LE14 Bass Bin

[John W]

I just purchased a pair of LE14a drivers and want to build a bass bin.

I chose this driver for a few reasons: first I have a pair of L222 Disco’s that I really enjoy. But, the previous owner had new foam surrounds installed and they glued them on the outside of the cones, which really bugs me.http://audioheritage.org/vbulletin/images/smilies/banghead.gif I may swap the LE14h out and install the new ones there instead. Secondly, it looks from the enclosure guide that the LE14s perform better in a smaller box than some of the 15s, which is important to my wife.

The question I have is what are the sound differences between a ported enclosure and a passive radiator system like in the L222? I have added mass to the PR15 to make it more like the L220, and like what I hear.

The goal is a three way system bi-amped with an active crossover at about 800hz with these for the low end, I am finishing up some 1200hz smith horns from another thread and have some 2470 drivers I plan on using with some yet to be determined tweeter.

[DavidF]

The question I have is what are the sound differences between a ported enclosure and a passive radiator system like in the L222?

The PR is a vent substitute. Two practical reasons to use a PR are to protect the woofer from very low bass resonances and/or to substitute a vent that does not fit well in an enclosure (fit meaning to long for a desired diameter, or too long in terms of length compared to cross section). PRs are a little harder to work with and tune. Usually, it does not matter where it is located relative the driven woofer.

David F

[Zilch]

Use Citation 7.4 as a model for a LE-14 based ported sub....

[Robh3606]

Which ever pair you will drive harder is where the 14H's should go. The 14A's have a more limited X-max so you have to watch them. I have a pair in 4 cubic ft enclosures under my mains as subs. You can get them into smaller boxes and trade off a little of the low end. Never tried a passive system. Took a look at it in Bass Box and it looked better in a reflex box. The PR was kind of funky especially on power handling and excursion. The program created the PR. Wonder what it looks like with the real deal a PR15C.

Giskard you have the T/S on the passives radiators or the required parameters to plug in???

Rob:)

[Steve Gonzales]

I'm pretty sure that the LE14A and H have the exact same Xmax, A little less than 6mm. The LE14H-1 has a bit more than 8mm. The weighting is crucial to the tuning of the enclosure when using a PR15. My L222's use the LE14H and the L220's use the LE14A. Both pairs use the 200gms of weighting. In a past thread, it was brought to my attention that some of the L220's and L222's used the PR15(c) without the weights, so I tried them without, BAD CHOICE. The tuning went from 26hz to around 40hz and the woofer flopped around. I run two pairs of these speakers in my listening room and they can shake the house if I choose to. The bass is tight and powerful. I can hear individual bass notes instead of muddy and muddled. the JBL tech notes say that the PR15 should not be placed more than 6 inches away or closer than 2 inches from the active driver. Use the sites "search" feature to find the chart for weighting/ enclosure size. It is that thin black bar below the Lansing Heritage Forums. Go to "search" and type in PR15. I'm not saying that you should or should not use a PR15(c), I'm saying that I personally love the idea and have had great results with my L222's and L220's and hope you at least try this because I've thought of doing the very same thing. Good luck with your project, Steve G.

Edit: here is the tuning information: http://audioheritage.org/vbulletin/showthread.php?s=&postid=5463&highlight=pr15c#post5463

Also: the Citation 7.4 idea is great too, especially with the LE14H-1's. KILLER LF drivers, I had a pair and LOVED them too, they just didn't have enough midrange extension (they roll off about 650hz) for my L222's but for your application, I'd give them the thumbs up too.

[Earl K]

- I agree with using the ferrite magnet motor ( le14h ) to drive the passive radiator / since the alnico has most likely lost some motor strength ( maybe 10% ) . A PR will demand the strongest ( freshest ) motor available to pull/push it.

- I think that the le14h and the le14a have the same Xmax .

- I know this opinion is contrary info to JBLs' published Ts parameters but those lists are already in some disrepute .

- I have a pair of le14h woofs. Their response signature does not correspond with that of a .75" deep coil winding in a 7mm gap. The le14h(s') response curve does matchup to that of a typical .6 " short coil / high BL figure operating in a 7mm deep gap ( ie the midband response rising after @ 400 hz & noticably spiking after 1.5K ).



:cheers:

[4313B]

Giskard you have the T/S on the passives radiators or the required parameters to plug in???Nope and measuring the PR15C, or any passive, is a pain because a test box is required (probably better off using the actual system enclosure although the L220 volume might be too big). If you guys are really interested in the JBL passives we could start running numbers for them. I'm pretty certain JBL never bothered.

- I think that the le14h and the le14a have the same Xmax .They'd better! They both use the C8RLE14A recone kit. :p

Here's the graphs you want posted Earl -

[Robh3606]

OK I am confused:blink:


Hello Giskard

The LE-14 A and H use the same recone kit. So there were A and H with white cones. The L250 has an LE-14A with a black cone?? Where does the -1 come into this?? The L240 uses H-1 black cone. How does JBL stock the White vs. Black cones?? As far as the passive I was just surprised by what came out of the Bass Box when I went with a passive and it calculated the passive for me. The response was great as far as extension but the group delay and power handling vs. the excursion was awful compared to a standard reflex alignment.


Hello Earl

I guess your right the tables wrong or should that H in the table have a dash number after it. I just take those tables as correct I guess by now I should know better.

Oh forget this I am going to listen to some music and sort some capacitors:banghead:

Rob:)

[Earl K]

Giskard ; Here's the graphs you want posted Earl -
Thanks ! :D

[Don C]

OK I am confused:blink:
The L250 has an LE-14A with a black cone?? Where does the -1 come into this?? The L240 uses H-1 black cone.
Rob:)
The L-250 uses the LE14H-1 Same as the 240 and 250 Ti.

[4313B]

The LE-14 A and H use the same recone kit. So there were A and H with white cones. The L250 has an LE-14A with a black cone??The L250 came after the alnico to SFG ferrite conversion and used the LE14H-1 as Don C has stated. A white woofer against the rosewood veneer would have looked horrific. I believe that one giveaway that an L220 or L222 has the LE14H is if the leads point straight down. I have never seen an LE14A with leads pointing straight down. I do believe a few batchs of LE14H's were run with the leads pointing at a "45" but I could be wrong. I know for a fact LE14H-1's were run in both versions. Anyway, the point is, leads straight down with a white face - highly likely it's an LE14H.

[Robh3606]

"The L-250 uses the LE14H-1 Same as the 240 and 250 Ti."

Ok that makes sense. Helps if you open the right Tech Sheet :banghead: I had the 222 open and was :blink: thinking I had the L250 open! LOL

Thanks Rob:)

[4313B]

The response was great as far as extension but the group delay and power handling vs. the excursion was awful compared to a standard reflex alignment.Yeah, they're all compromises. Gordon W has said he's played around with the newer passive radiators from other manufacturers and I believe he has gotten great results. It's all a balance and I've no doubt excellent PR systems can be realized. I'd be interested to see if JBL ever returns to using them.

Use Citation 7.4 as a model for a LE-14 based ported sub....Good idea! ;)

The question I have is what are the sound differences between a ported enclosure and a passive radiator system like in the L222?The vented enclosure will usually roll off at a rate of 18 dB to 24 dB per octave whereas the PR based system will usually roll off at a rate of 30 dB per octave. One result of this is that the PR based system won't be able to capitalize on room gain as well as a vented system (a sealed system with a roll off of 12 dB per octave is king with respect to capitalizing on room gain). Regardless - this is what matters -

I have added mass to the PR15 to make it more like the L220, and like what I hear.