5U4GB 5AS4A RCA Black Plates Tall Bottle Tested Tube Top Side Square Getter Rectifier Made in USA '60s
Note: This unit has a visible chip on the Bakelite base, as shown in the photographs. This is purely cosmetic and does not affect the valve's function, safety, electrical performance, or sonic accuracy. The price fully reflects the aesthetic condition described above.
Description:
The 5U4GB / 5AS4A RCA , in this Tall Bottle version with black plates and square getter in the upper and lateral position, represents one of the most robust and balanced rectifiers of the American production of the 60s.
The tall bottle is often associated with greater thermal dissipation and a more generous construction, useful for ensuring reliability and stability even in prolonged or high current demand applications .
Bass : Solid and well-controlled. The low range is notable for its firmness and articulation, without ever becoming intrusive. The power control provides a compact and coherent sound base, essential for systems that focus on detail and dynamics.
Mids : Natural, tidy, and slightly restrained. Voices integrate precisely into the soundscape, without unnatural projection. The typical RCA mids are recognized for their clarity and transparency, which are also very present in this tall bottle version.
Highs : Clean and silky. The high-range response is measured, never exuberant. Details emerge without harshness, with a restrained brilliance that enhances musicality and reduces listening fatigue.
Dynamics : Wide and smooth. The valve consistently follows both micro-variations and the most energetic transients, without introducing compression or instability. Behavior under load is progressive and well-controlled.
Soundstage : Wide and cohesive. The soundstage is stable and well-layered, with balanced spatial distribution and good depth, suitable for systems that aim for transparent but not overly analytical performance.
🎧 Use in Headphone Amplifiers and Hi-Fi Driver Stages
Ideal for tube preamps, tube DACs, and OTL amplifiers, where power control is crucial to achieving stable, clean, and three-dimensional sound. The Tall Bottle structure provides a useful power reserve for demanding configurations.
🎸 Use in Guitar and Bass Amplifiers
This RCA version is used in vintage American amplifiers (e.g., Fender Bandmaster , Super Reverb , Showman ) where the rectifier response directly affects feel and articulation. It offers progressive tube compression, with well-managed headroom and an excellent balance between detail and warmth.
🎯 Note for audiophiles and technicians
A reliable, balanced, and musically restrained rectifier, featuring Tall Bottle construction for superior heat dissipation and stable response even in professional or high-current settings. A perfect choice for systems requiring consistency, neutrality, and control.
Test Results
Tubes Tested on Funke W19 Tube Tester:
Voltage Test: Va = 100V, Vf = 5V
Good from: Ia = 78 mA
Average 100%: Ia = 120 mA
TEST RESULT: VERY STRONG
Valve :
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Section 1 : Ia = 139 mA
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Section 2 : Ia = 125 mA
Additional Tests Performed:
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Operation: Stable valve, quiet in operation, and suitable for regular and controlled power supply. Tested with a Funke W19 tester.
- Output Quality: Excellent – Very strong and stable output, no fluctuations.
- Short circuits and GAS: Absent.
Conditions:
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Condition: Vintage tubes - Tested and in perfect working order. Shipped in our custom box for optimal protection.
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Functionality: Fully functional.
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Cosmetic condition: Fair – All writing is completely gone, with obvious signs of wear and a chip on the plastic base. See photos for details.
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Manufacturing Code: Absent - Made by RCA USA - Year of manufacture missing, detected by the internal structure. Made in the early 1960s.
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