Firmware recipe for audio test tone generation

Mitch Bradley wmb at
Fri May 25 21:15:54 EDT 2007

How to play test tones in Open Firmware:

Using recent firmware (Q2C12 or later):

ok select /audio
ok decimal
ok 400 tone
ok 800 tone
ok 1000 tone
ok 2000 tone


The tone is played first on the left channel, then the right.

Frequencies that divide 12000 evenly have low distortion.  Other 
frequencies will have distortion to varying degrees because of the 
quarter-wave synthesis technique that is used.

The level is pre-set at the highest level that the speakers can handle 
before the onset of overload distortion (mechanical clipping, I think; 
the amplifier still has some headroom as determined by replacing the 
little speaker with a much better one).

If you want to change the level,

ok  patch  -15 -9  tone     \ Changes the output attenuation from the 
default of -9 to -15.

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