Under the hood

DVS: playing with timecode vinyl

Any deck can be driven from a turntable. The music comes from the Mac, your hand stays on the record.

What you need: turntables, control vinyl from Serato or Traktor Scratch, and an audio interface with four inputs – input and output on the same device.

In six steps

1. Wire up. Turntable 1 into input 1/2, turntable 2 into input 3/4. A turntable belongs in a phono input, a CD player in line.
2. Choose the device. In Settings → Audio & DVS, pick the same device as output and as timecode input. With two separate devices two clocks run against each other and the timecode jitters – an Aggregate Device in macOS's Audio MIDI Setup joins them. If you choose one of them on a different device, aDJusted asks and moves both together.
3. Set record and speed. Control vinyl Serato (1 kHz carrier) or Traktor Scratch (2 kHz), and 33⅓ or 45 rpm. With the wrong speed a normally running record reads 1.35× – and the decks run too fast.
4. Assign the decks. Input 1/2 plays deck A or C, input 3/4 deck B or D – so the back decks can run from vinyl too. If your interface has only one input pair, it may go to any of the four decks.
5. Check the signal. Each deck's scope should show a steady, round circle (see Reading the scope). If the record plays backwards, “swap channels” fixes reversed RCA cables.
6. Play. Switch the deck from INT to REL or ABS. The choice is kept for each deck across a restart; if aDJusted starts with no timecode input, remembered decks stay on INT until it is chosen again.

Joining two interfaces into one device (aggregate device)

When the timecode comes in on a different interface than the sound goes out on, macOS needs one device covering both – otherwise two clocks count independently, and that is exactly where the jitter comes from. macOS builds such a device itself: the Aggregate Device (in German since macOS 15 “Hauptgerät”).

1. Open Audio MIDI Setup (Applications → Utilities, or via Spotlight) and show the device list on the left.
2. Click + at the bottom left and choose “Create Aggregate Device”.
3. In the list on the right, tick Use for both interfaces – first the one with the phono/line input, then the one for output. The order decides the channel numbers: the inputs of the first ticked interface become channels 1/2, the next one's 3/4. aDJusted reads deck 1 (or C) on 1/2 and deck 2 (or D) on 3/4.
4. Set Clock Source to the interface the turntables are wired to: the timecode sets the beat.
5. Tick Drift Correction for every other interface, but not for the clock source.
6. Put both interfaces on the same sample rate (44.1 or 48 kHz). Mismatched rates are the most common reason an aggregate device clicks.
7. Double-click the aggregate device to give it a name.
8. In aDJusted, under Settings → Audio & DVS, pick that same aggregate device as output and as timecode input.

• A multi-output device is something else: it only fans out outputs and has no inputs at all – useless for DVS.
• An aggregate device rarely runs as tight as a single interface. If one interface can do input and output, it is the better choice.
• Unplug one of the interfaces and it drops out of the aggregate. After plugging it back in, check in Audio MIDI Setup that the tick is still there – otherwise it looks, from inside aDJusted, like a device with no signal.

The three modes

INT

The deck plays from the app as usual.

REL – relative

The record sets speed and direction; where the needle lands does not matter. When the needle runs into the lead-out groove, the deck switches to INT and carries on at the speed the record was turning – the mix holds. Put the needle back at the start of the record with it running and the deck returns to REL by itself, following the record again; put down in the middle, it stays on INT. If aDJusted loses the spot on the record while you scratch and finds it somewhere else, the track carries on without a jump.

ABS – absolute

Like REL, plus the position: drop the needle in the middle of the record and the track jumps there. A knock that throws the needle back a groove does not knock the track out of time. Hold the record and let it go again at the same spot and the track stays where it was – only a needle that lands somewhere else counts as a new position. This needs a position signal on the record – the Serato record has one, the Traktor record does not; then ABS behaves like REL. In ABS nothing jumps at the press of a button: the needle sets the position, so hot cue pads, the CUE button and saved loops trigger no jump. The pads still light up and an empty pad sets a cue; to jump, switch to REL.

Reading the scope

In Settings → Audio & DVS every deck shows its timecode signal as a circle. The radius is the level, the roundness the quality. Aim for close to 100 % – below 85 % you may run into trouble.

Fine-tuning: the noise threshold (−48 dB by default) sets the level from which anything counts as signal; “Estimate” sets it 12 dB above your setup's noise floor while the record stands still. L/R balance (±6 dB) turns an ellipse back into a circle when the channels are unevenly loud. Buffer: In Settings → Audio the buffer size can be chosen per audio device – smaller means less time between record and sound and more load; if it crackles, go one size up.

Measured delay

Measured on 23 October 2026 on a Pioneer DJM-S11 over USB, from the timecode at the input to the sound at the output: 11.5 ms with a buffer of 64 frames, 14.7 ms at 128 and 29.7 ms at 512 – the size macOS usually sets. About 4 ms of that is aDJusted itself; the rest is the buffer and the way through the mixer. Another mixer and another Mac come to other numbers, and a small buffer wants room: with keylock and stems, rather 128 frames or more.

Stems

aDJusted splits a track into drums, bass, vocals and everything else – on your Mac's own graphics chip, with no internet connection and no upload.

Time

On M2 or newer about a quarter of the playing time – roughly a minute and a half for five minutes of music. The first track after launch takes nearly twice as long.

On load

Out of the box a track is separated when you load it. Playback starts straight away; the stem pads light up once the separation is done.

Echo when switched off

A stem you switch off with MUTE plays on for 0.8 seconds and then dies away in an eighth-note echo – no hard cut in the middle of a bar. It can be turned off per stem in Settings → "Stems: echo when switched off"; solo always cuts the others at once.

Thoroughness

Thorough (the default), Balanced (about 8 % faster) or Fast (about 14 % faster) – in Settings → Library.

Cache

Separated parts are stored on the Mac, losslessly compressed, at about 40 MB per minute of audio. The limit ranges from 10 GB to unlimited, 50 GB by default; when it is reached, what has not been played for longest goes first.

MIDI controllers

Any MIDI controller can be taught to aDJusted. For many of them the app brings a ready-made mapping.

Mappings that come with the app

On first launch aDJusted asks which devices you want mappings for, with the one that is plugged in already ticked. Later, the same list is under Settings → Controller. What you have taught at the device is never overwritten without asking.

Mapping wizard

Walks you through every action one by one, with a “Learn” button and a live preview of the value the controller is sending. Single controls are quicker to fix straight in the list.

Bluetooth controllers

From aDJusted 0.6.4 you can pair controllers that send MIDI over Bluetooth – such as the Numark Mixtrack Go: put the controller in Bluetooth mode, click “Connect Bluetooth controller …” in Settings → Controller and pick the device. Once paired it behaves as over USB and uses the same mapping. Bluetooth carries the controls only, no sound. The sound comes through the audio device set in Settings → Audio & DVS – another controller, the Mac itself or an external sound card.

Schema

A clickable picture of the controller: click a control, see its actions and the MIDI address it learned, teach it again. A green line means taught.

Passing it on

A mapping is a single file. “Save to the Downloads folder”, then “Load …” on the second Mac – or send it to us, and we ship it with the next update for everyone with that device.

Controller displays are not supported yet. The protocols that drive jog wheel and browser displays are only made available by the makers to their official hardware partners. We have reached out to the makers so that aDJusted can drive these displays officially in future. Buttons, knobs, faders and jog wheels work over MIDI as usual regardless.