FS#12455 - Any EQ Low Shelf change from 0.0 causes click at start of tracks

Attached to Project: Rockbox
Opened by Julian Hughes (Takla) - Thursday, 15 December 2011, 19:14 GMT
Task Type Bugs
Category Music playback
Status Unconfirmed
Assigned To No-one
Operating System All players
Severity Low
Priority Normal
Reported Version Release 3.9
Due in Version Undecided
Due Date Undecided
Percent Complete 0%
Votes 0
Private No


Hardware: iriver H140, iriver H340, Sansa Clip+

Rockbox version: 3.10 downloaded from
I have also reproduced bug on official firmwares as old as 3.5.1, and on my own builds.

Settings: 100% default except for enabling EQ and setting an EQ i.e. using graphical EQ to set LS -0.5 at 60Hz or LS +1.5 at 60Hz

Expected behaviour: music track, however loaded, starts in normal way, with no sounds other than those decoded from file. Restarting the track results in the same normal playback.

Actual behaviour: music track starts with an obvious and intrusive click. This happens whether the track is loaded individually, or if it is the first track of an album loaded via .m3u playlist. When using playlist subsequent tracks play normally, without a click. But restarting any track causes the click.

It makes no difference if the EQ Low Shelf Filter settings are a big change from flat, or a tiny difference. To induce the bug it's enough that EQ is enabled and LS is not set to be flat i.e. just an increment of +/- 0.5 dB is enough, and changing the cut off frequency or the Q factor made no difference.

This bug is noticeable with any track that starts quietly, and especially with tracks from CDs that are not mastered to modern high levels.

The Clip does tend to make its own small click on manual track changes and some button presses; I am not confusing this with the bug I describe. On the irivers I get a single click, while on the Clip I get a very unmusical double click.

I've attached my H140 config to illustrate that the config is unremarkable and that apart from the EQ it is at default. If anyone needs me to try stuff or make any changes or try a patch that is fine, but I would prefer it to be on an iriver because the Sansa OF database refresh is so annoying.
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