The SPL TwinTube is a tube effects processor designed to add harmonics and tube saturation.

The SPL TwinTube features two independent stages that can be used simultaneously or separately. The Saturation stage distorts the signal by pushing the signal beyond the tube’s limits adding harmonic distortion, followed by limiting which resembles the sound of analogue tape distortion. The second stage is the harmonic stage uses a special circuit, which dynamically adds overtone processing to the signal across four frequency settings: 2kHz, 3kHz, 6kHz and 10kHz. This stage adds an increased presence adding air and bringing vocals and instruments forward in your mix.