SPL TwinTube

TwinTube models SPL’s hardware unit of the same name, which uses two separate tube stages to generate harmonic content. The first stage, Saturation, adds even-order harmonics (predominantly 2nd harmonic) and is well-suited to warming up sources that sound thin or clinical. The second stage, Harmonics, adds higher-order odd harmonics and produces a more aggressive, textured result. Both stages are independently controllable and can be blended together.

The plugin also includes a Tube Drive section that applies saturation more broadly across the signal. The hardware’s circuit used actual vacuum tubes; the plugin models their non-linear transfer functions including the way the harmonic profile shifts as drive is increased. It works on individual channels as a subtle warming tool, or on buses where a small amount of even-harmonic content can glue elements together without the phase issues that come from heavy bus compression.