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White rectangular in-wall volume control knob and faceplate

Monoprice Inc.

Monoprice 138163 70V In-Wall Volume Control 50W 11 Positions

SKU CH-F9V4-QGJ3Y

An in-wall rotary volume control for 70V music systems with 11 positions, make-before-break contacts and a 50-watt maximum load

  • TypeVolume Control
  • Weight0.90
  • FeaturesAn in-wall, inline volume control for 70V music systems.
  • 11 volume positions with make-before-break contacts for smooth level changes
  • 50 watt maximum load handles powerful 70 V speaker runs
  • Fits a single gang junction box for clean in-wall installation
  • Two controls fit side-by-side in a dual gang box for multi-zone setups
  • Inline design lets you adjust volume locally without reaching the amplifier

In-wall volume control for 70V systems

The Monoprice 138163 is an in-wall, inline volume control designed for 70V distributed audio installations. It provides local level adjustment for background music or paging zones in commercial or residential settings. The unit mounts in a standard single gang junction box for flush integration. It suits installers needing simple, passive attenuation without external power.

50-watt maximum load rating

This control supports a maximum connected load of 50 watts on a 70V line, which is the critical limit for amplifier matching. Exceeding this rating risks overheating or damage to the autotransformer. The 11 stepped positions use make-before-break contacts to prevent open-circuit spikes during adjustment. Verify the total speaker tap wattage on the zone does not surpass 50 watts before specifying this model.

Passive operation with no fan noise

The device operates passively, drawing no mains power and producing zero audible noise during use. Heat generated at high attenuation levels dissipates through the metal mounting strap into the wall cavity. No active cooling is required, making it suitable for quiet environments such as offices, restaurants or homes. Ensure the junction box provides adequate air space for thermal dissipation.

Highlights

  • 11 volume positions with make-before-break contacts for smooth level changes
  • 50 watt maximum load handles powerful 70 V speaker runs
  • Fits a single gang junction box for clean in-wall installation
  • Two controls fit side-by-side in a dual gang box for multi-zone setups
  • Inline design lets you adjust volume locally without reaching the amplifier

Specifications

BrandMonoprice
Model138163
Part Number138163
TypeVolume Control
Weight0.90
FeaturesAn in-wall, inline volume control for 70V music systems.

Questions about this item

What does the 50-watt maximum load mean for my 70V speaker system?

It sets the highest continuous power the control can handle from the amplifier before distortion or damage occurs on a 70V line.

How do the 11 volume positions work with make-before-break contacts?

Each step adjusts the transformer tap without interrupting the signal, so volume changes are silent and the amplifier always sees a load.

Will this fit in a standard single-gang wall box?

Yes, it mounts in a single gang junction box; two units or one RVC25-70 plus one RVC50-70 fit side-by-side in a dual gang box.

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