Red Hat Bugzilla – Bug 836154
should use lower pre-gain
Last modified: 2013-07-31 20:36:33 EDT
Description of problem:
The equalizer offsets the volume too high which leads to distortion for any band that is set above 0 dB in the equaliser (if the sound source is loud enough in that band).
Version-Release number of selected component (if applicable):
Steps to Reproduce:
0. use some good soundcard, amplifier and loudspeakers/headphones to eliminate possible problems caused by the low quality of hardware
1. run pulseaudio-equalizer-gtk
2. set some bands amplification above zero - for example +10 dB on 50 Hz and 100 Hz bands
3. play some music you know to be distinct in those bands - in the bass example, you may use e.g. Ace of Base - The Sign (http://www.youtube.com/watch?v=iqu132vTl5Y)
the sound is distorted
the sound is clean
I wonder if this is the same issue as bug #711152 ... however,
1) I wouldn't describe it like "Sound is distorted beyond comprehension" - it's more like a simple overdrive
2) if I understand that issue correctly, the distortion happens always when using the equaliser; for me, it happens only if I pull the sliders above zero, when set to zero or below, I cannot hear any distortion
looking into console output, I see there is:
Transferring current mute (0) & volume (50%) to LADSPA sink (ladspa_output.mbeq_1197.mbeq)...
Setting ALSA sink (alsa_output.pci-0000_00_1b.0.analog-stereo) preamp (1.0x)...
Setting LADSPA sink (ladspa_output.mbeq_1197.mbeq) as default sink...
Moving active PulseAudio clients to LADSPA sink (ladspa_output.mbeq_1197.mbeq)...
I've tried to modify the config file ~/.pulse/equalizerrc and set the fourth line, which seems to correspond to the preamp value, to 0.01, then to -10, and it doesn't have any effect on the volume
so it looks like the problem is here, that it a) doesn't get applied b) the default value is nonsense, it should be less than 1 to make room for the corrections
note, I see that LADSPA mbeq_1197 is used ... if it was pure ALSA solution then another plugin amp_1181 would be chained ... don't know how with pulseaudio though ...
Thanks Karel for reporting this bug.
I disabled preamp back at bug #639604.
You can try to rebuild it without the patch and see if it solves your problem.
For reference the patch is :
(In reply to comment #2)
> You can try to rebuild it without the patch and see if it solves your
unfortunately not, pulling the "preamp" slider just messes with the main volume ... hm, I see you mention this behaviour in bug 639604 comment 2
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