TDT MA3 Application guide

MA3 Microphone Amplier
Hardware Reference
Updated 2022-10-31

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MA3 Microphone Amplier | 2

Table of Contents
MA3 Microphone Amplier
4MA3 Overview
4Power
4MA3 Features
4Inputs
5Bias
5Gain Control
5Outputs
5MA3 Technical Specication
6MA3 Output
6MA3 Frequency Response
Table of Contents | 3

MA3 Microphone Amplier
MA3 Overview
The MA3 is a two-channel microphone amplier 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 amplication from 10 dB to 55 dB in 5 dB steps. A toggle switch provides 20 dB of
additional gain for over 5000x total amplication.
Power
The MA3 Microphone Amplier is powered via the System 3 zBus (ZB1PS). No PC interface is
required.
MA3 Features
Inputs
The MA3 comes with three inputs: an XLR microphone input and two ¼" TRS connector inputs.
Signals from two microphones can be amplied simultaneously.
MA3 Microphone Amplier | 4

Bias
The Bias switch produces a bias voltage for microphones that require it.
Gain Control
The gain control amplies 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 amplication of
~5600x.
Outputs
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 Specication
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 Microphone Amplier | 5

MA3 Output
MA3 Frequency Response
MA3 Microphone Amplier | 6