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Thread: L-200 woofer changes

  1. #31
    RIP 2011 Zilch's Avatar
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    If they got the factory kit, they're 2235H, pure and simple....

  2. #32
    Senior Member mbottz's Avatar
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    Hey Zilch (or anyone eles) another ?

    I aquired a set of L220 Crossovers very reasonably the other day and was wondering since these cross at 800hz and 5000hz, can I use these with any success until I get the custom units completed? Since the 220 used the cateye version of the 077 what is the drawback to adding a 077 and crossing at the lower frequency in the 200 cabinet using the drivers discussed?

    I appreciate all the good advise. Keep it coming

    Mike
    Restoring the legend, one cabinet at a time

  3. #33
    RIP 2011 Zilch's Avatar
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    I wouldn't use it, no.

    The impedances are different, and the crossover frequencies will shift....

  4. #34
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by mbottz
    ...what is the drawback to adding a 077 and crossing at the lower frequency...
    Bleeding ears.... and pained looks from your friends.


    Widget

  5. #35
    RIP 2010 scott fitlin's Avatar
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    The 077 will sound rough and ragged crossed over at 5K. Personally, I wouldnt use the 077/2405 below 8K.
    scottyj

  6. #36
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by mbottz
    Sure if you have some extra time I have always wanted to make a custom crossover. If you can tweak a design, I will attempt to build it.
    O.K., here 'tis, using L300's 8.5 kHz. A major change in addition to raising the crossover frequency is that the 077/2405 is now running with a 3-pole highpass filter which attenuates frequencies below that at 18 dB/octave, cleaning up its sound considerably.

    The circuit shown is the "cascade" configuration. The UHF tracks the MF L-Pad adjustment. If you want the UHF and MF independently adjustable, connect the UHF circuit before the MF L-Pad rather than after. I tried it both ways, and both work fine. It's a matter of preference - you can dial in lot more unnatural UHF "sizzle" (and sibilance) at lower MF settings with the independent UHF connection.

    If you separate the UHF entirely, as Toddalin suggested above, it's necessary to add fixed attenuation to bring the UHF L-Pad into a resonable adjustment range.

    Giskard's L300 circuit is here for comparison:

    http://audioheritage.csdco.com/vbull...=1042#post1042
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  7. #37
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    Quote Originally Posted by Zilch

    The circuit shown is the "cascade" configuration. The UHF tracks the MF L-Pad adjustment. If you want the UHF and MF independently adjustable, connect the UHF circuit before the MF L-Pad rather than after. I tried it both ways, and both work fine. It's a matter of preference - you can dial in lot more unnatural UHF "sizzle" at lower MF settings with the independent UHF connection.

    If you separate the UHF entirely, as Toddalin suggested above, it's necessary to add fixed attenuation to bring the UHF L-Pad into a resonable adjustment range.
    I don't agree that it is necessary to add fixed attenuation. Using the L-pad alone, the UHF can be adjusted over the full range, from nada to too bright.

    I actually prefer it up toward the brigher side and that's the way my RTA says to run it (though I don't put a lot of stake in my RTA up in that range as I think the mic rolls off).

    As the 077s are even less efficient than the 075s I used, and crossing it over about 8.5K (with smaller chokes and using an additional cap), as opposed to the ~7.25K I crossed it over at would further reduce its volume and any additional attenuation, beyond the L-pad, is really unnecessary.

    It seems to me that the only impact of adding fixed resistance would be to change the position of the L-pad, and add additional components into the signal path. My thought on crossover design, and purity of electronics in general, was that "less is more." It seems to me that the fewer components that a signal has to go through, the less chance there is for each component to leave its own sonic mark.

  8. #38
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by toddalin
    Using the L-pad alone, the UHF can be adjusted over the full range, from nada to too bright.
    Yes, of course. HOWEVER, it's difficult to get a precise or reproduceable adjustment in the lower half of that range.

    Plot the attenuation curve of an adjustable L-Pad vs. rotation for us, please.

    I'd suggest the "signature" of a fixed L-Pad attenuation, is, uhmmm, nil.

    In any case, here's the 2405H adjustment range with the UHF filter direct-connected to the input, LE85/HL91 midrange balanced with 2235H woofer. It needs about 4 dB additional padding, just about what the fixed pad in the MF circuit provides. Blue is at 9:00, i.e., ~20% "on."

    That's why I favor the "cascade" configuration. Balance the UHF with the MF, then adjust MF to balance with whatever woofer, and they will track. It may be necessary to alter the fixed L-Pad (R2, R3) to balance both with a substantially more or less sensitive woofer.

    Having just heard it, I can assure you there's decidedly scant merit in playing 2405H 6 dB "hot" (red, max)....
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  9. #39
    RIP 2011 Zilch's Avatar
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    To complete the picture, here's the midrange adjustability, below.

    How do these sound?

    Quite nice, in fact.

    HF is clean and natural, unlike my previous experience with 2405H crossed lower. Playing the slot alone, the vertical beaminess is obvious. Gotta be in the "window" to hear them at all.

    MF is very dynamic, a hint of horniness remains. I don't have any H92s to compare. Some resonance when Patricia Barber wails, but that may be from horn and driver not being mounted fixedly to a baffle.

    LF? Well, it's 2235H in 5 cuft. @ 34 Hz. End of THAT story....
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  10. #40
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    Zilch,

    - Up in post #36 there's an @ 7db hole centered around about 725 hz . It's quite wide.

    - What's going on there ?

    - Does that dip really exist / or / is it just a funny artifact of the way CLIO pastes together 3 separate traces ?
    - ie ; if you were to put your Behinger 1/3 octave RTA on it / would you still "see" that hole ?


