[sound]: capacitor that act like a high-pass filter and so removes the bass on the headphones jack

Andy Green andy at openmoko.com
Fri Nov 28 17:54:51 CET 2008

Hash: SHA1

Somebody in the thread at some point said:
|> I think I understand. I built one 10 F capacitor into the adapter (at the
|> mass), so the problem with the headphones should be fixed. I also
measured a
|> 1,59V current at the capacitor when plugged in and silent. Sound is
good as
|> before.
| It's beginning to sound very appealing.  I was very disappointed to
| discover that my FR is unusable as an MP3 player (and I'm not demanding:
| I usually find 64Kb/s Vorbis files good enough for such a use).
|> Unfortunately, the internal speaker sounds really bad now (distorted).
|> So I think i'll remove the silver again and find somebody who can help
|> me with the soldering...
| Hmm... why does it distort the interal speaker?

With the caps the transducer experiences -~1.5V .. +~1.5V worth of
deflection "down" and "up"; without the caps it experiences 0 .. ~3V
worth all "up".  So it's physically unable to deflect enough linearly I
would think.

| Would it be possible to add a 10 F capacitor on top of the 1 F one
| and connect it (in parallel) using your magic silver thingy (that
| I know nothing about), so as to avoid the soldering?

It is electrically possible but all of this is in a metal can with very
constrained height since the case and then battery sits on top of it.

- -Andy
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