Teenage Engineering’s KO II sampler is getting OS 2.5—its biggest update yet—bringing audio over USB, multiple selectable sample rates for lo-fi character, sample reverse, an arpeggiator, equal-length autochopping, and a jump in maximum sample length from 20 s
The KO II has always felt like a small sampler with outsized ambition—capable of pulling you from drum-chop fiddling to full-on song ideas. Now Teenage Engineering is giving it an update that pushes that range even further. starting with something practical you notice immediately: more time to sample.
OS 2.5 extends the KO II’s maximum sample length from 20 seconds to 40 seconds. The tradeoff is built into the change itself—Teenage Engineering is capturing mono audio instead of stereo for that longer recording window.
Alongside the extra sampling time, OS 2.5 adds equal-length autochopping. The transient-based autochopper that was already there had been great for isolating drum hits in a break. but it wasn’t as helpful for melodic material. With equal-length chopping now part of the toolset. the KO II becomes more comfortable at chopping up and rearranging loops—not just stripping beats down to pieces.
Then there’s the feature you can almost imagine coming later in life—sample reverse. It’s a simple idea, and that simplicity is exactly why it stands out as a surprise that it hadn’t been implemented earlier.
Teenage Engineering also adds an arpeggiator. On paper, an arpeggiator on a sampler can sound like an awkward fit. In practice. the update lands because the KO II is already good at repitching samples—something described here as comparable to the kind of sound people chase when they want a SK-1 successor. The arpeggiator, in other words, turns that sampling strength into something you can write with faster, including synthpop basslines.
The update’s most fun headline, though, is the new selectable sample rate. You can keep the standard 46 kHz mode, but OS 2.5 also introduces 32 kHz for added character and 26 kHz for full lo-fi grit—crunchy, digital, and aimed at the kind of texture producers actively hunt.
Those changes sit inside a wider OS package. OS 2.5 also brings improved time stretching, new scales, per-pad time shifting, and a large set of bug fixes. Teenage Engineering already issued multiple substantial updates for the KO II, and OS 2.5 is framed as one of the biggest yet.
The update doesn’t stop with the KO II either. OS 2.5 is also available for the KO II’s reggae-themed sibling, the Riddim.
But the company’s other sampler in the lineup—the EP-1320 Medieval—doesn’t get the same treatment. Teenage Engineering says the EP-1320 is finally getting an OS update, but it’s limited to USB audio and nothing else.
The question hanging over that split is obvious: why is the EP-1320 regularly left out of the update “fun”? Teenage Engineering has been asked about it, and the response hasn’t come back yet.
For owners, the practical next step is straightforward: you can update the OP-133 KO II, EP-40 Riddim, or EP-1320 Medieval via the update link provided by Teenage Engineering.
Teenage Engineering KO II OS 2.5 sampler update USB audio lo-fi mode sample reverse arpeggiator autochopping per-pad time shifting time stretching Riddim EP-1320 Medieval