  11. #41
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by Earl K
    Zilch,

    - Up in post #36 there's an @ 7db hole centered around about 725 hz . It's quite wide.

    - What's going on there ?
    Hi, Earl!

    I've fought that one before.

    Look at the cyan there -- the two (LF & MF) are not summing acoustically. I believe it's because the woofer and horn are nearly two feet apart, and there's a 4" lip at the top of the cabinet.

    I can't get back far enough for them to sum, apparently, under these conditions.

    3110 XO did the same thing earlier in this thread, so I'm ignoring it. Flipping the phase on the MF makes it worse.

    I'll move over onto a 4507, which has the woofer up near the top, and test that hypothesis....

  12. #42
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    Quote Originally Posted by Zilch
    Look at the cyan there. The two (LF & MF) are not summing. I believe it's because the woofer and horn are nearly two feet apart, and there's a 4" lip at the top of the cabinet.
    So does this cyan trace represent a "true" warts & all, fully summed response in CLIO ?

    Quote Originally Posted by Zilch
    I can't get back far enough for them to sum, apparently, under these conditions.
    You shouldn't need more than 3 or 4 ft to obtain the effects of proper summing.

    Quote Originally Posted by Zilch
    3110 XO did the same thing earlier in this thread, so I'm ignoring it. Flipping the phase on the MF makes it worse.
    Please, it's called "flipping the polarity" / you've got Bo's' disease .




    ps ;
    - I think you need to raise the lowpass point for these crossovers. I see, quite consistently, the same "hole" showing up across the board ( also with dmtp(s)' le14s ) .

    - As an exercise, calculate the F3 point for each of your individual passive components ( in the lowpass section ) . ( Your Zobel sets the impedance to 7 ohms / so use that as your load impedance .) Then multiply those two frequencies together . Then take the sqrt of their product / & / then let's talk .

    result ;

    - For 7 ohms / I get ; 506.4hz * 947.35hz = 479738.04
    - the sqrt of ( 479738.04 ) = 692.63 hz
    - This is not the F3 point since the "poles" are less than 1 octave apart. It is the intersection of the 2 reactive impedances. In this case, the F3 will be slightly higher / though I don't yet know the formula to derive the real F3 .

  13. #43
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    HEH. Laborious Calculations Averted!

    I DID hafta flip the polarity of the MF, tho....

    All I'm doin' is turning off the various drivers to get the individual curves.

    Orchid is full range, i.e., all of 'em running.

    Area of interest, bottom.

    I COULD dial it to 800 Hz, if I cranked up the MF a bit.

    Cursor calls that "X" point 886 Hz.

    Raising the MF 2 dB makes it 827 Hz.

    This LE85 shows a fairly noxious peak at 1350 Hz, tho.

    Original circuit calls for 7.5 Ohms in the Zobel. I spec'd 7.0 Ohms because PE don't stock 7.5.

    [It's not critical, according to Elliot, but ideally, Zobel'd be tweaked for Le of the specific woofer used and the desired response characteristic....]
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  14. #44
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    - Thanks for doing that ! It looks much better now .

    - Ah yes, polarity . That almost perfect "V" ( of a suckout ) was a good hint .

    - The nasty peak at 1350 hz ? Well, if it was my circuit / before I went and designed a series LCR ( strapped in parallel ) to attenuate it / I would explore just what percentage, the present hipass "bump-filter" is contributing to that "nasty" .

    - I calculate the reactive center point ( Fcr ) of that 3 pole bump-filter to be @ 1265 hz ( at 6.3 ohms ? ) . That's not that far from your measured 1350 peak .

    - For laughs, I'd swap in a "text-book derived", 850 hz, 3 pole Butterworth hipass and then remeasure. The comparison will show the effect of the present filter . This empirical study is ( perhaps ) still easier/cheaper to implement ( parts-wise ) than building up a "LCR fix". The text-book design does require some fairly large value caps .

    - You may find that a new bump-filter that is "broader , with less gain and designed around a slightly lower center frequency" / offers enough levelling to be considered a decent compromise ( without resorting to LCRs ) . I have one waiting in the wings for you to try ( if you're so inclined ). It uses all of the exisitng passives values / you'll just need to add in a 10uF cap to the exising 24uF / and lower the final load impedance to 5.5 ohms ( change the buildout resistor in the fixed Lpad ) to make it work properly . This filters "Fcr" is around 1177 hz / so / it's "peaking" only slightly lower .


  15. #45
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by Earl K
    Ah yes, polarity . That almost perfect "V" ( of a suckout ) was a good hint.
    I SWEAR I tried that in the original setup, as well, but I wouldn't put it past myself to have merely reinserted the leads into the samer terminals. It's all back on the L200s again, so I'll get another chance....

    Quote Originally Posted by Earl K
    The nasty peak at 1350 hz ? Well, if it was my circuit / before I went and designed a series LCR ( strapped in parallel ) to attenuate it / I would explore just what percentage, the present hipass "bump-filter" is contributing to that "nasty".
    I think the first thing I'll do is try a buncha different LE85s to get a statistical "feel" for whether the 1350 Hz peak is coming from the filter or the driver/horn/lens. I'm reluctant to start tweaking the crossover circuit until I establish it as the source. I've made plenty of crossovers that work beautifully on just one driver here.

    Also want to take a more detailed look at whether cascading the UHF on the MF yanks the main MF highpass around any. First look said not, but I'm not 100% confident of that.

    In the course, I'll try your mod and show what happens. It's clear I can't put this away just yet....

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