Electronics Engineering Firmware & Embedded EMC & Compliance Mechanical & Production Case Studies Our Lab Citadel Citadel Electronics

Hong Kong • Global Reach

Engineering the Sound of Music

Helping leading electronics brands design, engineer, and deliver groundbreaking audio products for over 25 years.

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250+ Products Delivered
30+ Global Brands
25+ Years Experience
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A Personal Note

From the Founder

Santiago Alvarez Click to view CV →

Hi, I'm Santiago Alvarez. I founded SED Engineering in 2016 with a simple goal: to help musicians, audio brands, and technology companies turn ambitious ideas into real, great-sounding products.

I bring over 25 years of hands-on experience working with leading global brands in the musical instrument and pro audio industry. I've designed, engineered, and delivered groundbreaking products in-house for names like Marshall Amplification and Behringer, and I've also worked behind the scenes, consulting and helping others bring their projects across the finish line.

I work across a broad range of electronics disciplines — audio, digital, analog, and embedded systems. Whatever the discipline, I bring the same drive: to push past "good enough" and deliver something exceptional. If you listen to or play music, chances are you've already heard — or used — at least one of the products I've worked on, maybe more. From world-class boutique amplification to affordable gear for new musicians, no matter where your project stands today, I can help shape your vision into a product that works.

Life brought me to Hong Kong, and I stayed — drawn by the city's unique position at the crossroads of global manufacturing, innovation, and opportunity. From here, I offer the engineering expertise, industry connections, and hands-on support you need to achieve the best possible outcome for your business.

MSc. Electronics Engineering, University of Oviedo, Spain
BSc. Industrial Engineering, University of Oviedo, Spain
13 years at Marshall Amplification — Technical Director
Full equipped laboratory — Audio Analyzers, Power Electronics, EMC, Safety

What We Do

Engineering Excellence

Full-spectrum product development from concept to production, with deep specialization in professional audio and musical equipment.

Electronics Engineering

Vacuum tube and solid-state analogue design, Class-D and SMPSU power circuits, digital circuitry and mixed-signal multilayer PCB design. From boutique tube amps to high-volume consumer products.

  • Tube & Solid-State Audio and Musical Instrument Amplifier Design
  • Class-D Power Amplifiers & SMPSU
  • USB Audio & DSP Processing
  • Mixed-Signal Multilayer PCB Design
  • Discrete & Low-Noise Analogue

Firmware & Embedded Systems

Bare-metal and RTOS firmware across 8/16/32-bit microcontrollers in assembler, C, and C++. PC software developed in C#. Real-time processing, USB stacks, DSP integration — all developed and debugged in-house alongside the hardware.

  • MCU Firmware — 8/16/32-bit, Assembler & C
  • Real-Time Control & Automation
  • USB Audio, MIDI
  • High-Speed Communication Protocols
  • DSP Co-Design & Firmware Integration. Support software in C#

EMC & Compliance Engineering

It is of no use to design the best circuit if it does not pass the required safety and EMC standards — we design products to comply from the start. We have the in-house equipment for pre-compliance testing and debugging, and also partner with local labs for full pre-scans when needed. Specialized in IEC 62368 for safety, as well as CISPR 32, CISPR 35, and FCC compliance.

  • IEC 62368 & Safety Compliance
  • CISPR 32 / CISPR 35 / FCC
  • EMC Pre-Compliance — Emissions & Immunity
  • EMI Debug & Remediation
  • Design-for-Compliance Methodology
  • Partnership with local accredited labs for formal testing

Mechanical & Production Engineering

We specialize in industrial-grade mechanical design and delivering manufacturing-ready packages. We offer DFM/DFA optimization, BOM cost reduction, and full OEM/ODM management through our established supply network in Asia. Our core expertise also includes:

  • Wood enclosure construction, Tolex covering & acoustic-friendly materials
  • Rapid prototyping — 3D printing (SLA/FDM) & quick-turn CNC machining
  • Rigid sheet metal, rack-mounted chassis
  • Molded plastic parts
  • Thermal management
  • Cable & harness preparation
  • Packaging design with manufacturer coordination
  • On-site manufacturing support & QA — incoming inspection to final goods

How We Work

From Concept to Production

01

Discovery

We learn your vision, target market, and technical requirements. Every great product starts with understanding what you need to achieve.

02

Design

Schematic capture, PCB layout, firmware architecture, and mechanical integration — all handled in-house with precision and creativity.

03

Prototype

Rapid prototyping with our fully equipped lab. Audio Precision analyzers, EMC pre-compliance, and thorough bench testing.

04

Refine

Iterative testing and refinement. We work with you to tune every detail — from tone and feel to thermal performance and reliability.

05

Deliver

Production-ready design package, compliance documentation, BOM optimization, and ongoing manufacturing support through our network.

Our Facility

The Lab

Every product we design is tested and debugged in-house before it ever reaches a compliance lab. Our facility is equipped for full-spectrum audio analysis, EMC pre-compliance, and stocked with a wide assortment of components so we can start building without waiting for deliveries.

SED Engineering lab bench The Lab — where designs come to life
Full list →

Audio Analyzers

Multiple Audio Precision instruments covering every test scenario — an APx525 for general-purpose production and design verification, an APx515 for high-speed multichannel measurements, and an older SYS-2522 for legacy project support, still widely referenced in the industry.

Full list →

EMC Pre-Compliance Station

Keysight CXA N9000A signal analyser, R&S ZNC3 vector network analyser, and Keysight 4433B RF generator feeding a full set of A.H. Systems broadband antennas, near-field probes, RF preamps, and CISPR 16 LISN for emissions pre-scanning. Full diagnostics before official lab submission.

