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