Lexicon DC-1 AV Preamplifier/Processor 
Home Theater Preamplifiers AV Preamps
Written by Kim Wilson   
Wednesday, 01 October 1997

The DC-1 is the flagship digital controller from Lexicon, a long time leader in digital processing technology. It is a combination preamplifier, A/V switcher, D-to-A converter (24-bit Delta Sigma) and digital processor whose design makes it possible to come in a variety of configurations. A fully loaded DC-1 incorporates Dolby Digital, DTS and THX processes.

The DC-1 continues to provide Pro Logic along with other surround processes for videotapes, TV programming and other source materials without DTS or Dolby Digital encoding. Several DSP (digital signal processing) modes are provided for adding ambience to stereo and monaural sources. All signal processing, including filters, EQ and crossovers, are performed in the digital domain.

The DC-1 also employs Lexicon's patented Logic 7 technology, which takes as low as a two-channel signal and digitally processes it to produce a discreet, multi-channel, full bandwidth surround signal. Logic 7 is included on many of the DC-1's surround parameters and can be enjoyed by listeners with as few as four loudspeakers.

Installation & Setup
It will probably take you at least an hour, possibly longer, to set up the DC-1 properly. Even after your initial set-up, you'll probably tweak your DC-1 several times before you get it exactly the way you want it. If you've never used a sophisticated 5.1 processor before, you may find the setup procedure initially awkward, but once you get a feel for the four position keys on the remote that cycles through all of the options, it should become less of a challenge.

While there are eight analog audio inputs, five video inputs (five composite, three S-video) and four digital audio inputs (two toslink and two coax), the DC-1 only has a total of eight, usable inputs. When you go through the Input Configuration setup, assign each input a specific `Audio In' and `Video In'. For example, assume you assign your DVD player to the input labeled `AUX'. It makes sense that the associated "Video In" will be the `AUX' video input. If you didn't want to use the `AUX' analog audio input, then you are probably using one of the four digital inputs. So for "Audio In", you might assign Coax-2. For me, this part of the setup was a little confusing at first, but not terribly difficult to figure out as the manual steps you through the setup procedure quite effectively.

The inputs do have a factory assigned name, but they also have the ability to be customized. Continuing with our example setup, if you assign the name DVD to the `AUX' input, it will be displayed as DVD in the LCD panel whenever you select the `AUX' input. Just make a note to remember what names you've assigned to your inputs since the selection buttons on the front panel and the remote are labeled only with the factory assigned names.

Any input can be defined as a tape monitor, or blocked from the second zone output. In addition, inputs can be configured to enable a 12v trigger to activate external devices, such as projection screens, lighting controllers or even drapes. Power control interconnects make it possible to switch the entire system on or off with the press of a single button.

The Speaker Configuration menu provides a wide range of adjustments depending on speaker placement and room parameters. If you are not using full range speakers, it's possible to set a crossover point to redistribute low frequency information to separate subwoofers.

An essential function in the setup process is the Time Alignment adjustment in the Listener Position. The Time Alignment setting electronically aligns all of the loudspeakers in your system to ensure accurate signal arrival times at the listening position. It was necessary to measure the distance from the primary listening position to the front of each speaker. These measurements were entered into the DC-1 and the proper alignment was automatically calculated, resulting in a smooth and balanced front speaker array. A specific effect can be assigned to each input. Let's say you assign the effect labeled THX 5.1 to the input associated to the DVD player. Every time you play a DVD, the system will automatically default to THX 5.1. Once the source material is in playback, you can then change the effect to something else if you prefer, by scrolling through the effects.

The DC-1 provides outputs for front, center, rear and side speakers, plus a subwoofer. An internal test tone can be used to set the output levels. An external noise test setting is also provided if you use some other source, such as a test tone CD, for adjusting output levels. Since Dolby Digital and DTS encoded soundtracks produce increased low frequency signals, the DC-1 incorporates a subwoofer peak limiter to prevent clipping.

Adding the LDD-1
The LDD-I is a separate RF demodulator and a required add-on component if you plan to play Dolby Digital encoded Laserdiscs. (Only Laserdiscs require a RF demodulator to playback Dolby Digital encoded material.) The separate component keeps potential RF interference out of the preamp/processor's signal path, eliminating degradation of D-to-A conversion and analog signals. Interfacing the LDD-1 with the DC-1 is very simple and it automatically comes on when the DC-1 is fired up.

Dolby Digital and DTS Settings
There are several effects on the DC-1, relating to Dolby Digital and DTS encoded sources. The 5.1 Two-Channel (AC-3) and DTS Two-Channel settings mix the 5.1 information into two channels for stereo playback. The DTS Music setting is best used for DTS encoded music recordings or film soundtracks with heavy musical content. The same function, 5.1 Music, exists for Dolby Digital sources. The standard Dolby Digital and DTS Film settings do not incorporate any Lexicon or THX enhancements.

