qi ear, using who when so also can Dian pour over future 擺, let treble in above, just this model courses JBL of 銘 brand above of Word on Dian pour has. High speed circuit switched data see 輩 before, Horn best veneered on the stadium in just the treble, bass unit under the stadium, home friends might try to try this both trumpet voice two kind of 擺 method on the difference.

In 4312 when generation, 4312, and 4312A stub 4312B are has mirror Yes airport design total, Horn has points around bian, station long 認 because Yes family with account, this is than 較 good of design total, at least in Horn 擺 bit Shang less has a real change number, 4312C JBL and modified back no has points around of design total, 2000 to 後 of type Hao for because positioning into family uses, so including 4312SX, and 4312D and 4312E all are has mirror Yes airport.

Say this much, what generation of 431x to be bought? If there are Alnico Jie, sure then is choose the L100 or 4310 and 4311, if care is Alnico,4312A after the Horn tweeter extends a lot better. Root data JBL Traditions, veneered Stadium quality it is not wrong, but sound-boxes, and encyclopedia are having, early-stage JBL audio still want blow Xu box how 堅-solid and durable, old right right after registration via a material. If household purposes, I'll build around Council bought mirror Symmetry products, these model courses can choose liquid out of style, only 4312, 4312A, 4312B, 4312SX, 4312D, stub 4312E. First generation veneered Stadium L100 can also test 慮 arranged vertically, not over this L100 although veneered Stadium of Symmetry, bass reflex port but is open at the same bian, Club Med still cause about Vocal tract differences, Yan degree depends on person skill and tolerance. Or still have a real Office law, is again making boxes, JBL this series box right in how model courses, making good use of the material a little redo voice definitely want much better.

Next article-long image: introduction of JBL 431x series damper design plan.

Reference information:

Article bian highlight DVD
2012/12/10 4312E photos