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Subject: Sound quality test

Sound quality test

From: Linus Nielsen Feltzing <>
Date: Mon, 22 Mar 2004 13:31:36 +0100

Hey all!

There is a discussion going on about the sound quality being worse with
Rockbox than with the original firmware. Some people claim that the
Rockbox stereo separation is "too wide, with too little punch".

I have created a debug screen called "Sound test" where you can tweak
the stereo separation. It can be found in the debug menu, as usual.


The debug screen shows the channel mix. LL tells you how much of the
channel is mixed into the ear, LR is how much of the channel is mixed
into the other ear. Don't mind that the numbers are negative.

LL and LR are the values for the left ear, there are also the RR and RL
settings, but they are set to the same values. See the MAS data sheet
for details.

Left ear = left * LL + right * RL
Right ear = right * RR + left * LR

This means that (-0.50, -0.50) gives a mono signal, (-1.00, -0.00) gives
you true stereo separation, and (-0.00, -1.00) reverses the channels.

LEFT decreases the LL (and RR) level
RIGHT increases the LL (and RR) level
PLAY lets you compare with the true stereo separation. To hear your
setting again, press PLAY again, or alter the LL value.

I want you audiophiles to try to find the combination that gives you the
"best" sound. Also try to find the combination that sounds like the
original firmware.



Received on 2004-03-22

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