My passion project/product

[EricfromSonocus]

S O N O C U S THA-1 — A New Chapter in My Amp Journey

Hi guys. I want to introduce you my passion project. About a year ago, I sat down at my bench with a simple goal: build the most refined headphone amp I could make with the skills and tools I’ve learned over the years. Not a concept piece or an experiment — just a clean, purposeful design where every choice made sense.

I’ve been using Eagle PCB for seven years and have built and sold over a hundred linestages in Korea as a side job. All were hand-assembled and tested by me. They were very well received, but I wanted to refine the layout, the grounding, and the noise performance to the point where there was nothing left to improve.

The result is a PCB with a clean, logical layout for every component. Many key parts are placed pin-to-pin for the shortest possible signal paths. Decoupling capacitors are mounted directly beneath smoothing caps and right next to IC pins for maximum effectiveness. The op-amp section follows textbook perfect guideline, improved even further with double-sided component placement. The ground plane is partitioned to control current paths intelligently, and RFI suppression rules are applied throughout.

The resulting product is one that priotizes build quality and circuit integrity over flashy but shallow exteriors. Unlike mass-produced, high-markup gear, it’s engineered to deliver lasting enjoyment and stand as a piece worth keeping for life. Simply, a machine that glows with inner beauty over outer appearance.

Key Features

Dual Mono triple stage PSU – Separate, isolated power for each channel. Active choke> nested feedback filteration per channel. (Talk about overkill!)

Modular Output Stage – Output is on its own dedicated board for lower noise, easier service, and infinite upgradability.

Two Output Modules Included – Discrete and IC versions, thus making TOS-1 the world's first ic/discrete switchable amp.

Open Source Output Module – Template file publically available for anyone to design and swap their own modules. Guaranteed future support and updates by yours truly.

PCB Design Highlights:

-Pin-to-pin placement of key components for minimal trace length.

-Decoupling capacitors directly under smoothing caps and IC pins.

-Partitioned ground plane for intelligent current control.

-RFI design rule set adherence for maximum noise suppression.

-Double-sided component placement for optimal layout efficiency.

A picture is worth 1000 words

 

[EricfromSonocus]

I actually drafted the above post last year then refrained showing it here due to lack of concrete result. But after much delay and an enormous amount of work, my passion project is finally complete — and the result exceeded even my own expectations.

What surprised me most was how dramatically the THA-1 transformed my AKG K701. I had always considered them somewhat lean-sounding headphones, but through this amp they revealed deep, articulate bass, exceptional dynamics, and a holographic soundstage with pinpoint imaging.

The two output modules each developed their own distinct character as intended. The OPA1641 module delivers a refined, airy presentation with that characteristic JFET shimmer, while the discrete module offers a richer, denser midrange with a more organic
presentation.

A major focus throughout development was circuit integrity: tightly matched gain stages using 0.1% thin-film resistors, extensive grounding optimization, carefully managed current paths, and multiple PCB revisions dedicated purely to lowering noise and improving stereo imaging.

The first sample unit was recently sent to a listener in the US, and the feedback has been extremely encouraging. I’m now working on the finalized production version with an updated chassis design, tighter layout refinement, and improved shielding.(last photo is the chassis mockup)

This project began as a personal pursuit to build the best amplifier I could with everything I’ve learned over the years. Seeing it finally come to life has been incredibly rewarding.
Thank you for following the journey

 

[MaxwellsEq]

Nice attention to detail on the PCB layout. Do you have measurements such bandwidth and noise?

 

[EricfromSonocus]

Not yet, tho i expect them to be extremely low. I will be sending a demo unit to amir in the near future

 

[EricfromSonocus]

Heres a render of what the chassis will look like. Variaties of colors will be available. Now the color panel material itself is a very unconventional- its FR4. The choice was made for several reasons, major ones being affordability and its shielding property.

Aluminium is actually a low tier shielding material, below copper and steel. The THA-1 will feature inner shell of stainless steel with the double sided copper laminate of FR4 outer shell, thereby easily surpassing the emf shielding performance of modern thin shell aluminium headphone amps. And because the outer shell is essentially modular, and because i will offer the CAD file as open source, those with access to 3d printer could go wild with custom fab and let their imagination fly.

 

[Redacted]

Once again, hats off to developers!

 

[EricfromSonocus]

Thank you Redacted!

The design of the production model is finished and the components been ordered. Im expected to have a working product at the end of this month.

Same layout has been preserved from the THA-1 prototype, but everything is little tighter, little more optimized.

New feature for this version is what id like to call SUPER DIRECT INPUT. the volume pot sits directly infront of the rca input and the knob extended to the front of the chassis via a shaft. This ensures the shortest signal path from input to the active stage, for highest signal integrity, and its the most optimal arrangement physically possible.

And ive made sure this time every component is pcb mount type so that there are no exposed wires anywhere. This i took inspiration from schiit's designbook and i do think it is the superior method.

 

[EricfromSonocus]

One thing id like the forum's input on is the color choices. Ive chosen blue faceplate/ebonized wood as the default color instead of the classic green, and not sure if that was the popular choice.