sE Electronics FluxCore FCP1 Caja DI

Passive Hi-Z DI Box for Pristine Instrument Signal Transfer

The sE Electronics FluxCore FCP1 is a single-channel passive direct box that routes high-impedance instrument signals to a mixing console with maximum fidelity. Its Hi-Z input keeps a light electrical load on pickups, preserving the natural character of guitars, basses, keyboards, and synthesizers. The fully passive design needs no batteries and operates without phantom power, suiting touring rigs and fixed installs. A custom-designed, shielded heavy-duty transformer delivers high headroom and low distortion, while the balanced XLR output isolates the signal from ground loops and RF interference.

Built-In Stereo Summing and Flexible Mounting

What sets the FCP1 apart from typical passive DI boxes is its switchable L+R mono summing circuit, which combines left and right stereo signals into a single mono feed from either the two 1/4" jacks or the dedicated 3.5 mm TRS stereo input. This saves mixer and stagebox channels when connecting laptops, media players, or stereo keyboards. The compact steel enclosure supports desktop placement, pedalboard mounting via hook-and-loop pads, and rack-mounting up to four units across 1U.

Connectivity and I/O

The FCP1's input and output configuration covers the most common instrument and console connections in a single box.

• Inputs: 6.3 mm TS jack (L), 6.3 mm TS jack (Thru/R), 3.5 mm TRS stereo jack
• Output: Balanced 3-pin male XLR — transformer-isolated feed to console
• Line & Instrument Inputs: Yes — accepts line-level media players and Hi-Z instruments

Electrical Performance

The passive transformer design delivers transparent signal handling with switchable attenuation to tame the hottest amplifier outputs.

• Gain: -20 dB — passive attenuation for line-level console inputs
• Attenuation Pad: 0 dB / -15 dB / -30 dB switchable
• Frequency Range: 18 Hz – 30 kHz (-0.3 dB)
• Input Impedance: 650 kΩ (0 dB) / 12 kΩ (-15 dB) / 10 kΩ (-30 dB)

Physical Build and Mounting

The compact, low-profile chassis is built for the road, with multiple mounting configurations included.

• Dimensions: 127 × 100 × 39 mm
• Weight: 795 g
• Rackmountable: Yes — up to four units across 1U
• Controls: Ground Lift (on+), PAD Switch, Polarity Switch