T-EP4 Safely Match EL34 Power Tubes on a Scope (Guitar Amp • Safe Method)

Описание: Learn a safe, real-world way to match EL34 power tubes using an oscilloscope—no high-voltage probing.

I feed a 1 kHz sine into a Rockitt Retro 50, load it with a Suhr Reactive Load, and read the line-out on the scope.

In a push–pull output stage, the top half of the sine is one tube and the bottom half is the other.

If both halves clip and curve the same → matched.

If one side clips earlier or looks different → mismatch/weak tube.

Setup: HP 3310B → amp input → Suhr RL (speaker in) → line-out → DSO

Scope: AC coupling • 0.2–0.5 ms/div (shape) • 10–50 ms/div (pops)

Bias sanity: 1 Ω cathode resistors → mV ≈ mA (idle)