BPM Sync vs Beat Sync: The Real Differences.

BPM Sync vs Beat Sync: The Real Differences

Two Names with Different Meanings

The problem starts with vocabulary. “Sync” describes two behaviours that feel very different in practice:

• Matching tempo: both tracks run at the same speed.
• Matching phase: their beats also land together.

A mode doing the first without the second leaves tracks at the same speed but misplaced. A mode doing both keeps them together.

Both are legitimate and useful. The choice is between delegating more and retaining control. Choosing a mode determines how much you automate and how much you can correct manually.

What Each Mode Matches

Complete mode: tempo and phase. In rekordbox, this is BEAT SYNC, with a precise official definition: BPM and beat positions of the playing track can automatically synchronise with the master-deck track. In Traktor, BeatSync documentation describes a mode that always maintains tempo and phase between decks: through scratching or beat jumps, playback stays synchronised to the master deck’s beat.

Partial mode: tempo only. Traktor calls it TempoSync, precisely defined as fixing tempo but not phase. Transport operations, such as scratching and jumps, can introduce beat offsets. When that happens, the sync button changes appearance and the phase meter shows displacement. rekordbox’s equivalent is BPM SYNC, selected in preferences as the sync type.

Phase Is the Difference You Hear

If you retain one idea, make it this: phase separates sounding together from sounding misplaced.

Two tracks at exactly 128 BPM can sound wrong. Tempo matches and the mental metronome fits, yet kicks do not land together. The ear immediately hears that offset as “these are not locked”. Matching tempo does not fix it; phase needs alignment.

The most useful functional difference, noticeable in the booth:

• Tempo-only mode lets you correct phase manually. Traktor documentation explicitly says TempoSync always permits phase pitch bend during playback, which BeatSync does not because it ties phase to the grid rather than the beat.
• Tempo-and-phase mode needs no phase correction. The system maintains it, making it the safest live mode with loops, jumps or scratching.

Partial mode is more manual rather than worse. It lets you decide phase; in exchange, losing attention allows audible phase drift.

The Actual Names in Each Program

Tutorials confuse this most because the same concepts use three vocabularies according to product and version:

• rekordbox officially distinguishes BEAT SYNC and BPM SYNC, selected in preferences. It does not call between-deck sync “Tempo Sync”.
• Traktor distinguishes BeatSync and TempoSync, selected in transport preferences.
• Programs name the reference deck differently: sync master in rekordbox, Tempo Master in Traktor, with a central Master Clock.

One warning avoids pointless arguments: “Tempo Sync” belongs to Traktor, not rekordbox. Someone saying “enable Tempo Sync in rekordbox” is mistranslating or mixing programs. Conversely, Traktor will not present “BPM SYNC” under that name.

A Note on Source Precision

Be exact here: guides often attribute words to rekordbox that are absent from its manual.

rekordbox documents the existence and names of both types, that BEAT SYNC synchronises BPM and beat positions with the master deck, and that BPM SYNC is used in specific contexts: the sampler, whose playback starts at the master track’s BPM, and automatic switching for inconsistent-BPM tracks.

The rekordbox manual does not contain a sentence contrasting the modes in phase terms, such as “BPM Sync matches only tempo, not phase”. Traktor’s manual explicitly states that contrast, using its own names. The concept and practical conclusion hold, but one brand should not be credited with another’s wording. When explaining this, identify which product says what.

Which to Use in Each Situation

There is no universal answer, but clear criteria exist:

Use complete mode, tempo and phase, when:

• playing live with Hot Cues, loops or Beat Jump, because it maintains lock through transport operations;
• wanting the mix to hold without constant attention, for example while preparing the next track;
• your beatgrid is corrected and trusted.

Use partial mode, tempo only, when:

• wanting to correct phase manually with pitch bend during playback, which complete mode does not allow;
• practising beatmatching, with the machine matching speed but leaving alignment to you;
• working with tracks where you do not want the machine imposing phase from a doubtful grid.

A cautious rule: when unsure, use complete mode. In the booth, maintaining phase prevents the most audible failure, misplaced beats, while you handle other tasks.

The Inconsistent-BPM Case

One documented situation takes the choice out of your hands: inconsistent-BPM tracks. rekordbox describes an option that, when using beat synchronisation with such a track, automatically switches BEAT SYNC to BPM SYNC to link mix points. If disabled, link synchronisation may be released on those tracks.

A reasonable interpretation is that forcing phase on a non-constant-tempo track is counterproductive, so the system falls back to tempo-only mode. Documentation describes behaviour rather than the reason: treat this as the author’s interpretation, not an official explanation.

A related rekordbox control is SYNC RATE, setting synchronised BPM to the original, double or half. Values cycle x1 → x2 → x1/2, and documentation states that x2 is skipped if doubling exceeds +100% tempo. This mixes tracks intentionally at half or double tempo.

Sync with DVS

With DVS, the turntable or CDJ dictates tempo and position through control tone, while sync uses the same beatgrid. Differences from a controller setup:

• Playback modes. Serato documents three: ABS follows absolute track position and is necessary to use the player’s own cues and loops; REL ignores absolute position, is recommended for CD players and offers more software functions; INT is for HID or controllers. The mode determines which transport you control in hardware and which the software handles.
• Control tone must arrive clean. Documentation is firm: the player’s keylock (Master Tempo) and effects must be disabled, because the control tone must reach software unchanged except for pitch. Use software keylock if needed.
• Smart Sync with DVS does exist. Serato states it is available with DVS enabled from version 1.9.6. The requirement remains correct beatgrids; without a grid, there is no beat synchronisation.
• Drift can come from timecode. Correct calibration can still leave natural BPM fluctuation, called BPM flutter. Serato’s Anti-Drift removes it: in CD/Vinyl preferences, off by default, available since 1.9.6. It corrects signal drift rather than mix drift.
• Calibrate every session. Documentation recommends calibration every time you play: stylus on the record, player stopped and background music at performance volume.

These sources do not cover how specific rekordbox or Traktor sync modes behave under DVS. If that is your combination, check your own setup rather than assuming the behaviour documented here.

Common Mistakes

Believing Both Modes Do the Same Thing. Phase distinguishes them, and phase is precisely what you hear in a mix.

Searching for “Tempo Sync” in rekordbox. That is Traktor’s name. rekordbox calls the equivalent mode BPM SYNC.

Attributing Traktor’s “Tempo Only” Contrast to rekordbox. The concept holds, but the wording belongs to another brand. Cite what each manual says.

Using Partial Mode and Expecting No Misalignment. Its function is tempo locking; phase is your responsibility. Failure to correct it is audible.

Using Complete Mode with a Doubtful Grid. It uses the grid and inherits its error, aligning phase against a false reference. Documentation itself warns that correctly placed grids are required.

Starting Beatmatching Practice with Complete Mode Enabled. It solves precisely what you want to learn. Partial mode is the more honest practice choice.