# @gokul https://tscircuit.com/gokul/

Channel: #designreview
Source: https://discord.com/channels/1233487248129921135/1565067740606374120
Started: 2026-10-28T18:20:55.297000+00:00
Last activity: 2026-10-28T18:21:23.910000+00:00

## Abse — 2026-10-28T18:20:26.913000+00:00

<@1366026906637434941> https://tscircuit.com/gokul/pocket-audio-player

## Abse — 2026-10-28T18:20:56.500000+00:00

The main findings:
1. USB routing is the largest layout concern. D+ and D− take separate routes across both copper layers, with multiple transitions. They don’t maintain a consistent differential-pair geometry. Rework this path with a continuous ground reference, controlled spacing, and fewer transitions. This is a reliability risk; I haven’t demonstrated that USB will fail. Espressif’s layout requirements.
2. The output capacitors noticeably reduce low bass. C48/C49 are 220 µF. My ideal RC calculation predicts:
   Headphone load    Bass loss at 20 Hz
   16 Ω    7.9 dB
   32 Ω    3.6 dB
   64 Ω    1.2 dB
   
   
   Choose the supported headphone impedance and frequency-response target. Larger capacitors or a suitable capless output design could improve this, with corresponding fit and startup checks.
3. Software sleep leaves significant loads powered. The power LED remains on, the regulator’s power-save mode is disabled by its hardwired PS/SYNC connection, and the SD supply remains connected. ESP32 deep sleep therefore won’t establish low whole-device consumption. Add power control where needed and measure system sleep current.
4. USB input current is fixed at the 500 mA mode. The charger cannot switch to USB100 or suspend under firmware control. Define behavior for computer ports versus known charging supplies, including attachment and suspend conditions. BQ24074 documentation.
5. Headphone insertion needs testing. The jack-detect contact is unused, and the jack-side capacitor nodes have no authored bleed resistors. The startup mute delay doesn’t establish quiet hot plugging. Measure insertion, shutdown, and wake transients.

## Abse — 2026-10-28T18:21:08.645000+00:00

check and address these

## gokul — 2026-10-28T18:21:23.910000+00:00

yeah i'll fix that