The AMZ 2-resistor mod for the Boss DS-1 Distortion pedal.
The DS-1 is a classic distortion pedal and is widely used by pros and amateurs alike. However, if it has any flaws, it is that the distortion is too extreme and the tone can be a bit harsh. This mod can fix both problems by merely changing two resistors.
The schematic at the top of this article is the input transistor gain stage in the DS-1, which is built around the Q2 bipolar transistor. It offers a lot of voltage gain and an extreme treble boost, which can make the distorted tone sound thin.
The two resistors that are changed in this mod will be R9, which controls gain, and then R6 to bring the bias back into the proper range. We want to decrease gain of the Q2 booster so the value of R9 is increased. Remove the 22 ohm original R9 and replace it with a 1k resistor. Next, take out R6 (100k) and put a 150k resistor in its place. That’s it!
I measured the collector voltage of Q2 after the mod and it was 4.72v, which is close to ideal. The lower gain of Q2 will give more control over the DS-1 boost, and will take it out of fuzz territory and solidly into the distortion range.
When R9 was increased, the input impedance also went up. This improves low end response and takes away some of the harshness. The drawing below illustrates the final configuration of the pedal after completing the mod.
If you don’t like the sound, the mod is easily reversed by replacing the original resistors. Give it a try and tell me how you like the improved fat DS-1 sound!
The Boss DS-1 is currently selling for $39 in our online store. It is a great pedal whether you mod it or not!