Sample Inversion

A trick known as “sample inversion”, though not fool-proof, can help you capture just the acapella of your favorite song. Sample inversion works by canceling out all of the background frequencies in a track, inverting the audio on the instrumental track, and leaving you with the vocal frequencies to do with as you please. Sample inversion can be applied by following these steps :

Step 1. In your favorite audio editor (I like using Audacity for this), import both the instrumental and the full song on to separate audio tracks.

Step 2. Since the song you’re working with is most likely in stereo, convert both tracks to mono audio and pan one all the way left and one all the way right. Audacity will split both stereo tracks when converting to mono, so also remove any extra tracks that may have been created during this step.

Step 3. Take care to make sure that both tracks are perfectly in sync with each other, lining up the start point of each waveform. The position of the peaks and valleys in the waveform and how well they line up is crucial here. This alignment must be surgically exact in order to isolate the vocal properly.

Step 4. Once you’ve lined up the audio, select your instrumental track and use the Invert option to flip the waveform upside down. This will create the audio cancellation effect we’re going for by adding interference to the instrumental of the layered tracks, letting the vocals shine through without any background frequencies.

If you hear a muffled backing track with a clean vocal part, then pat yourself on the back because you’ve successfully applied sample inversion! If not, you shouldn’t get discouraged. This technique relies heavily on both tracks being mastered in the same exact way at the same exact tempo and at a high quality bit-rate. Getting all these elements spot on can be difficult, but try using this technique on older tunes for surprising results.

Don't Go Deaf

Waking up after a long gig you find a tiny mosquito has taken up residence in your ear. You can try to get it out, but no amount of prying will shake free this annoyance. The unfortunate fact is, you never will because the high-pitched hum doesn’t actually exist. It’s a very cruel trick your damaged ear hairs are playing on your mind. For most people who experience this disturbing reality, it dissipates after a day, but an unlucky few are left with it for life. For a dramatic and comedic version of this all-too-common tale, check out the movie It’s All Gone Pete Tong.

(cheeky cockney slang for “it’s all gone wrong”). It’s what happens when a famous Ibiza club DJ gets tinnitus and eventually goes deaf from extreme noise levels. Hollywood exaggerations? Well, the average DJ booth is usually around 110 dB. According to industry standards, you should not be exposed to that level of noise for more than 30 minutes at a time before permanent damage can begin to take hold. Got your attention? Well, enough of the gloom and doom. Here is the good news: There is a simple way you can not only save your ears but also significantly clean up your mixes at the same time. All you need to do is let go of those clunky DJ headphones and try out in-ear monitoring.

In the past 20 years, the technology of personal ear monitors has progressed immensely. The quality of sound is now outstanding, and prices are much more accessible to your average performer. In-ears typically range from $100 to $500, and a quality pair of mid-level in-ears without custom molds comes in at around $250. There are many different manufacturers of earphone monitors — or “canal phones” — and two main categories of technology: armature and dynamic. The majority of in-ears are made with armature drivers (developed originally for hi-fidelity hearing aids). Armature drivers provide a detailed, flat picture of sound but tend to lack lower frequencies. To combat that, higher-end models frequently employ several armature drivers in a single ear bud. As many as three drivers connected by crossovers provide a complete sonic picture, which, with a proper seal, can reach down to 10 Hz in some models

Shure, Etymotic and Westone are all strong companies that use armature drivers in models that many different types of performers have. In my tests, dual-driver armatures sounded detailed and precise. They make poorly recorded MP3s painfully obvious and long plane rides seem shorter. The only drawback is the apparent lack of bass in some models. In a club environment, that’s not such a big deal because the subwoofers fill in the missing low end, but for personal listening, some models might be too bright for some people’s taste.

 admit, this concept may require rethinking the way you DJ. Single-earphone cueing is impossible, and it’s impractical to continually put them in and take them out of your ears. But there are several workarounds, including mixers with split cueing and using the waveform displays in some digital-DJ programs to check the phase of a mix. They will all require some patience and a little relearning, but the payoff is worth the effort.

The possibility of almost completely eliminating the noise problem offers a glimmer of hope for many DJs, including myself. I highly encourage you to try out the technology on your own and see if personal ear monitors can help improve and extend the life of your DJ career.

Advantages of Mixing Externally

Audio Routing

Using an external mixer means that you’ve got clear dedicated hardware control and independent outputs for everything imaginable. This means routing to the booth, record outputs, master speakers, and headphone jacks all with clear related volume control.

Controllers tend not to have a dedicated output for everything because of the added complexity and cost they require. These outputs (especially the headphone) can often be quite a bit louder on full-sized mixers due to the fact that they always have full power. Many small controllers, like the Traktor S2, are forced to compromise on output levels due to the fact that they run on USB power alone.

Mixing Control

Dedicated full-size mixing controls on a well designed surface usually beat out controllers (especially some of the smaller ones which compromise performance space for portability). Having proper space between all of the faders and EQ are critical to keeping a good mix and feeling comfortable in the heat of a set. Many mixers, like the Pioneer series, have their own built-in hardware effects that make it really easy to add dynamics and flavor on the fly with complex routing possibilities. One example I love putting an echo post crossfader and then using the fader to cut out the track, leaving a nice echo trail behind. Try to set that up in DJ software!

Integration Possibilities

When mixing externally, the potential for experimentation with FX units and inputs is endless.  Many mixers have a full FX send/return, meaning that the world of dedicated effects hardware is wide open