10) Inside the Innovation: Schwabe Digital Linear Phase Filterbank
We spent a year researching, testing, and refining our filterbank technology. Our expectations were ambitious: we set out to create a truly linear phase filter bank with minimal pre-ringing, ultra-low latency, and exceptional CPU efficiency—essentially, everything without compromise.
We consulted three mathematicians and expert developers, challenging each to create their own iteration of a filterbank. Then, we shared their work with one another, fostering a collaborative learning process. Each expert brought their unique perspective, ultimately converging on a filter bank design that exceeded even our expectations. Through countless iterations and relentless refinement, the Schwabe Digital Linear Phase Filterbank was born.
This technology is highly efficient, truly linear phase, and one of the most sophisticated and elegant approaches to linear phase processing we’ve encountered. It performs exceptionally well at any buffer rate with minimal latency and pre-ringing.
But we didn’t stop there. We developed Q Linear Phase, a technique that virtually eliminates pre-ringing while dynamically managing phase. Under normal conditions, the filters operate in true linear phase. However, during significant volume shifts between bands, a subtle phase rotation is introduced. Rather than being a drawback, this dynamic adjustment adds a natural, engaging character to the sound, making it feel more alive and musical.
True Linear Phase
The True Linear Phase Filterbank is the default setting and works best in almost all cases. It’s especially useful when using heavy parallel processing, keeping phase alignment intact across all parallel paths and preserving the integrity of the audio signal.
True Linear is the default setting because it provides the best balance of performance and perfect phase coherence.
The True Linear Filterbank uses elegantly optimized mathematics to deliver highly efficient, transparent performance. Its reduced transition curve minimizes bandwidth at crossover points, keeping the impulse response tightly focused and free from smearing.
Q Linear Phase
The Q-phase crossover design offers a fresh take on linear phase filters. While it delivers exceptional low-frequency transient clarity, adjusting gain between bands can introduce slight phase rotation at the crossover points. Interestingly, this subtle shift adds depth and movement, resulting in a richer, more engaging sound. It’s a precise yet characterful alternative to fully linear phase filters. The Q-phase crossover design ensures perfect linear-phase reconstruction while significantly reducing pre-ringing.
We’re excited to share the innovation behind the Schwabe Digital Linear Phase Filterbank.
Tag @SchwabeDigital in an Instagram story and show us how you are using Orange Clip—we’ll repost!
Be well,
Ryan Schwabe
Grammy-nominated and multi-platinum mixing & mastering engineer
Founder of Schwabe Digital
