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dennis j leisz
01-01-2004, 10:48 AM
Greetings, What is JBL's recommended frequency operating range for the LE14H-1. Highest recommended crossover point? How would a pair of these work with an 2344 horn with the 2426 driver in an MTM configuration? Happy New Year, Dennis

Mr. Widget
01-01-2004, 12:44 PM
Recommended and ideal are two distinctly different things. While the LE14A which is very similar to the LE14H-1 was used to 2500Hz in the 60's and 70's, today we demand better performance from a system.

While the LE14H-1 will put out higher frequencies, it like any 14" driver will be very beamy above 800Hz-1000Hz. More problematic with using any of the LE14 series woofers is that the massive coating of aquaplas that allows the various LE14s to produce prodigious bass tends to cause them to be less than ideal at higher frequencies. In the JBL K2-S9500 they use a very different 14" driver, the 1400ND. This driver has better mid-range performance and yet they still use a 650Hz crossover point.

This crossover frequency requires a horn that has a significantly lower cutoff point than the 2344. If you could find them I think a better bet would be to use a pair of 12" 2214H woofers. (The woofers from the 4425.) These woofers should work very well with the 2344 and 2426. In any case a significant amount of crossover tweaking will be in order to get this sort of system to work well in an MTM configuration.

Sounds like fun!

GordonW
01-01-2004, 02:57 PM
Ditto what Widget said... if you had a horn with an 800 Hz or lower cutoff like an old Altec 811 or 511 (especially the 500 Hz 511), I'd say go for it, it'd probably work. But with a crossover over 1KHZ, it's gonna be dicey ESPECIALLY with an MTM... the center-to-center distance is pretty hairy for a crossover that high, even if the drivers themselves were perfect up there...

Regards,
Gordon.

Don C
01-01-2004, 07:06 PM
In the 240Ti the crossover is 900hz, in the L250 and 250Ti it is 400hz Then for the 250Tibq it is listed as 350hz

GordonW
01-01-2004, 09:33 PM
Well two things:

First, the closest thing, IMHO, that a 240Ti has to a "weak link", is the upper midbass/lower midrange region "snap". The 250Ti, with its crossover an octave lower going into the 8", was a lot better ti my ears. The LE14 to me, is optimal up to about 500-600 Hz.

Secondly, even if the 14" drivers are OK out to beyond 1KHz, he's wanting an MTM... that means a woofer center-to-center distance of like, a foot and a half, with a horn in the middle! That would dictate that you really wouldn't want the crossover point higher than about 660 Hz or so... since that's a wavelength at that frequency. Even 800 Hz would be pushing it a bit, probably would still work, just would take some careful tweaking and such...

Regards,
Gordon.

4313B
01-02-2004, 12:07 PM
"First, the closest thing, IMHO, that a 240Ti has to a "weak link", is the upper midbass/lower midrange region "snap". The 250Ti, with its crossover an octave lower going into the 8", was a lot better ti my ears."

Well, the LE14H-1 lacks the ubiquitous "rising response" found in so many JBL transducers so that could be why one might find a system such as the 240Ti lacking. I personally like the 240Ti because it is so easy to sit and listen to.

Granted the 250Ti is a step up. The 108H in the 250Ti is a 2118 with aquaplas sprayed on the back to smooth out and flatten it's response. The LE14H-1 has a very nice smooth response with a fantastic roll-off, free from excessive peaks and dips.

You could try an MTM configuration but I think you would do best to follow the posted advice to limit the crossover frequency to ~ 650 Hz. Your filter would probably have to be shallower than it would be for the 1400Nd. LF response would be quite a bit better but as has been stated, midrange response might not be up to what you're after.

Current practice is to use systems such as the K2-S9500 right out of the box "as is" and then add in LF EQ as required/desired. This is in contrast to using older transducers such as the LE14H-1, 2235H, or 2245H with their extended LF response but comparably lacking transient character through the midrange. The 1400Nd has other characterisitics, such as lower distortion and lower power compression, that add to it's overall superiority over the LE14H-1, especially in a K2-S9500 type application. For LF and VLF applications though I would have to stay with the LE14H-1 or LE14H-3.

Now, a pair of K2-S9500's biamped to two twin LE14H-3 sub systems...

dennis j leisz
01-02-2004, 02:31 PM
Thanks to you all for the info. I have 4 LE14h-1's looking for an interesting application. It doesn't appear the MTM approach is feasable based on the specs. I will continue brainstorming . Any ideas? Dennis

GordonW
01-02-2004, 10:06 PM
Well, if you can use a 500 Hz horn, I wouldn't give up on the idea. Two LE14s will have pretty darn decent efficiency together, and with a PAIR of them, I'd doubt you'd have to drive them with enough power to induce much compression.

