Smart song selection and tight beat matching for smooth segues between songs are the core skills that every DJ must master. But after you have these essential skills under your belt, it's a wise idea to begin exploring other ways to enhance your live mixes so that you can stand out from the crowd of amateur DJs vying for fame and gigs. An innovative way to bring another dimension to your mixes is by employing MIDI instruments to add loops and sequences over the songs you're spinning. With a bit of planning, you can design a system that will let you to drop these elements into your mixes in beat and with minimal effort.
At the heart of such a system must be a master MIDI Clock source, a central timing device that any number of MIDI slave devices will follow. For example, your favorite groove box could be the master for a drum machine and a digital audio sequencer program running on a laptop computer. To connect these units, you'll need three MIDI cables and a MIDI splitter box, such as M-Audio's Thru 1×4. (A MIDI splitter guarantees that the MIDI Clock passes cleanly to the slave devices, because most MIDI instruments do not pass incoming MIDI Clock to their MIDI Thru ports untouched.) Connect the MIDI output of the groove box to the input of the splitter, and from the splitter, take a MIDI output to each slave device. (You'll need a USB-to-MIDI interface for the laptop, such as M-Audio's USB Uno.) Make sure that the groove box is set to output MIDI Clock, and set the drum machine's sequencer and the software program to receive external MIDI Clock. Now, when you adjust the groove box's tempo, the slave devices will keep time.
There are two basic methods of matching your master device's tempo to the beat of the song you're spinning: manually via a tap tempo key or automatically using an audio-to-bpm converter (also called auto bpm detection). To use tap tempo, you tap on a key to set the sequencer's tempo — it's as simple as that. If your timing is halfway decent, you'll be able to get a good beat match in no time flat. If your timing is a bit off, your beats will drift, but this can be corrected easily by simply tapping a few well-timed downbeats. Lots of groove boxes have a dedicated tap tempo key, such as Korg's Electribe units or Roland's classic MC series. Many of today's cutting-edge music software programs also have a tap feature, such as Ableton Live and Digidesign Pro Tools.
An audio-to-bpm converter can “listen” to a song's groove and calculate a tempo based on the time between the most prominent beats (which are hopefully the downbeats). Automatic beat detection works best with simple four-on-the-floor grooves and is rarely able to determine a tempo from more complex rhythms (such as busy drum 'n' bass grooves). To integrate a converter into your setup, take a feed from your DJ mixer, such as a zone output, and plug it into the converter's audio input jack. (Avoid sending the converter audio from its own slave device, such as when a slave device's channel is open and the converter is calculating bpm, as this will produce inaccurate results.) The converter's MIDI Output should go to the input of your MIDI splitter. When the converter sees audio, it will calculate a tempo and output MIDI Clock. Check out Korg's EMX-1, a groove box with a built-in converter.
A converter is nice because when it reads the beat correctly, slaved sequencers can stay in beat for long periods with little manual tempo correction. However, because the converter's success depends on what you're playing — and you obviously don't want to restrict your selections to purely four-on-the-floor grooves — a combination of the converter with the tap-tempo method will give you the best results. The EMX-1 lets you switch easily between tapping the tempo and auto bpm detection modes.
CUE IT UP
Connect the stereo outs of each MIDI device to its own channel on your DJ mixer so that the output from each MIDI instrument can be treated just like program material. For a device that has more than one stereo output, group similar types of sounds to each output. For example, assign percussion loops to outputs 1 and 2 and bass sequences to outputs 3 and 4. To connect all of these inputs, you'll need a DJ mixer that can handle at least four simultaneous inputs (such as the Tascam X-9). Having your inputs organized so that each channel is receiving a category of sounds (such as drum loops, percussion parts and synth effects) helps reduce hunting and pecking time and makes headphone cueing a simple affair.
When selecting a loop or sequence for your mix, watch out for pitched parts that will clash with your song's key. If you're unsure about your harmonic mixing skills, stick with loops and sequences that aren't in a key, such as percussion and sound effects. If you have a great ear for matching pitches, you can try writing your parts on the fly using a groove box's step sequencer. However, if programming isn't your thing and you're worried about having enough elements to work with, remember that most groove boxes come with bunches of stock sequences that are easily modified to fit just about any style. For example, if you like a stock sequence's percussion performance but nothing else, just mute the other parts.
The key to synchronizing multiple MIDI instruments to your turntables is to keep your setup manageable. A master clock device and one or two slave units will generally be plenty to handle. You never want so many things to deal with that it interferes with your ability to make good song selections or pay attention to your audience.