The Peavey MP-4 Specifications
By Lee Johnson
The Peavey MP-4 is a four channel mixer that can route the sound of four instruments or microphones through one common processor before it is sent to external speakers. The MP-4 includes a frequency contour contro to combat common high end frequency problems with dynamic microphones.
Equivalent Input Noise
The MP-4’s equivalent input noise is -108dBv, with the gain at 40dB. This calculation is for the noise generated with an input connected to the mixer. It is “equivalent” because the noise generated by the input is too low to be measured without applying gain. As a solution, the gain is turned up until the signal generates enough noise to be measured, and then the gain is subtracted from that figure. Hence, it is an “equivalent” calculation, not an actual measurement.
On the Low-Z (XLR) inputs the impedance is 2 kiloohms. On the quarter inch inputs it is 220 kiloohms. The impedance is basically the measurement of how much power a unit will accept.
Channel gain is a measurement of how much a signal is amplified by the mixer. The nominal gain levels are 15dB for the quarter inch inputs, and 30dB for the Low Z inputs. The lowest are -55dB for the quarter inch and -60dB for the Low Z inputs. The maximums are 36db for the quarter inch and 51dB for the Low Z inputs.
The input level is the decibel measurement for all levels. The minimum input level on the quarter inch inputs is -35dB, and on the Low Z inputs it is -50dB. Nominal is -30dB for the Low Z inputs and -14dB for the quarter inch inputs. The maximums are -9dB for the Low Z and +6dB for the quarter inch inputs.
The impedance on the output signals is 100 ohms for the main and effects outputs. With nominal levels, the output noise is -76dB. Nominal levels are set at 0dBv.
Rated Power and Load
The MP-4’s load for a 30 watt RMS is 8 ohms and 4 ohms for a 60 watt. It requires 103 watts of power, or 120 volt AC.
Lee Johnson has written for various publications and websites since 2005, covering science, music and a wide range of topics. He studies physics at the Open University, with a particular interest in quantum physics and cosmology. He's based in the UK and drinks too much tea.