Audio Precision System Two 2322


The Audio Precision System Two (APS2) can generate and analyze ultra-low distortion, low fequency sinewaves (10Hz-200kHz).


To use the APS2, you must log into the workstation adjacent to it using your eecs username. Currently this is badger.ece. Once logged in, run APWIN.exe. This is the user interface for the APS2. A common problem is for people to start the computer and the software and not power up the APS2. There is a power switch (I|0) on the front of the APS2 that must be turned on before the APS2 will function.


D/A Converter

  • Resolution: 18 bit dual-channel delta-sigma
  • Data Rate: 28.8 ks/sec to 52.8ks/sec
  • D/A Distortion: -96.5 dB THD+N @ 48 ks/sec

Variable Sine Wave:Two sine waves, same frequency, independent phase
Stereo Sine Wave:Two sine waves, independent frequency and amplitude, random phase
Dual Sine Wave:Twin sine waves of independent frequency and settable amplitude ratio applied to both output channels

  • Range: 10Hz to 20kHz
  • Resolution: ~0.0078Hz
  • Phase Accuracy:
1, 10Hz-5kHz
5, 5kHz-20kHz
  • Amplitude:
Balanced:<10μV to 26.66 Vrms
Unbalanced:<10μV to 13.33 Vrms

Analog Analyzer

  • Input Range: 40mV-160V
  • Max Input:230Vpk, 160Vrms
  • Input Impedance: ~100kΩ // 185pF
  • Level Meter Resolution:
4/sec 1/40,000
8/sec 1/40,000
16/sec 1/20,000
32/sec 1/10,000
64/sec 1/5,000
128/sec 1/2,500
  • Frequency Meter Range: 10Hz-500kHz
  • Phase Meter Range: 180,-90/+270, or 0/+360
  • Frequency/Phase Meter Min Input: 5mV
  • Phase Meter Accuracy:
10Hz-5kHz: 0.5
5kHz-20kHz: 1
20kHz-50kHz: 2


The AMS Lab does not have cables for the large connector on the front of APS2. Generally, the BNC I/O ports are used. There are two analog input and two analog output BNC ports on the front. There are also DSP and Digital Signal Generator Ports on the APS2. The operation of the digital portion of the APS2 is not discussed in this document.
Located next to the APS2 is an SIA-2322 Interface adapter. This can interface with the APS2 and allow communication with other pieces of test equipment. At the time the lab does not have the cables required to do this.

AudioPrecision Matlab Toolbox

The Matlab toolbox allows you to perform the following
1. Read APx waveforms saved by the Measurement Recorder into MATLAB.
2. Provide support for the user downloadable filter features in ATS 2 hardware.
3. Provide support for generator waveforms(from Matlab) and acquired waveforms in ATS-2. | Matlab Toolbox

External Links

Audio Precision
Audio Precision System 2 Manual
SIA-2322 Interface Adapter Manual\\