Amplifier Circuit Diagrams


Guitar Overdrive Distortion Effect Circuit:

This distortion effect circuit is specifically designed for guitars and utilizes the NE5532 op-amp. The circuit doesn’t rely on any critical components; all necessary materials are readily available in the market. The printed circuit board (PCB) and the accompanying box are designed with a stylish aesthetic. Notably, this distortion circuit boasts low current consumption, operating efficiently on a standard 9V battery. It features adjustable settings including Drive, Tone, Level, and a Hard-Soft-Bypass switch.

The complete package includes the distortion overdrive effect circuit diagram, PCB layout, box label, and a comprehensive material list. Notably, this circuit has been featured in a popular electronic magazine in the country, a testament to its quality and functionality.

Historical Significance:

The concept of this distortion effect harks back to the 1970s, pioneered by Keith Barr of MXR Innovations. Over the past four decades, this effect has played a pivotal role in shaping the sounds of renowned guitarists like Randy Rhoads and Bob Mold. Often, both distortion and overdrive effects are collectively referred to as “distortion,” despite their subtle differences in signal processing.

Circuit Design:

This system, detailed here, is elegantly simple, employing a pair of op-amps and a selection of discrete elements. Notably, it employs silicon diodes for signal cutoff, deviating from the original germanium diodes. The circuit is versatile, offering both soft clipping overload and hard clipping (distortion) effects. Furthermore, it features adjustable cut level, tone, and volume controls. Additionally, a bypass switch is integrated, allowing the signal to pass directly from the amplifier without undergoing distortion.



Signal clipping:

The impact of overdrive and distortion hinges on the precise clipping of the guitar signal. Clipping, a nonlinear process, generates harmonic frequencies not typically present in the audio signal. When the clean signal displays two rising and falling phases, this effect enhances the grip.

The duration is contingent on the overload or distortion overload condition: the higher the cutoff threshold value, the greater the signal level before clipping occurs. This scenario is elucidated below. The signal is interrupted only after a specific threshold voltage is reached. Below this threshold, the signal remains undistorted, resembling the original sound as if the effect were turned off.

When the string is plucked harder, the signal surpasses the threshold and is constrained, transitioning more abruptly, yet retaining rounded corners (soft clipping). The signal is perceived as a combination of harmonics, incorporating more of the rectangular signal. Consequently, the alteration in signal shape is interpreted as the addition of higher harmonics, resulting in a sharper sound. Overdrive produces a milder effect compared to distortion, which imparts a sharper and more metallic tone. Distortion’s clipping is more rigorous (hard clipping), causing “flat” parts in the waveform to emerge. The cutoff threshold is precisely set just before or during the signal intensification phase, leading to higher gain.

On the circuit:

You have the option to substitute the NE5532 op-amp with the TL072. If the high-tone cut (tone setting) proves inadequate, adjusting the value of the C11 capacitor from 4.7nF to a larger one, such as 6.8nF, allows smaller frequencies like 3.3nF to pass through, enhancing clipping. The VB sections indicated on the circuit board are outlined in the PCB drawing. When installing a perforated plate or reconstructing the PCB, all sections labeled VB should be consolidated.



Related Articles

Leave a Reply

Your email address will not be published.

Back to top button