100W Power Amplifier for Bass Guitar

My name is Javier Lara, and together with a group of classmates, we are students of Mechatronics Engineering at the Universidad Tecnológica de la Región Norte de Guerrero (UTRNG) in Guerrero, Mexico. We are in the final months of our degree, and over the years, we have developed a great interest in projects that combine theory and practice, especially in areas such as electronics and control systems. Additionally, we are passionate about applying technical knowledge to develop functional products that have a real impact in both domestic and industrial applications.

Our project consists of the design and construction of an audio amplifier as part of the integrative subject in our Mechatronics Engineering degree. In this project, my team and I are applying knowledge acquired in electronics, electricity, and calculus to develop a high-quality device with commercialization potential. The design includes the development of multiple PCBs to ensure optimal and stable performance.

The audio amplifier is designed to deliver a true 100-watt power output. It integrates a preamplifier for the instrument signal, a series of effects (such as brightness, bass cut, and attenuator), and features an active four-band equalizer. The power stage can operate at an 8-ohm load.

Image 1. PCB of the amplifier.

The main components and sections are as follows:

Preamplifier: It uses dual TL072 operational amplifiers, which ensure a clean sound without electrical interference. The first operational amplifier (U3A-B) amplifies the instrument signal and allows for the application of three effects: brightness, attenuator, and bass cut. Operational amplifiers U4 and U5 control the four-band equalizer: bass, low mid, high mid, and treble.

Image 2. Schematic of the preamp.

Power amplifier: Based on a class AB design, it uses 100W 2SC5200 transistors. This stage must be powered by a symmetric ±36VAC supply for proper operation and maximum efficiency.

Image 3. Schematic of the power amplifier.

In the attached file "Amp files" the schematics in KiCad and the Gerber files necessary for PCB manufacturing are included. Details and specifications of the components used are found in the schematic (sch) file.

I deeply appreciate the support PCBWay has provided to students and electronics enthusiasts in the past, and I believe that their sponsorship would be essential to the success of our final project. Their contribution would allow us to carry out this design at a professional level and complete our degree with a solid, applicable project. It would be an honor to share the results with the PCBWay community and contribute our project to their platform, enriching the educational and technical project repository on their site.

Thank you very much for your time and consideration!