Idea

From Turntable to Controller

A DJ deck was once one machine: the groove held the sound and the platter was the control. Fifty years of step changes pulled those two jobs apart, moved the sound engine into a laptop, and are now putting it back in the box.

Overview

Every DJ setup does two jobs. One is control: the surface a pair of hands touches to start, stop, nudge, scratch and blend. The other is the sound engine: the thing that holds the audio, plays it at the chosen speed and sends it to the mixer. On a turntable the two are the same object. The groove is the audio and the platter is the transport, so a hand on the record moves the sound directly.

The history of DJ gear can be told as a series of step changes in where those two jobs live. Direct-drive turntables made the platter strong enough to be played like an instrument. CD decks put the audio into memory and gave the hand a jog wheel that only reports motion. Timecode vinyl turned the record itself into a control signal for a computer, which held the real audio. MIDI and HID controllers dropped the media altogether and became pure control surfaces. Standalone players and all-in-one units then pulled the engine back into the hardware, now a small computer with a screen.

The thread running through all of it is a single question: who holds the audio buffer? Whatever answers that is the deck, wherever the hands happen to be.

In context

DJing began as radio. Playing records on air was common by the 1930s, and the word "disc jockey" is usually credited to the columnist Walter Winchell, describing the New York announcer Martin Block, whose Make Believe Ballroom began in 1935.1 Club DJing came later, and with it the idea of the DJ as a performer who joins records together rather than introducing them one by one.

Each later step reshaped what the DJ could do with the hands. Pitch control made beatmatching possible. A strong motor made scratching possible. Cue points and loops on CD decks made exact repetition easy. Timecode let a vinyl player use a hard drive full of files. Software brought sync, effects and, most recently, stems, where a single track can be pulled apart into vocals, drums, bass and the rest while it plays.

The deck over time
  1. 1972 Technics SL-1200 A direct-drive turntable that became the club and hip-hop standard.
  2. 1994 Pioneer CDJ-500 Pioneer's first CD player for DJs.
  3. 2004 Serato Scratch Live Timecode vinyl as a controller for a laptop engine.
  4. 2010 Traktor Kontrol S4 An all-in-one controller with no audio engine of its own.
  5. 2019 Denon DJ Prime 4 A four-deck standalone system: the engine back in the box.

Research

The sections below take the step changes in order, after a closer look at the split itself. Dates for DJ products are often misreported, even by manufacturers, so where sources disagree the disagreement is noted.

Controller and sound engine

A sound engine is the part that has the audio. It reads a file or a disc, decodes it into a stream of samples, keeps a short stretch of those samples in a buffer, and plays them out at whatever rate the deck is set to, bending pitch or stretching time as needed. A controller is the part that tells the engine what to do. In a modern rig the two can sit in the same box, in two boxes joined by a cable, or in a box and a phone.

Latency. Whenever control and engine are separate, a gesture has to travel. On a turntable the needle reads the groove under the hand, so there is nothing to wait for. In software, the main delay is the audio buffer: the engine fills a block of samples ahead of time, and a change only reaches the speakers once the next block plays. The Mixxx manual notes that a buffer of 23 to 64 milliseconds is fine for a keyboard, mouse or controller, while vinyl control wants less than 10.2 Smaller buffers need a faster computer and a better audio interface.2

Deep Dive: Latency and buffers

A buffer is a queue of samples waiting to be played, and its length in time is its size divided by the sample rate.3 At 44,100 samples a second, a buffer of 1,024 samples lasts about 23 milliseconds, 512 samples about 11.6, 256 samples about 5.8 and 128 samples about 2.9. The 23 milliseconds in the Mixxx manual's example is the first of these. The engine has to compute each block before the one in front of it runs out. If it is late, the sound card has nothing to play and the listener hears a click or a gap, which Mixxx counts as a buffer underflow.2 Small buffers leave the computer less time per block, so every heavy job in the engine, above all time-stretching to keep the key steady while the tempo moves, has to finish faster. The Mixxx manual advises testing a new setting for at least 30 minutes before playing out, since the glitches can be rare and irregular, and suggests a larger buffer, a lower sample rate, a different sound driver or a different time-stretching engine when they appear.2

The buffer is only one stage of the delay. A move on a controller first has to cross USB and the operating system, then wait for the next block the engine starts, then pass through that block and the sound card's output buffer and converter. The Mixxx manual says outright that real latency is longer than the buffer figure, and that routing audio through PulseAudio on Linux adds roughly two buffers more.2 The sound driver matters for the same reason. On Windows the manual rates ASIO and WDM-KS as good and DirectSound and MME as poor; on a Mac, Core Audio is the only choice.2

The controller adds its own small share. A HID device on full-speed USB is polled at most once a millisecond, so a wheel movement can wait up to a millisecond before the computer even sees it.4 A message on a classic MIDI cable takes close to a millisecond to send, and messages queue behind each other when many controls move at once.5 Neither number is large next to a buffer, but both vary from one gesture to the next, and variation is the part players notice. Added up, the path from hand to speaker is always longer than the buffer setting suggests.

