Sketch Audio releases Series 9000, a FREE Akai S900 filter plugin

Sketch Audio has released Series 9000, a free low-pass filter and distortion plugin for macOS, Windows, and iOS.

Series 9000 features a sixth-order low-pass filter based on a late-1980s rackmount sampler. The developer does not name the original unit, but I’m pretty sure that it emulates the Akai S900/S950 family.

That is definitely a fun source to borrow from because those samplers were anything but clean. The 12-bit grit gets a lot of attention, of course, but the steep low-pass filter is a big part of why the S900 sounded so interesting.

Series 9000 focuses on that filtering behavior and keeps the interface very simple. You get four controls: Cutoff, Drive, Q, and Env.

Cutoff controls the low-pass filter, and Sketch Audio notes that it behaves like the original hardware in the sense that the filter does not close completely. It’s a bit weird, but even at the lowest cutoff setting, some of the sound still comes through rather than disappearing into silence.

Drive adds saturation using custom saturators placed inside each filter stage. At 0 dB, the drive path is fully clean, but you can push it into more obvious distortion when you want the filter to bite harder.

The Q control handles resonance, which sounds insane with such a steep slope. A 36 dB/octave low-pass can remove top end very quickly, and adding resonance around the cutoff point adds a ton of color.

Env adds envelope follower modulation to the cutoff with adaptive release. With that, the filter can react to the dynamics of the incoming signal, opening and closing with the material. It’s pretty cool on drums and other percussive sounds.

Series 9000 is based on the DSP from Scissor Hands, Sketch Audio’s paid dual-filter plugin. Scissor Hands goes a lot deeper with high-pass filtering, multiple filter orders, modulation, and distortion options, but Series 9000 works as a focused free entry point into that sound.

The plugin is part of Sketch Audio’s Nugget Basket, a free plugin series with new entries rolling out every month this summer. We covered the first one last month, Lil’ Doc, a free Detroit-style compressor plugin, and Series 9000 continues the same small-but-specific approach.

Series 9000 is available in AAX, AUv2, AUv3, CLAP, and VST3 formats. It runs on macOS 11 or higher, Windows 10 or higher, and iOS 14 or higher. Desktop installers require a free Sketch Audio account, while the iOS version is available on the App Store.

Download: Sketch Audio Series 9000 (FREE)

More:

• Sketch Audio releases Lil’ Doc, a FREE Detroit-style compressor plugin
• Orra Audio releases Orra Pump, a FREE tempo-synced modulation filter

Last Updated on June 26, 2026 by Tomislav Zlatic.