Seeking Guidance on Designing a 500W RMS Class D Amp and Learning Class TD for a Future 5kW Output with Low THD

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Hi everyone,

I’m diving into Class D amplifier design and exploring Class TD (Tracking Class D) in parallel, and I’d really value the community’s insights to help me get started. My ultimate goal is to design a 3kW-4kW Class D amp at 4 ohms to power 21" and 18" outdoor speakers within the next two months. As a learning step, I’m focusing on building a 500W RMS Class D amp at 4 ohms. At the same time, I want to learn about Class TD to understand its benefits for high-efficiency, low-THD designs, aiming for a future 5kW output with minimal distortion for my outdoor audio setup.

My background: I’ve successfully built a 1000W RMS Class AB amp at 2 ohms, so I’m familiar with amplifier design, power supplies, and testing. I have a well-equipped workbench with an oscilloscope, load resistors, signal generators, and other tools. While I’m comfortable with Class AB, Class D and Class TD are new territory, and the switching concepts feel daunting. I’ve been searching online for resources, but I’m struggling to find clear, practical guidance on where to begin for both topologies.

Here’s what I’m looking for:

1. Roadmap for a 500W RMS Class D Amp (4 ohms):
   • A step-by-step approach to design a 500W RMS Class D amp, covering key components like PWM modulators, MOSFETs, gate drivers, and output filters.
   • Reference designs or schematics for a 500W Class D amp that I can build and learn from. Are ICs like IRS2092 or IR2110 suitable for beginners?
   • Tips on output filter design to minimize Total Harmonic Distortion (THD) and ensure clean audio.
   • Recommendations for simulation tools (e.g., LTspice, Multisim) and how to model Class D switching circuits accurately.
2. Learning Class TD in Parallel:
   • A beginner-friendly introduction to Class TD—how it differs from standard Class D, its advantages (e.g., efficiency, THD), and why it’s used in high-power audio.
   • Suggestions for resources (books, articles, videos, or tutorials) that explain Class TD design, focusing on practical steps for someone with Class AB experience.
   • Are there reference designs or ICs for Class TD amps I can study? How do Class TD designs adapt the power supply tracking to reduce losses?
   • Tips on how to start experimenting with Class TD concepts while working on my 500W Class D project—any small-scale circuits or simulations to try?
3. Minimizing THD for Both Topologies:
   • Techniques to achieve low THD in Class D and Class TD designs, especially for scaling to 5kW. What impacts distortion most (e.g., feedback loops, filter design, MOSFET choice)?
   • How Class TD’s tracking power supply helps reduce THD compared to Class D—any design tips to leverage this?
   • Testing methods to measure and optimize THD using my oscilloscope and signal generator, particularly for high-power loads like 21" and 18" speakers.
4. Learning Resources:
   • Recommendations for books, courses, or tutorials on Class D and Class TD design, ideally suited for someone transitioning from Class AB.
   • Resources that break down PWM, switching topologies, and tracking power supplies in a hands-on way.
5. Transitioning and Scaling:
   • Key differences between Class AB, Class D, and Class TD to understand (e.g., EMI, thermal management, efficiency).
   • Common pitfalls in Class D and Class TD design and how to avoid them as a beginner.
   • Design choices for the 500W Class D amp that will make scaling to a 3-5kW Class D or Class TD amp easier (e.g., power supply flexibility, thermal planning).
   • Advice on bridging/paralleling amps for 5kW output while maintaining low THD.

If you’ve designed Class D or Class TD amps, I’d love to hear about your journey! For the 500W Class D, what components or approaches worked best? For Class TD, how did you wrap your head around the tracking power supply concept? Are there specific MOSFETs, gate drivers, or filter designs you recommend for either topology? Also, any tips for managing EMI in outdoor speaker setups would be awesome.

I’m excited to learn both Class D and Class TD hands-on, starting with the 500W Class D build while studying Class TD theory and simulations. My focus is on low THD for pristine audio at high power. I plan to share my progress here and would deeply appreciate any guidance, resources, or encouragement to stay on track.