Timecode vinyl doubles the chain. The control signal has to come in through an input buffer, be decoded, move the track, and go back out through an output buffer before the hand hears the result. That is why Mixxx asks for under 10 milliseconds when a record is the controller and warns that higher settings distort the sound of scratches.26

How much delay is too much? A common target in the instrument-building world comes from David Wessel and Matthew Wright, who suggested in 2002 that a digital instrument should respond in under 10 milliseconds, with less than a millisecond of variation, or jitter.7 Robert Jack, Tony Stockman and Andrew McPherson tested that guideline in 2016 with musicians playing a percussive instrument. Players rated a steady 10 milliseconds about the same as no delay at all, but they rated 20 milliseconds lower, and they rated 10 milliseconds with three milliseconds of jitter as low as 20. Their timing accuracy hardly changed. What changed was how the instrument felt.7 For a DJ the lesson is that a steady delay can be learned and an unsteady one cannot.

Some delay is unavoidable even with no computer at all. Sound travels about 343 meters a second in room air, so a monitor speaker three meters away arrives almost nine milliseconds after the signal leaves it.8 A DJ already plays through that much delay in a booth. A turntable shares the room's delay with every other rig. What it avoids is the extra wait between the hand and the signal, and a digital rig spends much of its design effort keeping that wait short and even.

Clocking. Digital audio runs on a sample clock in the audio interface, 44,100 or 48,000 ticks a second. A standalone player has one clock for everything. A laptop rig has the interface's clock for the audio and a separate stream of USB messages for the controls, which arrive whenever they arrive. MIDI over USB has no guaranteed timing, so a controller has to work out wheel speed on its own side and send the result.9

Deep Dive: Where the clock lives

Every digital audio device keeps time with its own crystal, and no two crystals run at exactly the same rate. Software that uses two sound cards at once has to pick one to lead. Mixxx lets the main output interface drive the engine and asks the user to choose how the others follow, since two free-running clocks will slowly overfill one buffer and starve the other.2 Following the clock through each kind of rig shows where the deck really is.

Turntable. On a turntable the clock is the motor. The SL-1200MK2 held its platter speed against a quartz oscillator, and its pitch slider moved that speed by up to 8 percent either way without leaving quartz control.10 The signal leaving the cartridge is analog and has no sample clock at all until a mixer, recorder or sound card samples it. Two turntables in a booth drift apart only as their records and the DJ's hands make them, and the DJ corrects that drift by ear.

CD deck. A CD deck brings its own crystal, its own buffer and its own converter. Two CD decks in a booth are two separate clocks feeding a mixer, and they are beatmatched by ear like turntables. Networking changed this in part. Pioneer's Pro DJ Link let one player act as the master, and from the CDJ-2000nexus of 2012 a Beat Sync button snapped other players to its tempo and beat, using beat grids prepared in rekordbox.11 Each player still makes its own sound on its own clock, and the network shares only the beat.

Laptop and controller. In a laptop rig the clock that matters is in the audio interface. When that interface is built into a controller, as on the Traktor Kontrol S4, the controller holds the master clock even though the engine runs on the laptop. Over USB there are two ways to arrange this. In adaptive mode the interface adjusts its own clock to follow the stream the computer sends; in asynchronous mode the interface keeps a fixed clock and tells the computer how much data to send next.12 Either way the controls and the audio take different paths. Button and wheel messages arrive on their own schedule and are applied at the next buffer boundary, which is the jitter the MIDI and HID designers fight.

Timecode. A timecode rig solves this in a neat way. The control signal comes in as audio, sampled by the same interface on the same clock as the music going out, so control and sound share one timebase even though the engine is in the computer.13

Standalone. A standalone player or all-in-one has one clock for its controls, its engine and its outputs, which removes a whole class of timing problems at once.

Network. The newest arrangement gives up on a shared sample clock altogether. Ableton Link, released in 2016, keeps a shared beat timeline across devices on a local network. Any participant can change the tempo, there is no master, and devices agree on where the bar starts while each keeps running on its own audio clock.14 It is the logic of Beat Sync made open: share the beat, keep the samples local.

Step by step, the deck lives here:

  • Turntable and vinyl: control and engine are one object. The audio lives in the groove.
  • CD deck: the engine is inside the deck. The disc is read into memory and the jog wheel is a sensor.
  • CD deck in HID mode: the same deck becomes a controller. From 2009 a CDJ-900 could drive Serato over HID, with the engine in the laptop.15
  • Timecode vinyl or timecode CD: the deck plays a control signal. The engine is in the computer.
  • MIDI or HID controller: no media at all. The engine is in the computer, and sometimes the audio interface is in the controller.
  • Standalone player or all-in-one: the engine is back in the hardware, reading prepared files from USB or streams from the internet.
  • Phone or tablet: the screen is the controller and the engine is in the same device.

