300W Decora Style Volume Control Kit with Impedance Matching and A/B Switching - SVC405

There are two types of volume controller - Impedance matching and Non-impedance matching. If you connect your speaker parallel to the receiver or connect the speakers into an impedance protection speaker selector, use impedance matching volume controller. If you connect just one pair of speaker directly to the receiver or your speakers are connected directly into an impedance matching speaker selector, use regular volume controller.

OSD Audio SVC405 is a 300-Watt impedance-matching volume control with two-source (A/B) switching that allows you to adjust the volume of a pair of speakers independently of other speakers and control the volume of two audio sources and one pair of speakers or two pairs of speakers and one audio source. Ideal for both home and commercial installations, this decorative in-wall volume control includes an impedance-matching feature that stabilizes the ohm load so parallel connections of multiple volume controls can be installed without damaging the amplifier. The SVC405 maintains the full hi-fi audio frequency response with no low frequency roll-off and is rated at 300 Watts per channel (100W RMS). The rotary knob adjusts the volume from inaudible to loud, and when you order the SVC405, you get the complete kit that includes the junction box, screws and trim plate.

What is 2-Source (A/B) Switching?

A/B or dual-source switching is a convenient feature that allows flexibility when you’re designing your whole-house audio system. With A/B switching, you can connect two sets of speakers and one source, and those speakers can be in same room or separate rooms. For example, speakers connected to source A could be in the living room and speakers connected to source B could be in the dining room. Then simply use the A/B switch to choose between the zones. Another option would be to connect two sources such as one amp and one receiver to play through one set of speakers and switch between the sources.

What Is Impedance Protection?

Speakers are specified by impedance, which is a measurement of resistance to alternating current, and a common value for speakers is 8 ohms. When you’re connecting multiple speakers to a receiver or amplifier, you need to stay above the amp’s minimum load requirements because going below the impedance rating can overheat or even damage expensive equipment. The SVC100 allows you to match the impedance with the number of speakers being controlled with the capabilities of your amp. A basic multi-room system will typically have an amplifier/receiver, a speaker selector, four to eight pairs of speakers, and volume controls. Impedance-matching volume controls feature three settings depending on how many speakers you are connecting. For one to two pairs of 8-ohm speakers, the setting is 1/2x; for three or four pairs of 8 ohm speakers, the setting is 4X. Keep in mind that volume controls do not add gain (volume) to your speakers but simply attenuate the volume up or down. During setup, you'll set the source volume to its optimum level, then the volume control turns the sound down to inaudible levels.


  • Decorative, decora style impedance-matching volume control for whole house audio systems and dedicated audio zones
  • Rated at 300 Watts (100 RMS) per channel with minimal bass roll-off
  • Includes 2-source (A/B) switching for two pairs of speakers and one source
  • Impedance-matching feature stabilizes the ohm load so parallel connections of multiple volume controls can be installed without damaging the amplifier
  • Accepts up to 14-gauge wiring and fits in a standard gang box with a depth of 2.9”
  • Precision electronics provide low distortion and a ruler flat frequency response
  • Rotary-style knob for a wide range of listening volumes
  • Installs easily and works with almost any audio system

Additional Information

More Information
Model NumberSVC405
  • Impedance matching volume controller with A/B Switch
  • Power handling: 300W per channel
  • RMS Rating: 100W
  • Frequency Response 20Hz - 20kHz
  • Front-mounted switch allows for easy adjustment when 1 pair of speakers are connect 2 amplifiers or receivers.
  • Impedance matching for 2, 4 or 8 pairs of speakers and can be used as non-impedance matching if leaving default on jumper setting at 2X.
  • Steps: 12 (make before break)
  • Total Attenuation: 42 dB (Max)
  • Includes White Plate, Insert and Knob
  • Fit in single gang box
  • 5-yr warranty
California's Proposition 65
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