Boredbrain Music Xi3 Eurorack 3-Channel Mix Expander Module (Xcelon)

Manufacturer's description

MINI 3-CHANNEL MIX EXPANDER

• Adds three stereo/dual-mono channels to Xcelon mixer in just 8 HP
• Two stereo FX sends and two stereo output mix busses selectable per-channel
• VCA-based volume controls with CV input and responsive LED indicators
• Configurable jumpers for dual-mono operation allowing up to six mono sources
• Pre/post-fader direct output ports for all three stereo channels

More inputs, less HP

Xcelon Xi3 is a compact three-channel stereo audio input expander for the Xcelon eurorack mixer. The module includes core mixing features and connections meant to expand the number of mixer inputs without sacrificing valuable space.

The 8HP module provides essential channel parameters for each channel such as volume control, both stereo effects sends, and mix bus selection. Xi3 channels share the same mix bus and FX send architecture as the main mixer, integrating seamlessly within the Xcelon system. Like the Xcelon and XP3 channel expander, Xi3 also includes both pre and post-fader direct output headers for advanced routing and multi-channel recording.

Connection & Configuration

Xi3 is connected to the main Xcelon mixer using the supplied 16-pin ribbon cable, from its port labeled MIXER to one of Xcelon’s two expansion ports labeled EXPANDER 1 or EXPANDER 2. The mixer supports up to two channel expanders using any combination of Xi3 and/or XP3 modules. It is possible to connect more than two channel expanders using a flying bus cable, but low noise performance cannot be guaranteed.

IMPORTANT: The expander ports should NOT be connected to a eurorack power bus or damage to the module(s) can occur.

Each of the three channels has a pair of audio input jacks (IN 10 L, IN 10 R, etc.) for left and right stereo signals. These inputs are designed to accept typical eurorack-level audio signals from -5 V to +5 V (10 Vpp). The jacks are also normalled such that a single mono source in the left jack is simply copied to the right.

Alternatively, two discrete mono sources can also share a channel by configuring the two rear jumpers on the back of the module of the corresponding channel. In the default STEREO configuration, the two inputs are positioned hard left and hard right. With the jumpers in the DUAL-MONO position, the channel input signals are mixed together and positioned in stereo center. Signals that do not need stereo panning can then be doubled-up on a single channel, such as kick and snare drum, two different bass sounds, etc. This allows Xi3 to handle up to six independent mono sources in a compact footprint.

Channel Controls

The VOL parameter adjusts the channel volume with a linear response for smooth fade ins and outs. The jack directly below each pair of audio inputs is the channel’s volume CV input, which allows for external voltage control within a range of 0 to +5V. This voltage input is biased by the VOL knob position (summed). The brightness of the adjacent white LED indicates the channel volume level and any incoming CV.

The channel’s other two knobs, FX1 and FX2, are independent stereo effects sends. Using these parameters, an adjustable amount of the channel signal can be sent to Xcelon’s two shared effects busses FX SND 1 and FX SND 2, which are commonly used for time-based effects such as delay and reverb. On Xi3, both FX1 and FX2 are post-fader sends, meaning the amount of sent signal is also affected by the channel’s volume position.

Note: Unlike the main mixer channels, FX1 and FX2 send levels are manual only and do not have CV inputs.

The AB switch assigns the channel output to one or both of Xcelon’s main output mix busses. In the leftmost and rightmost positions, the channel is routed to only one of the two busses, either A or B. In the middle position, the channel is routed to both simultaneously, allowing for parallel processing, AFL monitoring (after fade listen), and other creative uses.

Expanded Mixing Applications

In addition to general channel expansion, Xi3 is ideal for inputs that do not require frequent hands-on control but remain an important part of the mix. These may include more advanced FX returns, where processed signals are sent back into the mix and rerouted back to the FX busses to create feedback effects or feed into other effect chains for complex textures.

Xi3 is also well suited for integrating stereo submixes, such as a drum submix from another mixer, or parallel processed signals returning from other modules. For example, signals tapped and sent out through the IO module for processing can be returned to Xi3 as stereo channels, with control over volume, stereo routing, and FX sends.

By handling these types of sources, Xi3 makes it easy to integrate supporting elements and processed layers without using full-featured mixer channels.

Direct Outputs

Just like the main Xcelon mixer and XP3 expander, Xi3 is equipped with direct output ports to access individual channel signals for multi-track recording and other routing. Its bank of three stereo channels has two direct output ports, PRE and POST, to tap the channel signals either before or after the volume control.

These groupings of six signals are connected using an 8-pin cable to the optional direct output modules– IO, TRS and DB25 for balanced line outputs, and the CUE module for PFL monitoring. They can be mixed and matched in any order, and both the PRE and POST direct outputs for a bank of channels can be used simultaneously.

Jumper Settings

Each channel has a custom jumper setting found on the back of the module.

INPUT 2 jumpers
STEREO (default) Stereo left and right input (panned left and right)
DUAL-MONO Two discrete mono inputs (mixed and panned center)

Because a channel’s two inputs share a volume parameter, signal balance in dual-mono mode must be adjusted prior to Xi3 input.