Why timecode felt like vinyl. A timecode record sends its control as audio. The computer reads it through the same interface, on the same sample clock, as continuous signal instead of occasional messages. Every tiny change in hand speed comes through, sample by sample, which is why scratch DJs accepted timecode years before they accepted jog wheels. The engine decodes speed, direction and position from the signal and moves the real track to match.13

Deep Dive: How a timecode record is read

A timecode record carries a steady tone in place of music. Serato's runs at 1,000 cycles a second, Final Scratch used 1,200 and Traktor's later vinyl 2,000.13 The right channel is a phase-shifted copy of the left, so the order in which the two channels cross zero gives the direction of travel. The speed of the tone against its normal frequency gives the playback speed.1613 If the software hears Serato's tone at 1,100 cycles a second, the record is running 10 percent fast; if the right channel suddenly leads instead of following, the hand has pulled the record back.

Position is written into the tone as a stream of bits: a high peak counts as a one, a low peak as a zero.1613 The decoder reads the left channel's height each time the right channel crosses zero from positive to negative, and compares it with a threshold.13 When the needle drops, the software has to read enough bits to know where it landed. Serato uses a sequence in which any 20 bits in a row are unique, so it can locate the needle after 20 cycles.13 The sequence comes from a 20-bit linear feedback shift register, a simple circuit that steps through 1,048,575 states before repeating. A record side of 980 seconds at 1,000 cycles a second needs 980,000 bits, which a 19-bit register could not supply and a 20-bit register just can.13 Final Scratch took a plainer route. It marked each position with the start pattern 0001 followed by 16 position bits, so the software needed at least 20 bits and as many as 39 to find its place after a drop.13 The Mixxx developers recovered Serato's sequence from recordings with the Berlekamp–Massey algorithm, which finds the shortest shift register that produces a given bit stream.13

A faster tone carries more bits a second and finds its place sooner, but it has to stay below half the audio sample rate; at 44.1 kHz that caps Serato's code at about 22 times normal speed and Traktor's at about 11.13 Below normal speed the trade runs the other way. At a tenth of normal speed Serato's tone drops to 100 cycles a second, so position takes ten times as long to confirm, while direction and speed still update every cycle.

Modes. DJ software gives the DJ a choice of how much of this to trust. In absolute mode the track follows both speed and position, so dropping the needle halfway through the record jumps halfway through the track, just as with real vinyl. In relative mode the software listens only to speed and direction, which frees cue points and loops at the cost of needle drops. Mixxx adds a constant mode that keeps the track playing when the needle runs off the end of the control record; Serato's version, internal mode, switches on automatically at the end of the record and hands playback to the software.617 Serato also offers a needle-drop option in relative mode that tells a deliberate move of the arm from an accidental skip and moves the playhead only for the first.17

Dust and level. Dust matters. The original Final Scratch code had little error checking, so a scratch on the record could make a stretch of timecode unreadable.16 Signal level matters more. The Mixxx manual calls it the most important factor: too loud or too quiet, and the position bits are lost, so absolute mode quietly behaves like relative mode.6 Mixxx draws the incoming signal as a ring, a round green "doughnut" when the two channels are healthy, shading to orange and red as they degrade. It also lets the DJ set a lead-in of 20 seconds or more where timecode is ignored, which makes it easier to back-cue the first beat and moves the track's start onto groove that has not been worn by thousands of cues.6

The open-source Mixxx project reads timecode with the decoder from xwax, another free DVS program.13 Its manual recommends Serato's control vinyl for new buyers, lists Traktor's first timecode as limited at high speeds, and notes that Traktor's second version, sold since 2011, is not yet supported.6

What HID gives over MIDI. MIDI was designed in the early 1980s to connect synthesizers, and its basic control values have 128 steps.1819 A typical early DJ controller sent a jog wheel as one relative MIDI message carrying direction and speed, which allowed only 63 speed steps each way.9 HID, the USB class used for keyboards and game controllers, lets a device report its whole state as a block of data. A 2012 DJ TechTools comparison described a Native Instruments controller reporting 10-bit wheel position every millisecond, leaving the computer to work out speed far more precisely.9 VirtualDJ's developer notes call HID much better than MIDI for high-resolution scratch wheels.20 The cost is portability: MIDI works with almost any software once mapped, while HID needs support written for each device in each program.9

Deep Dive: MIDI and HID by the numbers

The MIDI wire. MIDI 1.0 was a serial link running at 31,250 bits a second. Each byte travels with a start bit and a stop bit, ten bits in all, so a byte takes 320 microseconds.5 A control change, the message most DJ controllers send, is three bytes: a status byte naming the kind of message and the channel, a byte naming the control, and a byte for its value. On a classic five-pin cable that is close to a millisecond per message, and every knob, fader and button on the cable shares the same thousand or so messages a second. Each data byte gives up its top bit to mark it as data, which is where the 128 steps come from: values run from 0 to 127.5

MIDI already had a way past 128. Controllers 0 to 31 can be paired with controllers 32 to 63 as a most and least significant half, giving 16,384 steps, but the pairing was rarely implemented and receivers could not always tell whether a sender was using it.21 Most DJ controllers stayed with plain 7-bit values, which is why a jog wheel sent as a single relative message gets 63 speeds in each direction: one value in the middle means stopped, and the rest are split between forward and back. The same DJ TechTools comparison counted the cost of buttons as well. In MIDI, sixteen buttons pressed at once are 48 bytes of messages.9

MIDI over USB. USB removed the cable's speed limit but kept MIDI's message format and gave no guarantee of when a message would arrive.9 A controller that measures its wheel and sends a speed is doing its own physics, at its own resolution, and the computer can only trust the result.

