5U4G vs 5Y3GT
5U4G / 5U4GB versus 5Y3GT — two rectifiers compared.
5U4G vs 5Y3GT: which one to choose?
The 5U4G and 5Y3GT share a family but trade gain for headroom: 5Y3GT has the higher amplification factor (μ ≈ —), making it the typical choice for high-gain preamp stages. 5U4G runs lower μ (—) and is the standard cathode follower / phase-splitter / line-stage triode. They share the same envelope and base — wire them in the same socket and only the operating point changes.
Side-by-side specifications
| Spec | 5U4G | 5Y3GT |
|---|---|---|
| Full name | 5U4G / 5U4GB | 5Y3GT |
| Type | Rectifier | Rectifier |
| Primary use | Rectifier | Rectifier |
| Era | 1940 | 1938 |
| Heating | direct | direct |
| Heater voltage | 5 V | 5 V |
| Heater current | 3 A | 2 A |
| Amplification factor (μ) | — | — |
| Transconductance (gm) | — | — |
| Plate resistance (rp) | — | — |
| Max plate voltage | 550 V | 350 V |
| Max plate dissipation | — | — |
| Base | octal | octal |
| Manufacturer | RCA·Sylvania | RCA |
| 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 5U4G vs 5Y3GT in the interactive comparator →