- October 2002 -
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Taking advantage of structured wiring for whole
house music distribution system
This article describes ways of taking advantage of structured wiring for whole house music distribution system. It explores the problems and opportunities with structured wiring and offers solutions for whole house audio distribution. A brief review of the benefits and advantages of these novel solutions are also explained.
Over the last five years or more, many home builders have adopted various standards of structured wiring to make these homes future-proofed. Their answer to future proofing has been a bundle of wires homerun to a central location from various rooms in the house. Typically a couple of coaxial cables such as the RG6 or RG59, and a couple of category 5 cables are used in the bundle. Sometimes a couple of multi-mode glass fiber-optic cables are also included to assure the customers that the wiring is truly future-proofed! The basic usage of the coaxial cables is for antenna TV or CATV signal distribution to various rooms from the head-end unit. The other coaxial cable is presumed to future-proof the house for sending security camera or other channel modulated video signals to the head-end for combining with the TV or CATV signals and re-distribution around the house. In almost all cases, one of the category 5 cable is used for a standard telephone line distribution to all the rooms. The other category 5 cable is presumed for computer networking or a local area network (LAN) in the home. Almost 100% of the fiber optic cables that have been wired in these homes are there still sitting idle and presumably will be unused for the foreseeable future.
Unfortunately, very little attention has been paid to whole house music distribution in these industry standard structured wiring systems. Part of the problem has been lack of understanding on the builder community for what is really needed for distributed music system, as well as the substantial additional expenses for pre-wiring homes with the archaic speaker wire runs. Interested readers are referred to earlier articles by the author ( MultiRoom Audio on Cat5 / Whole House A/V ) published in 2001 to understand the problems and inefficiencies of speaker wire based distributed music systems. So most structured wiring homes are incapable of distributed music system without expensive and major retrofit for a traditional speaker run.
The system design
The first system addresses a basic whole house music system. It allows the user to take a music signal from an integrated receiver, a CD juke-box, a hard disk based audio server or even an MP3 player from a PC, and distribute it throughout the house on the category 5 cable of the existing structured wiring system. There are a few products on the market now that facilitate this but Figure 1 shows a very pragmatic solution based on patent pending PADS™ (Pragmatic Audio Distribution System). A PADS™ sender is housed in a single gang box that is located at the structured wiring end of the category 5 cable in the family room. The line level audio signal from the source is then sent on the category 5 cable to the central connection point in the closet. The PADS™ distribution unit receives this signal on the category 5 cable and redistributes it to four other rooms along with power for the in-wall amplifiers on the structured wiring category 5 cables. In the remote rooms, housed in single gang box is the volume control unit and high performance audio amplifiers that receive the signals and power to drive the floor standing or in-wall speakers. The PADS™ units deliver 24 watts per channel in each room with a 20Hz to 20KHz frequency response, a better than 100 dB signal to noise ratio and 100 dB dynamic range at the end of 300 ft. of category 5 cables. For shorter runs of category 5 wires up to 100 ft. it is also possible to use the optional 36 watts per channel amplifiers in the rooms.
There are some other products on the market that provide a similar functional solution but users are advised to look at the specifications. Most of them do not publish any specifications on the product since their units do not deliver more than three or four watts of power, and the frequency response, dynamic range and signal to noise ratio are not high-fidelity. Manufacturers that produce quality products always publish their product specifications to help the user in making a decision. Users are advised to ask for printed technical specifications or a limited time money-back guarantee before selecting products from any manufacturer. PADS™ solves the problem of a single source distribution throughout the home but there may be applications where a multi-source, multi-zone implementation is desired.
The multi-source, multi-zone design of DMS™ (Distributed Music System) is based on the TPA™ (Twisted Pair Audio) and SAA™ (Stereo Audio Amplifier) components with a digital pre-amplifier for volume control. A typical implementation for multi-source, multi-zone music distribution is shown in Figure 2.
The DMS4.4™ features a built-in TV/CATV/FM tuner as its first source. Three additional sources can be connected to the unit. As shown in the figure, there are two sources (CD jukebox and DSS audio receiver) in the network connection closet. Also a remote source such as an office PC with MP3 player can be connected via a TPA transmitter and receiver pair. Using the TPA™ line-level stereo audio transmitter, signals are transmitted over standard category 5 cables to the remote room. The SuperTranZ™ circuit incorporated in the TPA™ transmitters and receivers eliminates ground loops and noise pick up, and provides a clean signal in the remote room. The signals into the DMS4.4™ will have a signal-to-noise ratio in excess of 96 dB and a 20Khz bandwidth. Thus the signal quality is maintained throughout the installation.