HID. A HID device does the opposite. It sends a fixed-format report describing its whole state, and the host collects reports at a fixed rate. On a full-speed USB device the polling interval is counted in 1-millisecond frames, so the fastest rate is a report every millisecond, a thousand a second; high-speed USB counts in 125-microsecond microframes.4 The Native Instruments Traktor Kontrol S2 used this to report its wheel as a 10-bit relative position every millisecond, and the computer worked out speed from successive reports.9 A HID report is also compact. Sixteen buttons fit in two bytes, and Native Instruments' X1 described 34 buttons, eight knobs and four encoders in 24 bytes.9 Because the samples come at fixed intervals, the software knows exactly how much time passed between two wheel readings, and that is what makes HID scratching smooth.

The price is the one already noted: a HID device speaks its maker's private report format, and each program has to be taught it. VirtualDJ publishes notes for developers mapping HID devices, and Mixxx supports both HID and MIDI controllers, along with timecode.2013 CD players joined the same scheme in 2009, when the CDJ-900 could drive Serato over HID.15

MIDI 2.0. The MIDI Manufacturers Association adopted MIDI 2.0 at the NAMM show in January 2020. Its Universal MIDI Packet carries messages 32, 64, 96 or 128 bits long, with much higher-resolution controller messages, and devices negotiate the new features through MIDI Capability Inquiry, falling back to MIDI 1.0 when the other side does not understand them.22 On paper, that closes much of the gap HID filled for DJ wheels.

Two ways to describe a wheel. The difference comes down to who does the physics. A MIDI wheel interprets its own motion and reports a conclusion, such as "turning forward, speed 12." A HID wheel reports its position at fixed moments and leaves the interpretation to the engine. The second is closer to timecode, which reports a continuous signal on the audio clock, and to the turntable, where the engine is the record itself.

Class-compliant and proprietary. A class-compliant MIDI controller shows up in any program as a MIDI device, and a user can map its buttons however they like. A proprietary HID controller works best, sometimes only, with the software its maker supports. That trade decides whether a controller is a general instrument or one half of a matched pair.

Records and the first mixers

Before there was DJ gear, there was broadcast gear and hi-fi. The first club DJs worked with what existed, and the first DJ mixers were adapted from radio and public-address equipment.

Francis Grasso, working at the New York club Sanctuary from the late 1960s, is remembered as one of the first DJs to beatmatch, holding two records at the same tempo and blending between them.23 A DJ TechTools history of the first DJ mixer points to a 1970 flyer showing Grasso beatmatching before a headphone cue was available to him.24

The first DJ mixer had a nickname.

That mixer was the Bozak CMA-10-2DL of 1971, which the Rane DJ timeline lists as the first commercially available DJ mixer.25 It used rotary knobs. The horizontal crossfader, a single slider that moves the sound from one deck to the other, came in 1977, on the British Citronic SMP101 and the American GLI PMX 7000, whose crossfader was labeled "Transition Control."25

Before the deck was an instrument
  1. 1935 Make Believe Ballroom Martin Block's radio show; the "disc jockey" takes shape.
  2. 1971 Rosie and the Bozak The first DJ mixers, with headphone cueing.
  3. 1977 The crossfader Citronic and GLI add a horizontal crossfader.
  4. 1986 Rane MP 24 A club mixer with an assignable crossfader.

Direct drive

A belt-drive turntable spins its platter through a rubber belt. It is quiet but slow to start, and a hand on the record drags the belt. Direct drive puts the motor under the platter. Technics' SP-10, designed by Shuichi Obata at Matsushita, was the first direct-drive turntable sold, aimed at broadcasters; it was unveiled in 1969 and sold from 1970.2627 The SL-1200 followed in October 1972 as a home hi-fi model.28

Direct drive gave high torque. The platter reaches speed almost at once, holds it, and survives being held, pushed and pulled back.26 Those are the properties a DJ needs for slip-cueing, where the record is held still on a spinning platter and let go on the beat, and for scratching.

