For sale is a rare matched pair of JAN-CTL 6SN7GT / VT-231 vacuum tubes, manufactured by Tung-Sol in the USA. These are highly sought-after black glass, round plate versions, known for their exceptional audio performance and build quality.
These tubes feature military (JAN) specifications, ensuring superior reliability, consistency, and durability compared to standard consumer versions.
🔥 Key Features
- Genuine Tung-Sol JAN-CTL 6SN7GT
- Military designation: VT-231
- Black glass construction
- Round black plates (most desirable version)
- Oval getter
- Made in USA
- Excellent for hi-fi, guitar amps, and tube preamps
📊 Test Results (AVO CT160 – calibrated)
- Tube 1: 82% / 82%
- Tube 2: 98% / 97%
Both tubes test strong and are well-balanced.
🔧 Based on AVO CT160 calibration and typical 6SN7 specifications:
- Nominal plate current (Ia): ~9 mA
- Nominal transconductance (gm): ~2.6 mA/V
Estimated from test results:
- Tube 1: ~7.4-7.4 mA / 2.1-2.1 mA/V
- Tube 2: ~8.8–9.0 mA / 2.5–2.6 mA/V
👉 These values indicate strong emission and good transconductance, especially for vintage tubes of this age.
🎧 Sound Characteristics
Tung-Sol round plate 6SN7 tubes are famous for:
- Rich, warm midrange
- Excellent detail and imaging
- Smooth, musical highs
- Tight and controlled bass
A top-tier choice for audiophiles and collectors.
📦 Condition
- Tested and fully functional
- Clean glass with original markings visible
- No cracks or structural damage
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⚡ Why these are special
The Tung-Sol round plate 6SN7GT (VT-231) is widely considered one of the best-sounding 6SN7 tubes ever made, and increasingly rare—especially in matched pairs with strong test results.
This item is sold As-Described
This item is sold As-Described and cannot be returned unless it arrives in a condition different from how it was described or photographed. Items must be returned in original, as-shipped condition with all original packaging.Learn More.
| Listed | 2 months ago |
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| Condition | Very Good (Used) Very Good items may show a few slight marks or scratches but are fully functional and in overall great shape.Learn more |
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