Bugzilla – Bug 12830
Noise + tweeter gets hot
Last modified: 2012-02-27 17:33:35 UTC
By running the POP demo over the weekend on a PB1 and PA5 unit, there was noise on the the tweeter. A woosh-woosh-woosh noise. In addition, the tweeters were hot. I checked the input to the power amplifier for any oscillation, and found a large oscillation on the woofer channel. This could be caused by an instability in the crossover. Steven has heard this noise as well, and he's only heard it on the latest firmware builds (that have the crossover enabled).
I've repeated it a couple of times, just by rebooting several times. I captured an I2C trace, but I haven not been able to find a root cause of the issue yet. The issue can be resolved by simply plugging and un-plugging the headphone. Perhaps there's a subtle timing issue with the I2C bus. This looks more like a software issue, but it's still of unknown origin. I think MPQ can continue, assuming it's a software issue.
Mixing to mono turned off in r6555. Crossover disabled in r6556. Still need demo and factory test files with dsp applied.
We believe this is fixed by not touching the page-1 registers. Assigning to steven for verification.
I have not been able to reproduce since change r6555 and r6556 also the new demo file was modified to play properly without the crossover enabled. I am going to change the target to MP just to be sure to back out the changes to the demo file after the DSP is added back in.
Closing resolved bugs - if you feel this bug still exists please first re-test with the latest SW/FW version. If you are able to reproduce then feel free to reopen and attach new logs / steps to reproduce.