The SL-1200MK2, usually dated 1979 (Rane's timeline says 1978), moved the pitch control from a rotary knob to a long slider and used a quartz-locked motor.2528 The original had pitch control too, but the long slider gave a DJ a fader to ride by feel while beatmatching. The MK2 and its successors became the standard turntable for clubs and scratching from then on.28 Panasonic announced the end of Technics turntables on November 1, 2010, as DJs moved to CD players and laptops.28 After a petition and a vinyl revival the line returned at CES in January 2016 with the SL-1200G, and a new DJ model, the MK7, followed in 2019.2628

Deep Dive: Inside the SL-1200

Shuichi Obata, who led the design at Matsushita, started from a broadcaster's problem. Radio stations needed a platter that came up to speed at once and held it, so a record could be started on cue. His SP-10 of 1969 was the first electronic direct-drive turntable, and the Museum of Modern Art holds one in its collection.26 The SL-1200 followed three years later as a home model built on the same idea, and the MK2 turned it into the machine DJs kept for four decades.2628

The motor. The MK2's service manual lists a brushless DC motor whose rotor is built into the platter itself, a 2-kilogram die-cast aluminum disc 33.2 centimeters across. That motor gives 1.5 kilogram-centimeters of starting torque and brings the platter from rest to 33⅓ rpm in 0.7 seconds, which the manual describes as a quarter of a turn.10 A frequency generator built into the motor reports the platter's rotation, and the control circuit compares it with a quartz crystal and corrects the drive. The manual rates the speed change under load at zero for anything up to 1.0 kilogram-centimeter of drag, and wow and flutter at 0.01 percent by one standard and 0.025 percent by the stricter Japanese one.10 A fully electronic brake stops the platter as fast as it starts.10

Those figures describe exactly what a DJ does. A finger resting on the record's edge or a slipmat dragging under a held record is a small, steady load, and the servo pushes back until the load is gone. A platter started from rest is at speed within a quarter turn, so a deck started on the beat is in time almost at once. Belt-drive turntables could not do either, and the IEEE's hall of fame notes that scratching would simply have destroyed them.26

Quartz and the slider. The detail that made the MK2 a DJ instrument is in its feature list. Technics wrote that most quartz turntables of the time had to cut their quartz control out of the circuit when the pitch control was used, so the platter ran on an ordinary servo as soon as the speed moved off center. The MK2 kept quartz-locked control across its whole range, plus or minus 8 percent, moved continuously by a long slider beside the platter.10 A green light marked the exact center. Four rows of strobe dots on the platter's edge stood still under the strobe lamp at +6, +3.3, 0 and −3.3 percent, and the lamp itself flashed in step with the quartz oscillator, not the mains frequency, so the dots stayed honest from one club's power supply to the next.10 A DJ could set a speed, read it off the platter, and trust that it would stay there.

The cabinet mattered too. The manual describes a die-cast aluminum base on a heavy one-piece rubber underside and four large insulating feet, and says the deck was meant for use at very high sound levels.10 At 11 kilograms the whole machine resisted the thump of a club floor that would make a lighter deck skip.10

A long run. After the MK2, the changes were small for a generation. The MK5G of 2002 added a button to switch the pitch range to plus or minus 16 percent and moved pitch control into digital circuits.28 Technics marked two million sales with a limited edition in 1995 and three million with another in 2004, and an SL-1210MK2 is on show at the Science Museum in London among the objects that made the modern world.28 Panasonic stopped production on November 1, 2010, after 38 years, as DJs moved to CD decks and laptops.2628 The return in 2016 brought a new motor, a coreless twin-rotor design with rotary position sensors to reduce cogging, the small jerks a motor makes as its magnets pass the coils. The DJ-oriented MK7 followed in 2019, and in 2021 production moved from Japan to Malaysia.28

The SL-1200 is the clearest case of the two jobs on this page living in one object. The groove is the audio, the platter is the transport, and the quartz loop under the platter is the clock. Everything that came after had to recreate those three things separately.

The SL-1200 over time
  1. 1969 SP-10 Obata's first direct-drive turntable, built for broadcasters.
  2. 1972 SL-1200 A home hi-fi model on the same principle.
  3. 1979 MK2 Quartz-locked pitch slider; the DJ standard.
  4. 2010 Discontinued Panasonic ends Technics turntable production.
  5. 2019 MK7 A new DJ model after the 2016 return.

The crossfader as instrument

Hip-hop turned the turntable and the mixer into instruments. On August 11, 1973, Clive Campbell, DJ Kool Herc, played a back-to-school party organized by his sister Cindy in their Bronx building.29 He had seen dancers respond most to the instrumental breaks, so he played two copies of the same record on two turntables and switched between them with the mixer, stretching the break into a loop. He called it the merry-go-round.29

Grandmaster Flash made that switching precise. The Rane timeline dates his Quick Mix Theory, a method of cutting between two copies of a record, to 1974.25 Flash has described building his own cueing system, which he called a peek-a-boo, so he could hear the incoming record before the room did.30 Grand Wizzard Theodore, Flash's student, is credited with discovering the scratch in 1975, when he held a record still under the needle and moved it back and forth.2531 He first scratched in public in 1977.31

Scratching needed both of the earlier step changes. Without a torque-heavy direct-drive platter, a scratch would stall the motor; without a crossfader, the DJ could not cut the sound in and out fast enough to make rhythms from it.26

Mixers grew features made for scratching.

The CD deck

CD players for DJs arrived in the early 1990s. Denon's dual-deck rack unit of 1993, with variable pitch, a jog wheel and instant cue, set the early standard.15 Pioneer's first, the CDJ-500, came in 1994.32

The CD deck is the first point where control and engine part ways, even though both stay in one box. The disc is read into memory, and playback comes from that memory. The jog wheel is a sensor that reports how far and how fast it turns, and the engine decides what to do with that. Cue points and loops become exact.

