Le14a vs le15a

HiA few years ago I got some great help trying to figure out what to build with the drivers I had laying around. I turned out pretty well. The system sounds great I have done so for the past years. Now I find myself I a similar situation. I have some drivers, but I need to do something with them. I have at the moment the followering drivers 075, 2402H, 2404H, 2450, 2440J, 2445J and 2309/15090,Le15a or le14a My problem is what to do with the woofers. I can use the Le15a a make a classic 3 way system with Le15a/2440 and 075. But I have two pairs of the Le14a - so I could do something with two le14a pr side and 2440/075? I love the sound of the Le15a. But I have never head anything with two le14a?

I think I would give the dual LE14A concept a try. You would be best served going the helper woofer route like the 4435.

To avoid too much bottom end, you might try using a smaller than normal enclosure and play around with the port tuning to see what you can come up with. That said, the LE14A is substantially lower in sensitivity so if you like to play loud on occasion, then this might not be the choice for you.


Widget

Quote:

---

Originally Posted by Mr. Widget

I think I would give the dual LE14A concept a try. You would be best served going the helper woofer route like the 4435.To avoid too much bottom end, you might try using a smaller than normal enclosure and play around with the port tuning to see what you can come up with. That said, the LE14A is substantially lower in sensitivity so if you like to play loud on occasion, then this might not be the choice for you.Widget

---

I leaning towards that as well. I am running McIntosh mc2155 så I don't think it will be a problem. Thanks for your answer.

What cabinet size would provide an advantage using two LE14As? I have nine sitting around here.

Quote:

---

Originally Posted by turnitdown

What cabinet size would provide an advantage using two LE14As? I have nine sitting around here.

---

I think I would try a 4 cu ft enclosure for a pair of them and tune it to 30Hz.

It might suck, but that would be my guess. I would want to mock it up in a test box before I commented myself to the design.


Widget

Quote:

---

Originally Posted by turnitdown

What cabinet size would provide an advantage using two LE14As? I have nine sitting around here.

---

My two cents on this question is that I would not bother unless you want to fashion a more compact 4-way modeled on the 4350/55 with a midbass that comes in at about 300Hz. The issue is acoustic coupling, which creates a boost of up to 3 dB at frequencies depending on the distance between the woofer centers. If you play a pair of LE14As beyond about 300 Hz, the upper bass/midrange will be thin relative to the lower bass (and coming from too many places). The LE14A is more like the 2235 than the 2234 which is used in the 4435. Why didn't JBL use the 2235 in that speaker, which plays the second woofer up to about 150Hz? Who wants a fat bottom? Optimum cabinet size is 3.5 cu ft for the 14 inchers.The LE14A, at about 93-95 dB efficiency, plays credibly to a horn (Lancer 101 and Zilch's EconoWave 2-way); it's only advantage over a 15 would be a compact enclosure, but that does not comport well with crossing to the horn no higher (for me) than 800Hz. A later LE14 plays bass in a three-way and a four-way (L240 and 250). Rob uses it as a subwoofer below an E145. Always available in number on eBay, the truth is, it's a bit of an orphan, which is why the question of how to deploy it comes up with some regularity, and your garage is an orphanage, which reveals your compassionate side.What about an all-orphan compact disco speaker for very small venues—two LE14A's, a D123 mid bass and a 2370/2425 treble?An L55-sized enclosure with its LE14A biamped with an L20T sitting on it makes a pretty good garage speaker if you happen to have a Crown VFX2a and a pair of UREI amps sitting around with your LE14A's like some parties do.The best use, I think, would be helping preserve another JBL legacy, which is often seen orphaned without its bass module; use as a bass driver to the top three elements in the L212. The crossover, biamped again, could be moved up to 150-200Hz to flatten the upper bass bulge not treated in the network with a baffle step.

RE posts # 4 & 5

Attached quick modeling pic for LE14A (Vb 4 cu.ft. net /Fb 30 hz /double woofers) shows a valid box design to me. Not subwoofer material but a pair will certainly make noise. Plus response is reasonably flat, and F3 a little under 50 hz. The small Vas parameter (147 L) would possibly prevent this driver from being at ease in large cabinets.

Note there's a typo in the software with regards to LE14A size at 12" instead of 14", i could have corrected this going into the driver database, but i forgot. I checked the other parameters and they seem ok.

