Sam Kuper wrote: > 2008/10/13 <[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>> > > I was *very* disapointed when I discovered the audio quality via > headphones:in IRC they told me that it was because the capacitor(that is > between headphone out and the sound card)'s value was too low and > acted as > a filter... > As I am too afraid of breaking the openmoko i won't change the capacitor > myself...but what could I do? build/buy an external amplifier(will > it work > fine?) or find a place where they could remplace me the capacitor? > > > I wasn't aware of this problem, but if what you are saying is that the > headphone out socket of the phone has a capacitor connected across it > that is attenuating the high frequencies, then an external amplifier > connected to that socket will not be able to restore those frequencies.
The cap is 1uF in series - see the schematics at http://downloads.openmoko.org/schematics/GTA02/ and check the archives for a thorough analysis by Joerg: http://lists.openmoko.org/pipermail/openmoko-kernel/2008-March/001996.html An external amp will provide a high impedence load, so things will be better, but unless there was an unannounced change in the componenet values for the later boards you will be stuck with bass rolling off below 160Hz. On the hardware list you can find discussion of the modification options. > A well-designed amplifier that takes a digital audio feed from the USB > socket - a USB soundcard, essentially, would work in principle, but in > practice may be expensive/time-consuming to implement. There are any number of usb headsets out there. Many would be trivial to modify for use with other headphones. If you're serious about your audio there's always the HeadRoom BitHead. > My advice would be to try listening to music on your phone. If it sounds > fine, don't worry about it further. If it isn't fine, try using a distro > that is known to have good sound capabilities (someone else mentioned > that Debian gives high playback quality). Only if this fails to give you > adequate quality might it be worth investigating hardware > replacements/augmentation. > > Regards, > > Sam > > > ------------------------------------------------------------------------ > > _______________________________________________ > Openmoko community mailing list > community@lists.openmoko.org > http://lists.openmoko.org/mailman/listinfo/community -- SolutionTrax Limited, Registered in England & Wales, Trading as TrueBox Registered office: Silbury Court, 420 Silbury Boulevard, Milton Keynes, MK9 2AF, UK Company Number: 4494022 VAT Registration Number: 825 1952 26 Telephone: +44 (0)845 508 3397 _______________________________________________ Openmoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community