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6L6GC / KT66 / 5881 tubes

The most common types of 6L6 tubes and their European equivalents used today include:

6L6GC - The popular 6L6 beam-power pentode was introduced by RCA in 1936 and culminated in the development of the 6L6GC tube in the 1950s. The higher rated 6L6GC can be used in place of any of its predecessors, including the metal can 6L6, coke bottle 6L6G, compact 5881, and straight-sided 6L6GA and 6L6GB tubes. It can also be used interchangeably with its European rival, the KT66.

5881 - The 5881 was introduced by Tung-Sol in 1950. This consumer version of the military spec 6L6WGB tube featured higher plate and screen dissipation ratings and greater resistance to shock and vibration. The 5881 can be used to replace any 6L6 tube type except the 6L6GC, KT66, or 7581, which all have higher power ratings.

KT66 - The KT66 was introduced by Marconi-Osram 1937. KT66 tubes have large clear or gray glass coke bottle envelopes. The KT66 can be used interchangeably with its European competitor, the EL37, and its American rival, the 6L6GC.

Other tube types in the 6L6 family include: 6L6, 6L6G, VT-115A, 6L6Y, 6L6GA, 6L6GAY, 6L6WGA, 6L6GB, 6L6WGB, 1614, 1622, 5932, and 7581. The 7027A tube has similar power ratings but with a different pin-out. 6L6 tube types can vary greatly in size, so check the clearances in your chassis if you plan to sub one type for another.

Comparison of
design maximum values for 6L6 tube types (pentode connection)

5881 6L6GC KT66
Max. Plate Dissipation 23 Watts 30 Watts 30 Watts
Max. Plate Voltage 400 Volts 500 Volts 500 Volts
Max. Screen Voltage 400 Volts 450 Volts 500 Volts

6L6 tube types in stock now

Scroll down to browse our current selection of vintage 6L6 tubes and burned in, tested, and precision matched new production 6L6 power tubes. Click "more info" for pricing, availability, and matching options.

Displaying products 1 - 8 of 8 results
GE 6L6GC - premium matched pair
GE 6L6GC - precision matched pair
Price: $119.00
GE 6L6GC - precision matched pair
The GE 6L6GC power tubes in this precisely matched pair have gray plates, dual side getters, and black bases. The white print has the GE logo and 188-5 factory code (Owensboro, Ky). Tubes test as new and are matched for current draw (mA) and Gm.
GE 6L6GC - precision matched quad
GE 6L6GC - precision matched quad
Price: $249.00
GE 6L6GC - precision matched quad
The GE 6L6GC power tubes in this precisely matched quad have gray plates, dual side getters, black bases, and the 188-5 factory code (Owensboro, Ky). Tubes test as new and are precisely matched for both current draw (mA) and transconductance (Gm).
Genalex Gold Lion KT66 reissue - premium matched
Genalex Gold Lion KT66 reissue - precision matched
Price: $38.00
Genalex Gold Lion KT66 reissue - precision matched
These new production Genalex Gold Lion KT66 power tubes can be run in any amp that uses 6L6 or 5881 type tubes. They are a faithful reproduction of the tubes used in Clapton's Bluesbreaker amp and popular Heathkit and Leak hi-fi amps from the 1960s.
Vintage Svetlana /
SED "Winged C" 6L6GC - matched pair
Price: $109.00
SED "Winged C" 6L6GC - matched pair
The SED 6L6GC tubes in this precisely match quad were made at the original SPb factory in St. Petersburg, Russia. The tubes have the gold "Winged C" logo on the glass. Tubes test as new and are precisely matched for both current draw (mA) and Gm.
Tung-Sol 5881 reissue - premium matched
Tung-Sol 5881 reissue - precision matched
Price: $19.00
Tung-Sol 5881 reissue - precision matched
These new production Tung-Sol 5881 power tubes are based on the original 1960s Tung-Sol 5881. They are a 23 Watt 6L6GB equivalent rated for 400 V. Price includes extended burn-in and precision matching.
Tung-Sol STR 6L6GC reissue - premium matched
Tung-Sol STR 6L6GC reissue - precision matched
Price: $22.00
Tung-Sol STR 6L6GC reissue - precision matched
These new production Tung-Sol STR 6L6GC power tubes are built to the same Special Tube Request specs of leading 1960s amp manufacturers. These 30 Watt power tubes are rated for 500 Volts, making them a great choice for demanding guitar amp circuits.
Vintage Svetlana /
Vintage Svetlana / "Winged C" 6L6GC - matched quad
Price: $219.00
Vintage Svetlana / "Winged C" 6L6GC - matched quad
The 1998 Svetlana 6L6GC tubes in this precisely match quad were made at the original SPb factory in St. Petersburg, Russia before they lost the rights to the Svetlana name. Tubes test as new and are precisely matched for both current draw (mA) and Gm.
Sylvania 6L6G - engraved bases, matched pair
Sylvania 6L6G - engraved bases, matched pair
Price: $69.00
Sylvania 6L6G - engraved bases, matched pair
The early 1940s Sylvania 6L6G power tubes in this precisely matched pair are lower power predecessors to 6L6GC type tubes. They have large ST bottles, bottom getters, and engraved bases. One tube has a repaired guide pin. Both tubes test as new.
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TC Tubes specializes in precision testing and matching of vintage and new production vacuum tubes for guitar & bass players, audiophiles, and DIY tube audio enthusiasts. Our website features secure payment options and fast, convenient shipping around the world.

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