6V6GT NOS GM by Raytheon Black Plates Smoked Glass Square Getter Matched Pair Tubes USA 1957

6V6GT NOS GM by Raytheon Black Plates Smoked Glass Square Getter Tubes - Made in USA 1957 AMPLITREX Matched – VERY STRONG - Vintage American Raytheon Production Test Results: Tube tested on AMPLITREX AT-1000 Tube Tester: Test Conditions: Va = 250V; Vg2 = 250V; Vg = -12.5V 100% Average: Gm = 4.1 ; Ia = 45 mA Test Result: VERY STRONG Tube 1: Gm = 4.21 ; Ia = 42.6 mA Tube 2: Gm = 3.90 ; Ia = 40.6 mA Additional Tests Performed: Microphonics: Low. Tested and confirmed for use in hi-fi equipment and guitar amplifiers. Emission Quality: Excellent – Very strong and stable emission, without fluctuations. Shorts and GAS: None. Description: Selected pair of 6V6GT NOS – New Old Stock, marketed under the GM brand and manufactured in the United States by Raytheon Manufacturing Company. The code 280 717 identifies the Raytheon plant in Waltham, Massachusetts, and dates the production to the 17th week of 1957. The construction is the most sought-after version of the American Raytheons from the fifties: black plates, smoked glass, and square getter. A configuration of great historical charm, appreciated both by enthusiasts of vintage tube sound and by those looking for original components for vintage amplifiers and boutique builds. The two tubes have been carefully selected and matched on an Amplitrex AT-1000. Tube 1 recorded Gm 4.21 mA/V and Ia 42.6 mA, while Tube 2 measures Gm 3.90 mA/V and Ia 40.6 mA. The variance is contained within approximately 8% on transconductance and 5% on anode current, confirming a solid and consistent match for use in 6V6GT-compatible push-pull output stages. The transconductance values are respectively at approximately 103% and 95% of the nominal reference, accompanied by strong and closely matched anode currents. Both tubes showed very strong and stable emission, low microphonics, and a complete absence of gas, shorts, or fluctuations. In terms of sound, the fifties Raytheon black plates are generally appreciated for a dynamic, full-bodied, and natural presentation, with rich and well-articulated mids, solid low frequencies, and a defined high range without excessive aggression. They are particularly interesting for vintage hi-fi amplifiers and guitar amplifiers where a musical, authoritative, and authentically American response is desired. The pair is offered as NOS – New Old Stock, tested and perfectly functional. The markings are very well preserved and the cosmetic condition is excellent, with only minimal signs due to age. Supplied in customized Vacuum Tubes Treasures boxes. A pair of 1957 Raytheons of great interest, selected for accurate matching, very strong emission, and prestigious black plate construction with smoked glass and square getter. Conditions: Status: NOS - New Old Stock - Tested and functional - Supplied in our custom box for optimal protection. Functionality: Perfectly operational. Cosmetic Condition: Excellent – Markings well preserved, minimal signs of age. See photos for details. Manufacturing Code: 280 717 → 280 → Raytheon Manufacturing Company, Waltham 54, Mass. ; 717 → RMA/EIA Open Date Code → manufactured in the 17th week of 1957 Discover why our tubes are different →