Audio Test System Configurations
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Overview
This document presents a few example configurations for audio test systems including options for automated production line testing and compact, low-cost test systems. A brief overview of audio test system design and selection cinsiderations is also included. Visit ni.com/soundandvibration or contact National Instruments for more options or to customize a system for your specific application.
Table of Contents
Audio Test System Considerations
Basic instrumentation for audio test systems typically include 2 input channels, 2 output channels, and analysis software. From there, test system engineers can add a wide array of options from connectivity to a PC for automation or additional input and output channels or even measurement channels for non-audio data. The additive costs and differences in overall test system functionality vary greatly between different systems and vendors. Here are some factors that test designers should consider when developing systems:
- Addition Input and Output Channels - Designers have a choice of either additional simultaneous I/O (which can increase test throughput, shortening test time) or multiplexed I/O (which often results in lower cost). Additional I/O channels is becoming increasingly important in audio test because even the most basic car audio, home theater systems, and audio amplifiers now have 6, 8, 10, or even more channels.
- Floor Space - With the current trend to implement lean manufacturing procedures and optimize floor space, traditional rack and stack audio systems may take up significantly more space than PC or PXI-based audio test systems.
- Total Test Time - In terms of test time, traditional instruments are often limited to multi-tone tests to keep test times low. More powerful swept-sine analyses may take too much time on traditional DSP-based audio analyzers. With PC host-based processing, it is often possible to do swept-sine and other tests in the same amount of time as traditional multi-tone tests.
- Automation and Data Reporting - Connecting to a PC for test automation or data reporting is a common concern for test designers with choices of speed and latency over various data buses.
- Non-Audio Testing - Test systems often need to test additional points beyond the audio path. For high-accuracy DC measurements on the power supplies, designers need to deploy digital multimeters (DMM) as part of the system. Other additional test factors may include video test or RF analysis for radios. Performing all of these tests and the audio tests on the same platform can reduce overall system complexity.
Configuration 1: Audio Power Amplifier Testing for Consumer Electronics and Automotive Applications
One of the most common audio test applications is for power amplifier testing. In both consumer electronics and automotive industries, multi-channel power amplifiers with 5, 7, or more channels are the norm. A common setup includes an audio signal acquisition and generation device with typically two channels of each; a switch or multiplexer to choose between amplifier channels; and a digital multimeter with inductance and capacitance capabilities. The software requirements and test parameters are shown below.
Typical Test Parameters
- Frequency Response
- Distortion (THD+N)
- Relative Phase
- Crosstalk
- Intermodulation Distortion (IMD)
Hardware and Software Components
The list below shows a common configuration for multi-channel power amplifier testing with the necessary software to complete the analysis.
- Hardware
- NI PXI-1031 - 4-Slot PXI Chassis
- NI MXI-4 - Kit for PC control and communication
- NI PXI-4461 - Dynamic signal acquisition and generation with two 24-bit inputs and two 24-bit outputs
- NI PXI-2593 - 16 x 1 multiplexer (MUX)
- NI PXI-4072 - 6½-digit digital multimeter (DMM)
- Software
- NI LabVIEW Full Development System - Programming environment for test automation and data acquisition
- NI Sound & Vibration Toolkit - Analysis functions for audio applications
Configuration 2: Audio Testing for Broadcast and Production Studios
Another common audio test application is for production and broadcast studios. These applications often include analog-only audio equipment but require a high number of channels to be tested. As a result, these audio test systems include one or more switches/multiplexers to achieve a desired channel count. Again, the necessary software has been added to the systems as applicable.
Typical Test Parameters
- Frequency Response
- Noise
- Distortion
- Crosstalk
Hardware and Software Components
The list below shows a common configuration for multi-channel power amplifier testing with the necessary software to complete the analysis.
- Hardware
- NI PXI-1031 - 4-Slot PXI Chassis
- NI MXI-4 - Kit for PC control and communication
- NI PXI-4461 - Dynamic signal acquisition and generation with two 24-bit inputs and two 24-bit outputs
- Two (2) NI PXI-2593 - 16 x 1 multiplexers (MUX)
- Software
- NI LabVIEW Full Development System - Programming environment for test automation and data acquisition
- NI Sound & Vibration Toolkit - Analysis functions for audio applications
Configuration 3: Compact, Low-Cost Audio Test System
Test system designers may also find it necessary to implement a low-cost systems for manufacturing validating or portable applications. These systems often require maximum flexibility and simplicity to achieve desired test goals. The systems configured here have basic signal acquisition and generation capability typically at lower resolutions than configurations 1 or 2 above.
Hardware and Software Components - Option 1
This USB test system includes two types of 24-bit analog inputs for a total of 8 simultaneous input channels: a low voltage input module (+/- 5V) and a high voltage module for amplifiers (+/- 60V); as well as 4 channels of 16-bit analog output. Also provided is a simplified software environment for pass/fail testing with the NI Sound and Vibration Assistant (included in the NI Sound and Vibration Toolkit).
- Hardware
- NI cDAQ-9172 - 8-slot USB data acquisition chassis
- NI 9234 - 24-bit, 4 input module (+/- 5V)
- NI 9229 - 24-bit, 4 input high voltage module (+/- 60V)
- NI 9263 - 16-bit, 4 output module
- Software
- NI Sound & Vibration Assistant - (Included in the NI Sound and Vibration Toolkit) with basic pass/fail test capabilities and analysis functions for audio applications
Hardware and Software Components - Option 2
This PC-based test system utilizes a PCI slot in your test computer with 18-bit analog inputs and 16-bit analog outputs for basic audio measurements.
- Hardware
- NI PCI-6281 - Sixteen 18-bit multiplexed inputs and two 16-bit simultaneous analog outputs
- Software
- NI Sound & Vibration Assistant - (Included in the NI Sound and Vibration Toolkit) with basic pass/fail test capabilities and analysis functions for audio applications
Related Links:
- National Instruments Sound and Vibration Products
- Audio Measurements Made Easy with LabVIEW
- 10 Questions to Ask When Selecting Your Sound and Vibration Measurement System
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