Frequently asked questions

It depends on how you make music. If you work mostly with samples (chopping loops, finger-drumming kits, recording sounds with the built-in mic), the EP-133 K.O. II is the better fit. It's a hands-on sampler with pads, a fader and a simple screen. If you'd rather build tracks from synth engines and drums with deep step sequencing (per-step parameter locks, step components, separate drum, bass, lead, arp and chord tracks), the OP-Z suits you better. It has no screen, though, so you lean on the companion app or learn the key combos. On a budget, a PO-33 K.O! is a cheap way to try sampling. The OP-XY combines both approaches at a much higher price.

Over MIDI from the oplab module. Set the switch next to its out port to MIDI (not TRIG or PO), then run a 3.5 mm TRS cable from that port to the synth's minijack MIDI input. The OP-Z and many compact synths, the S-1 included, use the TRS "Type A" wiring, so no adapter is needed. A synth with a 5-pin DIN input needs a Type A adapter. You can then send notes and CCs from a track, or just clock to keep the two sequencers in step. Connecting two USB devices directly doesn't work, because neither one is a USB host. For audio, run the OP-Z's output into the synth's mix input if it has one, so both come out of one stereo pair.

If the OP-Z's synth sounds are your main gripe, the OP-XY targets exactly that: it has stronger synth engines, better sound quality, deeper sequencing, and real audio/CV I/O, so it's the natural upgrade. Adding external synths to the OP-Z keeps your setup cheaper and more portable, but you trade that for cables, extra boxes, and a more fiddly signal chain. Choose the OP-XY for an all-in-one step up, or external synths if you'd rather keep the OP-Z as a compact sequencer hub.

This is a common OP-Z problem, especially after the unit has been stored for a while. Start with Teenage Engineering's official "kickstart" procedure in their help center. If that doesn't work, owners have had luck with a few community tricks: fully drain the cell and recharge it, open the back and gently bump or reseat the battery on its contacts while the charger is connected, or briefly bridge the battery contacts with a stripped USB wire to wake the cell. Note the OP-Z still runs fine on USB power with the battery removed. If the cell is genuinely dead, replacements are hard to find — TE doesn't sell them and iFixit's are usually out of stock — so people fit a similar-spec LiPo by soldering it to the connector, or use a community adapter such as the open-source OP-Z replacement-battery kit (also sold on Reverb).

The OP-Z is class-compliant, so most USB-MIDI keyboards work — the real question is power. Low-draw controllers run straight off the OP-Z's USB-C port: people report the Korg nanoKEY/microKEY and Arturia MicroLab/KeyStep working directly, usually with pitch-bend and mod passing through. Power-hungry keyboards (e.g. Novation Launchkey/FLkey) need more than the OP-Z can supply, so you have to insert a powered USB hub that injects power to both sides — the TE-endorsed Kingston Nucleum is the classic pick, but any decent powered USB-C hub or camera-kit-style adapter can work. The other route is 5-pin MIDI: send MIDI out from the keyboard into the Oplab or Line module and power the keyboard separately. Whichever you use, set the keyboard to the track's MIDI channel and play.

The OP-Z is a class-compliant USB audio device, so the cleanest route is to record its output over USB. On a computer it appears as an audio interface that any DAW can record from. On Android you typically need a USB-audio app such as Audio Evolution Mobile Studio or USB Audio Recorder PRO to capture without crackle; on iOS connect via a USB-C / camera-kit cable into your recording app. If you just want to play out (for example to a Bluetooth speaker) you can route through an app on the phone, but expect some latency. If you'd rather stay in the analog domain, take the headphone/line output into a standard audio interface.

Long-time owners still rate it highly — there's enough depth that people keep finding new tricks years in. The well-known issues are real but mostly manageable: a slight frame bend can cause occasional double-triggers, and dials can feel loose. In practice double-triggers often affect only a few buttons and can be worked around by pressing firmly, with more involved physical fixes available, or sidestepped entirely by playing via a USB-MIDI keyboard. The weak point worth checking is the battery (see the OP-Z battery FAQ). Modules are sold separately and some (Line, Oplab) are discontinued and pricey secondhand — without one you lose CV/MIDI-DIN and some Pocket Operator / eurorack integration, but the core device is fully usable over USB. If buying used, test every button and encoder and confirm it actually charges.