GFX
Software Guitar
Sound Effects
Synthesizer
Abstract
The existing technology used to create guitar sound effects is often prohibitively expensive
to the amateur guitarist. The object of this project is to provide an affordable alternative
that uses the computational power of modern personal computers to simulate guitar effects.
The Universal Serial Bus (USB) provides a fast interface with the PC, allowing for soft
real time communication with the multi-effects pedal. Through this interface, the
computer modifies the guitar signal based on mathematical models for each effect. This
software implementation well enable the addition of other effects in the future.
Electric Guitar
Introduction
The electric guitar is a popular instrument in today’s music due to its broad range of effects. The cost of the effects hardware, however, is often too high for amateur
players, so the GFX project solves that problem by leveraging the PC and the new USB interface. The remaining hardware consists of USB microcontroller and
mechanical pedals for switching between effects, while the software simulates effects on the PC and controls the communication on the USB. The GFX system
tolerates temperature range within 50 to 80 degrees Fahrenheit and accepts electromagnetic interference from 60 Hz power lines. The major assumption involves the
user’s ownership of the electric guitar, audio amplifier with speakers, necessary cables, and a modern PC compatible with USB and a minimum processor speed of
500MHz. The limitations include a maximum of three mechanical on/off pedals and one analog pedal, while the sound quality will be limited by the resolution of the
ADC and DAC. The maximum amount of sound effects in a sequence will be limited by the speed of the host PC such that the maximum latency will be 10ms.
End Product Description
The Guitar Effects Synthesizer pedal has standard quarter inch audio in and out
phono jacks to be connected to an electric guitar and guitar amplifier. The device
also has a USB interface so that it can connect to a standard PC. The pedal has
three digital switches and one analog “expression” pedal for interactive control of
the effects produced. The PC software applies the user-defined combination of
effects (such as distortion, chorus, and wah) to the audio signal, and can be
controlled by the foot pedals as well as standard PC input devices.
Personal
Computer
Multi-Effects
Pedal
Design Requirements
The Guitar Effects Synthesizer must be easy for the guitar player
to use and have an easy to use software interface. It must support
a wide berth of effects and be inexpensive. The user interface
must allow users to switch and chain effects just like an existing
analog effects pedal. The pedals must be programmable so that
the user can choose what effects to use. The synthesizer must
correctly sample the input from the guitar, process the input, and
correctly output the modified signal. The Guitar Effects
Synthesizer must have negligible latency and be USB compatible.
It must also operate in a normal PC environment.
Milestones
•Selecting hardware
•Selecting development environment
•Establishing communication between PC and synthesizer's
microcontroller
•Implementing guitar effects signal processing algorithms
•Implementing graphical user interface
Budget
The total estimated cost of this project is $340.
The total estimated hours of personal effort estimated is 1651.
Technical and Testing Approach
The project is implemented using a parallel approach and is divided
into four parts: microcontroller and hardware, interface between
hardware and software, graphical user interface, and effects
programming. An iterative approach is used for testing which
involves testing at each stage of development.
Team number may0017:
1. Kevin Crotty
CprE
2. Lukasz Darowski
CprE
3. Nathan Linquist
CprE
4. Sriram Narayanan
CprE
5. Dan McPartland
CprE
Advisor/Client:
Dr. Stephenson
Web Page
http://seniord.ee.iastate.edu/may0017
Audio Output
Device