Rockbox General > Rockbox General Discussion

Line out for Sansa E200?

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Llorean:
At least via the headphone jack the OF has shown signs of digitally altering the gain (the option to choose whether the volume is normal or loud, if I recall correctly) so the OF may not be the best signatory of what "line level" is for the hardware. Not saying it isn't, but it bears consideration.

eevan:
I've just looked to the AS3514 block diagram and the relevant audio path goes like this: I2S -> 18 bit Stereo DAC -> Stereo Gain -> Mixer -> AGC -> Line_Out. The last block has the level control 0..–46.5 dB, 2*32steps + mute. So, the line out level from this codec can be programmed. „Stereo Gain“ block has to be set to 0 dB.

This document also states:

--- Quote ---Line Outputs
– volume control via serial interface
– 32 steps @1.5dB and MUTE
– 1Vp @10kΩ
--- End quote ---

PolloLoco:
Does that mean that line out would still allow volume modification per the Sansa specs?

I was just concerned that in Rockbox, line out merely meant a duplication of the headphone port.  I know that a firmware update to the official firmware locked down the volume of the Sansa's line out.  Originally, it was affected by the volume wheel.

eevan:
That's right. The AS3514 codec allows that. So it depends on a firmware how the codec will be used.

I'd set the Mixer and Line_Out gain to 0 dB and shut off the AGC (if it can be done, I have no datasheet):

PolloLoco:
Thanks for the help.  I'm not sure where the Mixer and AGC modifications are made, but I did set the volume gain to 0db on the Sansa - and ramped up the volume on my portable amp.  As a result I've gained the clarity I was expecting and had noticed from the official firmware.

By playing around I noticed that if I modified the gain too much - then I'd introduce a good amount of noise.  I have to say, that outside of the noise factor - I don't notice any improvement in sound over the headphone port.  But that noise reduction IS DEFINITELY significant.

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