100 Things #26: Production Line Polarity Measurement

SoundCheck offers a rapid production line polarity measurement that can identify correct wiring at the same time as other production line acoustic tests. This is valuable as the conventional method of polarity measurement –  determining if a diaphragm moves outward or inward when voltage is applied – is not practical on the production line.

Production Line Polarity Measurement in SoundCheck

Learn How to Measure Polarity in SoundCheck

Check out our knowledgebase article on Polarity Measurement.

More information is also available in the  SoundCheck Manual.


Video Script: Production Line Polarity Measurement

Having the proper polarity marking or wiring is a critical requirement for any transducer, particularly those that are used in conjunction with others.  If there are errors in wiring or terminal markings, the intended performance of the transducer and how it interacts with other transducers in a system can be compromised.

The simplest test for polarity might be applying a DC voltage to a speaker and determining if its diaphragm moves outward or inward as the voltage is applied.  If everything is wired or marked correctly, we would expect the diaphragm to respond with an outward motion when a positive voltage is applied.  While this method is simple and accurate, it is not practical for production line test.

For production line testing, SoundCheck has a couple of useful methods for polarity detection. The first option is to place limits on the phase response curve of the device under test. Since the phase response changes by 180 degrees when the polarity changes, this can be an accurate method for polarity detection. The other option is to enable the Polarity check box which can be found on the Time tab of most of SC’s analysis editors.  Once enabled, every time the Analysis step is applied, SC will calculate an impulse response of the current measurement. The impulse response is then analyzed to determine if the largest peak has a positive or negative value.  If positive, a value of 1 will be generated into the Memory List, if negative, a value of -1 will be generated into the Memory List. A limit can then be applied to this value to create a Pass/Fail verdict in the ML Results tab.

These polarity detection options have been available in SC since 2011 and provide the user with two accurate methods for measuring the polarity of your transducer.