Open a SpectrumAnalyzer and you'll see the harmonics are passing the 
Nyquist frequency, resulting in aliasing. Suggestions include upping the 
the sampling rate of SoundPlayer and adding some kind of low pass filter 
(see soundbuffer>>downSampledLowPassFiltering: ).

Eddie

Alan Grimes wrote:

>I've been hardware-hacking on my speakers and was trying to test them
>using PianoKeyboardMorph. I rigged it to offer all 8 octaves and to
>transcript the base frequency...
>
>The lower notes sound fine but the higher ones seem to have some issues.
>(I am trying to figure out whether this is due to a problem with the
>generator or an issue with the hardware mods I have made..)
>
>My new tweeter cuts in somewhere around 2,200 and the custom crossover
>is supposed to do the handoff at 3,500
>
>The weird frequencies are:
>
>2217.4 (somewhat modulated...)
>3729.3 (Sounds like it's an octive lower than it should be..)
>4434.9 (Sounds like there's a roughly 65 hz co-tone..)
>5274.0 (sounds lower than it sohuld be. )
>7458.0 (loudest frequency seems to be in the mid 100's...)
>
>I think I reset the instrument to default, I think it's playing as an
>oboe but this class is not factored especially well and its difficult to
>figure out exactly what it's doing...
>
>  
>