Giskard, WRT the 240 vs 250Ti... it wasn't the frequency response I found lacking in the 240... it seemed perfectly well balanced. It was the fact, that the transient response of the 250 was better in the region of snare drum hits, rim shots and such... which I deduced was due to the superior ability of the smaller 8" driver to accelerate on transients, without either "rounding off" the transients or "overhang" This, I attribute to the 8" being better at HF transient spikes... even with a crossover, there's SOME upper midrange going to the woofer of the 240Ti, which would be going more to the 8" in the '250...

However, with a 500 Hz crossover, I'd expect the whole transient issue to be fairly moot... IME, the LE14 is quite fine up to there...

Regards,
Gordon.

Earl K
01-03-2004, 06:02 PM
Hi Dennis

Others have already said it , but I'll repeat it, try your le14s in some sort of MTM setup. At the very worst, it'll be a very enlightening experience. I'd suggest a cabinet size of 3 to 3.5 cu ft tuned somewhere in the 30 to 35 hz range.

I use a le14h ( right now in a 2.8 cu' cab. - my next test box will be sized for 3.2 cu' apparent volume) with a le10 on the top ( in a .65 cu' cab. ). I found the heavily aquaplased cone ( 140 g Mms ) of the le14 produced a pretty "wooden" midrange from 150 hz on up. This wasn't to my liking. The aquaplased cone of the le10 really meshes nicely with the timbral makeup of the le14 ( a,h or h-1, I have some of each ) . The ten does have a livelier midrange ( afterall , the 10" cone is maybe 100 grams lighter - while still being driven by a large 3" voice coil ) . Once in a while I substitute in a 2123 or a 2012 - but I keep coming back to the homogenous sound provided by the two aquaplased cone types. The 2 le type speakers run paralleled together. The other midrange 10s need resistors added to balance them to the less efficient 14" woofer.

Center to center measurements for these two speakers is 22".

I use a 2450Sl diaphragm in a 2440 motor on a round mouthed Selenium horn. The 2450SL diaphragm is also aquaplased.

Crossover point is @ 800 hz ( electronic - 24 LR slopes ).

As it happens, my system seems to satisfy one of the criteria for successful MTM implementation. That criteria ( liberally interpreted ) is an absolute 90° phase difference between the middle tweeter (horn) and the surrounding midrange. It seems I lucked into this by having the horn-drivers' voice coil, offset ( behind the woofers ) by just about an exact 1/4 wavelength measurement of the crossover frequency. This is 4.25" at @ 800 hz . This phase offset seems to be very important - I've heard a lot of soundstage depth of field "flatten out" when an additional 90° of phase is switched into the circuit ( via DC blocking caps ). Electronically, Time-Aligning the woofer to horn produces a different sort of cohesion that is quite different than the sense of depth generated by the 90° offset . This all seems to work well with my small exponential horns - I suspect CD style horns will have a different mechanical measurement point since each horn type has a different apparent apex ( or acoustic center ).

Worth reviewing is Dons 12/19/03 update in the private Lansing Speaker Project. Some intriguing info from there ( regarding MTM stuff ) is the inference ( somewht between the lines ) made by Mr. G Timbers (& relayed by Don ) of just how certain MTM attributes will still dominate the MTM setup - even when other, seemingly "iconaclast" rules/or criteria are bent ( such as woofers having to have, equal frequency content ). Asan example, my woofers don't produce the exact same frequency content, but they still produce a good point source ( as long as the db difference, between the woofers isn't too large, @ a difference of 3 db over the top 2 octaves seems to effect a focal breakup ) .

Hopefully, a lot more of this sort of MTM info will become accessible as that project matures.

Anyways, enough blather, do try the MTM setup with at least a pair of your 14s'. At the very worst you'll gain a pair of very useful subwoofer boxes .

regards <> Earl K:)

4313B
10-05-2004, 01:46 PM
LE14H and LE14H-1

BMWCCA
01-27-2024, 04:23 PM
Well, the LE14H-1 lacks the ubiquitous "rising response" found in so many JBL transducers so that could be why one might find a system such as the 240Ti lacking. I personally like the 240Ti because it is so easy to sit and listen to. Old thread, I know—but now I understand what Giskard meant!
And soon to be able to compare the 240ti to the 250ti.
Soon!

https://live.staticflickr.com/65535/53491977734_d51b65f6cd_k.jpg

Triumph Don
01-28-2024, 03:42 PM
Looks like a good start on the refoam! I just did two pairs, one had nice old rock hard Lansaloy surrounds. What a pain

BMWCCA
01-28-2024, 08:14 PM
Looks like a good start on the refoam! I just did two pairs, one had nice old rock hard Lansaloy surrounds. What a pain

