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****** Page 1 ****** L7 Owner’s Manual Sunlement Speaker Placement Bi-Wiring and Bi-ArnpIification Drawing L-A — L7 position top view side-mounted woofers face inward Dr•awing L-B L7 position front view L7 Placement Drawing and L-B show optimat placement for your L7 loudspeakers. Note that the speakers’ side-mounted woofers should be placed inwards towards the center of the room. Bi-wiring The L7’s outer connection panel and internal dividing network are designed so that separate sets of speaker cable can be attached to the woofer (LF) and midrange/ treble (HF) portions of the dividing network. This configuration is called bi-wiring. Bi-wiring can provide several sonic advantages and considerably more flexibility in power amplifier selection. Reduction of intermodulation The majority of current flowing between an amplifier and speaker is devoted to the reproduction of bass. In fact, 60% or more of an amp’s power is destined for the woofers. When current flows through a wire, it produces a magnetic field (EMF) which expands and collapses at a rate

****** Page 2 ****** Preamp Steree amp Drawing L-C — One-Amp Bi-Wire Preamp wry-corded output Stereo amps Drawing L-D Two-Amp Bi-Wire Stereo tube amp Mono amps Drawing L-E Three-Amp Bi-Wire Preamp w/Y-corded output Mono tube amps Mono amps Drayving L-F Four-Amp Bi-Wire equal to that of the music’s complex frequency components. Ifa single speaker wire must con- duct the full musical frequency spectrum, this preponderance of low frequency information can interact with or modulate high frequencies. The resulting intermodulation 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 another. 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 amplifier power is destined for your L7’s woofers, so upon first consider- ation, it would make sense to use very thick wire for LF connections and thinner wire for HF connections. However, the very fact that treble is higher in frequency, means it is actually more sensitive to the type and gauge of wire used. High frequencies are prone to attenuation from a phenomenon called skin effect’. High quality speaker interconnect wires minimize skin effect by employing a large number of thin conductors with very low oxygen content2. Optimally, you should use audio- Philp interconnects for both HF and LF conductors. However, if your budget intervenes, use the best quality speaker cables for the high frequency connections and plan to add better bass cables later. Amplifier flexibility 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 Electrus alcxg atcns da surfce arq the This the ccndu&rs (cont:nültc inaused slül ar• nxxe than inchidtnl thidmes is a ommm irngnity wire The the better ccnducöiy. Zip cond is cfdectroböc touå apper (ETPC) and Ins more the oxygm-fræ hW’l conducöity cq:v (OH4C) 2

****** Page 3 ****** with one stereo amplifier, then add a second one later to quadruple power reserves. Three or four individual ampli- fiers provide eveh more possibilities, since you can’üSe dif- 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. 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 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. In fact, since the cross- over point for the L7’s HF/LF connections is 150Hzj using ampli- fiers ofthe 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 left L7, use a matching 200- watt Brand X amp for the right L7. Or if you’re powering the left L7 low frequency connection with a 150-watt Brand Y amp and the high frequencies with a 150-watt Brand 3 Z tube amplifier, use the same types and brands of amplifiers for respective right speaker HF and LF connections. Bi-wiring connections Drawings L-G and L-H show two bi-ampfification options: dual stereo amplifier and four-amplifier modes. IMPORTANT: l. The external “strapping bars” which normally connect the L7s’ HF and LF terminals MUST BE REMOVED as shown in Drawing L-l (on the next page) BEFORE BI-WIRING CONNECTIONS ARE MADE. 2. NEVER CONNECT TWO 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 amplifiers! 3. If your preamplifier has just one set of stereo outputs, you will Thaearesorne stpeötllt:e arnpfifzs which provide every bit as rnuch as sdid-süte Howe,ter, they are pwer and aæ vey, VRY exF1éve tylcder&ty-pricedube pweramp&s noderat.ebtgx»æer€ as They be acqtable for åe mi&ssfmidrange/ tru:k dti-wire:lLTs, in Of*lion, the dxiæ fa- law o O RIGHT LEFT Drawing L-G Two Amp Bi-Wire Detail Hook-up is identical for both L7 speakers o mono amplifier o Left speaker + mono amplifier mono amplifier o O to Right speaker + Ttlöno amplifier in a t*-büed sysæn Drawing L-H — Four-Amp Hook-Up Detail at ræEstic concat leas

****** Page 4 ****** need to use “Y” cords in ffe three-amp and four-amp bi-wire hook-ups. “Y” cords are available from many sources ipcluding your JBL dealer. 4. If you have hooked up your LTs in any of the bi-wire configura- tions indicated, it is not advisable to use additional speakers, either separately or simultaneously. 5. As with conventional one- amplifier connections shown in the main L Series manual, make sure that all speaker cables are the same length. Bi-amplification Another advanced operation alternative is bi-amplification. Instead of being divided by an inter- nal crossover, the full frequency spectrum is filtered into two segments by a 2-way external electronic crossover, which is con- nected between the preamplifier and power amplifiers. In bi-amplified mode, the LTs woofer and midrange/high- frequency transducers are connected drectly to separate amplifiers. Only a portion of die LTs inter- nal dividing netvork is used. The woofer and mid-bass transducer section of the crossover are by- passed via a special modification which can be performed by your JBL dealer. Do not attempt to bi- amplify your L7’s without having your JBL dealer do the proper JBL Consumer Products, Inc. 240 Crossways ParkWest, Woodbury, NY 11797 Balboa Boulevard, Northridge, California 91329 (516) 496-3400 modification. A suitable electronic crossover must be used. While dorft discourage hasten to note th+t the LTs intemal crossover is dificult to improve on. Is phase coherence, freedom from distor- tion and eficiency rival even the finest (and most expensive) electronic crossovers. Drawing L-l Rear of L 7 speaker with stapping bars disconnected H A Harman Intemational Company Part Number: 7391 G-L7A Printed in USA








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