DMP3 Dual mic preamp / direct box User Guide
Introduction Thank you for purchasing the M-Audio DMP3 Microphone/Instrument Pre-Amplifier. The DMP3 gives you two completely independent channels of high gain, ultra low noise pre-amps in a sturdy desktop unit. Each channel provides low impedance microphone inputs on XLR connectors with optional phantom power, plus an alternate high impedance instrument input on 1/4" TS jacks. The DMP3 outputs can be used as balanced or unbalanced via its 1/4” TRS jacks.
Front & Rear Panels 2 5 3 5 3 6 4 6 4 7 8 9 10 1 Front Panel 1. Gain Adjustment Knobs: Separate gain controls for pre-amp channels A and B adjust the output volume levels independently. Full 5 counter-clockwise is the minimum gain position, while full clockwise is maximum gain. 2. VU Meters: These VU meters show output level, calibrated to correspond to digital 3 peak meters, where 0 VU is approximately 3dB to 6dB below clipping. 1 3.
5 3 1 2 4 Rear Panel 1. 9vAC Power Supply Jack: This power jack accepts a 9v AC 1 Amp 2.5mm power supply. This power supply is included with your DMP3, and ONLY the proper supply should be used. 2. Output Jacks A and B: These 1/4” TRS jacks are the main outputs for the pre-amps. Using a TRS (tip-ring-sleeve) 1/4” plug, the DMP3 will provide a balanced line-level output. Using a TS (tip-sleeve) 1/4” plug, the outputs will be unbalanced. 3.
3 1 DMP3 Operation A preamp is a necessary component of any signal chain, when a microphone, guitar 2 4 pickup or other instrument needs an increase in gain to “line level.” The DMP3 will perform that role in your signal chain. The drawing below shows the DMP3 in use with a computer sound card, which in this case is the Delta 66 from M-Audio. It is conceivable that once the DMP3 is attached to your system and powered up, you will be plugging and unplugging different microphones and instruments.
Setting the Gain The DMP3 provides up to 66dB of gain on the XLR and 1/4” high impedance inputs. Microphones and guitar pickups typically emit a low signal level, requiring a "pre-amp" such as the DMP3. Other instruments, such as keyboard sound modules, may also benefit from a little bit of punch from the DMP3. Plug in your mic or instrument with the gain controls turned down, then turn the gain up incrementally while testing the mic or playing the instrument.
Hi/Lo Gain Switches Two gain ranges are provided for the DMP3 preamps. The “Hi/Lo Gain” switch on the front panel is used to select between the two gain ranges, with the ‘Out’ position being the default. The Hi/Lo Gain switch in the Out position is the “Hi Gain” range, while the ‘In’ position switches the DMP3 to the “Lo Gain” range. The gain range is considered to be from the beginning to the end of the Gain Adjustment Knob’s travel from left to right.
Phantom Power Unlike dynamic microphones, condenser microphones need to receive a DC voltage (generally 48v) from an external source before they can generate an output signal. If the condenser mic doesn’t come with its own power supply, then "Phantom Power" must be applied from the pre-amp. Pressing the "Phan" button and engaging phantom power on the DMP3 will send the necessary voltage to both of the XLR Mic Inputs.
Specifications Maximum Input: +10 dBv Maximum Output - Balanced: +22 dBv Maximum Output - Unbalanced: +16 dBv Headroom: 22 dB Meter headroom: 12 dB Meter level: 0 VU @ +12dBV, 1KHz Maximum Gain - Mic/Instr. In: 66 dB Gain Range: 13dB to 73dB Clip Indicator: 3 dB below threshold of clipping Low Cut Filter Cutoff: 3 dB down @ 72 Hz Low Cut Filter Slope: 18 dB/Octave Input Impedance (1 kHz) - Mic In: 3 kOhms Input Impedance (1 kHz) - Instr. In: 100 kOhms Noise Factor: < 1.
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