Download
Share
Print this page
Lexicon DC-1 Supplementary Manual
  1. Manuals
  2. Brands
  3. Lexicon Manuals
  4. Receiver
  5. DC-1
  6. Supplementary manual

Lexicon DC-1 Supplementary Manual

Lexicon dc-1: supplementary guide
Hide thumbs Also See for DC-1:

Advertisement

Quick Links

Download this manual See also: Owner's Manual, Quick Reference Manual
DC-1
Theory
and
Design

Advertisement

loading
Need help?

Need help?

Do you have a question about the DC-1 and is the answer not in the manual?

Questions and answers

Related Manuals for Lexicon DC-1

Summary of Contents for Lexicon DC-1

  • Page 1 DC-1 Theory Design...
  • Page 2 Acknowledgements The DC-1 is manufactured under license from Dolby Laboratories Licensing Corporation. "Dolby", "AC-3", "Pro Logic", and the double-D symbol are trademarks of Dolby Laboratories Licensing Corporation. The DC-1 is manufactured under license from Lucasfilm Ltd. U.S. patent numbers 5,043,970; 5,189,703; and 5,222,059. Foreign patents pending. Lucasfilm and THX are trademarks of Lucasfilm Ltd.
  • Page 3 DC-1 Theory Design...
  • Page 4 For music the DC-1 uses true stereo digital processing to recreate the original recording space or to create a new one of your choosing.
  • Page 5 DC-1 is optimized for each of these unique tasks. The Music Surround effect is specifically designed to optimally play conventional stereo music through any system which includes side or side-located rear speakers.
  • Page 6 Home THX provides reproduction of film soundtracks recorded in Dolby Digital or Dolby Pro Logic. In the DC-1, the two channel input THX Cinema effect includes a parameter which allows it to utilize the Lexicon 5 channel surround technology, although 7 channel operation is inhibited if dipole speakers are selected.
  • Page 7 Schroeder made binaural recordings in many halls. These recordings, played back through earphones, gave excellent reproduction of spatial qualities. Unfortunately, the stereo image tended to appear entirely inside the head, spoiling the accuracy of such recordings for some listeners. Lexicon...
  • Page 8 This technique, generically known as interaural crosstalk cancellation, was found to work well even without the anechoic chamber, and music pre- sented this way can be quite enjoyable. Lexicon incorporated this technique in many products as “Panorama”. Dwane Cooper coined the name “transaural reproduction”...
  • Page 9 This is better, but not ideal. With the DC-1, confusing short reflec- tions can be absorbed; the DC-1 will supply the essential lateral sound — which can simulate a much larger space. The more absorbent the playback room,...
  • Page 10 The Lexicon DC-1 resolves this deficiency by supplying appropriate signals to loudspeakers at the sides of the listener. The DC-1 gives the listener a choice: the sideways energy cues of the original recording can be extracted by the DC-1, or a different hall sound can be generated and supplied from the correct directions.
  • Page 11 Design Ambience Extraction The Panorama and Surround effects in the DC-1 extract the original acoustic cues from the recording and present them to the listener from the correct directions. We call this ambience extraction. The Panorama effect can do this even with only two loudspeakers.
  • Page 12 DC-1 Digital Controller Ambience Generation The ambience and reverb effects in the DC-1 — Nightclub, Concert Hall, Church and Cathedral — synthesize the side and rear sound of several different acoustic spaces. Rather than extracting the acoustic cues of the original hall from the recording, they generate a new environment, effec- tively enlarging and improving the acoustics of your listening room.
  • Page 13 Loudspeakers placed on either side of the listening position are the most effective and foolproof way to produce added Spatial Impression. Since it is not always possible to have side loudspeakers, the DC-1 uses crosstalk elimination to simulate them when they can’t physically be there. In Panorama the front speakers are driven entirely by the front digital outputs of the DC-1.
  • Page 14 Although the DC-1 provides adjustments to compensate for off- center listening and for varying speaker angles, maintaining a consistent listening position is still important and becomes more so with increasing frequency.
  • Page 15 Panorama is used in two ways in the DC-1. First, it is designed to reproduce as closely as possible the sound actually recorded by the engineer. If the recording has good natural ambience, Panorama will spread that ambience around the listener, giving a true impression of the original hall.
  • Page 16 Panorama is also used as an element in the ambience and reverb simulation effects, where it can synthesize side loudspeakers which are not present in the installation. In these effects, the stereo inputs to the DC-1 are fed directly to the front loudspeakers, with the digital outputs of the DC-1 mixed in according to the setting of the Effect Level control.
  • Page 17 . (You can perform this experiment for yourself with the DC-1 using the Ambience effect: Try the side speakers both in their usual positions and in the front corners.
  • Page 18 If the playback room is large and reverberant, its reflections may dominate those generated by the DC-1. Carpet, drapes and furniture can all be used to break up or absorb undesirable reflections, making it easier to hear the processor’s output. The balance between the side, rear and front speakers is also very important.

