Dual RCA Line/Auxiliary Inputs
The ACM120XL includes 8 microphone and line (auxiliary) inputs. The line inputs are via dual RCA connectors per
channel. Although the ACM120XL is a mono amplifier, dual RCA’s are provided to allow for easy connection to
domestic or professional line sources. The line inputs are suitable for a wide range of products including tuners, cassette
decks and CD players. As the output signal from line sources can vary immensely, four sensitivity settings are available
per line input. These settings are adjustable via dip switches 1 and 2 per channel. The options are:
Dip Switch 1 off, 2 off - 90mV at 47K ohms
Dip Switch 1 on, 2 off - 9dB pad (cut)
Dip Switch 1 off, 2 on - 12dB pad (cut)
Dip Switch 1 on, 2 on - 15dB pad (cut)
Dip Switch 3 is for the XLR microphone input and switches phantom power on and off (see “XLR Microphone In-
puts”).
Simultaneous Use of Mic and Line Inputs Per Channel
The ACM120XL has 8 microphone and 8 line inputs. In most situations only the XLR or the dual RCA’s would be used
on a particular channel. In some circumstances however, more channels may be needed in which case both the XLR and
RCA inputs can be used simultaneously per channel. When using both a mic and line input per channel, both inputs are
mixed and are controlled simultaneously via the channel level control.
Line Input Sensitivity
Four sensitivity adjustments are provided for each line input. See “Dual RCA Line/Auxiliary Inputs”.
Phantom Power
15v DC Phantom Power is selectable per XLR microphone input. See “XLR Microphone Inputs”. Phantom Power
should only be used on balanced electret microphones. Using phantom power with unbalanced microphones may dam-
age the microphone.
Muting
The ACM120XL includes an advanced priority/muting system which is installer adjustable. When shipped, the
ACM120XL has three priority inputs. From the factory, Input 1 has overall priority and mutes inputs 2-8 when signal is
present. Input 2 has secondary priority and mutes inputs 3-8 when signal is present. Input 3 has a third level of priority
and mutes inputs 4-8 when signal is present. Inputs 4-8 have no priority and are mixed. All muting in the ACM120XL
is activated by signal (VOX) whether it be on the XLR or RCA inputs.
A number of muting options are available and can be altered via a series of internal links located on the front mixer
board behind inputs 1and 2.
Muting for any of the first three inputs can be disabled. The muting circuit of input 1 can be disabled by moving the
jumper labelled JP1 (located on the front mixer PCB behind input 1 and 2’s level controls). Simply move the jumper
towards the back of the chassis to disable muting from input 1.
To disable muting from input 2, simply move jumper JP2 towards the back of the chassis.
To disable muting from input 3, simply move jumper JP3 towards the back of the chassis.
Another feature of the muting circuit of the ACM120XL is the ability to have inputs 1 and 2 on the same priority level.
This is handy for situations where phone paging and microphone paging (for example) are of equal importance. In this
mode, both inputs can be used at the same time and both will mute all remaining channels. This feature is also handy for
emergency systems where signal from a pre-recorded message could be mixed with a live microphone. To set inputs 1
and 2 to the same priority level, move jumper JP4 towards the front of the chassis and remove and discard jumper J6.
Please note that both jumpers (J4 moved and J6 removed) need to be adjusted for this feature to work.