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Thread: le15a or d130a

  1. #1
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    le15a or d130a

    I have a set of le15a's playing in a sealed box with drone 15 inch , I was thinking of removing the drone and using 2 le15a in the same box to increase my base response . Is this a good option ??? I figured that having two powered le15a that would increase my bass . I was also thinking of using d130a instead of the le15a and using two of those as well ,my first thought is crossover point and will these play in a seal box as well . Is there anyone that is doing what I am considering ?????. What would be the con to this whole idea I am using two 100w amps to drive both speakers so power should be fine , any thoughts would be fine or any idea for that reason.

  2. #2
    Dang. Amateur speakerdave's Avatar
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    I can't answer all your questions, but you may find it interesting, as I do, that there is a club in Japan owned by a friend of JBL, so to speak, who uses 2 130b's each side in 20 cu ft sealed enclosures, along with 075's and 375's playing through the large slant plate lenses, to play jazz from the time period these drivers were central to music reproduction, on vinyl, using JBL amplification. The club is called Basie and there is a thread here about it, posted by our fearless leader after he visited there with GT and some other folks from JBL.

    There is no D130a. There is a D130, an extended range driver with a metal dust dome; the later pro equivalent of that is the 2135. It has a characteristic rising response and is not that great for hi fi. There are a number of variants, meant for musical instrument amplification, with different model numbers. There is also the 130a/b/c woofer, impedances 8, 16 and 32 ohms, with a different frame and cone assembly and a paper dust dome. The frames and cones for these look very similar to the D130, but they are in fact different and are not interchangeable for intended uses. The later pro equivalent is the 2220.

    The 130a/b/c//2220 is technically an underhung driver, but only by about one mm, so that it has very little excursability without entering into nonlinearity distortion. It is meant for horn or bass reflex loading. That explains, I think, why Shoji ("Swifty") Sugawari uses two of them on each side in his sealed box set up. The 20 cu ft would allow the vas volume for each driver. A smaller box would result in loss of bass. EQ is really not an option for this driver. Personally, I bet that system sounds very good, and I'd like to hear it sometime.

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  3. #3
    Administrator Mr. Widget's Avatar
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    If you simply want more bass then turn down your high frequency units, if you want deeper bass you'll need either different woofers or just add a high quality sub. The D130 and 130A woofers are high sensitivity designs and actually have less low frequency output than the LE15As do.

    I would not add a second pair of LE15As unless you are after higher max SPL, and even then I would do it in a separate cabinet and not use them in place of the passive radiators.


    Widget

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    Ok , so far I see that running the two sets of le15a will not fair well , my question is it it because of the two speakers fighting each other ??? if that be the case would running them 180 out make a difference , one pushing one on the pull ???? . If the phase is not the issue , would it just be a box size issue internal playing volume ??whats the ?. anyone with speaker knowledge please math with this setup , will it cancel itself out or is it something else that I am not taking into account ?????.

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    One can see ( from the following pic ) that JBL recommends ( for best bass extension from an le15a ), an enclosure of ( at least ) 4.1 to 5.0 cu' ( that's ported ) .



    Using a smaller box ( than is optimal ) reduces the bass / going to a sealed box of similar size, will reduce the bass reproduction even more .

    Sticking two identical speakers into one ( optimal ) box simply divides the ( available cu' per speaker ) by a factor of two ( effectively giving 2 "non-optimal" tunings/alignments ) .

    Additionally ( if not most importantly ), if you still have the original cream-colored surrounds on your le15's, you should get them replaced for the more modern foam types ( you'll need to search out a local reconer who will do a simple "refoam/resurround" ).
    - Your surrounds ( if still original ) are undoubtedly stiff as a board and are limiting the available bass from your existing cabinets .


  6. #6
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by purejazz View Post
    Ok , so far I see that running the two sets of le15a will not fair well , my question is it it because of the two speakers fighting each other ??? if that be the case would running them 180 out make a difference , one pushing one on the pull ???? . If the phase is not the issue , would it just be a box size issue internal playing volume ??whats the ?. anyone with speaker knowledge please math with this setup , will it cancel itself out or is it something else that I am not taking into account ?????.
    What exactly are you trying to accomplish?

    Using woofers out of phase will kill bass, push-pull reduces distortion but won't extend or augment your bass response, and finally you may not realize what the passive radiators do in your cabinets. The passive radiators perform essentially the same function as a tuned port. Your cabinets are the correct size for a single LE15A.

