ETS MPI-1 Instructions

MPI-1 Microphone
Pre-Amplifier Instructions
The MPI-1 is a high quality, 12V-24VDC powered, Microphone pre-amplified microphone for use
with ETS ML1 series microphones and permits connections to DRVs, audio recorders, etc. Note-
the audio output of the MPI-1 is switch selectable "line level" (0db) or "microphone level" (-30db).
Microphone
The MPI-1 is designed to be used with ETS ML1 series microphones (or any other PC compatible
microphone). Plug the ML1 microphone into the "mic in" jack of the MPI-1. Do not mount the ML1
microphone near air conditioning vents, light fixtures or electrical equipment. The ML1
microphone should be placed as close as possible to the subject of interest. The ML1 microphone
is useable in the range of 3-25 feet but is dependent on the level of background noise in the area.
Experimentation in the environment will determine what distances work best.
Cable Runs
The length of the microphone input cable can be up to 25' long. The cable run from the audio out
jack to the end device should not exceed 1000' of high quality shielded cable. See Figure 1 for
connection diagram.
Mounting
The MPI-1 can be surface mounted on a wall behind a DVR, Audio recorder, PC, etc.
Adjusting the MPI-1 Gain
The MPI-1 output level is set by selecting the desired volume range and adjusting the gain
control.
The "Volume Range" switch should be set to the "LO" position when using the MPI-1 with devices
that utilize "microphone inputs" also known as "Mic. Level" inputs. This sets the maximum gain of
the MPI-1's pre-amp to x14. The switch should be placed in the "HI" position when connected to
"Line level" inputs of DVRs or other devices. This sets the maximum gain of the MPI-1's pre-amp
to x196.
The MPI-1 is shipped with the gain set at midrange. If the sound at the "head end" is distorted,
rotate the control towards the – mark (counter-clockwise). If the volume at the "head end" is too
low, rotate the control towards the + mark (clockwise).
Setting the MPI-1 Hi-Cut/Lo-Cut Switches
The normal frequency response of the MPI-1 microphone is 200-13Khz. The low cut filter can be
adjusted from 200-1khz. Rotating the control clockwise increases the lo cut frequency. Cutting the
low frequencies is useful when background noise needs to be reduced. We recommend
experimenting with the jumper settings to achieve the best acoustic result for your application.
Hum or radio station pick up
If you experience unwanted hum or pick up of AM radio stations on the microphone, try placing a
wire on the lower left ground screw of the MPI-1 to a known good electrical ground.