Filter 1 stands out to me as the most lo-fi one (probably the one which uses the least CPU) although that gives it a certain charm that I’d love to see included as an option in the final version of the product. What really gives away the different models, though, is the extreme OSC B > Filter Cutoff emulation. The filters (all five of them) sound really aggressive at high resonance settings. I took RePro-1 Alpha for a quick spin right after downloading it and you can see (and hear) that quick test (definitely not anything scientific or in-depth) below. The users are asked to share their opinion about the different filters (the download page features an actual poll), and thus influence the developer’s decision about which one(s) to include in the final version of RePro-1. Even more so, the current free version of the instrument comes with five different filter models (all based on the Pro One filter), with different sound quality and CPU cost. RePro-1 Alpha is a feature-limited version of the product which is expected for release later this year, however it delivers the same level of sound quality that you can expect to get from the final release.