The goal is a fixed installation for an exhibition—something interactive yet low-maintenance. It doesn’t need fancy controls or a screen but should handle sound input (a microphone), sound processing (a DSP chip), and sound output (a speaker). Here are the main requirements I jotted down:
- Input: Microphone for sound capture.
- Processing: Leave room for effects like reverb or delay in the future.
- Output: A small speaker to amplify and play back the processed sound.
- Power: Needs to run on batteries for portability.
The First Questions
- What kind of microphone should I use?
I found two options:- Electret Microphone: Reliable and cost-effective, but not very sensitive.
- Condenser Microphone: Better sensitivity, but requires phantom power.
- How will I process the audio?
I stumbled upon the ADAU1701 chip, which looked like a great solution. It’s a small DSP that can be programmed using SigmaStudio. I also plan to use an Arduino to integrate it. - How do I amplify the output for the speaker?
After some research, I settled on the PAM8403 module, which is simple and works well with 4Ω, 3W speakers. - What about power?
I already had two 18650 lithium batteries. With a TP4056 module for charging and an MT3608 module for boosting the voltage to 5V, this part seemed manageable.
Here’s what I ordered for the initial build:
- Microphones: Both electret and condenser types.
- LM386 Preamp: To boost the microphone signal.
- ADAU1701 DSP Module: For audio processing.
- PAM8403 Amplifier: To drive the speaker.
- TP4056 Charging Module: To handle the lithium batteries.
- MT3608 Boost Converter: To regulate power output.
I also grabbed breadboards, jumper wires, resistors, capacitors, and some basic tools. This should be enough to build a prototype.
I wanted the design to be modular, so each component could be replaced or upgraded later. For example:
- The DSP can be programmed to add effects down the line.
- The amplifier and speaker can be scaled up if needed.
I mentioned the acupunctual head model in my previous blog and I would have to get it from China. It usually takes 10-15 days to deliver after purchase and after price comparison I ordered all these gadgets from China as well. I lined out this whole plan in the early October and I wish all these components could be arrive soon so that I would be able to experiment earlier.