EE 445S Real-Time Digital Signal Processing Lab

Spring 2012

Lab 7Guitar Special Effects

Chao Jia

2

Outline Comb filters Allpass filters Notch filters Special effects with filters Other effects

3

Comb filters FIR comb filter (single echo)

Number of stopbands is R/2

4

Comb filters IIR comb filter (multiple echoes)

5

Allpass filters

6

Notch filters

7

Some special effects Echo

FIR or IIR comb filters Delay > 100ms

Flanging FIR comb filter with (periodically)

varying delay Delay between 1ms and 10ms

8

Some special effects Chorus

Several independent comb filters

9

Some special effects Reverb

Mimic a enclosed space (lots of echoes)

10

Other effects Special effects can also be generated by

altering the amplitude of the signal. Tremolo

Repetitive up/down variation in the volume

Fuzz Intentionally introduced distortion like

clipping