The CDJ-1000 of 2001 is the one that won the booth. Its large platter mimicked a turntable well enough that Rane's timeline calls it the first CD "turntable" accurately emulating vinyl.25 By the mid-2000s it was the most used CD deck in clubs.15

Then the disc went away. The CDJ-2000, announced on September 17, 2009, played files from USB sticks and SD cards and came with rekordbox, software that analyzes a DJ's music in advance so the player can load it with beat grids, cue points and waveforms ready.3334 Up to four players could share one source over a network link.33 The deck now played files prepared on a computer, then carried in a pocket.

The CDJ-3000 of 2020 has no CD drive. It runs on a new processor with a nine-inch touchscreen and gigabit networking, and in practice it is a dedicated computer built to play prepared files.35

Timecode: the pivot

Timecode vinyl is the conceptual turning point. The record stops carrying music and starts carrying a control signal, while the music sits on a computer.

The idea came from the Dutch company N2IT. Mark-Jan Bastian developed Final Scratch, announced in November 1998 for the BeOS operating system, with input from the techno DJs Richie Hawtin and John Acquaviva.1636 The first version ran on a modified Linux.16 Stanton brought it to market, with the first commercial product shown at the NAMM show in January 2002, and Native Instruments wrote the software from version 1.1 in 2003.36 Rane's timeline gives 1998 for the invention, and many accounts give 2001 for the product.2537

Serato, a New Zealand company founded around an algorithm for changing tempo without changing pitch, made the version that stuck. Scratch Live, released with Rane in 2004, came after a 2003 trade-show demo caught Rane's attention.38 AudioCulture credits its success over Final Scratch to better feel and more reliable software.38 Native Instruments, after splitting with Stanton at the end of 2006, launched its own Traktor Scratch in early 2007.36

Timecode ended up in court.

What timecode settled is that a deck could be pure control. The turntable kept its feel and its place in the booth, and the audio moved into a laptop running an engine with a crate of thousands of files.

Controllers

If the turntable could be reduced to a control signal, the next step was to build the control surface directly. MIDI, the protocol synthesizer makers agreed on in 1983, was the obvious wire.18

The Vestax VCI-100, shown at the NAMM show in January 2007, was one of the first professional-grade DJ controllers: two jog wheels, a mixer layout, a USB cable and no sound of its own, bundled with Traktor software.39 It led a wave of controllers built to sit in front of a laptop.40

Native Instruments' Traktor Kontrol S4, announced in August 2010, packed four mixer channels, two jog wheels and a built-in audio interface into one unit, sold together with the software.41 It had a sound card but no engine: the audio was still decoded, stretched and mixed in the laptop, with the controller passing control in and sound out. Pioneer's own controllers followed, starting with the DDJ-T1 for Traktor and DDJ-S1 for Serato in early 2011.42

Controllers then grew screens and motors. The Kontrol S4 MK3 of 2018 added motorized jog wheels with haptic feedback, so the wheel could push back against the hand, along with small displays showing track information.43 The RANE ONE, announced in January 2021, put real seven-inch motorized platters with acrylic discs on a Serato controller.44 It feels like a turntable and plays no sound of its own: the far end of the turntable-to-controller road.

The engine moves back into the box

From the late 2000s, the laptop's job began to move back into the hardware. Standalone players read prepared files from USB; all-in-one units combined two or four players and a mixer with a built-in screen.

Pioneer's XDJ-RX, shown at the NAMM show in January 2015, did exactly that for rekordbox users: two players, a mixer and a screen, reading files from USB, with no laptop needed.45 Denon DJ's Prime 4, announced at NAMM in January 2019, was billed as the first four-channel standalone system, with a ten-inch touchscreen.46 In August 2020 Denon's Engine OS software added Beatport and SoundCloud streaming directly on its players, alongside TIDAL, so a DJ could play tracks with no files on hand at all.47 Pioneer's Opus Quad of 2023 brought four-deck standalone playback to a Pioneer all-in-one.48

These units run full operating systems with their own processors, storage and network connections. In the terms of this page they are sound engines with a controller attached. Many of them can also switch roles and act as controllers for a laptop, so the same hardware can be either half of the split.45

Software

Most of the engine's story is software. Traktor, Serato, rekordbox, VirtualDJ and djay each run the same core: decoding, time-stretching, beat analysis, mixing and effects.

One DJ program is open source.

Ableton Live, released in October 2001 by Gerhard Behles and Robert Henke, came at the engine from the production side: software designed for playing loops and clips on stage.51 Many performers use it as a DJ engine, controlled by grids of pads.

