The SD-9 Sonic Distortion is a modified version of the original Ibanez/Maxon SD-9 pedal. While it was initially marketed as a more aggressive version of the Tube Screamer, it actually has a distinct sound of its own.The stock circuit of the SD-9 Sonic Distortion is highly regarded and offers a wide range of distortion. The tone control allows you to dial in anything from deep bass tones to piercing treble sounds, with a slight mid scoop. Additionally, an optional mid-shift toggle switch, inspired by the later SD-9M model, provides three different settings and allows you to eliminate the mid scoop if desired.For those looking to experiment further, there is an optional toggle switch for a second set of clipping diodes. This feature allows you to mix up the distortion even more. The toggle switch can be set to two-way operation or a three-way option with a diode-lift position, which provides a loud and dirty boost. If you choose this option, the pedal will come with red LEDs.To improve the output level, the unused op-amp in the original circuit has been repurposed as a gain recovery stage, following the design of the General Guitar Gadgets version. However, if you prefer the original low output, you can easily keep the pedal stock.While the recommendation from FDHQ is to keep the pedal stock, as it already sounds great, there is always room for personal preference and experimentation.

Summary created by AI from the original source.