Placing filters in series can create interesting sonic results.  In this Max/Msp patch a lowpass filter and highpass filter are patched in series. They share the same Q. The lowpass and highpess each receive a different multiplication factor of the fundamental which is triggered at different speeds by the metro objects. When you play this patch the Q, emphasize the shifting harmonics. The original sound, reduced in amplitude is fed back into the sound.

This techniques creates a nice ‘singing’ quality to the sound.

audio in blog foler