Stems are the latest change inside the engine. Native Instruments introduced its Stems file format in 2015, a single file carrying four separate parts such as drums, bass, harmony and vocals.52 It needed tracks released in that format. Real-time separation removed that need. In June 2020 Algoriddim's djay Pro AI and VirtualDJ 2021 both announced the ability to split any track into parts as it plays.53 Serato added Stems to Serato DJ Pro 3.0 in December 2022.54 The engine now does work a studio did before, and the controller gains new things to grab: a fader for the vocal, a button for the drums.

Inside the engine
  1. 2001 Ableton Live Loop-based performance software.
  2. 2006 djay Released as free software for the Mac.
  3. 2015 Stems format Native Instruments' four-part track files.
  4. 2020 Real-time stems djay and VirtualDJ split any track as it plays.

Where it is going

The direction of travel is toward the engine as software that can run anywhere, with the controller as a surface that can be anything.

Algoriddim released djay for the iPad on December 2, 2010, a whole DJ setup on a touchscreen.55 On a phone or tablet the controller and the engine are back in one object, as they were on a turntable, only now the object is general-purpose.

Open Sound Control, proposed by Matthew Wright and Adrian Freed at Berkeley in 1997, offers a network alternative to MIDI, with named addresses instead of numbered channels.56 A control surface that speaks it can sit on any device on the network.

Seen from here, the history runs in a loop. The turntable joined control and engine in one object. The CD deck separated them inside a box. Timecode and controllers moved the engine into a computer. Standalone players moved it back into the hardware. The next step may be an engine with no fixed home, which any surface can drive.

Footnotes

  1. Wikipedia, "History of radio disc jockeys" (secondary source; the 1935 coinage is widely repeated but the term's first known print use is 1941). en.wikipedia.org ↩

  2. Mixxx User Manual, "Sound Hardware." mixxx.org ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8

  3. MathWorks, "Measure Audio Latency," Audio Toolbox documentation (buffer latency as buffer size over sample rate; through a search summary). mathworks.com ↩

  4. Microsoft, "USB_ENDPOINT_DESCRIPTOR structure (usbspec.h)," Windows driver documentation (through a search summary). learn.microsoft.com ↩ ↩2

  5. "The MIDI Specification," Cornell ECE 476 course project page, 2000 (through a search summary). people.ece.cornell.edu ↩ ↩2 ↩3

  6. Mixxx User Manual, "Vinyl Control." manual.mixxx.org ↩ ↩2 ↩3 ↩4 ↩5

  7. Robert H. Jack, Tony Stockman and Andrew McPherson, "Effect of latency on performer interaction and subjective quality assessment of a digital musical instrument," Audio Mostly 2016, citing D. Wessel and M. Wright, "Problems and Prospects for Intimate Musical Control of Computers," Computer Music Journal 26(3), 2002. andrewmcpherson.org ↩ ↩2

  8. Wikipedia, "Speed of sound" (343 m/s in dry air at 20 °C). en.wikipedia.org ↩

  9. "HID vs Timecode: Comparing Digital DJ Control Systems," DJ TechTools, 1 March 2012. djtechtools.com ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8

  10. Technics, SL-1200MK2 Service Manual (Panasonic; specifications and features pages read). steampoweredradio.com ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8

  11. "Pioneer CDJ-2000nexus," DJBooth, 2012 (through a search summary). djbooth.net ↩

  12. "USB audio: synchronous, adaptive and asynchronous," HiFi Advice (audiophile site; through a search summary). hifi-advice.com ↩

  13. Jan Holthuis, "How Does Timecode Vinyl Actually Work? (Pt. 2)" (mirror of a Mixxx blog post). homepages.rub.de ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8 ↩9 ↩10 ↩11 ↩12 ↩13 ↩14

  14. Ableton, Live 12 Reference Manual, "Synchronizing with Link, Tempo Follower, and MIDI"; Ableton Link source header, 2016 (through a search summary). ableton.com ↩

  15. Wikipedia, "CDJ" (secondary source). en.wikipedia.org ↩ ↩2 ↩3 ↩4

  16. Wikipedia, "Final Scratch" (secondary source). en.wikipedia.org ↩ ↩2 ↩3 ↩4 ↩5

  17. Serato, "Learn: Play Modes" (blog) and Serato Support, "Internal Mode" (through a search summary). serato.com and support.serato.com ↩ ↩2

  18. Craig Anderton, "A Brief History of MIDI," MIDI Association (through a search summary). midi.org ↩ ↩2

  19. "HID Mode / Midi, whats that all about?," DJ TechTools forum (user posts; weak source for the 128-step figure). forum.djtechtools.com ↩

  20. VirtualDJ, "HID implementation" (developer wiki). virtualdj.com ↩ ↩2

  21. Jeffrey Hass, "Chapter Three: MIDI," Introduction to Computer Music, Indiana University, on 14-bit controller pairs (through a search summary). cmtext.indiana.edu ↩

  22. Wikipedia, "MIDI 2.0" (secondary source); "MIDI 2.0 Standard Has Been Officially Adopted," Sonicstate, 28 January 2020 (through a search summary). en.wikipedia.org and sonicstate.com ↩

