THE BLUE BOXMiles Blair Cody Dinges

Derek Glass Greg Entzel

• Members:Miles BlairCody DingesGreg EntzelDerek Glass

• Abstract:The aim of this project is to design and construct an analog guitar amplifier with integrated guitar effects filters that are configurable via a smartphone user interface. To this end, we hope to provide instrumentalists with desired analog guitar tones and effects accompanied with a modern take on a traditional amplifier and effect pedal knobs. In this way, we are able to bridge the gap between a retro amplifier design and devices commonplace amongst the general public today (smart phones). This design has serious impact on the way guitarists think about analog guitar effects; eliminating the need for a large effects board for desired sounds, and removing the tedious nature of changing settings on equalizers and effects pedals. By making tone modification cleaner and more manageable, players can explore and save new guitar sounds with ease, and ultimately focus more heavily on playing techniques.

Introduction

• Why tubes?• Tubes provide a range of tones from mellow to

gritty• Benefits to versatility in tone control appeal to

advanced guitarists

Background – Tube Amplifiers

• Complicated foot pedal board configurations

• Large number of effects needed with unique settings

Background – Filtering/Effects

• Configuring analog effects is limited to pushbuttons and potentiometers• Large configurations have a huge number of settings and thus

knobs• Lack of presets with the touch of one button• Digital alternatives exist• Lose tone with digital sampling

Background – Filter/Effect Control

Approach – Level 0 Decomposition

Approach – Level 1Decomposition

Implementation – Level 2 Decomposition

• Effects and filtering implement digitally controlled analog passive components.• Digitally set potentiometers and resistors for various

functionality• Amplification consists of pre-amplification and power-

amplification• Pre-amp triode tubes provide signal amplitude required for

power-amp• Power-amp provides high-gain

Implementation – Analog Board

Implementation – System Context Diagram

Implementation – Android UI

Main UI Preset UI EQ/FX UI

• Also utilizes Android menu and back buttons:

Implementation - Foot Pedal Interface

• Effects buttons assigned by Android settings• Triggered buttons change color and engage analog

effects via digitally controlled potentiometers/resistors

• 7-Segment displays indicate preset• “Next” and “Previous” preset change buttons below

display• Sequence of presets determined either in order or in

performance mode

Task Derek Glass Cody Dinges Greg Entzel Miles BlairBuild and test filters X     XBuild power supply X X   XBuild amplifier X X X XAndroid initialization   X X  Design User Interface X X X X

ARM data Interfacing   X X  Foot Pedal Interfacing     X XConstruction of Amp X     X

Division of Labor

Schedule

• Power supply – High Voltages• Tube power – Narrow design limits

• Tube interference and sensitivity to noise• Pre-amp design limitations• Bluetooth transmission distance/reliability• Database complexity

Risks