Yeah I'm sure the LE14H-1 is much easier than one with Lansaloy. The original foam pretty much falls apart. In fact my first step is now to run around the perimeter with a small nozzle on a shop-vac which sucks up most of the dust that is pretending to be a surround. I finished that last one today, which makes my fourth LE14H-1 in maybe six-months. There's not a lot of room to adjust anything so, luckily, Rick Cobb's surrounds fit very well. The hardest part to clean is really the plastic retaining ring. I'll hopefully get the 250tis down to the new house tomorrow. It needs to stop raining! :(

DerekTheGreat
01-29-2024, 04:59 AM
...The original foam pretty much falls apart. In fact my first step is now to run around the perimeter with a small nozzle on a shop-vac which sucks up most of the dust that is pretending to be a surround...

That's a great idea, going to stow that away for the future.



...There's not a lot of room to adjust anything so, luckily, Rick Cobb's surrounds fit very well. The hardest part to clean is really the plastic retaining ring...

I almost missed that. Is it the retaining ring that holds the surround to the basket? I've only refoamed one set of woofers so far, 2215's. That went pretty well, but there was a generous area for the foam to seat on the basket.

BMWCCA
01-29-2024, 06:14 AM
I almost missed that. Is it the retaining ring that holds the surround to the basket? I've only refoamed one set of woofers so far, 2215's. That went pretty well, but there was a generous area for the foam to seat on the basket. No, the "ledge" where the surround sits is very narrow, not as wide as it is tall and not much wider than the retaining ring, as you can see in the photo of the stripped-down frame above. Just not a lot of room for adjustment.

If you were shimming the voice-coil I'm not sure it would make any difference. The surround wants to be where it has to be. Not really any alternative.

I'm sure some of the pros will disagree! :dont-know:

Robh3606
01-29-2024, 11:55 AM
That's a great idea, going to stow that away for the future.

I almost missed that. Is it the retaining ring that holds the surround to the basket? I've only refoamed one set of woofers so far, 2215's. That went pretty well, but there was a generous area for the foam to seat on the basket.

All of the JBL square frames have a very small ledge compared to the standard frames. I have done Le-14's, 2108's and 2122's. With Ricks Surrounds they almost self center. If you dry fit the surround and install the retaining ring you can actually play the 30hz disk at low level it will self center.

Those surrounds are spot on.

Rob :)

DerekTheGreat
01-30-2024, 05:25 AM
The surrounds we got were from Mr. Cobb. :) They fit really well, although we followed the method outlined by Simply Speakers on YouTube after watching them refoam a 128H, so no test tone. Although I got to wondering if the surround would've stayed stuck to the cone or frame. The glue didn't get tacky for some time (was ~68 in the house) and then when it did, we still went over areas many times, especially on the basket as the surround kept lifting in areas after working the cone up & down like they did. Beginner things, I guess. I think next time I will make the effort to get a test tone going.

BMWCCA
01-30-2024, 07:40 AM
The surrounds we got were from Mr. Cobb. :) They fit really well, although we followed the method outlined by Simply Speakers on YouTube after watching them refoam a 128H, so no test tone. Although I got to wondering if the surround would've stayed stuck to the cone or frame. The glue didn't get tacky for some time (was ~68 in the house) and then when it did, we still went over areas many times, especially on the basket as the surround kept lifting in areas after working the cone up & down like they did. Beginner things, I guess. I think next time I will make the effort to get a test tone going.I am unquestionably a rank-amateur on this stuff and the pros here will likely laugh or cringe when I show my method. Long and tedious, but I'm done and don't have to work today! ;)

Having just done four 128H and two PR300s, I'm wondering what Simply Speakers was thinking about with no test-tone on the 128H.

I find getting just the right amount of glue applied in the first place (don't overdo it) aids in drying and adhesion time. Rick has stopped sending me his 30Hz CD and I can usually remember where I last put one, as well as his glue. I find that the basic Aleene's Original Tacky Glue works for me. It's easy to find, easy to clean-up, gives the right amount of setup time for adjustment, and dries clear. On the LE14H-1 I flip them face-down on a paper towel on my turntable and apply the glue, spreading it out evenly and thinly on the back of the cone's edge with a paint brush. Then I flipped it over, slip the surround in from the front, flip it back over to adjust and periodically go around it to make sure nothing has moved or popped up. I have various sizes of plates and pie pans, determined by the stage of the install and the size of the speaker. Letting the cone hang down (magnet up) helps with getting the surround to lay down but using less glue helps it to dry faster. I have a custom-carved popsicle stick I use to smooth the under-cone edge during drying and then the rounded end to apply a continuous bead of pressure while turning the speaker on the turntable. Once that sets (often overnight to be sure), I flip it back over, run a bead around the thin ledge of the frame lifting the surround with the popsicle stick or paint-brush handle as the glue goes down then, again, spreading it out thinly with a small, stiff paintbrush. That's when I run the test-tone, though there really isn't any movement room at that point. While drying with the tone, I run around the perimeter with the round end of the popsicle stick occasionally. After an hour or so, I turn off the tone, run another thin bead around in the groove between the edge of the surround and the frame using the turntable and then the brush. I install the (clean) retainer ring, then flip the speaker over on a flat surface, face down. At this point the frame and retainer ring will be flush just from the weight of the driver and the surround is not flattened.