  23. Wikipedia, "Francis Grasso" (secondary source). en.wikipedia.org ↩

  24. "Rosie, the first mixer made just for DJs: a love letter," DJ TechTools, 5 October 2021. djtechtools.com ↩ ↩2 ↩3

  25. Rane Corporation, "DJ Technology Timeline," 2006 (manufacturer document; product "firsts" are Rane's own claims). ranecommercial.com ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8 ↩9

  26. "The Consumer Electronics Hall of Fame: The Matsushita/Technics SL-1200," IEEE Spectrum. spectrum.ieee.org ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8

  27. Technics, "SL-1200 Heritage" (manufacturer page; blocked direct reading, through a search summary). technics.com ↩

  28. Wikipedia, "Technics SL-1200" (secondary source, with citation-needed tags). en.wikipedia.org ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8 ↩9 ↩10

  29. "DJ Kool Herc and Cindy Campbell on the 50th anniversary of hip-hop," Grammy.com, 2023. grammy.com ↩ ↩2

  30. "Fresh Air celebrates 50 years of hip-hop: Grandmaster Flash," NPR, 28 August 2023 (through a search summary). npr.org ↩

  31. "1977: Grand Wizzard Theodore and the Invention of Scratching," KEXP, 15 February 2023 (through a search summary). kexp.org ↩ ↩2

  32. "Pioneer celebrates 30 years of the CDJ with limited edition zine," MusicTech, 2024 (through a search summary). musictech.com ↩

  33. "Pioneer CDJ-2000 and CDJ-900," DJ TechTools, 17 September 2009 (through a search summary). djtechtools.com ↩ ↩2

  34. rekordbox, "About rekordbox" (manufacturer page, through a search summary). rekordbox.com ↩

  35. "Pioneer DJ introduces the MPU-powered CDJ-3000," Attack Magazine, September 2020 (through a search summary). attackmagazine.com ↩

  36. Peter Kirn, "NI Ends Legal Dispute Over Traktor Scratch Digital Vinyl; Twisty, Turny History," CDM, 28 April 2008. cdm.link ↩ ↩2 ↩3 ↩4

  37. "How Final Scratch shaped DJ history," DJ Courses Online, 20 January 2021 (through a search summary). djcoursesonline.com ↩

  38. "Serato: the New Zealand-created global standard in DJing," AudioCulture. audioculture.co.nz ↩ ↩2

  39. "NAMM: Vestax VCI-100, heavy metal MIDI controller for the DJ," CDM, 24 January 2007 (through a search summary). cdm.link ↩

  40. "Vestax VCI-100: The Controller That Started It All," Digital DJ Tips (retrospective; through a search summary). digitaldjtips.com ↩

  41. "NI Traktor Kontrol S4: integrated DJ hardware," CDM, August 2010 (through a search summary). cdm.link ↩

  42. "DDJ-S1 and DDJ-T1: the full scoop," DJ TechTools, 11 January 2011 (through a search summary). djtechtools.com ↩

  43. "Traktor Kontrol S4 MK3: motorized jog wheels with haptic feedback," DJ TechTools, 6 September 2018 (through a search summary). djtechtools.com ↩

  44. "RANE Unveils The ONE: The Only Motorized DJ Controller With RANE's Famous Industrial Build Quality," RANE press release via Studio, 12 January 2021 (through a search summary). studio.se ↩

  45. "NAMM 2015: Pioneer XDJ-RX," DJBooth, January 2015 (through a search summary; also notes it can act as a controller for Traktor). djbooth.net ↩ ↩2

  46. "Denon DJ Prime 4 Announced: The World's First 4-Channel Standalone DJ System," Digital DJ Tips, January 2019 (through a search summary). digitaldjtips.com ↩

  47. "Denon DJ Engine OS lets you stream Beatport and SoundCloud tracks straight from the decks," MusicTech, August 2020 (through a search summary). musictech.com ↩

  48. Resident Advisor news on the Pioneer DJ OPUS-QUAD, 8 March 2023. ra.co ↩

  49. Mixxx, "About Mixxx." mixxx.org ↩

  50. Tue Haste Andersen, "Mixxx: Towards Novel DJ Interfaces," NIME 2003 (abstract through a search summary). nime.org ↩

  51. "20 years of Ableton Live: a history told by the founders and developers," MusicRadar (through a search summary). musicradar.com ↩

  52. "Native Instruments launches open file format Stems," KVR Audio, 2015 (through a search summary). kvraudio.com ↩

  53. Sam Willings, "Algoriddim djay and Virtual DJ introduce realtime stem separation," MusicTech, 24 June 2020. musictech.com ↩

  54. "Serato DJ Pro & Lite 3.0 With Stems Launches," Digital DJ Tips, December 2022 (through a search summary). digitaldjtips.com ↩

  55. Algoriddim, "Algoriddim debuts djay for iPad app on the App Store," press release, 2 December 2010 (through a search summary). cdn.algoriddim.com ↩

  56. Matthew Wright and Adrian Freed, "Open SoundControl: A New Protocol for Communicating with Sound Synthesizers," ICMC 1997 (through a search summary). opensoundcontrol.stanford.edu ↩