Skip to content

MA3 Microphone Amplifier

MA3 Overview

The MA3 is a two-channel microphone amplifier for auditory scientists. This high-quality low-cost system is designed for use with both ¼" audio jack microphones and balanced XLR inputs for optimum impedance and noise characteristics. The MA3 can provide a bias voltage for microphones that require it. Two BNC connectors provide analog output. A variable gain knob provides amplification from 10 dB to 55 dB in 5 dB steps. A toggle switch provides 20 dB of additional gain for over 5000x total amplification.


The MA3 Microphone Amplifier is powered via the System 3 zBus (ZB1PS). No PC interface is required.

MA3 Features


The MA3 comes with three inputs: an XLR microphone input and two ¼" TRS connector inputs. Signals from two microphones can be amplified simultaneously.


The Bias switch produces a bias voltage for microphones that require it.

Gain Control

The gain control amplifies the microphone input in 5 dB steps from 10-55 dB (~3x - ~560x). The Gain Switch adds an additional 20 dB (10x) of gain for a maximum amplification of ~5600x.


Two BNC outputs give easy connection to any TDT System 3 device. The maximum voltage output is ±10 Volts. Clip lights indicate and overvoltage on the signal output.

MA3 Technical Specification

Input Signal Range ±10 V peak
-3 dB Bandwidth 200 kHz @ 40 dB gain
Gain Accuracy ±1 dB
Spectral Variation 1 dB from 20 Hz to 20 kHz
Signal/Noise 110 dB (20 Hz to 30 kHz at 9.9 V)
Noise Floor 9.2 uVrms
THD <0.002% (1 kHz tone, ±7 V peak)
Input Impedance 600 Ohm
Output Signal Range ±10 V peak
Bias Voltage 10 V, 150 mA max, superimposed onto microphone
Output Impedance 5 Ohm

MA3 Output

MA3 Frequency Response