Firmware - PM16

This release fixes PM15's configuration saving problem. In every other respect, it is very similar to PM14, implementing Oratory1990s recommended 15-band EQ correction.

Known limitations:

• Erasing configurations still fails occasionally. If you want to erase your configuration, you can do so by trying multiple times, since it doesn't fail every time. IMPORTANT NOTE: TAKE YOUR HEADPHONES OFF YOUR HEAD BEFORE YOU DO THIS. Failure results in wideband noise at very high volume.

Firmware - PM15-BETA

This release implements a post EQ gain stage, which allows the gain of the output stage to be adjusted separately from the EQ gain.

This version of the firmware is compatible with Toolbox version 0.0.5, which you can get here.

**NOTE: This release (temporarily, hopefully) breaks the download config to file functionality. If you need this, stick to PM14 and Toolbox app version 0.0.4. **

Firmware - PM14

This new firmware comes with @oratory1990's 15-band EQ, which matches the Harmon 2018 curve to an average of 0.66dB.

In order to achieve this, this build includes @george-norton's firmware speed optimisations, which took the number of available EQ bands from 7 to around 18.

This is a breaking change for the Headphones Toolbox; if you have a previous version of the Headphones Toolbox installed, you'll need a new version, which you can get here.

Firmware - PM13

Fixes a number of bugs affecting the firmware due to the increased number of filters. This release alleviates issues with changing the volume, the DAC being "stuck" on mute, drivers failing to work after unplugging and replugging, and a number of other issues.

Firmware - PM12

Update the default EQ to an 8-band set based on measurements from Oratory1990 and VSG. Should conform broadly to the Harman OE 2018 target, with a little less emphasis on bass (frequencies below 80Hz or so) than the profile recommends.

Known issues:

• If you have used the Headphones Toolbox to set a custom EQ and would like to try this firmware, you will have to erase the custom configuration. To do this, click the burger (three vertical dots) in the top right corner of the Toolbox window and select "Erase Selected Configuration." Then close the app and power cycle the DAC. On startup, the DAC should read the default configuration in firmware.

Firmware - PM11

• Fixes a bug that causes some DACs to operate fully after they are first programmed, but fail to startup after they've been power-cycled. Big thanks to @Roosta078 and @keeb-time for diagnosing and contributing the fix to this issue.

Firmware - PM10

• Compatible with @george-norton 's very lovely Headphones Toolbox.
• Implements a Q3.28 fixed point scheme for DSP that reduces the DAC noise floor by about 10dB.

Known issues:

• Using filters with biquad coefficients >abs(4) may cause clipping due to numerical overflow; high and low shelf filters are particularly prone to this. If in doubt, calculate the coefficients manually to verify they are in range.