EL34 vs 6550
EL34 versus 6550 — Pentode vs Tetrode compared.
EL34 vs 6550: which one to choose?
The EL34 and 6550 are the two classic rivals of their power class. 6550 delivers more raw plate dissipation (~42 W vs ~25 W), and is generally tighter and faster on transients. EL34 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 | EL34 | 6550 |
|---|---|---|
| Full name | EL34 | 6550 |
| Type | Pentode | Tetrode |
| Primary use | Power (PP) | Power (PP) |
| Era | 1955 | 1955 |
| Heating | indirect | indirect |
| Heater voltage | 6.3 V | 6.3 V |
| Heater current | 1.5 A | 1.6 A |
| Amplification factor (μ) | — | — |
| Transconductance (gm) | 11 mA/V | 11 mA/V |
| Plate resistance (rp) | — | — |
| Max plate voltage | 800 V | 600 V |
| Max plate dissipation | 25 W | 42 W |
| Base | octal | octal |
| Manufacturer | Mullard·Philips | Tung-Sol·GE |
| Rarity | Common | Common |
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 EL34 vs 6550 in the interactive comparator →