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Thread: "drop-in" OK for 250ti ?

  1. #16
    Heather [Senorita member] hjames's Avatar
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    Quote Originally Posted by BMWCCA View Post
    According to the L7 supplement, neither bi-wiring or bi-amping require removing the internal jumper, but only the external ones at the input terminals. The internal blue wire is (according to the L7 designer) supposed to be moved when used with an active crossover: http://www.audioheritage.org/vbullet...&postcount=152
    Well - how would you be biamping it without an external active crossover?

    that would just be biwiring ...

    heck, no WONDER its confusing!!

    I guess it all depends on what the definition of is is ...!
    2ch: Oppo, JoLida 502CRC, JBL L212, 18ti,240ti; Heath AS101, Von Schweikert VR4
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  2. #17
    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by hjames View Post
    Well - how would you be biamping it without an external active crossover?

    that would just be biwiring ...

    heck, no WONDER its confusing!!

    I guess it all depends on what the definition of is is ...!
    The L7 has two pairs of input terminals joined via strapping bars, just like the crossover in the first post in this thread. (That's pretty much why we're stuck discussing this in this thread.) The L7 crossover is essentially two separate crossovers, each with its own part number. When you remove the external straps you separate the 12" from the other three drivers but you keep the high-cut so when you wire in two amps the LE120H-1 doesn't go full-range even without an active crossover. The question is why doesn't this gain you some power advantage if you use two amps and the suggestion was that you wouldn't because of the passive crossover. That's what's confusing. The L7 manual draws a distinction between bi-wiring with one amp per speaker and bi-wiring with two-amps per speaker. Perhaps the confusion is that I've been referring to the latter arrangement as bi-amping when they still call it bi-wiring. That might explain why all the intelligent members here bailed a while back on any attempt to beat some sense into me. Here's a sample of JBL's confusing language.

    The manual says:
    Drawings L-G and L-H show two bi-amplifìcation options: dual stereo amplifier and four-amplifier modes.

    Bi-wiring also allows you the option of using separate stereo power amplifiers for left and right L7 loudspeakers or even four mono power amplifiers. Using two stereo amplifiers (drawing L-D) can not only add sonic improvements but upgrade convenience as well. From a sound standpoint dual amplifiers reduce intermodulation between left and right channels, since a complete set of input and power supply circuits are devoted to each speaker. Dual amps also provide an easy power upgrade path: you can start out w¡th one stereo amplifier; then add a second one later to quadruple power reserves. Three or four individual amplifiers provide even more possibilities, since you can use different brands and types of amps for HF and LF power. Many serious listeners prefer the midrange and treble sound quality produced by tube amplifiers. However, many tube designs do not provide as "tight" a bass sound as solid state models and often produce less power3. Bi-wiring with separate bass and treble amplifiers allows use of both tube and solid state designs, where each is most desirable.

    Whether you are using two or four amplifiers, it is important to use the same brand and power rating to power like connections
    on the L7's. ln fact, since the cross-over point for the L7's HF/LF connections is l50Hz (the specs say 180—pm), using amplifiers of the same power for both woofer and midbass/midrange/treble connections is recommended.
    Got that?? I'm assuming this is similar to the way the 250Ti crossover works, above, just to show that I'm sort of on topic!

    Here's a link to the L7 supplement which talks about true bi-amping, as well: http://manuals.harman.com/JBL/HOM/Ow...Supplement.pdf

  3. #18
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    Phil I am with you on what make sense to me about bi amping, 2 amps per speaker seem to be bi amped and again to me Bi amping w/active XO would be bi amping w/active XO.

    Now that I understand the definition

    Please correct me if I am wrong

    1) bi wiring w/2 amps(all the same make and model) per speaker will yield more power to the speaker (thus more DBs). 200 + 200
    2) would this 200w + 200w = a single 400w I wouldn't think so but???
    3)The amps will each see full range because of the XO and still will filter out the top end on the woofer and the lower end of "top half" , IE the amps don't get told to only produce part of the sound spectrum but the full range and the rest(highs from the low end and lows from the high end) are dissapated to heat (i guess??)

    If the amps are producing full range what are the benefits of doing this?

    Mark
    Think center channel for 250TIs; (2) 108s, a 104 and a 44ti, now what?

  4. #19
    Administrator Robh3606's Avatar
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    You need to look at the Tech Sheet. It's really odd. There is a moveble 4" Blue jumper in the woofer section that if you move it takes out the lowpass filter. That said the bandpass filter on the 8" midbass driver looks like it has no such provisions for the highpass portion??? So if you moved the strap you could "biamp" the woofer but not the Midwoofer without extensive modifications. Or at least taking the 90uf out of the picture. Strange????

    http://manuals.harman.com/JBL/HOM/Te...et/L7%20ts.pdf

    Rob
    "I could be arguing in my spare time"

  5. #20
    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by BMWCCA View Post
    That might explain why all the intelligent members here bailed a while back on any attempt to beat some sense into me.
    That was not meant to imply that either Opi or Heather lack intelligence. They'll stay around to beat some sense into me because they know I'm nutz. I can't help but think the EEs here are just laughing at the basic theories we are ignoring so cavalierly out of pure ignorance.

    That's OK. As Heather said, "The joy of the pie is in the eating .." I've got a pair of D150A-IIs, a pair of PS-200s, a pair of PS-400s, a pair of Pro-Control-Fours, a pair of DX-4200s . . . and two pairs of L7s. If I can't make a valid comparison of the wiring schemes with that pile of crap, I'd be pretty worthless. Yeah, I know . . .

  6. #21
    Heather [Senorita member] hjames's Avatar
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    Quote Originally Posted by BMWCCA View Post

    That's OK. As Heather said, "The joy of the pie is in the eating .." .
    Unless its hagis!
    2ch: Oppo, JoLida 502CRC, JBL L212, 18ti,240ti; Heath AS101, Von Schweikert VR4
    7.1: Oppo BDP103D, B&K, UREI 809A, JBL B460

  7. #22
    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by Robh3606 View Post
    It's really odd. There is a moveble 4" Blue jumper in the woofer section that if you move it takes out the lowpass filter.
    Yep. Odd it is. But this is the best info we have to go on, including a photo of the blue jumper wire:
    Quote Originally Posted by BMWCCA
    The internal blue wire is (according to the L7 designer) supposed to be moved when used with an active crossover: http://www.audioheritage.org/vbullet...&postcount=152

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