Audio recorder (.wav) w/o audio shield


New member
Hello everyone for a project I want to record audio signals from a line-in signal as a .wav file on a sd card. I'm using a teensy 4.1. I found some projects that can do just that (for example:, however they all use the teensy audio shield. Is there a way to record .wav files without the audio shield and if so, are there any libraries or examples that could help me doing that?

p.s. I'm still quite inexperienced in that field so keep it simple
In order to use line-in you need an audio-shield. Teensy 4.1 does not provide line-in.
If you have an I2S device (digital Microphone) then you do not need audioshield.
In both cases you can use/modify most recorders published over the years here on this forum as the audioshied uses I2S to transfer data to Teensy.
Teensy 4.x does NOT have any ADCs.

EDIT: Got confused. It does have ADCs but NO DACs. Sorry, had a bad night last night. Brain not running on all cylinders this morning. OOps it's afternoon, told you.
Last edited:
what if i connect the outputs of a microphone to the ADC's of the Teensy?

You can connect an audio signal to A2 (pin 16), but it must be approx 3V peak-to-peak level. The tiny voltage directly from a microphone won't work. You'll need a preamp to boost the level. Details here:

A strong drive (or low impedance in more technically correct terms) at the A2 pin is required to overcome coupling from the digital circuitry inside the main chip. Even if you do this the quality is not as good as using the audio shield. But it is possible if you can deal with these limitations and live with mediocre quality.