The software calculated the woofer's sensitivity at 91.9 db. Checking this with JBL's own driver efficiency data of 0.95% mid-band, it matches since Eargle's eff./sen. table gives 1% = 92 db.

So simplified, one driver 92 db, two drivers 95 db, and a pair of double woofer boxes would give 98 db, enough possibilities to rattle the silver...

Richard

It seems like there are some different opinions on the subject. The reason I think I could work, or I the reason I would like it to, is that it would serve as a more compact 3 way version of my other homemade JBL which is 2xLe15a, 2123h, 2440/2397 and 2403. But as I understand there are no advantages I 4 Le14a over one Le15a?Thank for all your replies.

Louis,

RE But as I understand there are no advantages I 4 Le14a over one Le15a?

I will reply to your last question tomorrow, i have to go sleep zzzzzzzzzzzzz

Btw i don't agree there are no advantages in that context.

Richard

Quote:

---

Originally Posted by Louis

It seems like there are some different opinions on the subject. The reason I think I could work, or I the reason I would like it to, is that it would serve as a more compact 3 way version of my other homemade JBL which is 2xLe15a, 2123h, 2440/2397 and 2403. But as I understand there are no advantages I 4 Le14a over one Le15a?Thank for all your replies.

---

Depending on cabinet size and tuning, you could get LOWER bass in a smaller cabinet with one LE14A than with one LE15A. If you use a mid bass like the 2123 with two LE14As per side, essentially what I was recommending, crossing over at about 300Hz, I see no problem; you would indeed get performance very similar to what you have now—in a smaller package and possibly with greater extension into the VLF, if you give the woofers room to breathe, i.e. closer to 3.5 cu ft per woofer than 2.0.

Louis,

RE But as I understand there are no advantages I 4 Le14a over one Le15a?

I quickly modeled the single LE15A in a comparable box (4 cu.ft./Fb 30 hz) and i get essentially the same response curve and F3 close to 50 hz of the LE14A. Very little difference (this reminds me of the 2205 i own and the 2225 that replaced it). There's more than one road to go to Rome. In the case of the LE15A the engineer gave it a very large Vas of 736 L and a pretty low Qts of .21 (LE14A: 147 L and .32 respectively). These two parameters are the proper box size influencers.

The main advantages between 4 X LE14A VS single LE15A are output (db spl) and distortion. With the four drivers you get higher sensitivity, increased max level due to higher power capacity and lower distortion due to higher efficiency (the latter is documented in my BGW thread).

Moreover, with regards to distorsion, the LE14A has a little higher cone excursion capability than LE15A. Every bit of this matters when pretty old drivers are involved, as these were not born with a whole lot of it.

The software calculated the LE15A sensitivity at 96.2 db. Higher than the single 14" at 92 db, but here we are talking about multiple 14", hence the advantage. I also checked the 2.6% efficiency rating of the LE15A, in Eargle's eff./sen. table, and it matches at 96 db sensitivity.

One of the modelings i did confirms what Speakerdave said about a single driver in 3.5 cu.ft. box or two of them in a double size box. But then the OP has to kiss goodbye the small size cabinets he had in mind for double LE14A: 7 cu.ft. net might require around 8 cu.ft. gross due to driver, bracing, etc. taking space, then a pretty large one...

Other option, if you have an equalizer, i'd go for multiple LE14A in the smaller cab, then EQ with the 40 hz slider to obtain somewhat more deeper bass, while preserving a good part of the cone travel capability for those times when you want to beat on the system.

Remember an advantage may have more or less value depending on user preferences or application. For example, a 2 KW power amp makes no sense to me, more so in view of my use and listening levels, but manufacturers do make and sell 2 KW amplifiers or more!

If you're a high drive user multiple drivers would make sense, however a low drive audiophile might not value or enjoy the benefits.

Richard

Single LE15A in 4 c f /Fb 30 hz. Very similar response to double LE14A in same box.

Single LE14A in 3.5 c f as mentioned by Speakerdave. Not bad but a double woofer version would lead to a big box...

From E-V speaker building document. As a bonus you get the 2nd paragraph, lol

From Eargle Loudspeaker Handbook 2nd ed. p. 93

Discussing two adjacent woofers in parallel and implications.