Support and General Use > Hardware
Hardware EQ for Ipod 5th gen.
h.finn:
Ok,
Here's my setup:
Graph. Eq:
2.5 60 6.4
5.5 450 6.0
1.5 4000 2.1
2.5 15530 2.2
Bass: +8
Treble: +12
Volume:-76dB
And the Bass is way more distorted than with the same settings on the Mini!!
I use a good quality LOD (Line Out Dock) and "class T" amp + excellent Italian loudspeakers from the early 80s.
The files are almost all uncompressed flac.
Many thanks,
H.
torne:
You're using the software graphic equaliser *and* the hardware tone controls? That's kind of an odd thing to be doing. You are boosting the bass twice: first Rockbox's equaliser adds 2.5dB to all the frequencies under 60Hz, then the DAC is doing it again by 8dB (not sure what shelf it uses). That's a lot of boost and doing it in two seperate ways probably doesn't help. Also, your Q value for the bass shelf is 6.4 - the manual explicitly says that you should leave it as 0.7 for the shelf filters. You're doing the same for the treble, of course...
-76dB volume is incredibly quiet. You mention you are using line out, which means that the entire top range of the volume adjustment will do nothing, since line out is line level by definition; however, Rockbox supports a wider range of volume adjustment than the DAC does, and we simulate the extra range by digital processing of the audio to reduce the volume before passing it ot the DAC. If you have it turned down to -76 in order to reach this, then this means you are introducing a *third* set of audio processing. You shouldn't use the volume control this way; leave it on a normal setting and control the volume externally if you are using line out.
The DACs and analogue hardware are not identical between the different models, so while yes, normally people expect the Video to sound better, your settings are highly abnormal and it's hard to say what to expect ;)
h.finn:
Hi Torne,
I appreciate your precious suggestions!
So: I should use either the graphical eq or the hardware, right?
If I go for the former: any suggestion about a good bass boost? ;)
I put the volume at -76dB (and obviously increase the volume on my amp) to avoid any distortion.
That's the only effective way I found to do it.
I don't understand:
"You mention you are using line out, which means that the entire top range of the volume adjustment will do nothing, since line out is line level by definition; however, Rockbox supports a wider range of volume adjustment than the DAC does, and we simulate the extra range by digital processing of the audio to reduce the volume before passing it ot the DAC"
Thanks again,
H.
torne:
Line out is line level, 0dB, i.e. it's not affected by volume changes. This is normal and should not cause distortion.
Turning the volume down *very* far, as you are doing, switches Rockbox to a mode where it actually reduces the volume of the digital audio in the DSP stage; this is not something you should have to be using to avoid distortion.
Read the manual for suggestions as to how to configure the graphical equaliser; it's a matter of taste, but as saratoga pointed out, you generally want to either *lower* certain frequencies, or set the precut (overall volume reduction) to be at least as big as the highest boost amount, to avoid distortion and clipping.
The hardware tone controls (the bass/treble settings) automatically precut the volume as needed, but I'm not sure if this precut actually works on line-out. If you can get the audio effect you want using only those, then it's more efficient to leave the equaliser disabled, since the tone controls are "free" whereas the EQ uses CPU time.
h.finn:
Allright,
.........so basically you suggest I stick to the bass/treble settings (by the way, the bass precut works through the LOD dock) and leave the graphical eq "untouched" (i.e. the way it is when first installing RB)?
Thanks
P.S.: could you tell me how to know the "current" eq settings, the ones using at any given time?
P.P.S.: just found this:
http://www.rockbox.org/tracker/10768
"Details
I'm reporting a bug which we tracked down in the german rockbox forum.
Rockbox plays a loud distortion (without music) if you have bass and equalizer both turned on. Any bass setting above 0 shows this behavior.
Tested with a current build after reseting the settings. (r23566-091108)
steps to reproduce:
01. download current build
02. reset settings
03. apply bass
(no distortion this far when resuming playback via menu)
04. apply EQ, > distortion when resuming playback after stop
05. turn off bass > no distortion"
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