GEN-300B Update #3: Power Matters — Continuing to Push the Budget Limits

Hi everyone,

We’ve begun implementing Caddock resistors in the power section of our Gen series amplifiers.

We believe the power stage to be one of the core elements of a tube amplifier.

Below is a brief look at our approach to Caddock resistors .

Traditional Power Resistors

Most traditional power resistors used in tube amplifiers fall into a few categories:

Wirewound

• Formed by winding resistive wire

• Inherently inductive

• Large thermal mass

• Under dynamic load, they don’t behave as purely resistive elements. They store energy, both electrically and thermally.

Metal Oxide Film

• Lower noise and stable than wirewound

Cement / Sand Cast

• Essentially wirewound inside a ceramic body

• Mechanically robust

• Very slow thermal behavior

The Caddock MP: What It Is, and Why It’s Different

The Caddock MP are thick-film resistive element bonded directly to a ceramic substrate, with a metal backing designed for controlled heat transfer.

That leads to a few key differences:

Non-Inductive by Design

The MP series is inherently non-inductive.

There is no winding structure, and the element geometry is optimized to minimize parasitic inductance (typically ~10–20 nH).

In high-voltage tube supplies, this helps maintain stable transient behavior and avoids unwanted high-frequency effects.

Micronox® Thick-Film Construction

Caddock’s Micronox® resistive film is fired onto a flat ceramic substrate.

This planar structure provides:

• high stability

• low noise under load

• predictable performance over temperature

  
  

Thermal Architecture

The resistor is built with a direct thermal path:

resistive film → ceramic → mounting surface

Unlike traditional resistors acts as a thermal reservoir, MP is faster heat transfer and minimal thermal storage.

Dynamic Stability

With faster thermal tracking:

• resistance drift under load is reduced

• voltage behavior remains more consistent

This improves supply stability under dynamic conditions.

High Voltage Reliability

Designed for high-stress environments:

• stable under continuous high voltage

• low temperature coefficient (down to ±80 ppm/°C)

• strong long-term load stability

Why This Matters in a Tube Amplifier

In a tube amplifier, the power supply shapes the operating condition of the circuit.

And in that system, the behavior of the power resistor is not negligible.

Compared to Traditional Resistors

typically have higher thermal inertia, some level of parasitic inductance and slower thermal tracking under load.

Under steady conditions, this is not an issue.

But under changing load, their behavior is not perfectly instantaneous.

What the MP Series Changes

The MP series improves a few of these aspects:

• lower inductance

• faster thermal response

• more controlled heat dissipation

After implementing the Caddock, we noticed a cleaner background, more stable low-level detail, and less compression under dynamic swings. The presentation is also more open, with greater image density and an even better sense of space.

Are We the First?

Hard to say definitively.

But we haven’t seen many tube amplifier designs using the MP series in this way —especially not in production. Most designs still rely on wirewound, cement or standard metal oxide resistors.

More soon.

Layer Audio Design

Quick reminder: Early Bird pricing ends on March 29, 2026.