KO II Sampler Evolves with Major OS Update

Swedish music equipment manufacturer Teenage Engineering released OS 2.5 for their sampler “EP-133 KO II” on June 27, 2026. This update is the most extensive since the product’s launch, introducing features such as USB audio input/output support, selectable lo-fi sample rates, sample reverse, an arpeggiator, equal-length auto-chopping, and a doubling of the maximum sample time from 20 seconds to 40 seconds.

Long-Awaited Features Arrive All at Once

Priced at $329, the EP-133 KO II is renowned for its impressive versatility despite its compact size. According to reporting by The Verge, the new features in OS 2.5 incorporate many of the functions that users have long been requesting.

One standout feature is the sample reverse function, which is so fundamental that many found its absence in earlier versions puzzling. While Teenage Engineering has provided several major updates in the past, this latest release surpasses them in scope.

Lo-fi Expression Enhanced with Sample

Rate Options

One of the most notable additions in this update is the ability to select sample rates. In addition to the standard 46kHz, users can now choose between 32kHz and 26kHz modes. The 32kHz mode adds a warm character to the sound, while the 26kHz mode delivers a truly lo-fi aesthetic. For creators of lo-fi music, a genre that thrives on digital grit and imperfection, this feature allows for an entirely self-contained workflow using just the hardware.

Previously, achieving a lo-fi sound required post-processing in a DAW or using external effects. Now, the KO II can add bit-crushed textures during sampling, opening up new possibilities for real-time sound design in live performances and field recording environments.

The Arpeggiator Indicates a New Direction

While arpeggiators are not typically associated with samplers, the KO II’s high-quality pitch resampling makes it easier to generate basslines for synth-pop tracks. The Verge’s Terrence O’Brien described KO II’s pitch resampling as “the successor to the CASIO SK-1 that I’ve always wanted.”

The addition of an arpeggiator further emphasizes KO II’s evolving role as more than just a sampler—it is increasingly taking on characteristics of a synthesizer. For users who incorporate melodic materials into their performances, this enhancement offers substantial practical value.

Improved Auto-Chopping Functionality

The new equal-length auto-chopping feature significantly streamlines the process of slicing and editing samples or loops. While transient-based auto-choppers have been excellent for isolating drum hits in breakbeats, they have been less effective for melodic content.

Equal-length chopping divides beats or loops into even segments, making it ideal for resequencing rap or vocal samples, as well as remixing melodic loops. The doubling of maximum sample time from 20 to 40 seconds further amplifies its utility. By switching to mono recording, users can achieve twice the recording time compared to stereo mode, which is a practical trade-off for most sampling purposes.

The Importance of USB Audio Support

The addition of USB audio support is a crucial upgrade for integrating the KO II into a computer-based setup. Previously reliant on analog connections, users had to go through an audio interface for recording or playback. With direct USB connectivity, seamless integration with DAWs is now possible.

This feature will also be available for Teenage Engineering’s sibling device, the Riddim. However, the EP-1320 Medieval Sampler, a special edition with a medieval theme, will only receive USB audio support without other updates. When contacted by The Verge, Teenage Engineering did not provide an explanation for why the Medieval model has consistently been excluded from major updates.

Additional Improvements

Beyond the headline features, OS 2.5 includes enhancements such as improved time-stretching, new musical scales, per-pad time shift options, and numerous bug fixes. Teenage Engineering has established a reputation for providing long-term firmware updates for its hardware products, and OS 2.5 exemplifies the success of the company’s product lifecycle strategy.

Although the company’s products are praised for their design and sound quality, they are often criticized for their limited functionality at launch. This update significantly expands the capabilities of the KO II compared to its initial release. Users can download the firmware from the company’s official update page and apply it via USB.

Editorial Opinion

In the short term, KO II users will likely view this update as a major step forward, significantly lowering the barrier to entry for prospective buyers. The addition of USB audio support and extended sample time, in particular, removes obstacles for those considering the device for studio use. The update may also increase the KO II’s resale value on the secondhand market.

In the long term, Teenage Engineering’s commitment to providing ongoing firmware updates post-purchase sets it apart from competitors. In a market crowded with emerging modular synth and sampler manufacturers, this long-term support strategy is likely to foster loyalty among professional users.

However, the continued exclusion of the Medieval model from major updates highlights a lack of clarity in Teenage Engineering’s product portfolio strategy. Questions remain about the company’s priorities for investing in updates for niche, themed products.

References

• The Verge — Published on 2026-06-27