5V4G GZ32 RCA ST Shape Black Plates Bottom Square Getter Tested Tube Made in USA '58
Description:
The 5V4G / GZ32 RCA, in this refined 1958 version with ST bottle, symmetrical black plates, and bottom square getter, represents one of the most balanced and musical options among classic American rectifiers for hi-fi applications. Built with the care typical of RCA’s golden years, it combines electrical robustness, low noise operation, and refined tonal performance.
Especially appreciated in systems with sensitive power supplies or vintage integrated amplifiers, this tube is ideal for those seeking stable voltage, smooth startup, and a sound output that preserves the natural character of the audio signal.
Bass: tight and extended. The low-end response is more precise and defined compared to other contemporary 5V4G models, with good hold even under dynamic load conditions. It delivers firm and musical bass, capable of authoritatively supporting the harmonic foundation.
Midrange: transparent and neutral. The mid frequencies are dry but not cold, with excellent vocal clarity and a natural rendering of acoustic instruments. No tonal coloration, just a clarity that enhances the system’s timbral coherence.
Highs: open and discreet. The top end extends with fineness and control, without harshness or roughness. Details emerge with refinement, revealing micro-information without ever becoming intrusive.
Dynamics: fluid and responsive. The tube tracks transients well, with energetic yet never edgy behavior. The dynamic response is linear and progressive, enhancing both delicate passages and those requiring more energy.
Soundstage: well-organized and deep. The stereo image is stable, centered, and coherent, with good layering and a three-dimensional presentation that respects the spatial integrity of the music.
🎧 Use in Headphone Amplifiers and Hi-Fi Driver Stages
Ideal for tube preamps, DACs with tube rectification, or headphone amps with medium-high impedance. Thanks to its electrical transparency and low noise emission, this tube performs without introducing coloration, enhancing detail and microdynamics even in reference-grade systems.
🎸 Use in Guitar and Bass Amplifiers
Occasionally used in mid-range American amps from the 1950s, this 5V4G contributes to a soft and musical sag, with a non-aggressive dynamic response. Ideal for jazz, blues, studio cleans, and genres that favor natural compression and controlled attack.
🎯 Note for Audiophiles and Technicians
A balanced and uncompromising tube, perfect for those seeking a rectifier that is transparent, stable, and technically flawless. The ST design with bottom square getter and symmetrical black plates also makes it a premium choice for vintage restorations, both sonically and aesthetically.
Test Results
Tube tested on Funke W19 Tube Tester:
Voltage Test: Va = 60V, Vf = 5V
Good from: Ia = 55 mA
100% Average: Ia = 84.6 mA
TEST RESULT: VERY STRONG
Tube Readings:
- Section 1: Ia = 82 mA
- Section 2: Ia = 80 mA
Additional Tests Performed:
- Emission Quality: Excellent – Very strong and stable emission, no fluctuations.
- Shorts and GAS: None.
Condition:
- Condition: Vintage tube – Tested and fully functional. Supplied in our custom box for optimal protection.
- Functionality: Fully operational.
- Aesthetic condition: Very Good – Legible print with minor signs of age, some smearing on the logo silkscreen. See photos for details.
- Factory Code: K2 – RCA Manufacturing. March-April 1958.
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