6SL7GT AMPEREX GLOBE AMPLITREX Tested Pair Black Plates Square Getter Tubes USA 60s

6SL7GT AMPEREX GLOBE AMPLITREX Tested Pair Black Plates Square Getter Tubes USA 60s

Description
This pair of 6SL7GT AMPEREX GLOBE , USA production from the 1960s , is a version of great historical and sonically interest, made by RCA for the Amperex Company . These examples feature black plates , square getters and the characteristic smoked glass , typical elements of the best RCA productions of the time destined for leading brands such as Amperex.
The tubes have been tested with the Amplitrex AT-1000 and both are in TEST VERY STRONG conditions, with high output, stable operation and no shorts or gas.

Sound Characteristics

The 6SL7 RCA black plates with smoked glass are appreciated for their rich, authoritative and very musical tone, with a very recognizable classic American character.

Bass
Full, solid, and well-controlled. The low end has body and depth, while maintaining good articulation and stability.

Medium
Warm, dense, and highly expressive. Vocals sound natural and present, with a particularly convincing performance on jazz, blues, and vocal music.
The midrange is one of the strong points of this RCA configuration.

High
Smooth, fluid, and never aggressive. The smoked glass contributes to an elegant and slightly silky presentation, with a well-integrated, harsh-free finish.

Dynamics
Robust and progressive. The response is energetic but controlled, with a very musical behavior consistent with the VERY STRONG state of the tubes.

Soundstage
Wide and three-dimensional, with good depth and separation of musical lines. The soundstage is stable and natural, typical of the best American 6SL7s of the 1960s.

🎧 Use in Hi-Fi Stereo Amplifiers
Suitable for:

• tube preamplifiers,

• input and driver stages,

• Vintage American and European amplifiers using 6SL7s.

The warm and authoritative timbre makes them ideal for jazz, vocal, classical and prolonged listening, as long as a perfect balance between the two tubes is not required.

🎸 Use in Music Amplifiers
Excellent for:

• guitar and bass amplifiers with 6SL7,

• vintage circuits and boutiques,

• positions where character, body and rich harmonics are sought.

Microphonics: Standard. Recommended for use in V2, V3, V4, as a driver or in less critical stages. Not recommended for V1.

🎯 Note for audiophiles and technicians

A premium choice for enthusiasts, restorers, and musicians seeking authentic 1960s RCA tone, with the allure of the Amperex Globe brand.

Test Results:

Valves tested on Amplitrex AT-1000 Tube tester :

• Test Conditions: Va = 250V, Vg = -2V
• Average 100% Gm = 1600 ; Ia = 2.3 mA

Valve 1:

• Section 1: Gm = 1700 ; Ia = 2.3 mA
• Section 2: Gm = 1700 ; Ia = 2.5 mA

Valve 2:

• Section 1: Gm = 1400 ; Ia = 2.0 mA
• Section 2: Gm = 1500 ; Ia = 2.1 mA

• Microphonics: Standard. Tested and approved for use in hi-fi and guitar amplifiers. Recommended for use in V2, V3, V4, as a driver, or in less critical stages. Not recommended for use in V1.
• Balance: The two sections show coherent and well-aligned values, making the valve also ideal as a phase inverter in hi-fi and instrumental applications.
• Output Quality: Excellent – Very strong and stable output, no fluctuations.
• Short circuits and GAS: Absent.

Conditions:

• Condition: Vintage Valves - Tested and in perfect working order - Supplied in original box.
  
• Functionality: Fully functional.
  
• Cosmetic condition: Excellent – Excellently preserved lettering, minimal signs of wear. See photos for details.
  
• Manufacturing Code: None – Made by RCA USA for AMPEREX, identifiable by its construction features. 1960s

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