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I am trying to use a UDA1334A I2S DAC module (pictured below on the right) with an ESP32-S3. UDA1334A I2S DAC module I connected everything as described in the documentation by Adafruit (https://learn.adafruit.com/adafruit-i2s-stereo-decoder-uda1334a?view=all) and it mostly works as expected. Here is a summary of the connections:

DAC     ESP32
VIN --- 5Vin
3VO --- not connected
GND --- GND
WSEL--- 5 
DIN --- 18
BCLK--- 4

The module works fine for low amplitude signals but when I try to increase the amplitude to 2^23 (maximum for 24-bit DAC) the signal gets very distorted (sine wave sounds more like a square wave).

I measured the output signal with an oscilloscope, and it is indeed very distorted when the headphones (20ohm) are connected: distorted signal

However, when I disconnect the headphones, the signal appears normal: normal signal

What could be the cause of this issue and is there a way I could fix it?

I bought the DAC module from AliExpress (https://www.aliexpress.com/item/1005004350631653.html?spm=a2g0o.order_list.order_list_main.54.16081802mjz3qN).

I also tried a different DAC based on PCM5102A (https://www.aliexpress.com/item/32917291480.html?spm=a2g0o.order_list.order_list_main.35.16081802mjz3qN) and experienced the same problem.

The culprit for the problem could be the too weak power supply from the ESP32, so I tried to connect the DAC module to a lab bench power supply. But the distorted sdignal remained unaffected.

Perhaps the problem is caused by the poor quality of these modules. If that is the case, I would love to hear suggestions for a better module.

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    \$\begingroup\$ Is the UDA1334 capable of driving headphones directly? I think you need a power amplifier in addition to the DAC. \$\endgroup\$
    – Hearth
    Oct 9, 2023 at 13:05

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There is no issue, these modules do not need fixing, and they are not bad quality (at least not in this regard).

You are just using the modules incorrectly by connecting headphones to them.

They are not intended to drive headphones.

It even reads "LINE OUT" on both modules, at least in the links you show. That means, do not connect headphones, connect to audio system with line input.

If you want to drive headphones, use an amplifier that can drive headphones.

This section from the module webpage describes the expected behaviour in detail:

Note that this DAC was intended for use with a separate amplifier and is rated for a 3 KΩ load. However, we've found you can plug in 32Ω headphones and the output is current-limited so it won't damage the DAC but you will get distortions. (Powered headphones won't have this issue)

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