For VU-Meter, I think you'll need an external LOG convertor such as one of these op-amp circuits ...
http://en.wikipedia.org/wiki/Operati...rithmic_output
http://www.st-andrews.ac.uk/~www_pa/...rt8/Page3.html

Without the LOG convertor, you'll only see big peaks in the bargraph and none of the lower level signals.

I need some help to convert reading from frequency to the bars
If you're thinking of a Spectrum Analyzer, then nope, can't help there.
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