  • Page 19: Theory And Design

    DC-1 Theory and Design Reverb Reverb is very good for simulating a large reverberant space. While the Ambience effect simulates the early reflections of real halls, the Reverb effect, used in Church and Cathedral, is more concerned with what happens to the sound after the first hundred milliseconds or so. The first reflections are not intended to simulate any particular hall and no real shape will be audible.
  • Page 20 The DC-1 is able to optimize the listening experience of any material precisely because it provides such a wide range of processing options. This...
  • Page 21 Pro Logic, but there is a decorrelation effect between the left and right side channels. A Stereo Surround parameter in the DC-1 provides further enhancement, making the effect similar to Logic 7, but with no differentiation between the sides and rears.
  • Page 22 — not contained in the recording. In the surround effects, surround channel information is extracted from signals encoded on the recording by the sound mixer — the DC-1 does not add anything to the sound. On films, this surround information is intended to be reproduced in monaural from an array of speakers all around the rear of the listener.
  • Page 23 DC-1 Theory and Design sense of the music coming from all around you, but the violins and cellos are equally loud from both sides. Music Surround solves this problem in a novel way. The side speakers reproduce the left and right front loudspeaker signals with two additions: delay and inverse steering.
  • Page 24 Film Surround The goal of the DC-1 film surround effects is to maximize viewer involve- ment and to faithfully reproduce the director’s intentions for the soundtrack in your own listening environment. Before explaining the way each of the...
  • Page 25 The Home THX Cinema system was designed to address this need, and the DC-1 incorporates it into the THX Cinema effect.
  • Page 26 The DC-1 Mono Logic effect electronically identifies certain properties of film speech and removes it from the stereo synthesis. This allows music and effects in the dialog to be spread out while leaving the dialog centered. The remaining music and effects are directed to the input of a room simulation mode that creates a space the size of a large room or small theater.
  • Page 27 DC-1 Theory and Design Stereo Films Films originally have four channels: one for dialog and three for music and effects. To make a Dolby Stereo film, these are combined to two. With conventional surround any sound comes from at least three directions.
  • Page 28 This does not, however, reduce the sibilants in the side speakers. Some non-Pro Logic decoders reduce these side-channel sibilants by narrowing the spread of the front channels in the presence of dialog; this compromise is unnecessary in the DC-1. DC-1 Theory and Design...
  • Page 29 DC-1 allow accurate decod- ing of matrix surround. The DC-1 decoder is unusual in a number of ways. First of all, it is entirely digital. (Most surround decoders advertise that they are digital because there is a digital delay line for the surround channel but the matrix and the logic decoding are done in analog.) Because the DC-1 is all digital, we can...
  • Page 30 Pro Logic decoder, so full compatibility is maintained. The action of the decoder has been extensively tested both at Lexicon and at Lucasfilm to ensure the intent of the film director is accurately reproduced.
  • Page 31 5000 made in matrix stereo) to be reproduced as they were heard in the film studio dubbing stage — no matter what delivery system is used. The DC-1 is a completely digital, Dolby Pro Logic decoder with patented automatic correction of inter-channel phase and channel-balance errors.
  • Page 32 12-18 speakers are generally impractical. To diffuse the perceived sound, the DC-1 (in the decorrelated mode) provides a decorrelation algorithm which, after the monaural signal is split in two, alters the phase/time relationships between channels slightly.
  • Page 33 Lexicon 5.1 Enhancements 5.1 Logic 7 combines the re-equalization, subwoofer crossover, and adap- tive de-correlation features of 5.1 THX Cinema with Lexicon's Logic 7 matrix technology. 5.1 Logic 7 differentiates between the side and rear speakers with a combination of delay and directional steering. For...

  • Page 34: Speaker Placement

    Center output of the DC-1 into the audio input of your video monitor and use its built-in speaker (if it has one) than it is to run the dialog through the main loudspeakers.
  • Page 35 A Center Delay parameter (along with other “Listener Position” controls) is provided in the Setup menu of the Base and THX versions of the DC-1. The Dolby Digital version provides Time Alignment, which electronically compen- sates for differences in the distance of all speakers from the listener position.

  • Page 36: The Listening Room

    DC-1 Theory and Design DC-1 Digital Controller The Listening Room If you are using THX speakers, be aware that they have significant design differences from standard (non-THX) speakers. Extensive information is available from the manufacturer on their design and on maximizing their effectiveness in a room.

  • Page 37: Room Reflections

    DC-1 Theory and Design Room reflections Room reflections cause blurring of the image of a localized front sound- stage. Sounds which are ideally perceived as coming from the screen, reach the listener from other directions, spoiling the illusion. These unwanted reflections can be eliminated by placing absorbent or diffusive material at the point of reflection.

  • Page 38: Structural Resonance

    DC-1 Digital Controller Room echoes cause interference which results in an unnaturally “bright” sound. These echoes can also be absorbed or diffused. Use heavy insulating drapes over large expanses of glass. Bass frequencies have long wave lengths — these may be as long as one of the dimensions of your room.
  • Page 39 DC-1 Theory and Design Creating a Custom Concert Hall Seat The DC-1 allows you to create virtu- ally any acoustic space you desire. It is extremely simple to walk through the parameters of a program, vary them to your liking, name the space, and store it.
  • Page 40 DC-1 Theory and Design DC-1 Digital Controller References 1. Schroeder, M.R., Gottlob, D. and Siebrasse, K.F.,”Comparative Study of European Concert Halls: Correlation of Subjective Preference with Geomet- ric and Acoustic Parameters”, J. Acoust. Soc. Am., vol. 56, pp. 1195-1204 (1974).
  • Page 41 DC-1 Theory and Design Lexicon...
  • Page 42 Lexicon, Inc. 3 Oak Park, Bedford MA 01730-1441 USA Telephone: 781-280-0300 Fax: 781-280-0490 Lexicon Part #070-11278 Printed in the United States of America...