    Also, Earl brings up an excellent point. If your LE15As have their original yellowish surrounds your speakers will most likely offer very little low end because the system resonance has been significantly increased in frequency as the surround has stiffened with age.


    Widget

  7. #7
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    What i am trying to accomplish is to have more bass at lower volume , I have good bass but it like a give and take situation , using the eq i can turn up the bass for the woofer , but then the top end starts to suffer as well , there is a point where both are pretty good , but I was thinking of lowering my bass on eq and then adding another set of le15a which in my theory would double my bass response at a lower gain on eq . I knew going in that my idea may have issues with the math , but being that the box is 11cu i figured i was safe , based on what I am hearing the volume of the box is one part of the equation . I was just trying to hold off on building another set of boxes , if there are any other ideas out there please let me know , thanks to those who gave their input.

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    An enclosure that's 11 cu' can easily support two le15a speakers sharing it's gross volume. I guess you must have a custom enclosure . What are it's internal dimensions ?

    You won't enjoy the impression of a doubling in bass levels ( that equates to an @ 10db increase which you won't get with this approach ) . You will achieve an approximate 6 db increase in bass output ( if executed properly ) .

    Once you fill that second ( drone ) opening with an active speaker, you're going to have to port ( & tune ) your cabinet ( unless you prefer to continue boosting LF with your EQ ).


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    The box external dim are 30 *16*40 , yes it is a custom box . if I were to port the box , what would be a good sounding port in a room about 20ft long and about 12 wide . I would like a bass thats not way over the top but enough where my jazz sounds good in the room , dia and length of ports for a good starting reference . also will the tonality of the bass change from sealed to ported ????

  10. #10
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    Your enclosure is more likely 9 to 9.2 cu' ( given those external dimensions ) .

    There is a change in tonality when moving between sealed & ported .

    The thing is, you currently have a drone cone / which more closely resembles ( if not duplicates ) the tuning of a ported box .

    Sorry, this computer won't do box tunings ( I don't have the software loaded on it ) / so I can't help you there .

    You can always still load a second le15a ( into the place currently occupied by the drone cone ) / though you'll still have to use the EQ on lower frequencies to achieve reasonably flat bass response.


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    Quote Originally Posted by purejazz View Post
    The box external dim are 30 *16*40 , yes it is a custom box . if I were to port the box , what would be a good sounding port in a room about 20ft long and about 12 wide . I would like a bass thats not way over the top but enough where my jazz sounds good in the room , dia and length of ports for a good starting reference . also will the tonality of the bass change from sealed to ported ????
    From the engineering chart, JBL recommends approx. 40 square inch port with a 2" duct (tunnel). Of further interest, the PR15 drone cone is designed for enclosures from 5 - 8 cubic feet. So, you are well outside that spec. Not surprised the bass performance is less than ideal.

  12. #12
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    I know the boxes I have is large enough for a good bass response , from what I can tell my bass response is good , but to get a really strong bass I need to increase the gain on the eq , only thing wrong with that is it also changes the overall sound of everything else . that is what I was trying to remedy .

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    Senior Member gibber's Avatar
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    Quote Originally Posted by purejazz View Post
    ... to get a really strong bass I need to increase the gain on the eq , only thing wrong with that is it also changes the overall sound of everything else . that is what I was trying to remedy .
    If you want more kind of kcking bass and a faster low-mid on acoustic-bass and cello, change to K145 and leave the drone cone as a first trial.

    If you want that huge thumping bass for modern dance stuff, widen the cutout to accept an 18" like 2243 or 2245. The 2235 will do some kind of 2245 emulation without changing the box. Both 2235/45 cost a ton even if fairly worn down, so maybe try 2243 in that case.

    Ralph

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    Aren't 2243's a rare bird? I've never even seen on. But you can make a 2245 from a 2240 frame, and those are cheap, at least in the USA. Can't say about other parts of the world.

    Nick

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    Senior Member gibber's Avatar
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    Quote Originally Posted by NickH View Post
    Aren't 2243's a rare bird? I've never even seen on. But you can make a 2245 from a 2240 frame, and those are cheap, at least in the USA. Can't say about other parts of the world.

    Nick

    Yeah, probably depends where you live. Over here 2243s are easy to get and cheaper than 2241 (or the 2245 recone kit you would need to make the 2240 upgrade you propose). But imports are nothing the US guys do, i noticed. Quite different the other way 'round, i buy tons of stuff on eBay-US or CA.

    Ralph

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