Darkglass Microtubes X Ultra

Darkglass Microtubes X Ultra — Parallel Distortion Preamp for Bass

The Darkglass Microtubes X Ultra brings the dual-band processing approach used by studio engineers into a stompbox format, compressing only the low-pass side of the signal while saturating only the high-pass side. Sitting at the top of the Ultra Series, the Microtubes X Ultra builds on the original Microtubes X7 with a graphic EQ, loadable impulse-response cabinet simulation, an aux input, and a clean channel. Inside one compact chassis it covers the entire bass distortion spectrum from articulate mild overdrive to raw fuzz.

What Sets the Circuit Apart

What separates this preamp from a typical drive pedal is the true variable crossover: two filters at the input decide which frequencies feed the compressor and which feed the drive stage, then recombine downstream without losing the low-end foundation. A Micro USB B connector on the rear loads custom impulse responses from the Darkglass Suite, so the same pedal doubles as a balanced DI for direct recording sessions without placing a microphone in front of a cabinet.

The Filter and Drive Engine

The crossover circuit sits at the heart of the design and lets players choose exactly where compression stops and where saturation starts across the frequency spectrum.

• Low Pass Frequency: 50–500 Hz — selects which bass content receives compression, from sub-bass only up to full preservation of clean mids
• High Pass Frequency: 100 Hz–1 kHz — chooses where distortion enters the signal, from thick fuzz saturation to ultra-sharp articulation
• Drawing 200 mA from a regulated 9 V DC center-negative supply, the unit runs on standard pedalboard power and accepts no battery operation.

Graphic EQ and Cabinet Simulation

A 6-band graphic equalizer stacks a bass shelf and treble shelf around four mid-band controls, making it quick to carve any speaker response or match a room.

• Bass: ±12 dB @ 80 Hz low shelf — anchors the fundamental before either compression or distortion
• Four mid-band controls at 250 Hz, 500 Hz, 1.5 kHz, and 3 kHz each offer ±10 dB of range, giving surgical access to the growl, vowel, and presence zones.
• Treble: ±12 dB @ 5 kHz high shelf — adds pick attack and air without harsh peaks

I/O and Physical Footprint

Built in Finland for both FOH and silent home use, the unit packs a balanced recording output and a stereo rehearsal rig into a pedalboard-friendly chassis.

• Inputs and outputs cover 6.3 mm mono, balanced XLR with ground lift, 3.5 mm aux input, 3.5 mm stereo headphone output driving loads down to 16 Ω, and Micro USB B for firmware and IR loading — all on a single rear panel.
• Dimensions (W × D × H): 125 × 96 × 57 mm
• Weight: 430 g