MCM Electronics

Automatic A/B Line Level Switch By Speakercraft (LL-ONE) MCM Part #50-8385

5 stars 6 ratings and 5 reviews

Specifications Top

Automatic A/B Line Level Switch
This switching device automatically selects between two line level sources to a single amplifier input. RCA female input/output connections accommodate left and right channels, making it perfect for all consumer electronic devices.

Note: This unit requires 12VDC, AC adapter sold separately, MCM Model #28-19361. Default Input–A is selected when no signal is present. When a signal is sensed at Input–B, the selector automatically switches to that input. A separate 12VDC, 100mA signal is also provided to trigger other external devices.

Trigger sensitivity is fully adjustable from 10~100mV. Off delay (from B back to A after absence of signal) is adjustable in eight steps from 0.5 seconds to 10 minutes.
Part Numbers
MCM Part #:50-8385
Speakercraft Part #:LL-ONE
Package Specifications & Dimensions
Weight:0.25 lbs.
Warranty:1825 days
Need to Return?
Length:5 in.
Width:4 in.
Height:1.5 in.
Shipping Information
Extra Shipping Charge:No
Drop Ship:No

Product Reviews Top

  • by praudio

    on 2/7/2017

    Works very well!

    Overall: 4.5 out of 5

    With just a little "tweaking" of the controls (will vary a little from situation to situation), this unit works very well. The manual is brief, but concise and easily understood by anyone into audio, I would think. The physical installation and hookup is easy, esp. if the unit can go on the wall behind an equipment cabinet. My only gripe is that the unit does not come with the power supply, which has to be ordered separately.

  • by tquesnel

    on 12/29/2016

    A must have for Amazon Echo Dot

    Overall: 4 out of 5

    The Amazon Echo Dot allows you to make any dumb speaker, smart. But the problem is that even modern day receivers still don't natively support a way of sensing line level changes from 2 sources on a single mode. Instead they expect you will manually switch to the input you want to use. That doesn't work for something like the Echo because you want on-demand results as soon as you start talking to it, but still want to have the normal sound source the rest of the time.

    With this, you can take your normal TV source and couple it with the output from Amazon Echo and have it automatically switch over to Alexa when she is responding to you, then switch back to the original source. I have one in my basement and it works perfectly. I am buying another for my upstairs family room.

    Now I can be watching a movie with full surround sound, and then ask Alexa for restaurants in the area and she take control of the speaker for a few secs, then have it go back to my movie.

  • by Bridge City Games

    on 10/26/2012


    Overall: 5 out of 5

    this item we have bought in the past and had very good success with


    on 6/8/2011

    electronics tech

    Overall: 4.5 out of 5

    very good product easy to use...needs to come with power supply

  • by jkliquid

    on 4/20/2010

    Good switch.

    Overall: 4.5 out of 5
    Top 10 Contributor

    Works very well.

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