Analog testing

June 1, 2010

Tech Tips, July 2010

Ed Treese is a contract engineer based in Kansas City. While his work includes plenty of digital signals, he still encounters plenty of analog equipment in his work. He shared some notes on his favorite piece of analog test equipment: a pair of headphones.

He keeps a pair of Sennheiser HD414 high-impedance headphones in his toolkit. The original version of these headphones had an impedance around 2k ohms. Most headphones available today are 50 ohms or less. Because of the high impedance, Treese can tap them into an active audio circuit with little or no effect to the audio path.

Treese also keeps a few adapters handy to simplify connections. He has a stereo headphone jack that is monoed to alligator clips. He also keeps a TAC clip on hand to slip on two rows of 66 punch blocks. He also carries an XLR through connector with a stereo headphone jack (again monoed) all in parallel. The XLRs can be used individually or in-line with the audio circuit.

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