Audiophile Phono Preamp & Low-Noise PSU

Project Story:

This project focuses on building a high-fidelity, ultra-low-noise phono preamplifier and its matching dedicated linear dual power supply, based on the highly regarded open-source Muffsy Hifi designs. The preamplifier features passive RIAA equalization, variable gain settings (32-43 dB), and customizable input impedance (17k-150k ohms via onboard DIP switches) to seamlessly match any Moving Magnet (MM) turntable cartridge.

My Decision To Attempt This Build

As a vinyl enthusiast who is getting a new turntable the Fluance RT85, it needs to have a Preamp, and I was just learning about this is class so I figured what better way to learn more and being dedicated to high-fidelity analog playback, I wanted a premium phono stage that didn't compromise on signal purity or introduce power line interference. Building this from open-source designs allows for meticulous component matching (such as precision 1% metal film resistors and high-quality film capacitors) to achieve spectacular RIAA compliance and an incredibly low noise floor. 

How Does It Work:

The circuit uses high-performance, low-noise operational amplifiers paired with a completely passive RIAA equalization network positioned between the two gain stages. To prevent any AC hum or ripple from polluting the delicate millivolt-level audio signals coming from the turntable cartridge, the dedicated power supply delivers a rock-solid, regulated +/-15V DC output with a minuscule 0.1 mV of ripple, isolated entirely from the main AC line.

Who I Am:

For the past 20+ years, I have worked as a 3D Environment Artist in the video game industry. Recently, I decided to pivot my career and am now a student in an Electronic Engineering Technician program.

As a long-time creative professional, I’ve translated my eye for detail into a deep passion for high-fidelity audio, precision hardware assembly, and analog physical media. Whether I'm diving deep into my circuit design coursework, building custom circuits, or refurbishing vintage audio hardware in my spare time, I absolutely love the process of bringing high-quality physical builds to life.

Project Description:

A complete DIY audiophile phono stage system consisting of two custom PCBs: 1. The Phono Preamplifier PCB: Features dual-layer routing with a full ground plane, onboard DIP switches for input impedance and gain adjustment, box-type film capacitors, and high-performance operational amplifiers in machined DIL sockets. 2. The Dedicated Linear Dual Power Supply PCB: Provides ultra-clean, fully regulated +/-15V DC power with minimal ripple using an external AC wall adapter to keep mains voltage completely isolated from the audio enclosure. I plan on 3D printing something similar to the main image for the housing using my 3D Printer and using copper tape to make a faraday cage.

Final Words:

Thank you for providing the global maker community with incredibly precise PCB manufacturing capabilities. For an analog audio project like a phono preamp, high-quality trace definition, uniform copper weight, and superb solder mask quality are absolutely critical to ensuring excellent grounding and shielding. I would be proud to feature PCBWay's manufacturing quality in this audiophile build and share the completed logs with the community!

Here are links to the Open Source Project I'm following:

https://www.muffsy.com/muffsy-pp4

https://www.muffsy.com/build-the-muffsy-psu-v3