In each of the bedrooms, the In-Wall keypad and amplifier fits in a single gang box. The keypads also offer direct keypad access to the source selection. Source control using an Infra-Red remote control is made possible with the built-in IR re-transmission. Also all the keypads are networked together on an RS-485 serial data bus along with the DMS4.4™ main unit so integration with a home automation or PC based control system is simple. In this set-up one category 5 cable is used for the audio, IR and control signals for the amplifiers and keypads. Another category 5 cable in the existing structured wiring bundle can be used for connecting to the central power supply unit. For new construction, it is recommended that an 18/2 AWG wire be used for the power in the wiring bundle. Having a heavier gauge wire for the power opens up the possibility to upgrade to a 36 watts per channel or 48 watts per channel in-wall amplifier keypad.
The DSP based high performance and high efficiency amplifiers in the room produce big luxurious sound, yet fit into a standard size junction box! The small, powerful package delivers true high fidelity performance that actually rivals the sound quality of large amplifiers. It consists of two separate mono-block amplifiers that provide extremely clean state-of-the-art power producing unexpected sound depth and musical clarity. The advanced protection circuitry of the amplifiers guards against system damage from overload, over-temperature, or short circuits. This makes them almost indestructible. The amplifiers provide clean 24 watts per channel with a power bandwidth of 100KHz and distortion less than 0.02% in the listening range.
Each room is capable of listening to and controlling a different source to create complete four sources, four zone distributed music system. The system can be expanded to additional 4 more zones by adding another DMS4.4™ unit in the network connection center.
There may be products on the market from other manufacturers that appear to operate similarly but once again the user is advised to check for the specifications. A low output of 3 or 4 watts per channel will sound terrible even for background music.
Besides the salient features of the DMS™ system discussed here, it is possible to upgrade the implementation to include full DVD quality video and Infra-red remote control communications on the same category 5 cable using the advanced CATS™ products which are not discussed here. It can be envisioned that in the future the same category 5 cable can be used to carry Dolby Digital™, DTS™ or other multi-channel formats as well as HDTV signals using Pragmatics' patent pending technologies. More information can be obtained from the web site www.wireless-experts.com .
In summary, it can be seen that the structured wiring can be re-utilized properly for a high quality distributed music system. The plug-and-play simplicity of the PADS™ and DMS™, not only benefits the professional installers in completing their installations with speed and performance but also enables the do-it-yourselfers to have a high quality music distribution system installed by themselves without any problems. Also the new homeowners in recent years who have been lucky enough to have their homes pre-wired with structured wiring can benefit from the ease and simplicity of this design. They can add high quality of music to their homes without any additional wiring. Conclusion
The DMS™ represents a major breakthrough in high quality music distribution. It solves problems that have not been addressed by the traditional methods for over four decades. The superior signal quality level, the versatility of the system, and the complete avoidance of problems which plague traditional methods, make DMS™ the best overall approach to whole house music distribution.
The DMS™ has been successfully installed in a variety of commercial applications including music distribution at a resort and also residential applications involving connections of MP3 music from a personal computer in the home office to the main audio system in the family room.
About the Company
Pragmatic Communications Systems, Inc., is a Silicon valley based company established in 1994 to design, develop, and produce a variety of innovative products for wireless audio, video, and data communications. The majority of company's products until 1997 were primarily designed for industrial and commercial applications. The success of these products has led to a strong and dynamic technology base, which has been applied to new generation of products such as the PADS™ and DMS™ as described in this article, and others like the CATS™, TrueMusic™ wireless hi-fi system and TrueView™ wireless video system. The company's philosophy is to use its technologies to solve problems that have gone unresolved for decades. For more information: Pragmatic Communications Systems, Inc. 544 E. Weddell Drive, Unit 8 Sunnyvale, CA 94089 USA Tel. (408) 542 0330 Fax (408) 542 0339 Email: email@example.com Web: www.wireless-experts.com
Prasanna M. Shah is the Chief Pragmatist and Thinker at Pragmatic Communications Systems, Inc. He earned his M.S. degree in Electrical Engineering from Stanford University and B.S. degree in Electrical Engineering from Santa Clara University, Santa Clara, CA. He has more than two decades of experience working on semiconductors for analog and digital audio, video, cellular telephones, wireless communications, fiber optic communications, data communications, data acquisition and industrial controls in the Silicon Valley. He holds patents on power line and wireless data communications, and several patents pending on audio, video and wireless multimedia systems. An avid audiophile and music lover, in his free time, he likes to apply his pragmatic thinking to solve complex problems.
PADS™, DMS™, SAA™, TPA™, SuperTranZ™, TrueView™, TrueMusic™ and CATS™ are trademarks of Pragmatic Communications Systems, Inc.