The Bridge - Issue 2, 2020 - 16

Chapter Spotlight

Graduate School Spotlight

Senior Design Poster Competition
Congratulations to the winner of the Senior Design Poster Competition, Matan Silver,
the President of the Gamma Beta Chapter at Northeastern University. Matan and his team
developed a "Wireless Audio Control Interface" as part of their capstone project.

Wireless Audio Control Interface (WACI)

Custom circuit board manages
communications between user's computer
and wireless modules
* Implements circuitry for 6 input, 8 output
audio interface
* Support for 192kHz/24 bit sampling
* Four inputs have microphone preamps;
each can provide phantom power
* Preamplifier circuitry introduces minimal
noise to incoming signals
* Over 600 electronic components per Hub
* Custom firmware on XMOS microcontroller
to implement Audio Class 2, CDC serial port
and DFU firmware upgrade services
* Communicates wirelessly with Modules
using ESP32 wireless card
* Requires no additional hardware besides a
computer and wall plug
* Schematic and layout in Altium Designer



System Overview

* Seamless distributed system for small performing ensembles to wirelessly control
audio effects and processing for multiple musicians
* Leverages musicians' existing audio processing software for simple learning curve
* The Hub supports class-compliant multichannel audio input/output over USB
* Users can send MIDI commands to any connected device
* Cost and reliability advantages over using smartphones for wireless control
* All circuit boards designed,
populated, tested, and reworked
by hand
* Laser-cut enclosure for the Hub
prevents mechanical strain on the
circuit board



Jess Bardio, Louisa Beckwith, Joshua Berlin, Philip Del Signore,
Matan Silver, Andrew Whitaker; Advisor: Prof. Bahram Shafai


Are You
Eta Kappa Nu?


Battery powered Modules send encoded
MIDI commands to Hub over Wi-Fi
Fully wireless; can be freely moved around
the stage within a 200-foot radius
Each Module can be outfitted with various
UI components (knobs, buttons, foot
switches, screens, etc.) to fit musician's
OLED display shows status/configuration
Low cost; each musician can use multiple
Low-power design enables 24 hour battery
Battery charging over USB-C
USB port allows Modules to act as an
ad-hoc Hub

Show Your Eta Kappa Nu!

Matan Silver

If it's not on your card, it's not in your
IEEE membership record. Let us know!
Andrew Whitaker

MS and PhD Programs
Bio | Communications | Embedded
Optics | Quantum | Wireless

Jess Bardio

Apply at
Joshua Berlin

Louisa Beckwith

* Cross-platform desktop
application programmed
in Electron enables
pairing and configuration
of Modules to the Hub

Philip Del Signore

Musicians are increasingly utilizing digital effects to create unique sounds during live performances. In a band with many performers,
a dedicated technician will typically operate the audio system; a portable, customizable system allowing all musicians to fine-tune their
effects in real time does not currently exist on the market. To bridge this gap and introduce a lower-budget solution, the Wireless Audio
Control Interface (WACI) system implements a new method for controlling and mixing audio using conventional performance software.
The WACI system consists of a central Hub that can connect to many wireless Modules to suit users' needs. The system doubles as
a 6-input, 8-output audio interface with MIDI support. In this system, each musician can have a Module to control their own effect
models, while the Hub provides a central processing link for all instruments. The Hub is a circuit board developed by this capstone
group that contains all electronic subsystems necessary for live audio processing. Four XLR/TRS combo jacks allow instruments
or microphones to be plugged directly into the board. The Hub also includes circuitry to power devices such as microphones that
require a 48V "phantom power" supply. These analog signals are converted to high-resolution digital representations at up to
194kSPS/24bit and sent to a computer over USB for effects processing. The commands to apply and alter these effects are sent to
the Hub, and then to the computer over USB-MIDI, from wireless Modules via an 802.11 WiFi connection. Finally, processed digital
audio streams are sent from the computer to the Hub over USB, where the Hub converts them back to analog signals and outputs
them to speakers or an amplifier. The USB connection is managed by the main microprocessor, whose firmware implements USB
Audio Class 2 over a Type C connector for native operation in Windows 10 or MacOS. The Hub is powered by a standard 12V DC
wall adapter. The Modules are wireless control panels resembling guitar pedals or control panels that musicians can use to remotely
adjust audio parameters on the computer. Each Module is battery-powered and has re-assignable physical controls. Module hardware
configurations include pushbuttons, sliders, knobs, and foot pedals, allowing for various modes of adjustment that feel natural to a
musician. Each Module has a display to show status information. The Module circuit boards were developed during the capstone term.
Finally, the WACI system is managed by a custom cross-platform desktop application with the ability to connect Modules and manage
settings, such as Module names and MIDI commands. The desktop application also displays critical Module status information,
including battery charge level and wireless signal strength. Based on configurations made in the desktop application, the Modules
can wirelessly update effects running in any audio processing software.




The Bridge - Issue 2, 2020

Table of Contents for the Digital Edition of The Bridge - Issue 2, 2020

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The Bridge - Issue 2, 2020 - Contents
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The Bridge - Issue 2, 2020 - Cover3
The Bridge - Issue 2, 2020 - Cover4