Jason Donnelly, aka DJ Puzzle has been a working DJ in Chicago for over a decade. He has also worked for Sonic Foundry in Madison and continues to release loop libraries--which are often used by DJs around the country live and in remixes. Donnelly took some time to talk to Gearwire about DJ gear for DJs who spin at different clubs constantly. He says DJs on the move need to balance absolute need with portability.

"The first thing you need are Final Scratch or Serato--both laptop integrated DJ software and hardware," says Donnelly. "Or just the software Traktor DJ. Any of they three of these will fly."

With these a DJ can play, mix and beat-match MP3s with little headache. Headaches can arise from other sources when DJing with MP3s, however. Most notably with the quality of the MP3.

"The thing to do is to make sure you are getting songs from a reliable source." says Donnelly. "Also, if you are a DJ you know the record labels you like and a lot of them are offering digital downloads."

Some of the sources he uses most include Beatport.com and Juno.co.uk, but there are others. The key is knowing you will get high quality downloads. If you are not sure, your mixing skills won't save you. Part of that quality? Mp3 encoding. Donnelly recommends MP3s encoded at a minimum of 320 kb.

"I wouldn't suggest going lower than this," he says. "With 320 kb you are getting close to a CD quality sound."

Other tips for the DJ on the go, running to work different rooms and clubs, seem to be no-brainers. When you are running from one gig to another, however, a DJ may well forget his or her brain. Counting on a club having even basic equipment can sometimes lead to problems--especially in venues where there DJs are not constantly spinning. Imagine a sports bar that has a hip hop night in the off season or a Sunday reggae DJ. One thing to be sure of, if you plan to play vinyl along with your MP3s, is that the club has turntables (and serviceable ones). If you are trying to travel light leaving yours at home is best.

"Also check to see if the club has a three or four-channel mixer because any extra electronics will need to be plugged into the mixer." says Donnelly.

These days there are plenty of other gear possibilities, including CD decks compatible with both data and audio discs. The hottest among these right now, according to Donnelly, is the Pioneer CDJ 1000. Technics also have a model (SL-DZ1200). If you are aiming to go low-cost (for instance if you are just starting out) you might want to go with all-in-one units made by companies like Gemini and Stanton. Gemini, for instance, make a CD and vinyl turntable which allows a DJ to play both discs and vinyl. You can also "scratch" using your CDs.

"When you put a CD in it you can use an encoded vinyl record to scratch the CD," says Donnelly. "There is a time code burned into the vinyl."

Serato and Final Scratch also allow DJs to do this.

Another, expensive, alternative for DJs has been using iPod mixers. One of these (model) allows pitch adjustment. If you are playing dance music or anything where beat matching is essential you will need pitch adjustment.

"You don't want the one (iPod mixer) that just cross fades. Pitch adjustment allows you to match the beats," says Donnelly. "In rock clubs I have seen them use the ones with just the fader because they are not going to mix beats."

But if you are doing more than playing Foreigner after Boston you are probably going to want the option of pitch adjustment.

There are a lot of other types of gear and software available and new worlds open up when you DJ at clubs that have their own top notch gear but this is a good place to start the learning curve for the new DJ on the go.