Class D Power Amps – The Anatomy of Modern Guitar Power
Class D power amplifiers have become the hidden engine behind compact guitar amps, pedal‑style amplifiers, and lightweight heads. Although often misunderstood as “digital,” they are in fact analog high‑efficiency amplifiers that use pulse‑width modulation (PWM) to deliver serious power with minimal heat and weight.
🔹 How a Class D Power Amp Works
A Class D amplifier does not amplify the signal in a continuous analog way. Instead, it:
Converts the incoming analog signal into a high‑frequency stream of pulses
Uses MOSFETs that operate as switches (fully ON or fully OFF)
Reconstructs the amplified analog signal through an LC output filter
This switching method is the key to its efficiency.
Result: Massive power, tiny size, almost no heat.
🔹 Why Class D Dominates Modern Compact Guitar Amps
85–95% efficiency → almost no wasted energy
Minimal heat → no big heat sinks or transformers
Very low weight → modules often under 500 g
High power density → 20W, 30W, 50W, even 100W in pedal format
Stable performance with 4Ω or 8Ω cabinets
Perfect for pedalboards and portable rigs
This is why pedal‑style amps can deliver the kind of power that once required a heavy head.
🔹 How Class D Sounds
A Class D power amp is neutral. It does not add color, sag, compression, or harmonic distortion.
It simply magnifies whatever the preamp gives it.
This makes it ideal for players who build their tone with:
If your tone lives in your pedals, Class D is the perfect power multiplier.
🔹 Weaknesses
No natural “tube‑like” compression
No power‑amp breakup
No sag or bloom
Some players find it “too clean” or “too fast”
But these are characteristics, not flaws. Class D is designed for precision, not vintage coloration.
🔹 The Mythic Dimension
A Class D power amp acts like an energy amplifier: it takes the signal you’ve sculpted — fuzz, cosmic textures, ambient layers — and projects it into the physical world without altering its essence.
It is the final gate between your inner sonic universe and the air that moves in the room.
Class D vs Class AB – The Battle of Power Stages for Guitar
Class AB power amps are the soul of classic tube amplifiers. Class D power amps are the engine of modern compact rigs. Each serves a different philosophy.
1. Tone & Character
Class AB
“Sag” that gives elasticity and feel
Beautiful breakup when pushed
Strong interaction with the speaker
A Class AB power amp is part of the tone.
Class D
Neutral
Fast, clean, accurate
No added color
No compression
No breakup
A Class D power amp amplifies the tone you already created.
2. Efficiency & Heat
Class AB
~50–60% efficiency
Generates significant heat
Requires large transformers
Heavy and bulky
Class D
85–95% efficiency
Very low heat
Extremely lightweight
Ideal for pedalboards and travel rigs
3. Interaction with Effects & Fuzz
Class AB
Interacts with fuzz and drives
Softens harsh frequencies
Adds character and compression
Class D
Reproduces exactly what enters
Perfect for preamp pedals
Ideal for IR loaders and cab sims
Great for ambient, experimental, and fuzz‑heavy rigs
For your cosmic‑fuzz‑ambient universe, Π, Class D is a pure power multiplier.
4. Weight & Portability
Class AB
10–25 kg for combos
7–15 kg for heads
Class D
300–800 g for pedal‑style amps
1–3 kg for compact heads
The difference is night and day.
5. Live & Studio Use
Class AB
Perfect for mic’d live setups
Ideal for vintage rock, blues, classic tones
Class D
Perfect for direct recording
Excellent for modern rigs, ambient, fuzz, experimental
Consistent at any volume
If you want character, compression, vintage feel → choose Class AB
If you want neutrality, portability, clean power, pedalboard integration → choose Class D
Both have their place. They simply serve different sonic philosophies.