Mono audio output on GTA02?
joerg.twinklephone at gmx.de
Sat Feb 9 01:33:18 CET 2008
Am Sa 9. Februar 2008 schrieb Clarke Wixon:
> joerg <joerg.twinklephone at ...> writes:
> > The amp is for the speaker(s) only, and GTA02 has only one of
> > them (mono). That's fine, for one good speaker will yield a better sound
> > 2 small ones.
> Unfortunately, I don't think we're getting "one good speaker" in the
> The second speaker was removed to make room for WiFi, so the remaining
> is likely to be of comparable (identical?) quality to half of the original
:-( Anyway, 2 speakers don't make a stereo output yet, when built in such a
small case. So it's not so bad to lose one of them.
> But you're right, the headphones should still be fine.
However without circuit diagrams, we can't say for sure what they 've done and
why. Seems i was wrong with direct connection of HPh to codec chip.
see spec of wolfson mixer codec chip:
On-chip Headphone Driver with cap-less output option
- 40mW output power on 16Ω / 3.3V
- with 16Ω load: SNR 90dB, THD –75dB
- with 10kΩ load: SNR 94dB, THD –90dB
On-chip speaker driver with 0.5W into 8R
I don't know why they use a dedicated amp LM4853, which is good for nothing it
near same power, mono *OR* stereo output, no capacitor-free bridge out for
stereo. Additional parts needed for headphone detection to system.
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