1. Andrew Lash ECE 3551 DSP on BlackFin BF533
Bass Effects
Andrew Lash
ECE 3551
DSP on BlackFin BF533

2. Purpose Create a bass guitar multi-effects processor
Delay
Chorus
Flanger
Vibrato
Single unit to replace multiple effects processors

3. Solution - Operation Board has 4 Pushbuttons
Left: Switches between effects
Middle-Left: Current delay time
Middle-Right: Varies on effect
Delay: None
Chorus, Flanger, and Vibrato: Frequency
Right: Amount of decay

4. Solution – Operation Board has six LEDs
Two on left: Show current effect mode
00 – Delay
10 – Chorus
01 – Flanger
11 – Vibrato
Four on right: Show the current value for the selected effect characteristic

5. Solution – Usability Use the first button to switch between modes
Other 3 buttons: Press once to set that characteristic as active
LEDs will update
Press more to increment value by 1 as desired

6. Solutions – Delay Professional Samples My Samples  *x[n-D] h[n] 1 
Z-D
y[n] D
Professional Samples
My Samples

7. Sinusoidal Low Frequency Oscillator Variable sinusoidal Delay d(n)
Solutions - Chorus
Sinusoidal Low Frequency Oscillator
LFO 
x[n-d(n)]
x[n]
Z-N
y[n]
Delay-Line Gain
Modulating Center of Delay-Line
Professional Samples
My Samples
x[n]
Variable sinusoidal Delay d(n)

8. Solutions - Flanger Flanger effect is similar to Chorus
The amount of overall delay is lower
The frequency rate is much higher
Professional Samples
My Samples

9. Modulating Center of Delay-Line
Solutions - Vibrato
Sine Wave 
x[n-d(n)]
x[n]
Z-N
y[n]
Delay-Line Gain
Modulating Center of Delay-Line
Professional Samples
My Samples
N=Variable Delay d(n)

10. Difficulties Flanger and Chorus are very similar
Hard to differentiate between effects
Designing with only 4 buttons and 6 LEDs is very limiting
Had to be creative when designing user interface
Limits how much functionality that can be implemented in the display

11. Results Delay effect works extremely well! Chorus sounds as expected
Flanger works ok but not as well I as I would like it to
Vibrato works really well

12. References http://my.fit.edu/~vkepuska/ece3551/