Audio in 4-9 rooms using two receivers, a connecting block, and impedance-matched volume controls

Another way to expand the multi-room possibilities of a two-receiver system is to install in-wall, impedance-matched (IM) volume controls in each room where you're installing speakers. With this setup, you can wire up to 8 sets of speakers to a single set of speaker outputs on your receiver using a connecting block (instead of a speaker selector). Some connecting blocks can even accommodate up to 16 pairs of speakers.

"What do I need?"
You can use the same types of receivers described on page 4, though you'll probably want a more powerful stereo receiver to ensure that you don't underpower (and potentially damage) your speakers (see the chart below). You'll also need a connecting (or distribution) block. Connecting blocks don't include any of the special protection circuitry that speaker selectors often do, so you'll need to install IM volume controls in each room. These controls let you select the correct level of impedance magnification for the number of speaker pairs in the system. This is how you keep the overall speaker load, or resistance, within the amplifier's allowable range. All of the IM volume controls connected to the same amplifier must have the same impedance setting.

The power delivered to speakers by impedance-matching volume controls depends on how many speaker pairs are connected and where the impedance is set.

The chart above provides an example of how much power may be delivered to multiple sets of speakers with properly set IM volume controls. The numbers may surprise you, but bear in mind that 5 watts are plenty for listening at moderate volume in a relatively small room; if you'd like to be able to crank up the volume on occasion, or will be listening in medium-to-large rooms, you may want more power (possibly from a multi-room amplifier).

Diagram E — Audio for 4-9 rooms using a second (stereo) receiver and impedance-matched volume controls (main-room home theater system not pictured)

Pros:

• You don't have to worry about damaging your amp, assuming you've properly set all of the volume control jumpers.
• If your home theater or stereo receiver has an extra set of preamp outputs, you can easily expand this system by connecting a second stereo receiver and speaker selector.

Cons:

• The more speakers you add, the less power they get. With more than 4 pairs of speakers, you won't have enough power for high-volume listening, particularly in an outdoor setting.
• You can't increase the amount of power delivered to one pair of speakers by turning off your other speakers.
• With the exception of your main room, you can't listen to different sources in each area — the same music will play through all speakers.

Tips:

• Each speaker pair must be connected to an impedance-matching volume control. All of the volume controls must have the same protection setting.