Category Archives: Documentation

Nexus Update: MIDI Module

      Documentation, Electronics, Nexus, Support Electronics

This is the third part of the Nexus documentation series. The first part documents the Basic Kit, the second part details the Mixer Module. This time, we explore the MIDI Module. Eventually, all of this will end up in a single document.

The MIDI Module converts control voltages (CV) from the guitar to MIDI. The basic firmware supports up to 6 analog and 7 digital inputs. The Multichannel Guitar Input (see Basic Kit) can carry up to seven control voltages or switches. Some of the back panel 1/4″ jacks may also be repurposed to carry additional control voltages or switches. The MIDI output is sent through a standard 5-pin DIN connector at the back panel.

Note: Please do not be confused with MIDI control and MIDI conversion. The MIDI module does not do any pitch tracking and MIDI conversion of the notes.

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Nexus Update: Mixer Module

      Documentation, Nexus, Support Electronics

This is the second part of the Nexus documentation series. The first part documents the Basic Kit. This time, we investigate the Mixer Module. Eventually, all of this will end up in a single document.

The (optional) Mixer module is a daughter board that sits atop the Main Board (see Basic Kit). This module provides a simple, yet extensible and hackable mechanism for mixing (up to) 12 audio channels down to stereo. Each channel can be mixed to either left or right using the L/R selector configuration headers.

The diagram at the right shows the routing for each channel. The center pins connect to the buffered outputs of channels 1 through 12 via 10K summing resistors. The left and right pins connect to the summing junctions of a dual OpAmp (OPA2209 low noise precision operational amplifier). The mixer gain is -1.

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Nexus Update: Basic Kit

      Documentation, Nexus, Support Electronics

I’ll be providing the Nexus documentation in tranches. This is the first part of the series. Eventually, all of this will end up in a single document. Let’s start with the Basic Kit.

nexus-block-diagramThe Basic Kit includes the 1) Main Board where all signals from the multichannel input as well as control voltages pass through, plus where power regulation and conditioning are handled, 2) I/O Module: 12 channels where each channel can be configured as an input or output. Typically, these are used to send multichannel audio to your effects, amp, mixer or multichannel audio interface. But, if you do not need all 12 channels, they can also be configured as inputs (e.g. Foot switches and Expression pedals). The Basic Kit includes the blue boxes in the Nexus block diagram at the right.

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