300B vs 2A3
300B versus 2A3 — two triodes compared.
300B vs 2A3: which one to choose?
The 300B and 2A3 are the two classic rivals of their power class. 300B delivers more raw plate dissipation (~40 W vs ~15 W), and is generally tighter and faster on transients. 2A3 compresses earlier, breaks up earlier into pleasant harmonic content, and is the canonical choice when the goal is the singing midrange that defined the golden-era hi-fi sound. Bias points and output transformers differ — never swap blindly.
Side-by-side specifications
| Spec | 300B | 2A3 |
|---|---|---|
| Full name | 300B | 2A3 |
| Type | Triode | Triode |
| Primary use | Power (SET) | Power (SET) |
| Era | 1938 | 1932 |
| Heating | direct | direct |
| Heater voltage | 5 V | 2.5 V |
| Heater current | 1.2 A | 2.5 A |
| Amplification factor (μ) | 3.85 | 4.2 |
| Transconductance (gm) | 5.3 mA/V | 5.25 mA/V |
| Plate resistance (rp) | 700 Ω | 800 Ω |
| Max plate voltage | 450 V | 300 V |
| Max plate dissipation | 40 W | 15 W |
| Base | ux4 | ux4 |
| Manufacturer | Western Electric | RCA·WE·Shuguang |
| Rarity | Legendary | Collector |
Sonic character
Need an interactive deep dive?
The Amperatubes comparator visualises loadlines for both tubes side-by-side, simulates the SPICE response, and lets you adjust the operating point in real time.
Open 300B vs 2A3 in the interactive comparator →