Walrus Audio announces Mantle bass preamp and DI

January 13, 2026 · 4 sources

Walrus Audio announced the Mantle Analog Bass Preamp // D.I. on January 13, 2026, a preamp pedal for electric bass developed with bassist and educator Ian Martin Allison¹. Pre-orders opened that day at $749.99, with shipments beginning in early February, according to Bass Magazine¹. The maker describes it as "a premium preamp and DI for electric bass, created in close collaboration with Ian Martin Allison"².

The circuit runs from a high-impedance JFET input buffer through low-pass and high-pass filters or a dry path, an input transformer with gain from -6dB to +23dB, a boost EQ stage and an output transformer². Walrus says both are its custom-wound Sapphire Transformers: the input is based on Neve designs and the output on the output stage of an API 312². The maker claims the internal supply runs at +24V from a 9VDC, 500mA center-negative input, and that the transformer-balanced XLR output can be used at the same time as the 1/4-inch output². A Ground Lift switch separates the XLR ground from circuit ground, and an Active/Passive switch applies a -10dB input pad².

Bass and Treble are eleven-position rotary switches, flat at position 6². Boosting adds +3dB per step up to +15dB; cutting engages a -18dB/octave high-pass filter on Bass at 30Hz, 50Hz, 80Hz, 100Hz or 120Hz, and a low-pass filter on Treble at 8kHz, 6kHz, 4kHz, 2kHz or 1kHz². Guitar World reports the boost center frequencies as fixed at 60Hz for Bass and 4.9kHz for Treble, with the boost narrowing as it rises³. Walrus lists the enclosure at 6.09 by 4.7 by 2.28 inches and the weight at 2.2lbs²³. No power supply is included².

Guitar World's review rated the Mantle four and a half stars out of five overall, praising its ease of operation and calling it "studio-style processing in a stompbox," while listing the absence of a power supply and a price it called "somewhat exclusive" among reasons to avoid³. Walrus also lists a blemished version at $637.49, describing blemish as cosmetic only⁴.