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Published Sunday, May 12, 1996, in the Miami Herald.

5-channel amps: sound compromise

By HARRY SOMERFIELD
Special to The Herald

When most people think about building a multichannel home theater, they focus on speakers. Yet the real conundrum is choosing amplification for the system.

The easiest way is with an all-in-one A/V receiver that holds an FM/AM tuner, audio/ video switcher, preamp/ surround decoder and five channels of amplification -- for left-front, center-front, right-front, left-rear and right-rear speakers -- all on one chassis. The most complex, and arguably the best sounding, approach is to use all separate components, including five state-of-the-art, mono-block amplifiers -- one for each of the five channels.

The third alternative, and the one I would propose, requires two pieces of equipment -- an integrated A/V tuner/preamp (that contains the FM/AM tuner, switcher, preamp and surround decoder) and an all-on-one-chassis, five-channel amplifier.

While the do-everything receiver is the least costly and most compact, and the mono-block amp approach is at the opposite extreme, the multichannel amp offers a compromise in terms of expense, space utilization and performance.

Five-channel amps are available in a wide range designs and are priced from $849 to $4,500.
Multichannel amps

If you think a multichannel amp might suit your needs, here are some things to consider:

  • Be sure you buy an amp with sufficient power to drive your speakers. It's not a bad idea to pick one with a little extra power, for reproducing the sound tracks of those Arnold Schwarzenegger movies.

  • Amps with separate power supplies for each channel are better than those that share a power supply among several channels.

  • Try to choose an amp with individual volume controls (trim pots). They will simplify basic setup of your system.

  • Look for amps equipped with ``5-way binding posts'' for connecting speaker wires. These offer the flexibility of using ``banana'' (push on) plugs, ``spade'' connectors or even bare wire.

  • Make sure the back-panel terminals are not mounted to a flimsy surface. You'll be plugging and unplugging wires for years, so be sure the unit is up to the task.

  • If you think you might want to have a ``passive'' subwoofer (one that doesn't have its own, built-in amp), look for an amp with six channels.

  • Amps that are ``bridgeable'' allow two channels to be connected together to double the power for a power-hungry speaker.

  • Many amps have an ``auto-on'' feature that either senses an audio signal or a change in voltage. Both types free you from throwing another switch to turn your system on or off.

  • Audiophiles should look for amps that specify a total harmonic distortion (THD) of 0.05 percent or less. These amps will sound the best, but most of us needn't be so picky.

  • Give your amp a ``test drive'' in your home for a week or two. Make sure it meets your sonic requirements before you decide to keep it.
    Good five-channel models

    Here are three good examples of five-channel amplifiers:

    Carver model AV-405, delivers 100 watts to the three front channels, 50 watts to the two (rear) surround channels, THD 0.05 percent, not bridgeable. It employs a mono-block design, which means it has separate power supplies. Suggested retail price is $849.

    ADCOM model GF A6000 has 100 watts for each of the three front channels, 60 watts for each of the two (rear) surround channels, THD 0.09 percent, not bridgeable, 5-way binding posts. It has separate level controls for each channel, to make level-balancing easier and is priced at $900.

    Forte model FT1 has 125 watts for each of the three front channels, 55 watts for each of the two (rear) surround channels, THD 0.15 percent, not bridgeable, 5-way binding posts. An auto power-on feature lets it power-up automatically with your other components. It costs $1,790.

    Harry Somerfield is technical editor of Audio/Video Interiors magazine. His internet address is http://www.e-town.com



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