ECE 110/120 Honors Lab Section : _Audio Channel Strip

Timeline:

1. Research Phase (3/10/2022):
   1. Decide Designs, Parts Order List, 3D Printing Housing
   2. Order Parts before/during Spring Break
   3. Implement Digital Logic (Arduino controlled Light System)
2. Protyping Phase (3/20/2022):
   1. Construct on BreadBoard
   2. Test each Component & Debug
3. Final Design Phase (4/5/2022):
   1. Fix Problems 
   2. Design PCB
   3. Order PCB
4. Manufacturing (4/10/2022):
   1. Build Final PCB
5. FINAL TEST / PRESENTATION (5/01/2022):
   1. Test PCB and Final Presentation

Statement of Purpose 

The goal of this project is to create a simple audio mixer channel strip with an equalizer! The goal of our project is to create a hardware audio equalizer that will take in input from a microphone, amplify it, filter it, and output the sound to a speaker or DAC to a computer. Our project will be unique because the hardware implementation will be on a custom PCB that will be made by our group. This will also be a cheaper, more portable solution to buying a high-end audio equalizer.

Background Research

We have looked into audio filtering such as high pass, low pass, and band-pass filtering. This project was inspired from learning more about audio frequencies and audio signals. Although this is a higher-level topic, it will give our group room to explore and learn material related to ECE 110 & ECE 120. This project is important because it allows our group to gain hands-on experience with electronics and signal processing. 

Other projects that we considered completing were creating user devices like a keyboard or calculator. We also looked into making a drawing paper, which would have the same functionality as a normal drawing pad, but it will have the texture of normal paper. Out final proposal, an audio equalizer, it a more involved project that would give us more room to learn.

Block Diagram / Flow Chart

System Overview

1. XLR input

Receive analog audio signal with a XLR(RCA?) connector.

2. Gain control

Amplify the input signal to a higher level signal. Can decide to what degree it is amplified.

3. Equalizer

Filter the audio signal by cutting and boosting certain frequencies, e.g. a high pass filter, and shape the sound.

4. Panning

Control the amount of audio signal going to left and right speakers. Stereo control.

5. Fader

Control the Volume after the signal has been processed by the above processors/filters.

6. Output

Port for the output signal. XLR or 1/4in Female connector.

Parts

Possible Challenges

Poor manufacturing may degrade the audio signal.

The Equalizer filter may not work as desired - changing different frequencies than intended, or causing artifacts in the processed signal.

The transition between adjusting different signal levels may not be smooth, resulting in undesired noises.

The XLR and 1/4in ports have to be mechanically stable to withstand plugging in and unplugging cables, and not be ripped out from the circuit.

Need to split up the signal into two separate signals for stereo output. Or make the channel stereo (two input signals) in the first place.

Crosstalk?

References

[1]A. Bhatt, "Circuit Design: Automatic Gain Control", Engineers Garage, 2022. [Online]. Available: https://www.engineersgarage.com/circuit-design-automatic-gain-control/. [Accessed: 14- Feb- 2022]

[2]F. Donald, "2 channel Audio Equalizer circuit - Gadgetronicx", Gadgetronicx, 2022. [Online]. Available: https://www.gadgetronicx.com/2-channel-audio-equalizer-circuit/. [Accessed: 14- Feb- 2022]

[3]"Simple Panning Mixer / Mixer Circuit", Sagittronics, 2022. [Online]. Available: https://sagittronics.wordpress.com/2019/02/17/simple-panning-mixer-mixer-circuit/. [Accessed: 14- Feb- 2022]

[4]T. Organic Chemistry Tutor, Youtube.com, 2022. [Online]. Available: https://www.youtube.com/watch?v=CKaDxZrjaGA&t=568s&ab_channel=TheOrganicChemistryTutor. [Accessed: 14- Feb- 2022]