Sing-a-Long Song Devocalizer

Cancel out vocals, isolate instruments, and create fascinating audio effects with this inexpensive DIY device.

By Jeffrey M. Goller and Nathan Goller-Deitsch

AS A MUSICIAN I FREQUENTLY NEED TO LEARN NEW SONGS, and it can be difficult to hear individual instruments in recordings I want to study. I have often wished for an easy way to eliminate or reduce the vocals and isolate the instruments. Expensive, inconvenient solutions exist, but I wanted a cheap method that I could use anywhere, on any device with a ⅛" stereo headphone jack.

Then, one night, I was fiddling with a pair of headphones with a defective plug. When moved a certain way, it gave the exact vocals-canceling effect I had been looking for!

To understand what happened, I researched online, bought some components at RadioShack, and tested various wiring combinations. Together with my 10-year-old son Nathan, I designed and built a circuit that replicates the effect.

How It Works

When songs are mixed from individual tracks, the waveforms of the isolated instruments and voices are added together to form the left and right channels of the stereo mix. Typically, vocal tracks are placed in the center of the mix, which results in mathematically identical waveforms being sent to the left and right channels.

The Devocalizer lifts the common ground for the stereo signals, and instead uses the opposite channel as the new ground, putting the signals 180° out of phase from each other. Each stereo channel is added to an inverse copy of the opposite channel, canceling any audio that’s mixed in both channels. Result: Vocals magically vanish!

The isolation of instruments using the technique can be remarkable. We’ve found that about 20% of songs have fantastic vocal cancellation—you could use them for karaoke, no problem. In 50%–60% of songs, the effect is less pronounced but you’ll still hear instrumental parts you never heard before. About 15% are duds, and 5% have a fascinating, totally unexpected, robotic audio sound that’s difficult to describe. Experiment, have fun, and let us know if you find any tunes with especially pronounced or weird effects!

The waveforms of various musical instruments and voices are combined to form the left and right channels of a stereo mix.

The Sing-a-Long Song Devocalizer causes the stereo signals to become 180° out of phase.

Result: Anything mixed evenly to both right and left channels will magically disappear.

Time Required: 1 Hour Cost: $40-$60

JEFFREY M. GOLLER
is an emergency physician in sunny Charleston, S.C., who originally hails from Cincinnati. He plays the upright bass with The SouthRail Bluegrass Band, and enjoys designing and building musical instruments.

NATHAN GOLLER-DEITSCH
is a 10-year-old home-schooled programmer/developer (who also happens to be the son of Jeffrey Goller). He programs in Visual Basic .NET, PHP, and HTML, and wants to move to Silicon Valley (when he is old enough) to have his own start-up company.

Gunther Kirsch