ETS MPI-1P User manual

MPI-1P High Performance Microphone
Pre-Amplifier Instructions
The MPI-1P is a high performance, 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-1P is switch selectable “line level”
(0db) or “microphone level” (-30db).
Microphone
The MPI-1P 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-1P. 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-1P can be surface mounted on a wall behind a DVR, Audio recorder, PC, etc.
Adjusting the SM1-PA Gain
The MPI-1P 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-1P with devices that utilize
“microphone inputs” also known as “Mic. Level” inputs. This sets the maximum gain of the MPI-1P’s pre-amp to x14. The
switch should be placed in the “HI” position when using “Line level” inputs of DVRs etc. This sets the maximum gain of the
MPI-1P’s pre-amp to x196.
The MPI-1P 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).
Adjusting the Lo-Cut and Hi-cut filters
The MPI-1P’s high and low frequency response can be trimmed to reduce background noise. If you are primarily
interested in capturing conversations and want to reduce air conditioning and other noises, rotate both controls (hi-cut and
lo-cut) to just short of full clockwise. Some experimentation may be required to achieve the best results for a given
environment.
Adjusting the Automatic Gain Control
The SM1-P features automatic control of gain. This is useful for environments where it is anticipated that sound levels will
range from quiet to loud. This prevents the end user from having to constantly readjust the volume of the base station to
the audio environment and to reduce the possibility of pre-amplifier clipping (distortion). The best way to set this control is
to adjust it to a comfortable volume level (on an ETS base station or PC monitor speakers) when the loudest sounds are
present and constant. Turning the control CW will increase the amount of gain reduction during loud sound intervals. If the
sound is reduced too much during loud sounds, turn the control CCW a small amount and experiment until a comfortable
medium is found.
Hum or radio station pick up
If you experience unwanted hum or pickup of AM radio stations on the microphone, try placing a wire on the lower left
ground screw of the MPI-1P to a known good electrical ground.

Figure 1.
Caution
It may be against the law to install this microphone kit in certain environments. It may also be against the law to record conversations of
the person(s) being monitored without their knowledge. It is the responsibility of the installation company and end-user to determine if
the application of this product is legal. These laws vary from state to state. If you are not informed on these matters, consult a qualified
attorney or contact the appropriate state agency. A sticker is provided with this kit for the applications where notification must be
posted.
Warranty
All ETS products carry a one year parts and labor warranty. This warranty does not cover damages as a result of misuse, improper
handling of the unit or exposure to extreme temperatures or moisture. At its discretion, ETS reserves the right to repair or replace this
unit under the conditions of the warranty. If you experience problems with your equipment call ETS at: 505-888-3923 to obtain a return
authorization number. Equipment requiring repair beyond the warranty period or units that have been damaged or are not covered
under the warranty can be repaired by ETS for a minimal cost under most conditions.
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