Sunnaudio returns with Helion R2D3 guitar and bass preamp

February 27, 2025 · 2 sources

Sunnaudio has returned with the Helion R2D3 Guitar & Bass Preamp, its first pedal since 2021, according to a Pedal of the Day article published on February 27, 2025¹. The article describes the unit as a preamp aimed at bass, electric guitar, acoustic guitar with passive or active pickups, electric violin, cello and other acoustic-electric instruments¹.

The R2D3 has a parametric EQ with adjustable frequency for bass, mid and treble, and a selectable tuned EQ or shelving mode for speaker simulation¹. It offers 5 Meg and 700K input impedance, a balanced XLR output and a 1/4 inch output, with the XLR carrying an independent signal mode for console use¹. The saturation sweeps from clean to saturation to over-drive, and an adjustable Rabid control adds gain that the article says tips into fuzz tones¹. A Focus control adjusts sub-harmonic frequencies to inject more low end, and a Tone control shapes the mids of the drive¹. There is an insert TRS jack, a bypass or mute mode for the footswitch, and separately selectable signal points for the XLR output¹. Power comes from an external 9-12v DC supply, XLR phantom power or a battery¹. The circuit is transformer-less, and the article describes it as quiet¹.

Trim pots and dip switches on the top side set the clean level against the drive level, and a second trim pot sets how much clean remains in the drive, with B for bass and G for guitar settings¹. The unit ships set to low gain via an internal diode dip switch, which the article says works for bass and more subtle overdrive on both guitar and bass¹. Sunnaudio units are handmade in small batches, the article states¹.

Bass Magazine reviewed the R2D3 in March 2024 and listed a price of $475². It gave the dimensions as 4.75 by 3.75 by 1.75 inches, which it called less than half the size of most other preamp/DIs². That review describes a large Drive knob fixed in the center next to a Volume knob that lights with a green LED when the pedal is activated, a Tone knob for the overdrive, and Rabid and Focus knobs each with an activation button². It lists EQ frequency controls of 60Hz to 300Hz, 0.8kHz to 3kHz and 3kHz to 12kHz, an XLR Out switch offering all EQ, no EQ or bypass, and four back-panel DIP switches for input impedance, tone range, bass EQ shape and treble EQ shape². Reviewer Jon D'Auria wrote that after a few days with the unit it was hard to find flaws in its design or execution, and listed no cons².