Project

Initially, Project Spacetrip was going to be tasked to solely build an analog synthesizer. After meeting the team’s advisor, Professor Barry Dorr, a final decision was made to have the team split into two, one working on the synthesizer and the other on an audio amplifier. This key decision was made for two reasons: to divide the work of the project fairly among all team members and to have a more complete project by the end of Senior Design. Upon completion, the team will have a fully demoable setup that can be played during the Design Day Fall 2019.

The primary goal of the amplifier team is to create a low cost, efficient, and effective audio amplifier to compliment Project Spacetrip’s synthesizer. The synthesizer will be a compact modular synth with its own standard MIDI input. Our design will be similarly sized with a single channel ¼’’ stereo/mono input. The final setup will be comprised of the following: a MIDI keyboard, the analog modular synthesizer, our audio amplifier, and a speaker box to be designed by our team.

Another major project design decision was to have our audio amplifier separate from the speaker box. The team decided to make these separate to make the amplifier compatible to other 4 Ohm speakers, that is to allow the user to be able to replace just the speaker if needed rather than have to replace an entire unit comprised of both amplifier and speaker in a single box. Again, this was decided to maximize cost-effectiveness and convenience for the user.

This leads us to our most important design decision, the type of amplifier to be constructed. Audio amplifiers can get costly and there are so many to choose from. When deciding on one, it is important to know what it will be used for as they come in a variety of sizes for different purposes. Our amplifier is a cost effective solution to anyone who is looking to get into electronic music, as well as for any audio musical enjoyment. With that in mind, it was a relatively easy decision to design a Class D amplifier.

Unlike other classes of amplifiers, Class D is known for its high efficiency ranging from 80% to as high as 95%. This is because Class D amplifiers are switching amplifiers in contrast to traditional Class AB, A, and B amps which are linear amplifiers. While linear amplifiers dissipate considerable power, power dissipation in Class D amps is close to zero. The trade-off is that Class D amplifiers exhibit THD of 0.1% to 1% at best in comparison to the other types achieving THD below 0.01%. Linear amplifiers are recommended for high fidelity applications for this reason. However, our amplifier is meant for small scale applications. Class D application for the amplifier will allows for amp to be low cost, efficient, and compact.