EL34 vs KT88
EL34 versus KT88 — Pentode vs Tetrode compared.
EL34 vs KT88: which one to choose?
Moving from the EL34 to the KT88 is one of the classic upgrade paths in tube audio. The KT88 delivers more power (~35 W vs ~25 W), more bass authority, and tighter control — at the cost of a different sonic signature and a substantially higher running cost (current consumption, transformer requirements, NOS prices). Most builds cannot socket-swap; the chassis layout, output transformer, and power supply must be re-engineered.
Side-by-side specifications
| Spec | EL34 | KT88 |
|---|---|---|
| Full name | EL34 | KT88 |
| Type | Pentode | Tetrode |
| Primary use | Power (PP) | Power (PP) |
| Era | 1955 | 1956 |
| 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 | 11.5 mA/V |
| Plate resistance (rp) | — | — |
| Max plate voltage | 800 V | 800 V |
| Max plate dissipation | 25 W | 35 W |
| Base | octal | octal |
| Manufacturer | Mullard·Philips | GEC |
| Rarity | Common | Sought-after |
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 KT88 in the interactive comparator →