Tag Archive for: directional measurements

Directional Audio Measurements with the MDT-4000 Turntable

Have you ever wondered about the thought process that goes into designing a new audio test product? Our sales and support teams worked closely with Portland Tool & Die during the design of the MDT-4000 turntable for directional audio measurements to ensure it addressed all the pain-points that our customers had with other brands – speed, accuracy, portability, control and more. In this short video, designer Kris Hett demonstrates these features and you can see how seamless integration is with SoundCheck.

 Directional Audio Measurements with the MDT-4000 Turntable

Learn more about the MDT-4000 Turntable

Check out our product information page, and our comparison of the MDT-4000 specifications with other popular turntables

Free polar plot test sequence for use with the MDT-4000 Turntable. This gets you up and running quickly with polar plots, and can be used as a base for creating your own measurement sequences.

More Information?

Curious? Contact our sales team for more information and pricing.

Microphone Polar Plot Sequence

mic_polar_plot_screenshotThis sequence measures the directional response of a microphone and graphs the result as a polar plot. A log sweep stimulus is played from 100 Hz to 10 kHz at each angular increment, and the acquired waveform is analyzed using the Time Selective Response algorithm. This method allows the test to be performed in a non-anechoic environment by placing a window around the direct signal, eliminating the influence of reflections. Commands are sent automatically to the LT360 turntable via an RS-232 connection, instructing it to move in 10 degree increments after each measurement. The sequence measures the response every 10 degrees from 0 to 180 and mirrors the polar image, simulating a full 360 degree test while saving time. The response at each angular increment is compared against the on-axis response to create a normalized curve. This removes the influence of the device’s frequency response and sensitivity, such that the polar plot only shows the directional response. The final display also contains a graph of the directivity index in decibels versus frequency.