A DJ mixer is mostly faders, knobs and switches, and every one of them is a part that wears. The good news is that a mixer is easy to test thoroughly if you are methodical: one source, headphones, and a slow pass over every control on every channel. This guide covers four-channel club mixers and two-channel battle mixers, what each one does with a computer, and how to check a used one.
The mixers in brief
Club mixers
- Pioneer DJM-900NXS2: four channels with a phono input on each, Magvel contactless faders, a 96 kHz/24-bit USB sound card, 14 Beat FX, six Sound Color FX, two USB ports with an A/B switch, and send/return for external effects. It works with rekordbox's DVS. Serato lists it as needing a paid Serato DJ Pro licence, plus the paid DVS expansion for control vinyl.
- Pioneer DJM-450: two channels, a Magvel crossfader, eight Beat FX and four Sound Color FX. It supports rekordbox DVS and Traktor Pro 3 DVS.
- Allen & Heath Xone:92: a four-band EQ and the Xone filters. A Xone:92 MK2 now exists with revised phono preamps, a revised filter and a mini innoFader Pro crossfader with an adjustable curve, so check which version you are being offered.
- Allen & Heath Xone:96: an analogue 6+2-channel layout with a four-band EQ, dual VCF filters, an innoFader crossfader and two 32-bit/96 kHz USB sound cards for two computers.
- Allen & Heath Xone:23: the compact Xone. A 23C version also exists, so match the model on the panel to the listing.
- Denon X1850 Prime: four channels with four phono and four line inputs, two USB audio connections, a "flex-fader" crossfader, and a LAN hub that links up to four Denon SC players. Serato lists Serato DJ Pro and DVS as paid upgrades for it.
Battle mixers
- Pioneer DJM-S9: two channels, a Magvel Fader Pro crossfader with a Feeling Adjust dial for weight, two USB sound cards and performance pads. Serato says it unlocks Serato DJ Pro and Serato DVS. Pioneer says rekordbox DVS on it needs a rekordbox Core plan or above.
- Pioneer DJM-S11: two channels for four decks, an enhanced Magvel Fader Pro, a 4.3-inch touch display and larger pads. It works with Serato DJ Pro (Serato says it unlocks DJ Pro and DVS) and with rekordbox.
- Rane Seventy-Two: a 4.3-inch touch screen, a Mag Three crossfader, dual USB ports and 16 pads. Serato says it unlocks DJ Pro and DVS. Rane has since released a Seventy-Two MKII, so check which one you are looking at.
- Rane Seventy: three Mag Four contactless faders (both upfaders and the crossfader) and 16 pads. Serato says it unlocks DJ Pro and DVS.
- Rane TTM 57SL: an older Rane battle mixer. See the software support section below before buying one for laptop use.
Crossfader
Contactless faders (Pioneer's Magvel, Rane's Mag Three and Mag Four, the innoFader family) don't wear the way carbon-track faders do, but they still fail. A shaft can be bent by a knock, the action can become gritty, and the cut-in point can drift. With music on both sides, make short, fast cuts at each end and check the sound cuts in at the same distance from the edge every time, with no bleed when the fader is fully closed. Try each curve setting and, on the S9 and S11, turn the Feeling Adjust dial through its range. On club mixers, sweep slowly from one side to the other and listen for dips or jumps in level halfway across. Replacement faders are available for many mixers; Allen & Heath, for example, sells a replacement Xone:92 channel fader on its own board that fits without soldering. Check part availability for your model before you count on a cheap fix.
Channel faders
Play music into each channel in turn and move the upfader slowly from bottom to top and back. The level should rise smoothly with no crackle, no drop-outs and no sudden jumps. Then make quick cuts with the upfader, as a scratch DJ would.
Pots, EQ and kills
Turn every knob slowly through its full range: gain, each EQ band, filter, pan or balance, headphone level, cue mix, booth and master. On an analogue mixer, worn or dirty pots crackle while they move, or drop a channel at certain positions. On a digital mixer, listen for steps or jumps where the sound should change smoothly. Turn each EQ band fully down to check it cuts as far as it should, and test any kill switches or isolator mode. Light crackle can sometimes be cleaned out, but a pot that cuts the channel needs replacing.
Effects
Run every effect on every channel it can be assigned to. On the DJM-900NXS2 that means the Beat FX (including the X-Pad), the Sound Color FX on every channel, and the send/return loop if you use outboard effects. On the Xone:92 and Xone:96, sweep each filter through its modes. On the X1850, try the Sweep FX, the BPM effects and the Touchstrip. An effect that works on three channels but not the fourth points to a fault on that channel's board.
USB sound cards and DVS
If you plan to use the mixer with a laptop, test it with your laptop and your software. Plug into each USB port, check the computer sees the mixer, play audio through every channel, and record from it if you plan to. For DVS, play control vinyl on each deck and check it tracks cleanly. Check what the hardware unlocks versus what you will have to pay for, using Serato's page for that model and Pioneer's product page. The S9, S11, Seventy-Two and Seventy unlock Serato DJ Pro and DVS; the DJM-900NXS2 and X1850 need paid Serato licences for the same use.
Driver and OS support for older units
AlphaTheta's macOS Tahoe 26 compatibility page lists the DJM-900NXS2, DJM-450, DJM-S9 and DJM-S11, and says models not listed are no longer supported. For older or discontinued mixers, including the TTM 57SL, check the manufacturer's support page for a driver that matches your current operating system before you buy. Rane keeps a legacy products section on its site. A mixer whose sound card no longer has a current driver can still work perfectly as an analogue mixer, but don't pay a laptop-mixer price for it.
Phono, line and grounding
Phono inputs include a preamp for turntables; line inputs expect CD players, media players or a laptop. A turntable plugged into a line input sounds quiet and thin. A line-level player plugged into a phono input sounds loud and distorted. Check that each channel's input selector switches cleanly between its sources. With turntables connected, attach their ground wires to the mixer's ground post and listen with the volume up and nothing playing: a little hiss is normal, but a loud hum points to a grounding problem or a faulty phono stage.
Test every channel
- Feed one source into channel 1 and check gain, EQ, filter, upfader, cue and the meter.
- Move the same source to channel 2, then 3 and 4, and repeat. Don't skip any.
- Test phono and line on each channel that has both.
- Check master, booth and record outputs, and both balanced and unbalanced outputs if fitted.
- Check both headphone sockets if there are two, with cue on each channel.
- Test the mic inputs with a microphone, including talkover if fitted.
- Connect a computer to each USB port and play and record through it.
Quick checklist
- Crossfader cuts in cleanly at both ends with no bleed; every curve setting works.
- Every upfader and pot is free of crackle and drop-outs.
- Every effect works on every channel.
- Every USB port and sound card works with your computer and software.
- A current driver exists for your OS, or you don't need one.
- No hum with turntables grounded.
Pairing it with decks? See used CDJs and media players or Technics SL-1200 generations.
