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Thread: Homebrew Center channel speaker

  1. #31
    Moderator hjames's Avatar
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    Quote Originally Posted by Zilch
    How about this: Biamp the mids and highs with the $30 PE T-Amp?

    Pair LE-10s gonna be the best woofer match, probably. Stack the mid/tweet between a pair of those.

    116As in closed box would work, too, if you need smaller....
    So - I wouldn't want to look for a pair of 2122s?

    Dang!!

    Guess I'll have to put them aside for now, until I get around to making up some 4345s ... sigh
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  2. #32
    Senior Member grumpy's Avatar
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    So - I wouldn't want to look for a pair of 2122s?
    Sure you would! Just not necessarily for this -grumpy

  3. #33
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    Quote Originally Posted by GordonW
    Anyone got any derelict 116A frames around? It'd be interesting to see if you could "shoe-horn" a 2118J cone kit into a 116A frame. That'd make an alnico 16 ohm 8"... inherently shielded.
    - Nice idea . I always enjoy your inventiveness .
    - Though I do believe twin 2118a(s) "alnico/hybrids" / arranged with the DD66000 style of asymmetrical crossover, will better suit the sensitivitiy figure needed to keep up to her original woofers ( 2216s or le15b , unless I'm remembering her 4320(s)' components incorrectly ) .
    - I'm thinking the target sensitivity for this box needs to be 96 or 97 db / a fairly tall order .


    Quote Originally Posted by GordonW
    Wouldn't matter if it matched any existing designs... he's BUILDING a cabinet, anyway, so he can tune it for whatever the parameters wind up being!
    - "She", Gordon ,,, "She" is having to build a cabinet for this project.




    PS - I don't do H.T. , so maybe I'll just shutup now .

  4. #34
    Senior Member GordonW's Avatar
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    A few other options- I've used all of these woofers before, and can vouch, they DO work well:

    Parts Express has a Dayton 6.5" shielded 4 ohm driver:
    http://www.partsexpress.com/pe/showd...number=295-308

    A pair of these, wired in SERIES, would give 8 ohms. Very good bottom end whomp, good midbass, IME.

    Or, for more horsepower, the 8" DVC driver. They call it a sub, but it's fine out to 1KHz:
    http://www.partsexpress.com/pe/showd...number=295-480

    Wire the voice coils in each drivers in SERIES (to make 16 ohm drivers), then wire the two drivers in parallel, to get back to 8 ohms. These things have SERIOUS whomp, for what they are, and are pretty clean sounding to boot...

    Regards,
    Gordon.

  5. #35
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    Quote Originally Posted by Heather
    So - I wouldn't want to look for a pair of 2122s?

    Dang!!
    - Sure you should, everyone should own a pair .

    - If you put new 2122H cone kits into K110 baskets ( alnico magnets ) you could use them for this project of a center speaker .
    - I do have mixed feelings about "wasting" those cone kits in an alnico magnet-assembly.




  6. #36
    Senior Member GordonW's Avatar
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    Quote Originally Posted by Earl K
    - "She", Gordon ,,, "She" is having to build a cabinet for this project.



    DOHHHHH!!!!!!!!!

    Regards,
    Gordon.

  7. #37
    Senior Member GordonW's Avatar
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    Quote Originally Posted by Earl K
    - Sure you should, everyone should own a pair .

    - If you put new 2122H cone kits into K110 baskets ( alnico magnets ) you could use them for this project of a center speaker .
    - I do have mixed feelings about "wasting" those cone kits in a alnico magnet assembly.



    Still have the 8 ohm issue... 2122H are 8 ohm each. Would need 16 ohm kits.

    2123J kits in K110, LE10A or D110 baskets would work, and would not "waste" scarce 2122 kits (and it would cost less, too!). Probably would want to have someone coat the cones with "wet look" or something, to tame down the rising response a bit, to make 'em match the 3133 crossover better...

    Regards,
    Gordon.

  8. #38
    Administrator Robh3606's Avatar
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    So - I wouldn't want to look for a pair of 2122s?

    Dang!!
    Ideally you would want 16 ohm drivers and Alnico at that. The 2122's will work however they are ferrite and 8 ohms. The 8 ohms may not be a problem depending on the amp. You could look for some older 10" frames like the 2121 or K110/Le-10A that are Alnico and drop 2122 cone kits into them after they are recharged and checked out. You need to make sure first that the 2122 kits will work in those cores. If you get a good working pair of Le-10A's just use them however box size may still be a proplem. If I were you I would do a cardboard mock-up of the front baffle to see just how much space a pair of 10" drivers the 5x10" Lense and the 2405 will take up. You may only end up wanting to do a single 2122/Le10 and lay it down like the L and Right. Would make things a bit easier.

