How do I remove vocals from a mix?

This is the most frequently asked question by far. Other variations are:

Can I remove the guitar from a mix?
How do I isolate one voice in a recorded conversation?

What follows is my attempt to provide the most complete and definitive answer to these questions so that we can all refer to it in the future.

The most direct answer to all of these questions is no. You can't really remove a sound from a recording after it's been mixed. There are a few techniques for manipulating these files that may allow you to reduce a sound, but not without unintended side effects. More on that later...

If the sound you want to remove isn't musical, but noise (buzz, hum, clicking, etc.), there may be some hope for you with audio restoration techniques. For the purpose of this FAQ, though, I'm assuming you've got a vocal line or some other sort of musical sound you want to remove.

Think of the mixed audio file as a cake. Just as it is not possible to extract the eggs or sugar from a cake after it has been baked, neither is it possible to extract a vocal, guitar, or any other musical part from music after it has been mixed.

The most helpful suggestion I can give you is this... If you are trying to remove the vocal line from any commercially-available CD to create a karaoke or backing track, you'll save yourself a lot of time if you just go buy the karaoke version of that song. Most of them are available to purchase on a per-song basis for less than a dollar from the iTunes Music Store, Yahoo Music, and other pay-per-download sites. Searching for and purchasing the song will take you five minutes, and the quality will be much, much better than anything you could do yourself with even the best tools available.

Although it is not possible to remove any part of a recorded mix, there are a number of techniques, gadgets, and software applications that attempt to do exactly that, with varying degrees of success. They all use some variation of a technique called center channel cancellation. Here's how it works...

The idea behind center channel cancellation is pretty simple. If you have a piece of stereo audio, you can invert the polarity of either the left or right channel, and combine them. This takes any material common to the left and right channels and cancels it out. Since it is common to place the lead vocal in the center of a stereo mix, this technique can effectively remove the vocals.

But there are some big problems with center channel cancellation. First, although it is common to put lead vocals in the center of a stereo mix, it is also very common to put effects (reverb, delay, etc) on the lead vocal that cover the entire stereo field. So although you might remove the (dry) lead vocal, what you'll leave behind is the reverb tails and the strange remnants of a vocal that's no longer there.

The second big problem is that the lead vocal isn't the only thing placed in the center of a mix. Center channel cancellation removes EVERYTHING in the center. Kick drum, snare, lead guitar, bass. Whatever's there gets cancelled. And even those instruments that aren't placed squarely in the center can suffer from center channel cancellation. Usually what you end up with is a hollow shell that used to sound like music.

This is the simplest form of center channel cancellation. You can do this yourself (if you really want to, that is) using just the phase invert button on your mixer (or in software) or a cable with the polarity reversed. There are also a number of products on the market which use this basic technique:

The Mackie DFX series of mixers...

The Tascam Vocal Trainer CD player:

Center channel cancellation can be improved somewhat by selecting which frequencies you are effecting and combining the phase inversion with EQ filtering. If you know, for instance, that you are working with a female vocal with no meaningful content below 200 Hz, you can allow everything 200 Hz and below (kick drum, for instance) to pass on through and only cancel frequencies 200 Hz and up. There are a couple of other products which use this modified technique:

The Alesis Vocal Zapper:


Perhaps the best known (and most expensive) device of this type is the Thompson Vocal Eliminator:



Some software applications (such as Adobe Audition) also employ this modified cancellation technique.

The success of any of these devices will depend greatly on the music you are working with. Generally speaking, the older the mix, the better this will work. In the early days of stereo recording, producers generally placed the vocals in the center and panned everything else pretty widely. Higher quality files work best. Original CD's and .WAV's work better than MP3's. And since all of this relies on stereo imaging, mono files won't work at all.

I'll repeat the warning that I started with, though... Most people who have attempted this have not gotten satisfactory results, regardless of which tools they use. You'll be much happier with a karaoke track if you can find one. Apart from that, the only real way to do a "no-vocal remix" is to get the original multitrack session and repeat the mixdown sans-vocal.