Dorset Sound & Communications

Sound system design for the 21st Century

Extension and Distributed Speakers

Your system may have or need a number of distributed speakers in the lobby, nursery or offices. To string speakers together from the same amplifier, limit signal loss over the wire and control conditions that would ordinarily damage an amplifier, we use what is called a high voltage distribution system. It is much like the high voltage transmission scheme that utilities use to get power to you and your neighbors. A high voltage speaker system may be rated as either 25 volts or 70 volts. Which one you have will depend somewhat on construction codes. Technically, 70 volt (or even 100 volt) system distribution cable should be run in conduit while 25 volt system may be open wired (National Electrical Code). The output of the amplifier has a step-up transformer attached (or internal). Each speaker has a step-down transformer attached that matches it to the speaker line. Additional speakers must have transformers and any wall mounted volume controls should be "stepped transformer attenuators".

There are two common problems that occur with distributed systems. First, are obscure shorted speaker lines which bring down the whole system. Second are unauthorized extensions. Someone adds a stereo speaker or ceiling speaker without the transformer. The addition sounds superb, but suddenly the sound level in every other speaker drops drastically.

A business variation is the sound masking system. The system generates low level background noise to confuse intelligibility and provide a degree of privacy between workstations in open plan offices and counseling facilities.

Please contact us at DS&C about the distributed system you need to make sure it is done right. Give DS&C a call for help assembling your sound system and the training to use it effectively. We can also set up preventive measures and scheduled maintenance visits. Don't be caught unprepared. Enjoy effortless sound. Do it now.


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