Honors Theses

Date of Award

Spring 5-1-2021

Document Type

Undergraduate Thesis

Department

Electrical Engineering

First Advisor

Paul Goggans

Second Advisor

Elliott Hutchcraft

Third Advisor

Barry Muldrey

Relational Format

Dissertation/Thesis

Abstract

A dynamic loudspeaker mounted in an open baffle has the same parameters as a loudspeaker in free space. A subwoofer mounted in an open baffle has a small total quality factor and therefore the frequency above which the driver has a significant output is too high despite the subwoofer's low resonant frequency. To address this issue, we implemented a motional feedback circuit with the goal of introducing both velocity feedback and acceleration feedback into the loudspeaker system and thus altering the resonant frequency and total quality factor of the system. After verifying the efficacy of our feedback circuit with computer simulations, we first tested it using a Sallen-Key highpass filter to model the power amplifier, loudspeaker, and accelerometer and we were able to obtain desired results. We then connected the motional feedback circuit to our loudspeaker and collected pertinent testing data. While this data was not perfect due to noise within the circuit we are able to see the effects of the feedback circuit on the frequency response of the loudspeaker and get velocity and acceleration responses that we were looking for.

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