Niles Audio CM8SW guide

Using Speaker Selectors With Standard Volume Controls

In multi-room systems with standard vol- ume controls any Niles speaker selector will maintain a four ohm load if you leave one set of room outputs unused for every speaker system with an impedance of less than four ohms (such as a CM8SW con- nected to a pair of four ohm satellite speakers). The protection switch must be constantly engaged. Niles HDL series speaker selectors have a rear panel con- stant protection feature. (See Figure 8).

The benefit of a speaker selector is that even with the protection circuit constant- ly engaged, more power will be delivered to any single pair of speakers playing by itself (all other speakers off).

In a multi-room system there is one indis- pensible control for true convenience—a local volume control. It allows you to adjust the volume of the speakers and the subwoofer without leaving the room.

Niles makes a wide range of high perfor- mance indoor and outdoor volume controls in Standard or Decora® style face plates (just like your light switches and dimmers). All of these volume controls enable full power to be delivered to each speaker sys- tem when turned all the way up.

The combination of a speaker selector and a standard volume control will deliver high volume when only one pair of speak- ers is playing.

Using Impedance Magnifying Volume Controls

The simplest way to increase the imped- ance of a satellite/subwoofer system is to install a Niles VCS-2D-IM or VCS-2S-IM impedance magnifying volume control instead of a standard volume control. This control has a behind the wall jumper which is set at the time of installation to “magnify” the speaker system impedance. (See Figure 9).

➟

For example: In the two times position, an IM volume control will enable an eight ohm stable amplifier to play a 4 ohm speaker system without overheating. The available power will decrease, which you will perceive as a 3dB drop in maximum undistorted volume.

If the jumper is set to the 4x position, a 6dB drop in volume will be perceived.

If the jumper is set to the 8x position, a 9dB drop in volume will be perceived.

A 10dB drop is perceived as half as loud, so there are limits to the amount of magni- fication you can use unless the amplifier is very powerful (3dB increase every time you double the power) or you never listen at high volumes. Consult the Decibels and Power chart on page 4.

Impedance