    Rob

  9. #39
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    Quote Originally Posted by Gordon
    Still have the 8 ohm issue... 2122H are 8 ohm each. Would need 16 ohm kits.
    Quote Originally Posted by Rob
    Ideally you would want 16 ohm drivers and Alnico at that. The 2122's will work however they are ferrite and 8 ohms.
    - I can see there's a fundamental difference in opinion on this matter of what driver impedances are needed to make this work ( assuming the use of midrange-efficient / bass-shy transducers ) .

    - I was envisioning a crossover design that presents ( to the amp ) an asymmetrical impedance load from the twinned woofer section . ie; ( from LF to MF ) transitioning from @ 4 ohms, up to 8 ohms .
    - The 4 ohms "pulls" more current only in the LF area and reinforces just this lower frequency range .
    - ie; With a large inline coil ( on just a single woofer ) adding its' ever climbing series impedance into the overall ( paralleled ) load / by the crossover point the composite ( woofer ) load is more or less back to where it should be ( from a sensitivity perspective ).
    - This of course requires an amp that is stable, driving a 4 ohm load into the lower frequencies .



  10. #40
    Dang. Amateur speakerdave's Avatar
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    You do need the low loss Alnico magnet structures JBL used on its classic drivers, or, alternatively, a modern self-shielding neodymium driver. The LE10A (or L111A, if you prefer the black woofer cone) is likely the best match to your front L/R speakers. I'm not aware of 16 ohm versions, although the early literature lists them as 8-16 ohms under JBL's old flex-impedance standard. The easiest way to test this idea may be to set some L77's up there on either side of your horn and UHF. Custom cabinets could be minimum height, and you could get the required volume with your shelf depth.

    There is a driver that would meet all your specified conditions, but it is rare, and that is the 2115B. That would give you plenty of life in the voice range, and it can be used in a 1-foot cabinet. The eight-inch frame would save you another 2" of cabinet height blocking the light. It wouldn't give you the bass depth of the LE10 family with their larger surfaces and aquaplased cones, but it would be a much better sensitivity match (92 dB plus acoustic coupling of 3 dB) and impedance match--the "B" is sixteen ohms. Be aware, though, these are not reconeable so you need a clean pair. The LE8T-2 is a similar driver, but I'm not aware of 16-ohm versions; it is somewhat less rare (used in the S109/Aquarius 4). The LE8T is much more common, but is unfortunately not a sensitivity match, even in pairs, making biamping, the only way to use them. Biamping would also solve the impedance issue, remember.

    If you decide to surrender more light, there are a number of woofers in the 123A family that would work. A pair would have nearly the same cone surface as a 15, and you could make flatter custom cabinets. The 122A from the L65B might be the best of these for you, despite what Rob says about it not working for him (he's using E145 midbasses over LE14A's, after all!). In this size the very best modern self-shielding JBL woofer is the 252G from the LSR series, but it is 4-ohms. Again you could make your cabinet top and bottom tight to the woofer frame to leave as much window uncovered as you can and use your shelf depth to make up the volume you need.

    David

  11. #41
    RIP 2011 Zilch's Avatar
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    I'm seeing the stacked horn and slot as controlling the minimum height.

    Biamp's not a big deal. The T-Amp can easily drive the MF/HF:

    http://www.partsexpress.com/pe/showd...number=300-952

    Too cheap? There's also this one:

    http://www.partsexpress.com/pe/showd...number=300-956

    Either one with the main amp would TRIamp a center channel, if you just HADTA tweak it to the max....

  12. #42
    Dang. Amateur speakerdave's Avatar
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    Quote Originally Posted by Zilch
    I'm seeing the stacked horn and slot as controlling the minimum height....
    Yes, but it could be a bump in the middle.

    David

  13. #43
    Administrator Robh3606's Avatar
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    The 122A from the L65B might be the best of these for you, despite what Rob says about it not working for him (he's using E145 midbasses over LE14A's, after all!).
    Hello Dave

    The top didn't work! The Le-5 just doesn't cut it compared to a 2425 . I like your suggestion of a single woofer and a 122A is good chioce. That worked just fine. I am just concerned about the overall baffle size and it being too big when all is said and done.

    Rob

    Rob

  14. #44
    Dang. Amateur speakerdave's Avatar
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    Quote Originally Posted by Robh3606
    . . . . The top didn't work! The Le-5 just doesn't cut it compared to a 2425. . . . .
    I think we came to the same conclusion about that. I finally had to put my L65's behind an upholstered chair.

    David

  15. #45
    Administrator Robh3606's Avatar
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    Hello Earl

    The 2122's will work however they are ferrite and 8 ohms.
    More for the ferrite than the 8 ohms.

    The 8 ohms may not be a problem depending on the amp.
    transitioning from @ 4 ohms, up to 8 ohms .
    It may a bit lower that that depending on the drivers.

    http://www.audioheritage.org/vbullet...ad.php?t=10663

    http://www.audioheritage.org/vbullet...ad.php?t=10637


    Just trying to stay "safe". Center channels get quite a workout.

    Rob

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