Browse Categories

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 - 10 of 10 results
GE 6L6GC - premium matched octet
GE 6L6GC - premium matched octet
Price: $519.00
GE 6L6GC - premium matched octet
The GE 6L6GC power tubes in this premium matched octet 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).
GE 6L6GC - premium matched pair
GE 6L6GC - premium matched pair
Price: $126.00
GE 6L6GC - premium matched pair
The GE 6L6GC power tubes in this premium matched pair have gray plates, dual side getters, and black bases. They also have matching date codes and the 188-5 factory code (Owensboro, Ky). Tubes test as new and are precisely matched.
GE 6L6GC - premium matched quad
GE 6L6GC - premium matched quad
Price: $252.00
GE 6L6GC - premium matched quad
The GE 6L6GC power tubes in this premium 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).
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: $19.00
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.
GE 7581A - matched pair
GE 7581A / 6L6GC - matched pair
Price: $189.00
GE 7581A / 6L6GC - matched pair
The GE 7581A power tubes in this precisely matched pair are premium 6L6GC tubes with a higher power rating. They have gray plates and dual side getters with lots of flashing. Tubes test as new and are matched for current draw (53.2 & 54.9 mA) and Gm.
Mullard EL37 / 6L6GC - matched pair
Mullard EL37 / 6L6GC - matched pair 1
Price: $374.00
Mullard EL37 / 6L6GC - matched pair 1
The 1962 Mullard EL37 power tubes in this precisely matched pair are 6L6GC type tubes. They have smoked glass, gray plates, and dual bottom getters (R62 series). Both tubes test as new and are matched for both current draw (43.4 mA & 44.2 mA) and Gm.
Mullard EL37 / 6L6GC - matched pair 2
Mullard EL37 / 6L6GC - matched pair 2
Price: $374.00
Sale Price: $261.80
Mullard EL37 / 6L6GC - matched pair 2
The 1956 Mullard EL37 power tubes in this precisely matched pair are 6L6GC type tubes. They have smoked glass, gray plates, and dual bottom getters (R61 series). Both tubes test as new and are matched for both current draw (43.0 mA & 45.4 mA) and Gm.
on sale
Sylvania 6L6GC - matched pair
Sylvania 6L6GC - matched pair
Price: $109.00
Sylvania 6L6GC - matched pair
The 1960s Sylvania 6L6GC power tubes in this precisely matched pair have gray plates with copper grid posts and halo getters. The red print on the base has the Sylvania logo on one tube and the Zenith logo on the other tube. Both tubes test as new.
Tung-Sol 5881 / 6L6WGB - matched pair, various labels
Tung-Sol 5881 / 6L6WGB - matched pair, various labels
Price: $107.00
Tung-Sol 5881 / 6L6WGB - matched pair, various labels
The 1960s Tung-Sol 5881 power tubes in this precisely matched pair are 6L6GB type tubes. They have gray plates, top getters, and brown bases. One tube has the Raytheon logo and the other tube has the GE logo. Both tubes test as new.
Search
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.

Shopping Cart
Your cart is empty.