6SN7GTB by GE-coin base-short bottle-vacuum tubes-Amplitrex tested-dated 78 pair

Up for sale is a premium-grade, vintage General Electric (GE) 6SN7GTB "Coin Base" short bottle vacuum tube, manufactured in the USA in 1978.The late-70s GE "coin base" (wafer-base) variant is highly coveted by audiophiles and guitar players alike. This unique flat, glass-pressed bottom seal significantly lowers the tube's physical profile and minimizes microphonics and structural vibrations. It delivers a remarkably clean, quiet, and balanced soundstage with superb low-end definition, organic mid-range, and incredibly transparent highs.This particular tube features classic GE gray plates, a robust side-getter configuration, and pristine structural integrity engineered for heavy-duty operational longevity. See pictures for full test results.. I test all tubes I sell for noise on both the Amplitrex At-1000 and on my personal headphone amplifier.
⚙️ Item Specifics

• Brand: General Electric (GE)
• Tube Type: 6SN7GTB / 6SN7 (Dual Triode)
• Base Type: Coin Base / Wafer Base
• Date Code: 1978 (Matching GE factory stencils)
• Country of Manufacture: USA
• Application: High-end hi-fi audio preamps, headphone amplifiers, and vintage guitar amplifiers.

🔬 Condition & Professional TestingThis tube has been thoroughly inspected and professionally tested on a Amplitrex AT-1000 tube tester. It performs exactly at the tube's official industry nominal factory design specifications, ensuring perfectly balanced triode halves.

• Physical Condition: Excellent vintage condition. The glass envelope is flawless and clear. The pins are straight and clean to ensure perfect electrical continuity. Original GE factory branding and text are crisp and fully legible.
• • Context: 2,600 µmhos (Gm) is the official RCA/GE factory datasheet nominal specification for a new 6SN7 triode sectio
• • Context: 9.0 mA is the official factory datasheet nominal plate current specification under standard test conditions (250V plate / -8V grid).
• Shorts & Gas Test: Checked and passed. Absolute zero shorts, zero leakage, and zero gas grid current.
• Packaging: Will ship safely secured in a brand new, protective white generic box.