OSD Audio SLK 300W Screwless Knob In-Wall 300W Volume Control, Impedance Matching, White

Now you can match your favorite decora light switch with screwless volume control. All speakers have an impedance rating, typically 8 ohm for a pair of home speakers. To operate in the safest mode, most standard amplifiers and basic two-channel receivers are rated for an 8-ohm incoming load. To operate safely and consistently, the amp needs to see an 8 ohm load, and that’s where speaker selectors and impedance-matching volume controls come into play.

 

In a basic multi room system, only a Speaker Selector is used to connect the speakers to the amplifier/receiver. Not only does the Speaker Selector allow you to connect multiple speakers to the amplifier but also adds internal Impedance Protection which is enabled by a manual protection switch. Both our ISS and DSM series Speaker Selectors feature internal Resistors that protect the amplifier. The down side is that the power rating normally 140 watts is cut in half when the protection switch is enabled so rated at 70 watts with protection.

 

In a standard multi-room system (using Impedance Matching VC) you will typically have an amplifier/receiver, a speaker selector with 4 to 8 zones, and volume controls connected to all the speakers. Impedance-matching volume controls provide more precise protection for the amplifier/receiver versus the protection built into the standard speaker selector. Plus with the protection switch in the off position you will have the maximum power handling capability of the respective speaker selector. It is important that the protection switch is turned off when using the Impedance matching Volume Controls.

 

Most impedance-matching volume controls feature three standard settings: 1/2x, 4x and 8x, while some add a 16-ohm setting like our VMS series. These settings correspond to a chart in the owner’s manual based upon the type of amplifier (4 or 8 ohm) and the number of 4 or 8 ohm speakers that you will be using in the multi-zone/room/speaker system. You can use both 4 and 8 ohm speakers when setting up your system. But you need to count a 4 ohm speaker as two 8 ohm speakers when calculating your Impedance setting.