But, that all being said, the most difficult part of the assembly was another issue with JBL's T-nut similar to the problem I had with the L150A. This time it was on the mid-bass driver where the bolts had been very stiff coming out. Going back in was worse on two of them and I used a longer 10-32 bolt I had bought to set the T-nut in the L150A just to make sure all the threads were good and the holes lined up. But one nut got stuck and I tried to power it through with my longer bolt and ended up using a claw hammer and brute force just to remove the bolt, nut, and driver in the mid-bass sealed compartment. Moments of panic and thoughts of a bolt cutter crossed my mind. But I was so pissed by then that I went into town in search of a 10-32 SAE tap and found the smallest tap-and-die set at Harbor Freight that had a 10-32 tap. About $19.99 versus just the tap at Lowe's for $7. Now I'm equipped for the duration! I also bought out all of Lowe's 10-32 T-nut stock (6)!

You can see in the photo below my tapping all the T-nuts after that, with the stripped one sitting there for show. The problem nut in the L150a was simply not threaded all the way through and a tap might have saved that. As it was, I tapped all the T-nuts on both 250tis, and several really needed it. I think, in the case of the 250ti, the gasket on the back of the mid-bass driver was installed just enough off to make lining the bolt up at the factory just off enough have cross-threaded the nut without damage to the bolt. At least that's my guess. In any case, the tap did a great job and the bolts didn't need to be run through the die. I guess the factory uses power-drivers to run the bolts in. I use my best Snap-On Phillips hand tool, to make sure I have a good fit in the screw slots and I stop at the least resistance. There aren't that many to require a power-tool and I trust my hands more than my Dewalt in delicate cases.

https://live.staticflickr.com/65535/53498054723_190e4d14af_k.jpg

https://live.staticflickr.com/65535/53498136109_bd0fc75fb6_k.jpg

Mr. Widget
01-30-2024, 08:17 AM
What a happy family photo!


Widget

DerekTheGreat
01-30-2024, 10:13 AM
Definitely! Is that a Crown SR-II I see back there???

Did that driver need to come out, the one with the accordion surround? I thought those were good for life? Superb job on your woofers though.

The dude on Simply Speakers seemed like a pro, he was fast and precise. I realized real fast that I'm about as coordinated as a reanimated corpse, yet we still got it done. I don't think we used too much glue, but the tube Rick provides is ultra stiff, I had to glue Angie's surround for her as a result. Aileen's glue, eh? Where can a bloke get some of that? Not that I'll need it soon, but for reference. Not sure how long my 2245's will hold out, they seem ok though. Although I think I'll want to get my 2215's reconed [again] at some point, as I noticed the cones on it do not have Aquaplas on either front or rear. Thought they were supposed to? :dont-know:

BMWCCA
01-30-2024, 10:46 AM
Definitely! Is that a Crown SR-II I see back there???

Did that driver need to come out, the one with the accordion surround? I thought those were good for life? Superb job on your woofers though.

The dude on Simply Speakers seemed like a pro, he was fast and precise. I realized real fast that I'm about as coordinated as a reanimated corpse, yet we still got it done. I don't think we used too much glue, but the tube Rick provides is ultra stiff, I had to glue Angie's surround for her as a result. Aileen's glue, eh? Where can a bloke get some of that? Not that I'll need it soon, but for reference. Not sure how long my 2245's will hold out, they seem ok though. Although I think I'll want to get my 2215's reconed [again] at some point, as I noticed the cones on it do not have Aquaplas on either front or rear. Thought they were supposed to? :dont-know:Yeah, I bought that Crown just for the 250ti, but I use it on everything in the basement. It doesn't care what I ask it to drive—or how many!!

Aleene's makes a full line of glues, most of which are available at any Michael's store, or other craft stores. Not much more than a couple of bucks. I had to order one which is a heat-activated fabric glue I'm going to try on grille cloth that's worked loose on the L112 and 240 before it gets worse. I just need my wife to find her old iron that she'll allow me to use.

No, that mid-bass driver didn't need to come out, I just figured it was easy to do and any weight I could take off would make it that much easier to move them. Glad I did now that I know how badly they F'd up the T-nuts! All fine now.
:thmbsup: