Rare New Old Stock (NOS) 6SL7 dual-triode preamplifier tubes from Fivre, manufactured in Italy during the 1940s. These are original vintage vacuum tubes — not reissues — selected for high-fidelity audio applications.

All units share identical production markings, including the distinctive code “186” stamped on the glass, confirming same-batch origin and military-grade consistency.

Key physical features:

• Brown bakelite base (original 1940s style)
• “Fatboy” anode: large, smooth black plate with robust construction
• Square getter at the bottom (D-type)
• Full mica insulation on top, with clear glass envelope
• No stains, no clouding — pristine vintage condition

These preamp tubes were used in high-end broadcast and studio equipment of the era. Each unit is individually tested for transconductance & emission over original datasheet specifications and guaranteed low microphonics.

Available as matched pairs or quads, with full documentation upon request.

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