Rockbox General > Rockbox General Discussion
Setting limit volume on rockbox?
scharkalvin:
You know I think Apple was SUED by someone who claimed an ipod damaged their hearing, and I think they ended up adding something in the hw or software that limits the volume to the earphones. Setting an upper limit would be just compare current volume setting in db to limit, if less allow increment, else stop at limit.
Two lines of C code maybe. (but more need to build a menu to set the limit. Still the menu could be a plugin and the limit a global byte of ram?)
Of course you could also do something similar with a battery, a resistor or two, and two back to back diodes wired in series with the earphones and the earphone jack to clip the volume at a maximum voltage level. Maybe use Zener diodes to eliminate the battery.
In other words an inline volume control, which many headphones have. So just set rockbox at max volume, adjust the headphone volume control to a comfortable max level, scotch tape the volume control, and then use rockbox to control volume.
Febs:
--- Quote from: scharkalvin on November 13, 2007, 02:13:15 PM ---You know I think Apple was SUED by someone who claimed an ipod damaged their hearing, and I think they ended up adding something in the hw or software that limits the volume to the earphones.
--- End quote ---
Far too much speculation here.
--- Quote ---Setting an upper limit would be just compare current volume setting in db to limit, if less allow increment, else stop at limit.
Two lines of C code maybe. (but more need to build a menu to set the limit. Still the menu could be a plugin and the limit a global byte of ram?)
--- End quote ---
Why is this necessary when a total of 36dB of gain reduction can be applied via the Replaygain pre-amp and the EQ pre-cut?
yapper:
If the 'safe listening' levels in this article (http://www.usatoday.com/tech/news/2006-03-29-ipod-volume_x.htm) can be trusted, the 36dB reduction mentioned by Febs would reduce the playback level to a 'safe' level ....
but if you are playing your music in the car, you have another amp that isn't limited by Rockbox, so there isn't going to be an absolute sure fire solution to the 'problem'.
soap:
The sonic energy delivered to your eardrum depends on so many factors*, there is no place for blanket statements at all. I too have seen 80-85 decibels quoted as safe...
*ear shape, headphone style (IEM, buds, supra aural, etc.), headphone efficiency, physical placement of headphone on/in ear, yadda yadda yadda
Febs:
Also note that "safe" volume levels are measured in dB SPL (where the SPL = "sound pressure level"), which has no bearing whatsoever to the Rockbox volume scale.
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