Lexicon LX-7 Multi-channel Power Amplifier 
Home Theater Power Amplifiers Multi-Channel Amplifiers
Written by Thomas Garcia   
Friday, 01 August 2003

Not surprisingly, multi-channel systems are growing in popularity, especially with surround sound cinema and multi-channel music becoming more mainstream. In this era of high-resolution multi-channel media, each component must be capable of extracting all that these new formats deliver. The synergistic match between the electronic components and selected loudspeakers is no longer merely a desirable facet, but a prerequisite for any true reference-quality playback system. Lexicon, a Harman Specialty Group company, is fully aware of this, and has released the LX-7 seven-channel amplifier ($5,995.00), which is designed to excel with all types of media. Lexicon has devoted substantial engineering resources and technology to design products, such as their new series of processors, amplifiers, and a universal disc player, all of which have been designed to meet the expectations of today’s more demanding and sophisticated consumer. Intended to mate optimally with their MC-12 and MC-8 Digital Controllers, the LX-7 is equally capable of complementing any other manufacturers’ equipment.

The Lexicon LX-7 multi-channel amplifier is a perfect match of aesthetics and function, designed to complement their MC-12 and MC-8 processors, as well as their RT-10 disc player. With their soft-brushed aluminum faceplates, rounded edges, and aligning V-notches, they make for an extremely eye-catching combination. The LX-7 utilizes small cobalt blue LED lights, like the colored display of the MC-12, to indicate the operational status of each channel. The overall look of the Lexicon LX-7 is quite sophisticated and exudes an element of elegance that I find extremely attractive. Measurements for the LX-7 are a relatively compact five-and-five-eighths inches high by 17.3 inches wide by 19 inches deep and weighs a manageable 56 pounds. The chassis size is minimized by utilizing quiet, microprocessor- controlled, forced air-cooling. Rated at 200 watts per channel into eight ohms, it is possible to bridge adjacent channel pairs for a robust output capacity of 400 watts. It utilizes four hand-graded, custom output transistors per channel, and is designed with an oversized, low DC resistance toroidal power transformer to maintain the performance of the amplifier to its full-specified output with all channels driven. This is coupled with what Lexicon terms as Junction Temperature Simulation (JTS) to provide maximum performance from the output transistors. The THX Ultra Certified LX-7 is an extremely bulletproof design, featuring extensive protection circuitry to guard against short circuits, thermal overload, device failures, and low or unusual loudspeaker impedance loads. The rear panel offers seven RCA and XLR (including one-quarter inch Tip Ring Sleeve) inputs, a trigger input for power control from an external device, seven heavy-duty gold-plated loudspeaker outputs, and a ground lift switch to mitigate potential grounding and hum issues caused by multiple ground paths.

I connected the LX-7 power amplifier to Lexicon’s MC-12B digital controller, and performed a full level calibration with the combination. A variety of DVD-Audio, SACD, and standard 16-bit audio players were utilized for this review. Most of my listening was through the Revel Ultima Salons and Revel surround speaker system. I used the unbalanced inputs throughout my audition of the amplifier. Finally, a dedicated 20 amp circuit was provided. As expected, the setup of this amplifier was simple and uneventful.

To commence with my audition of the LX-7, I selected two movies featuring Tom Hanks. The rocket launch sequence from the DTS 5.1 version of “Apollo 13” (Universal Studios Home Video) provided a good litmus test for the dynamic capabilities of the Lexicon amplifier. It was definitely up to the task, rattling everything within my listening room, causing the rest of my house to creak and groan in agony. Equally impressive was the musical score by composer James Horner, sounding stunningly dynamic through the LX-7, with astonishing realism and impressive lucidity. The surrounds are used more aggressively as the film progresses, and the LX-7 remained poised and neutral. The Lexicon captured the smallest nuances of various vocal ensembles, strings, and percussion arrangements, while creating an added tension to the more dramatic sequences. From the beeping control panels and buzzing alarms, to the distinctly different environments of the spacecraft and mission control, the LX-7 painted a picture that was solid and utterly realistic.

