Audio Electronics and Acoustics Consulting Services

Loudspeaker Characterization

Accurate measurement is critical to insure compliance and repeatabilty. SAI can work with speaker suppliers and customers to develop speakers that will perform to your requirements.

Precise Speaker Frequency Response Measurement

The gold standard for speaker frequency response measurement is the "Half Space", which measures only the speaker, not its baffle or surroundings.

SAI uses an intergrated electronics-acoustics system that creates a "Virtual Half Space" setup. Your speaker's response can be obtained without environmental coloration. The speaker can be measured at any angle from 0 to 90 degrees.

Virtual Half-Space Method

The VHS baffle is larger than a typical small IEC baffle, yet maintains uneven path lengths to stagger unwanted pulse returns.

The Virtual Half Space Baffle

The VHS system uses the Quasi-Anechoic measurement approach developed by Richard Stroud of SAI. This methodology closely duplicates anechoic chamber measurement.

Measurement Equipment Utilized

SAI uses a number of elements in the Virtual Half Space measurement system which insure your data accuracy, including:

• Heavy wooden vertical baffle with rigid speaker mounting and anti-vibration weighting
• Well-damped low-resonance microphone positioning arm
• Back-electret condenser measurement microphones
• B and K Pistonphone and other microphone calibrators
• Reference channel fed from speaker drive signal, with Kelvin connection for precise level setting
• Special measurement and analysis software with averaging FFT
• High-power driving amplifier for large speaker life testing

Measurement Data Output

SAI can provide you with data that helps you communicate with your suppliers and please your customers.

Loudspeaker Frequency Response Curve

Additional Speaker Measurement Services

In addition to frequency response (on and off axis), many other kinds of speaker measurement are available:

• Impedance vs. Frequency
• Distortion, THD, spectral components
• Power Compression, a measure of excursion capability at high levels
• Large excursion high-frequency distortion
• Thiele-Small parameters
• Large-signal parameters, BL vs. displacement, compliance vs. displacement
• Power handling testing, with less-destructive impedance rise failure prediction

Speaker Impedance Curve

We also offer LQ response analysis, an experimental new procedure developed by SAI is designed for high-end loudspeaker systems. LQ analysis looks at ripples in the response curve to see if self-masking can occur to dull musical transients.

Home Speakers

Stroud Audio Inc. can perform anechoic and in-room evaluation of your home style enclosed speakers and integrated systems, as well as your raw loudspeakers.

Satellite speakers and big subwoofers can be evaulated with Virtual Half Space technology. This technology typically makes low-frequency performance analysis using suspended speaker or ground plane testing unnecessary.

Microphones and Headphones

SAI can perform testing of other acoustic transducers, such as in-vehicle microphones and headphones.

Hands-free cell phone testing is done with the "Talker" seen below.

Cellular Microphone Testing

Additional types of testing are available upon request. Please contact SAI for further information.