Third Party > Repairing and Upgrading Rockbox Capable Players

ipod video with DC Coupled headphone output

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strider:
I read the manual WM's, and I
 found an interesting idea.
The idea to remake out of my Ipod.
this steps:

1) remake wm8758 driver
and recompile firmware

2) remove lineout capacitors  and connect to headphones GND
Warning!
 New headphones GND should`not be connected to GND of mainboard, as previously.

3) remove out1L/R capacitors and connect to headphones L/R

and I got excellent sound)))
but now can not use the original firmware.(if I use original firmware then i can damage the out1 and out2)

Chronon:
I'm not really sure of the purpose of this.  Is there some special purpose that requires DC signals?

strider:
only manual build and hands

gomem:

--- Quote from: Chronon on November 28, 2009, 05:03:33 PM ---I'm not really sure of the purpose of this.  Is there some special purpose that requires DC signals?

--- End quote ---

I think the idea of the DC coupling is to try and improve SQ, especially on the bass. AC coupling with a low impedance load like headphones can degrade bass response, if the capacitors not up to par. Some people reckoned the original iPod Shuffle had better SQ than the other iPods, because it was DC coupled. Expensive HiFi amplifiers tend to use DC coupling for the same reasons, rather than putting the signal through electrolytic capacitors which could degrade the SQ.

Chronon:
That makes a certain amount of sense, though you can push the corner frequency of the high-pass filter down by using higher impedance phones.  My phones present a 64 ohm load.

Alternatively, if you're cracking the case you could replace (or simply augment) the capacitors.

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