When “Forrest Gump” (Paramount Home Entertainment) was first released back in 1994, the film received an enormous amount of critical acclaim. Tom Hanks did a phenomenal job of transforming himself into the role, assimilating mannerisms, speech, and expressions that truly defined the life and character of Forrest Gump. The Dolby Digital 5.1 mix was flawless, capturing the beautiful and mesmerizing score by Alan Silvestri. The soundtrack of this film is quite diverse, providing many dynamic and uncompressed passages that the LX-7 produced beautifully. The same goes for the variety of classic songs played throughout the movie, even those that are just part of the background. The LX-7 was very transparent, with low-level sounds throughout the movie, such as doors opening, the rustling of trees waving back and forth, and the serene, contemplative moments of Forrest Gump. The LX-7 proved it was capable of operating at a much more demanding pace, especially during the more intense scenes. Crowds cheering at football games, rain and explosions during the Vietnam combat sequences and Forest facing a storm while hunting for shrimp really place you right in the action. The audio mix features good transparency and solid bass extension. Dialogue was clear and easily intelligible through the LX-7. Overall, viewing this film with the Lexicon amplifier in the system was truly enjoyable.

To evaluate the LX-7’s multi-channel music playback capabilities, I decided to embark on a bit of nostalgia with the DVD-Audio mix of Emerson Lake & Palmer’s Brain Salad Surgery (Warner/Rhino Records). The passionately musical trio of Keith Emerson, Greg Lake and Carl Palmer have crafted some wonderful albums throughout their career, including Tarkus, Trilogy, and Pictures at an Exhibition. Many ELP fans find the charismatic and artistic prowess of Brain Salad Surgery to represent the trio at their best. The album is filled with a wide variety of synthesized, orchestral, and acoustical sections that create a wide sonic arena for the LX-7 to show its proficiency. "Toccata,” an adaptation of the 4th Movement of Ginastera's 1st Piano Concerto, features a volley of musical variances, which range from vibrant orchestral passages to bombastic percussive fireworks. "Still...You Turn Me On" is a lovely ballad written by Lake, with liquid vocals, full-bodied instrumentation and broad frequency extension, all of which were captured effortlessly by the LX-7. Fortunately, this cut was not overly manipulated during the surround sound process, but presents a subtle amount of ambience that allows the front speakers to blossom.

I next used two channels of the LX-7 to evaluate its playback of standard 16-bit/44.1kHz CD material. Once again, it was obvious that the LX-7 remained true to its function, amplifying the source without any alteration or coloration of the music. This was particularly apparent when listening to Facing Future (Mountain Apple Company) and the transcendental voice of Hawaiian singer Israel "Iz" Kamawiwo'ole. Iz died in 1997, leaving a legacy of recorded music, both as a solo artist and as a member of the Hawiiana band Makaha Sons of Niihau.

Iz's voice, like the life of the singer, is powerfully moving yet angelic in presence. The LX-7 masterfully captured the forceful drums, the sweet, soaring orchestral background, and minute changes of Iz’s vocal timbre throughout both Track One, “Hawai’i 78 Introduction,” and the final cut, “Hawai’i 78.” This album is truly an eclectic mix, including an islandized version of “Country Roads,” a variety of local tunes sung in the native Hawaiian language, and what is probably Israel’s most commercially recognizable medley, "Over The Rainbow/What a Wonderful World." Facing Future infuses a ukulele throughout many of the musical arrangements, and it was pleasurable listening to the Lexicon’s neutral portrayal of this unique instrument. During my audition of the LX-7, I found myself immersed in the music, intellectually and emotionally detached from the equipment that was creating it. Ultimately, the LX-7 amplifier achieved its purpose of providing an accurate portrayal of the recording, adding and subtracting nothing, a very high compliment indeed.

The Downside
Though the LX-7 was extremely neutral and powerful for the majority of my audition, there were times when it seemed to run out of headroom during some of the more dynamic sections when played at relatively high volumes. Some of this is definitely attributable to the challenging load of the Revel Salons. Using the bridgeable feature and supplying 400 watts to the main channels would surely cure any power limitations.

Lexicon has consistently been developing leading-edge products for the playback of new high-resolution sources, allowing consumers to experience performance that was unavailable a mere decade ago. This is most evident with their new processors, amplifiers and universal disc player. The Lexicon LX-7 Multi-Channel Power Amplifier performed flawlessly and did exactly what an amplifier is expected to do, which is to take an input signal and pass it through without adding any coloration or character of its own. With its single and bridgeable channel options, the LX-7 provides the end user with a variety of possible power configurations that would work well with any two- to-seven channel playback system. Although the Lexicon amplifier would be at home with many different systems, I found the LX-7 mated with the MC-12 to be quite a magical marriage. Tie this and the matching RT-10 universal disc player together and you have a combination of stunning cosmetics and sonic performance that is truly stellar.
Manufacturer Lexicon
Model LX-7 Multi-channel Power Amplifier
Reviewer Tom Garcia

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