1. In order to fully capitalise on the potentially mind-blowing shock value of jamming two incongruent tracks together, there's got to be some kind of contrast between them. For example, The Prodigy and Rage Against the Machine may seem like ideal candidates for a mash-up, but surely The Prodigy vs Katie Melua is a more cunning partnership? Also, avoid using overused tracks, such as Public Enemy's Rebel Without a Pause, for example.
2. Though it's possible to create bootlegs and mash-ups with any sequencer, some have particular features that make them ideal for the task. In particular, Ableton Live and Sony Acid Pro are perfect for syncing tracks that need to be timestretched in order to work at the same tempo. If your sequencer doesn't have any audio warping features, you'll find syncing tracks a tedious undertaking: check out the Live demo at the Ableton website for a less time-consuming alternative.
3. Try to think outside the box (or DJ booth) when looking for source material - many club smashes take non dance-based material (eg, Gary Numan's Cars sampled on Armand Van Helden's Koochy). See what old gems you can dig up in local charity shops - the seven-inches you pick up may be in poor condition, but if a track works particularly well and an individual element requires re-sampling, you should be able to find a CD of the required track.
4. Even with these labour-saving software packages, getting each track properly beat-mapped can take a while. If you're doing a lot of mash-ups, you may find it's easier to Acidize or save Live information for a selection of tracks before you begin the audition process. This will enable you to quickly see which tracks work together, without having to go through the beat-mapping process between each one.
5. In order to get the best sound quality possible, consider ripping tracks from CD directly, rather than downloading MP3s (or other compressed formats) from the internet. CD quality audio is preferable to MP3 as it hasn't been compressed, a process which can distort a track's top-end, and muddy up its bottom.
6. Records are another viable sound source, though samples taken from vinyl can suffer from tempo drift. When this occurs it confuses automatic tempo detection tools, which don't compensate for the uneven speed of the turntable. One way to circumvent this problem is to chop your track into several sections of the same number of bars in length, then load them into Acid to set them to exactly the same tempo. When exported, this will create a single file with a more reliable tempo.
7. If you have a large collection of instrumentals and acappellas, organise them in folders by key and tempo to make auditioning new elements a piece of cake.
8. As well as getting your chosen tracks in time, it's also important to get them in tune. In an ideal world your source material will all be in the same key, but if it isn't, transposition is something you may need to consider. Extreme pitchshifting is not recommended, as unnecessary processing can make a vocal or instrumental sound unnatural and nasty. As a general rule, try to avoid transposing anything more than a couple of semitones - the more you transpose, the more you interfere with the original sample's feel.
9. A good source of sample-able material is stuff from the early stereo years. Back then producers were just getting to grips with the new format, and many took it to the extreme by panning certain parts hard left or right. This separation makes is easy to pilfer instrument, vocal or drum parts - if you have any old vinyl lying around listen to it on your headphones to discover any potential samples.
10. Making sure acappella vocal files are in time with the rest of your track can be a real pain, but Acid Pro's beat-mapping features can make this a lot easier. First, beat-map the full version of the track, preferably with the downbeat marker placed on a beat with a vocal. Now repeat the process on the acappella version of the track - simply copying the offset and tempo settings from the Stretch tab in the Track Properties inspector.
11. A question often asked by novice bootleggers is how to isolate the vocal from the full mix of a track. While there are several so-called 'vocal removal' plug-ins available on the internet, none of them deliver perfect results. However, there are plenty of ways to get your hands on acappella tracks via the internet - check out the official Beastie Boys acappellas page, for example.
12. If you find that your chosen acappella is a little off-key, try putting this right using your sequencer's built-in pitchshift function. However, if only certain notes need changing, pitch correction software such as Melodyne (demo available from Celemony Software's website) will do the trick. If you can't afford this dedicated tool, you could cut any offending notes out in your sequencer and pitchshift them separately, though this is a much more time-consuming process.
13. Vocal sounding muddy or indistinct compared to the rest of the track? A mid-cut or high-boost EQ on the acappella will help bring it out, but don't change the sound any more than necessary - extreme EQ settings will make the vocal sound unnatural. The same goes for effects and other processing; err on the side of caution to keep each element as clear and intelligible as possible.
14. If you can get your tracks in sync and in something approaching the right key, then you're pretty much sorted as the arrangement can be altered as you see fit. For example, it's possible to extend or curtail an instrumental section to fit with a vocal's arrangement. You can also forge extended breakdowns or build-ups to create a more dance-floor friendly track should you wish.
15. Avoid using too many disparate elements and conflicting melodies - mash-ups work best when the melody of the vocal fits with the chord progression of the backing track. If you have multiple melodies playing at the same time the results are likely to be a confusing mess. Remember, with digital technology you're free to re-edit tracks at will, so include everything you want - just not at the same time.
16. When it comes to adding a bit of processing to a mash-up track, the most important tool is without a doubt equalisation. EQ should be used to make the tracks sit together comfortably - you may find easing up on the bottom or top end of a track will help it sit much better with another track. Don't go too over the top - if your processing is too extreme you'll end up taking away from the feel of a track. Instead, try to get it so that both tracks sound like they're being played in the same space. If one of the tracks you're using has been sampled from vinyl, you may find that a low-frequency (around 50Hz) high-pass filter cuts out any unwanted bass rumble.
17. If you're attempting to make a big dance-floor anthem but your track doesn't have the necessary bottom end, try sampling a rhythm part from another, more dance-based track. If more bass is what you need, try downloading a MIDI file of a song you're using and play the bass part through a soft synth to beef things up. MIDI files can be found on the internet through sites such as MusicRobot.
18. As well as getting your tracks in key and in time, take a little time to check the level of the vocals - if they're too quiet, people may not be able to make them out.
19. When using effects on full tracks, you may find the bass frequencies become indistinct, or too much stereo information is added to the signal. These problems can be remedied by adding a high-pass filter or EQ to your effect channel to tame the bass frequencies, and using an effect such as dfx monomaker to control the stereo panorama.
20. Non-sequenced tracks with loose live playing can be another bootlegging nightmare, but if you have a sequencer with audio quantisation or warping features, such as Live or Cubase, you can manually adjust the timing of the track yourself. Getting the timing as close to your sequencer's metronome as possible is a good idea if you intend to use the
track in a DJ set - rogue beats can make a track sound like it's being mixed badly.
21. If you're attempting to mix together two tracks with uncomplimentary basslines, you can use a high-pass filter to cut the bass part out of one of the tracks. Should a filter sound too extreme, a more subtle effect can be achieved via EQ.
22. When attempting to mix two tracks with a severe tempo difference (a 90bpm hip-hop track with a 175bpm drum 'n' bass track, for example), try to see if you can get the slower track to work at half the tempo of the faster track rather than full speed. This can cause some unusual polyrhythms if you're using two full tracks, but if you have an instrumental and an acappella this won't be a problem.