JBL L7 Owners Manual

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JBL L7 Owners Manual

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Page 1

equal to that of the music's complex frequency components. lf a single speaker wire must con- duct the full musical frequency spectrum, this preponderance of low frequency information can interact with or modulote hþh frequencies. The resulting intermodulotion can create audible changes to treble even before it reaches your loudspeakers. By using separate conductors for high and low frequencies (drawing L-C), unwanted treble modulation is avoided. Bass flows through one, treble through anothen Frequency-optimized cables Having the opportunity to use separate HF and LF cables, allows you to employ conductors best suited to each frequency range. As previously noted, most amplifìer power ís destined for your L7's woofers, so upon first consider- ation, ¡t would make sense to use veq/ thick wire for LF connections and tjrinner wire for HF connections. Howeve[the very fact that treble is hþher in frequency, means it is actually more sensitive to the type and gauge of wire used. Hþh frequencies are prone to attenuation from a phenomenon called skr:n effedt. High quality speaker interconnect wires minimize skin effect by employing a large number of thin conductors with very low oxygen content2. Optimall¡you should use audio- phile interconnects for both HF and LF conductors. Howeven if ydirr budget intervenes, use the best quality speaker cables for the high frequency connections and plan to add better bass cables laæn Amplifier flexibility Bi-wiring also allows you the option of using separute stereo power amplifiers for left and rþht 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 standpoing 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 e:Ny power upgrade path: you can start out lEeoors acaallyflo,,ralorgfie orærmostatorm of a wire, nthertJæn irside. The nrcre s.¡ráce aleâ, dæ less resbance to o-rrrern Tlns üre number cf indvidul conducors (conmbutírgin

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w¡th one stereo amplifìer; then add a second one ldter to quadruple POWer reseryes. Three or four individual ampli- fìers provide evñro¡u possibilitíes, since you càn't¡3d ¿¡f- ferent brands and types.of amps for HF and LF power. Many seri- ous listeners prefer the midrange and treble sound quality produced by tube amplifiers. Howeve¡ many tube designs do not provide as "tþht" a bass sound as solid state models and often produce less power3. Bi-wiring with separate bass and treble amplifìers allows use of both tube and solid state de- signs, 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 facL since the cross- over point for the L7's HF/LF connections is l50H¿ using ampli- fìers of the same power for both woofer and midbass/midrange/ treble connections is recom- mended. For example, in a 2-amplifier bi-wire hook-up, if you are using a 200-watt Brand X amp for the leftLT,use a matching 200- watt Br¿nd X amp for the rþht L7. Or if you'r:e powering the left L7 low frequency connection with a 1SO-watt BrandY amp and the high frequencies with a 1S0-watt Brand 3 Ztube amplifier; use the same types and brands of amplifiers for respective rþht speaker HF and LF connections. Bi-wiring connections Drawings L-G and L-H show two bi-amplifìcation options: dual stereo amplÍfìer and four-amplifier modes. IMPORÏANT l. The -xt-rnal "strapping bars" which normally connect the L7s' HF and LF terminals MUST BE REMOVED as shown in Drawing LJ (on the next page) BEFORE BI-WIRING CONNECTIONSARE MADE. 2. NEVER CONNECTTWO AMPLIFIER CHANNELSTO THE SAME LOUDSPEAKER WITHOUT FIRST REMOVING THE STRAPPING BARS. Operating two amplifier channels with the L7 strapping bars in place can seriously damage the amplifìers! 3. lf your preamplifier has just one set of stereo outputs, you will tns c not to oy ú,"ttfrey cant There are some *perb ulbe amplifiers whió prwirle wery bit as mudr tþtnr-*as solidslãte des¡gns Howwer, úey are high power modeb and are very, VERY epersive Moderåt-ly"riced obe porver amplifurs tend to be nndenæly powered aswdL They midn be accepable forpowerír6de mldbesfmËrarrgd reble poni