GZ34 vs 5U4G
GZ34 / 5AR4 versus 5U4G / 5U4GB — two rectifiers compared.
GZ34 vs 5U4G: which one to choose?
The GZ34 and 5U4G are the two classic rivals of their power class. 5U4G delivers more raw plate dissipation (~— W vs ~— W), and is generally tighter and faster on transients. GZ34 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 | GZ34 | 5U4G |
|---|---|---|
| Full name | GZ34 / 5AR4 | 5U4G / 5U4GB |
| Type | Rectifier | Rectifier |
| Primary use | Rectifier | Rectifier |
| Era | 1954 | 1940 |
| Heating | direct | direct |
| Heater voltage | 5 V | 5 V |
| Heater current | 1.9 A | 3 A |
| Amplification factor (μ) | — | — |
| Transconductance (gm) | — | — |
| Plate resistance (rp) | — | — |
| Max plate voltage | 550 V | 550 V |
| Max plate dissipation | — | — |
| Base | octal | octal |
| Manufacturer | Mullard·Philips | RCA·Sylvania |
| Rarity | Sought-after | 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 GZ34 vs 5U4G in the interactive comparator →