Distortion effects is the most commonly used effects for guitars. Every guitar player knows how to use them. Distortion are usually built-in on most guitar amplifiers today on the market. But some amplifiers has overdrive instead of distortion. Overdrive is just a soft distortion and it started way back on vacuum tube days. Overdrive is an effect you hear when cranking up the volume of a tube amplifier. Distortion is produced by hard clipping the signal by using signal diodes.
The Circuit
The circuit is based on the popular sonic distortion with some modifications. This is a classic distortion who made its first appearance on the 80’s. It is still popular on this digital era and a lot of guitarist still prefer analog including me. Sonic distortion is popular for its fat sounding rich distortion. Most high gain distortion today has really thin sound, this is the price you pay for having high gain.
Circuit Analysis and Simulations
I simulated the circuit using simetrix which free to use. Too bad, this software has no MAC OS version, you can only use it on MAC using wine. Wine is used to be able to run windows software on MAC.
PCB Design
My PCB design is small 5cm x 5cm which is small enough for most enclosure you can buy on the market. To be able to fit it in a small board, i have to design it in 2 layers. Don’t worry for those who can’t built it in 2 layers, I have a 1 layer design that I can share with you. But the 1 layer version is not as good as this 2 layer version.
The 3PDT footswitch is already incorporated on the PCB which will lessen wires for you to connect.
Completed board assembly:
1 Problem I encounter is that the 3PDT switch has wrong footprint connection. You have to rotate it 90 degrees to make it work, the problem is that it wont fit so I have to bend its pin to make it fit. I don’t know why this happen, maybe the 3PDT I bought is different from what I used in the eagle library. The funny thing is that it fit perfectly, just the wrong side.
Complete with plastic chassis. I can’t afford to do it with a metal one because it is too noisy to drill it. Our neighbor would yell at me saying their baby is asleep.haha
Parts List
RESISTOR 1/4W
10k – R13, R14, R5, R11,
1k – R17, R10
2.2k – R6, R8
510k – R2, R18, R16
1M – R1, R12
33k – R3
6.8k – R9, R7
470 ohm – R15, R4
CERAMIC CAPACITORS
220p – C4
0.1uF – C9, C6
0.047uF – C13, C1
0.01uF – C5
0.027uF – C7
ELECTROLYTIC CAPACITORS
220uF/16v – C10
22uF/16V – C11
47uF/16v – C2
1uF/16v – C8, CX(series sa pin2 ng volume)
10uF/16v – C12
diode
D3 – 1N4001
Potentiometer
Volume – 50k
Tone – 25k
Drive – 250k or 500k