Is Ipod Audio Good Enough?
Ipods and their work-a-likes are the rage among consumers, but there are many professional opinions about whether they are good enough to use as a playback source in sound reinforcement systems. I decided to investigate by testing some personal media players.
Some personal media players are appropriate for sound system testing, some are not. The best ones are the iPod Video and iPod Nano. They passed all tests with flying colors, and even proved to be superior to the on-board computer sound cards that were tested, likely because of the increased isolation from electrical noise from being a standalone device.
A word of caution: The iPod has unacceptable distortion when full-scale sine waves are played at full playback level (about 1Vrms or 0dBV). For optimum results, turn down the unit about 3dB when conducting system tests.
The iPod shuffle did not fare as well, contrary to some marketing claims of it being the optimum iPod for audio. It's amazingly small and lightweight, but the distortion, noise, and crosstalk specs were not up to par with its larger siblings, probably because of the very compact design. It's fine for use while jogging or in the weight room, but stick with the Nano or Video for system testing and serious listening.Mic or Line?
Most personal media players have full-scale output levels of about 0dBV. This is more than enough to drive the line-level input of a mixer. While the output impedance is low enough to drive the typical microphone input, I would not suggest doing so. While I did not test for it, phantom power could be a problem. A simple stereo 3.5mm-to-1/4-inch cable should be fine for driving the mixer directly with a few meters of cable. If you need to drive a long line or a microphone input, a number of unbalanced-to-balanced interface boxes are available, such as ProCo, Whirlwind, or Jensen.
I am not a big fan of integrating consumer gear into professional systems, but the iPod is a notable exception. The audio performance is up to par for system testing and better than the typical PC sound card. Factor in the convenience of having test waveforms and a music library in your shirt pocket, and it's hard to not love these devices.
Pat Brown is president of Synergetic Audio Concepts (Syn-Aud-Con) Inc. and Electro-Acoustic Testing Company (ETC) Inc. Syn-Aud-Con conducts training seminars in audio and acoustics worldwide for those who operate, install, and design sound reinforcement systems. ETC performs precision loudspeaker testing for the audio industry. Pat can be reached at firstname.lastname@example.org.