I have designed a USB audio codec based on the TI PCM2900C/PCM2902C USB CODEC chip. It is for characterizing the signals being received from speakers by simultaneously sampling the signal from the microphone and the signal being sent to the speakers. It has the following features:
It can be fabbed and populated by an fabricator/assembler such as JLCPCB. It is available as gerbers or a kicad file at
GitHub - profdc9/AudioMapperUSB
- Amplification for two microphone inputs (up to a gain of 125 or 42 dB gain). The gain stages may be jumpered out if desired to provide a standard line input.
- Phantom power provided to microphone inputs (10 kohm resistor for 5 volts) so that electret or dynamic microphones may be used.
- DAC is 44.1 kHz/48 kHz 16-bit stereo output.
- ADC is 44.1 kHz/48 kHz 16-bit stereo input.
- Can sample the outputs back to the input for synchronizing the audio output signal to the audio input signal.
- Several boards may be chained together to synchronize them.
- A provision for external power input so that the USB power noise (especially USB traffic) does not produce noise on the microphone inputs. It is recommended that a 9-12 VDC linear power supply is used.
- SPDIF input and outputs.
- Feedback resistors can be surface mount or through hole for easy gain adjustments.
It can be fabbed and populated by an fabricator/assembler such as JLCPCB. It is available as gerbers or a kicad file at
GitHub - profdc9/AudioMapperUSB