The THX 5.1 (AC-3) and DTS THX 5.1 settings add THX enhancement, incorporating the patented technologies of re-equalization, timbre matching and decorrelation. Re-equalization prevents films from sounding too bright and decorrelation increases spaciousness to monaural rear channel effects. Timbre Matching, smoothes front to rear, as well as split surround pans for a natural, continuous and cohesive soundfield. THX processing is designed to compensate for the acoustical differences between the original dubbing stage where the movie was mixed and the typical home theater environment. The 5.1 Logic 7 combines Dolby Digital, THX features and Lexicon's proprietary Logic 7 matrix technology, which enhances the steering between the side and rear speakers, for a fuller 360 degree soundfield. The DTS Logic 7 setting provides the same enhancement for DTS encoded sources.

Listening Test
In Twister (DVD, Dolby Digital, Warner Brothers) I found the standard Dolby Digital setting almost too localized. Movement from front to rear (and vice versa) tended to jump. Using the THX 5.1 setting, the 360 degree imaging was overall more coherent, creating a wash of sound that did not effect the stereo surround localization. (This was also true of the DTS THX 5.1 versus the DTS Film setting with the Laserdisc of Crimson Tide [Buena Vista].)

On Evita (DVD, Dolby Digital, Hollywood Pictures), I compared the THX 5.1 setting with the 5.1 Music setting that is recommended for soundtracks with a strong musical content. I still preferred the THX 5.1 setting, as there was more separation to the front left and right speakers, resulting in a wider soundfield. This result proved to be strange in that the two modes are almost identical, spare a slight shelving EQ on the THX mode. Vocals and solo instrumentation were locked onto the center channel and the surrounds were enveloping. In 5.1 Music there was more of an equal blend of the left, center, and right speakers. It was more like a wall of sound without as much separation. The THX 5.1 setting seemed more in line with the director's original intent.

The DC-1 as a preamp
As a stand-alone preamp, the DC-1 performs exceptionally. Whether you want to play your stereo recordings with or without DSP environmental enhancements, you'll appreciate the overall sound quality of the DC-1.

The track "Into the Dark" from Jesse Cook's 20-bit Mastered CD, Gravity (Narada Equinox), demonstrated a transparent and delicate quality with finely detailed articulation in his fast guitar runs. The saxophone on the title track from Ernie Watts's (XRCD) "The Long Road Home", was smooth, smoky and sexy without any mid-range emphasis that can cause a honking-like tone. The ethereal, "Skin" from Madonna's Ray of Light (Maverick), delivers a blend of synthesizer textures and multiple layers of guitars and vocals. The spaciousness and airy quality between instruments was very impressive.

I liked the Panorama effect on several of the two-channel recordings. The image exceeded the boundaries of the front left and right speakers. Solo instruments were locked to the center channel with just a hint of ambience in the rear channels, increasing depth without any artificiality. (The rear channel volume can be adjusted for this effect.) The Concert Hall effect on "In My Time of Dying" from Led Zeppelin's Physical Graffiti, transformed this rather dull and aged 1975 recording into an exciting, open "live" performance. Guitars sounded rich and fat, while vocals had a great, saucy "reverb," a Lexicon Trademark from its pro audio roots.

I used the DTS Music setting for Vince Gill's DTS-encoded CD of his album, High Lonesome Sound (MCA). Compared to the DTS Film setting, the DTS Music setting had a wider and slightly more robust soundfield. There was a greater concentration of directionality to the center channel. The title track isolated the solo instruments in different channels for a unique and enveloping 3-D musical experience.

Unfortunately, I was physically unable to test the Logic 7 mode with seven speakers. Logic 7, much like Dolby Pro Logic, creates a five-channel signal from as few as a two-channel source. Logic 7, unlike Pro Logic reproduces full bandwidth (20 Hz to 20 kHz) signal as well as discrete rear channels, unlike Pro Logic's mono rears which roll off at 7 kHz. Logic 7 basically is a surround format that digitally `rides the gain' over the 4 to 8 (or more) speakers, in order to give your less than state-of-the-art surround sources a performance boost over Pro Logic. The DC-1 also uses the Logic 7 type algorithms in its music surround formats. Depending on your software collection, you may find that the Logic 7 feature is the closer for you on a DC-1.

The LDD-1 isn't the most beautiful add on piece. It was designed to use a short run of RF cable and sit behind a Laserdisc player in a rack. It is separated from the DC-1 to provide extra value for the majority of DC-1 customers who opt to go without RF inputs from a Laserdisc Player. If you have a large collection like me, you may want more sex appeal for your $699.00.

I wish there were more coax type digital inputs. With everything going digital, even four inputs aren't enough. Moreover, many people prefer the coax to the toslink connectors, limiting the potential inputs even further.

The basic DC-1 starts at $1,995. The fully loaded model with Dolby Digital, DTS or THX tops out at $4,995. The LDD-I is an additional $699.00 (only required for Dolby Digital encoded Laserdiscs). It's definitely not the cheapest solution, nor is it the most expensive. Still, for its extraordinary and unique features, surround parameters and sound, the price seems quite appropriate.

The DC-1/LDD-1 combo is a serious contender for anyone developing a high-end, home theater system. Its flexible and varied adjustment parameters allow you to contour the DC-1 to fit your specific needs. The DC-1 does lack some of the subtle nuances in sonic performance that can be heard in pricier units, like the Theta Casablanca. However, if you consider the price-to-performance ratio of the Lexicon DC-1, you'll understand exactly why it is worth every penny.
Manufacturer Lexicon
Model DC-1 AV Preamplifier/Processor
Reviewer Kim Wilson

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