[ANN] Bass-Rework = Headset Audio Quality Enhancement available in EU

[Dr. H. Nikolaus Schaller]

Dear Freerunner owners in the EU harmonized market,

a known problem of the Neo Freerunner design is that the headset  
output lacks some low frequency signals (bass). Thererfore music  
played through the headsets does not sound as expected and compared to  
other digital music players.
There is an improvement rework by adding larger coupling capacitors to  
the output amplifier. This became known as the Bass Rework (http://wiki.openmoko.org/wiki/GTA02_bass_fix 
). Although there is a description of a rework solution (http://people.openmoko.org/andy/additional-headset-audio-caps.pdf 
) we do not expect that you can do it yourself and not in the required  
quality. Just a note what the problem is: we need 47 uF in 0805  
dimensions and they are a little expensive and difficult to get and  
space is very close. Therefore, we have worked on a professional  
approach.

With the help of a local SMD specialist company in Munich, we can now  
offer a rework service to those who want to improve audio quality. The  
price is 49 EUR (incl. German VAT) plus shipment.

Details can be found at:

	http://www.handheld-linux.com/wiki.php?page=Bass-Rework

Finally a note of caution: acoustic quality is very subjective so that  
we can't guarantee that the result is good enough for your  
expectations. We can only guarantee that there is a technical  
improvement.

Nikolaus Schaller



Some Pictures

How the rework looks like:

	http://www.handheld-linux.com/images/Bass-Rework1.jpg

Oscilloscope signals of a sine wave sweeping from 10 Hz to 100 Hz (for  
an original unit and for a reworked unit):

	http://www.handheld-linux.com/images/Bass-Rework2.jpg

	http://www.handheld-linux.com/images/Bass-Rework3.jpg

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