1. EE 445S Real-Time Digital Signal Processing Lab Spring 2012
Lab 7 Guitar 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