Full list →

Safety Test Equipment

HIPOT tester, ground bond, insulation resistance, and leakage current measurement for IEC 62368 and UL safety qualification. Full dielectric strength and endurance testing in-house.

Full list →

Oscilloscopes & Logic Analysers

Multiple 4-channela 1-4GHz DSO with deep memory, mixed-signal logic analyzer, current probes for power stage characterisation, switching loss analysis, and time-domain debug.

Full list →

Network Analysis

R&S ZNC3 vector network analyser and an OMICRON BODE-100 for S-parameter characterisation of filters, antennas, impedance matching networks, and high-frequency PCBs up to 3 GHz.

Full list →

AC & DC Power Supplies

Multiple programmable DC supplies and AC power sources covering a wide voltage and current range. Precision biasing for analogue stages, high-current rails for power amplifiers, and mains simulation for ancillary supply design.

Full list →

Thermal & General Measurement

Thermal Camera, Graphtec GL240 Data Logger, digital callipers, micrometers, bore gauges, thread gauges and optical inspection microscope for precise mechanical measurement of enclosures, PCB outlines, hole diameters, hardware and custom tooling.

Full list →

Components & Tools Stock

Extensive in-house inventory of passives, semiconductors, connectors, and hardware — resistors, capacitors, magnetics, op-amps, MCUs, and more. We can start prototyping immediately without waiting for parts to arrive.

Full list →

Soldering & Rework Station

Professional SMD rework station, hot-air reflow, stereo microscope, and precision soldering for prototyping, rework, and small-batch production of complex mixed-signal assemblies.

Selected Work

Featured Projects*

A selection from 250+ products delivered across 30+ global brands.

* All featured projects are actual designs developed for real clients — either currently in production or scheduled for production release.
Details have been omitted for confidentiality.

SEDEngineering IR Processor
Audio DSPC / C#Custom Hardware

Custom IR Processor

A bespoke desktop application for driving custom DSP hardware. Load impulse responses, shape them with parametric EQ, visualize pole-zero plots in real time, and push the processed IRs to hardware for live convolution — all in one integrated toolchain.

SEDEngineering EMC Troubleshooting
CISPR 32/35LISNConductedRadiated

EMC Troubleshooting & Debug

Customer amplifier failing conducted and radiated emissions. Diagnosed root causes using in-house LISN and broadband antenna set, implemented fixes, and verified compliance — passed formal re-test on first submission.

SEDEngineering High-End DSP
DSPADSP21xxx6-Layer PCBDDR RAM

High-End DSP Processor

Custom high-performance DSP platform built around the Analog Devices ADSP21xxx series with external DDR RAM, 6-layer mixed-signal PCB, and comprehensive I/O routing. Designed for demanding real-time audio processing applications with ultra-low latency.

SEDEngineering High-Gain Tube Amp
Tube Amp3-ChannelDSP4×12AX7

3-Channel High-Gain Tube Amplifier

Custom three-channel high-gain tube guitar amplifier with integrated DSP processing. Features 4 × 12AX7 preamp tubes, 2 × 6L6GC power section, and comprehensive MIDI-controlled connectivity — designed for professional touring and studio use.

SEDEngineering Mechanical Design
Sheet MetalWoodPlasticsDFM/DFA

Mechanical Design & Manufacturing

End-to-end mechanical design and production engineering for professional audio products. Sheet metal chassis, wood enclosures, molded plastics, and full DFM/DFA optimisation — backed by an established manufacturing network in Asia.

SEDEngineering Mic Preamplifier
Class ADiscrete65 dB GainUltra-Low Noise

Ultra-Low Noise Mic Preamplifier

Discrete Class A microphone preamplifier delivering 65 dB of ultra-low-noise gain with Hi-Z instrument input, switchable high-pass filter, and PAD. Designed for a computer audio interface — studio-grade front-end performance in a compact footprint.

SEDEngineering Condenser Mic
Pro AudioAnalogueUltra Low Noise

Multipattern Condenser Microphone

A studio-grade multipattern condenser microphone with continuously adjustable polar pattern and bias voltage. Ultra-low-noise JFET front-end, dual-capsule design, and transformerless balanced output — purpose-built for critical recording and broadcast applications.

SEDEngineering 2400W Class D PA
Class D4-Ch Power Amplifier

2400 W Class D Power Amplifier

Four-channel 600 W per channel Class D power amplifier, bridgeable to 2 × 1200 W. Designed for professional audio installations and live sound reinforcement. Delivers clean, efficient power with comprehensive protection circuitry and robust thermal management.

SEDEngineering Shop-Made Software
C# / .NETThermalIR EditorTest Tools

Shop-Made Software Tools

Purpose-built desktop applications developed in C# for customer requests, lab use, and project integration. Thermal analysis, IR editing, burst wave generation, and engineering calculators — tools that solve real problems.

Trusted By

Clients & Partners

30+ global brands have trusted SED Engineering to deliver their most critical audio products.

…and many more across pro audio, MI, and consumer electronics.

Testimonials

What Partners Say

“Working with Santiago makes getting what you are looking to achieve easier. He understands how to read a project brief but more importantly how to question what you are asking for, so you get the right results. His result-focused approach allowed us to deliver every time. Now with SED, his expertise is my go-to resource for the brands I work with.”
LG
Luke Green Director, Ballistica Consulting — Former Product Director, Marshall Amplification

Get In Touch

Start the Conversation

Whether your project is at the concept stage or needs resolution to get to market, let's talk.

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Citadel is our sister brand — a dedicated line where we design and manufacture our own musical instrument products. From amplifiers and effects to custom electronics, Citadel represents the creative and engineering freedom that comes from building our own designs, our way.

Visit citadel-electronics.com →

Lab Equipment

As good engineers we like to work with the best equipment for the job — and we can't resist acquiring tools that make our work easier. Here's what we've got in the lab.