Which Socket fits which Tube / Valve

Author: Kevin M  Date Posted:27 October 2026 

Tube Socket Guide: Which Socket Fits Which Valve?

Every valve plugs into a socket built for its base. Get the base right and the tube drops straight in; get it wrong and it won't fit at all. This guide lists every tube type Evatco stocks and the socket it needs, plus reference sockets for popular tubes we don't carry, such as the B9D Magnoval socket used by the EL509.

1Find your tube in the table below (or search for it).

2Note the socket family: Octal, Noval B9A, Magnoval B9D and so on.

3Pick a mounting style: chassis, under-chassis or PCB, and the hole size.

4Check the pinout. Same socket does not mean same wiring.

 

Tubes We Stock and the Socket They Need

Click a tube name to shop that type, or click the socket family to jump to the matching sockets.

Tube Common equivalents Type Base Socket family
Preamp tubes
12AX7 ECC83, 7025, ECC803S, E83CC, 5751 (lower gain) Dual triode B9A Noval 9-pin
E83CC 12AX7, ECC83 Dual triode B9A Noval 9-pin
12AT7 ECC81, 6201, CV4024 Dual triode B9A Noval 9-pin
12AU7 ECC82, 5814, 6189, ECC802S Dual triode B9A Noval 9-pin
12AY7 6072 Dual triode B9A Noval 9-pin
12BH7 12BH7A Dual triode B9A Noval 9-pin
12DW7 ECC832, 7247 Dual triode (mixed) B9A Noval 9-pin
5751 12AX7 family (about 70% gain) Dual triode B9A Noval 9-pin
6AQ8 ECC85 Dual triode B9A Noval 9-pin
6BM8 ECL82 Triode-pentode B9A Noval 9-pin
6CG7 6FQ7 Dual triode B9A Noval 9-pin
6H30pi 6N30P-DR Dual triode B9A Noval 9-pin
6N1P 6N1P-EV, 6H1n Dual triode B9A Noval 9-pin
E88CC 6922, 6DJ8, ECC88, 7308 Dual triode B9A Noval 9-pin
ECC823 12AX7 family (high grade) Dual triode B9A Noval 9-pin
ECC99 None direct Dual triode B9A Noval 9-pin
EF86 EF806, 6267, Z729 Pentode B9A Noval 9-pin
SV83 None direct Pentode B9A Noval 9-pin
6SL7 6SL7GT, 6H9C, ECC35 Dual triode Octal (K8A) Octal 8-pin
6SN7 6SN7GT, 6H8C, ECC33, 5692 Dual triode Octal (K8A) Octal 8-pin
6SC7 6SC7GT Dual triode Octal (K8A) Octal 8-pin
Power tubes
6L6 6L6GC, 6L6WGC, 5881, KT66 (check bias) Beam tetrode Octal (K8A) Octal 8-pin
5881 6L6WGB Beam tetrode Octal (K8A) Octal 8-pin
7027 7027A (6L6 family, extra pin connections) Beam tetrode Octal (K8A) Octal 8-pin
7581 7581A, 6L6 family Beam tetrode Octal (K8A) Octal 8-pin
6V6 6V6GT, 6V6S, 5871 Beam tetrode Octal (K8A) Octal 8-pin
EL34 6CA7, KT77 (close substitute) Pentode Octal (K8A) Octal 8-pin
6CA7 EL34 Pentode / beam tetrode Octal (K8A) Octal 8-pin
KT77 EL34 / 6CA7 replacement Beam tetrode Octal (K8A) Octal 8-pin
KT66 6L6 family (larger bulb, more heater current) Beam tetrode Octal (K8A) Octal 8-pin
KT88 6550 (check bias) Beam tetrode Octal (K8A) Octal 8-pin
6550 6550A, 6550C, KT88 Beam tetrode Octal (K8A) Octal 8-pin
KT90 KT88 / 6550 upgrade Beam tetrode Octal (K8A) Octal 8-pin
KT120 KT88 / 6550 upgrade Beam tetrode Octal (K8A) Octal 8-pin
KT150 KT88 / KT120 upgrade (large bulb) Beam tetrode Octal (K8A) Octal 8-pin
KT170 KT88 / KT150 upgrade (large bulb) Beam tetrode Octal (K8A) Octal 8-pin
7591 7591A (own pinout, not a 6L6 swap) Beam tetrode Octal (K8A) Octal 8-pin
EL84 6BQ5, 7189, 6P14P Pentode B9A Noval 9-pin
6973 None (different pinout to EL84) Beam tetrode B9A Noval 9-pin
7868 None direct (a 9-pin version of the 7591) Pentode Current production: Magnoval
Vintage NOS: Novar (B9E)		 Magnoval 9-pin
Vintage NOS: Novar
300B WE300B, 300B-98 Direct-heated triode UX4 UX4 4-pin
2A3 6A3 (6.3V heater); the 6B4G is octal Direct-heated triode UX4 UX4 4-pin
Rectifier tubes
5AR4 GZ34, 5U4 / 5Y3 (check current and voltage drop) Dual diode Octal (K8A) Octal 8-pin
5U4GB 5U4G, 5AS4 Dual diode Octal (K8A) Octal 8-pin
5Y3 5Y3GT, 5Y3S Dual diode Octal (K8A) Octal 8-pin
6CA4 EZ81 Dual diode B9A Noval 9-pin

Equivalents are listed as a guide only. Many are direct swaps, but some need a bias check, more heater current, or a pinout check first.

Same socket does not mean same tube. A socket only matches the shape of the base. The EL84 and 6973 both fit a noval socket but are wired differently, and the 7591 fits an octal socket but is not a 6L6 swap. Always check the datasheet pinout before you swap tube types.

Socket Families and the Sockets We Stock

Each family below lists the tubes it suits, including popular tubes we don't stock, so you can find the right socket for nearly any project.

Octal 8-pin K8A / IO

8 pins in a circle around a keyed centre spigot. The standard power and rectifier socket in Fender, Marshall and most hi-fi amps.

Fits: 6L6, 5881, 7027, 7581, 6V6, EL34, 6CA7, KT66, KT77, KT88, 6550, KT90, KT120, KT150, KT170, 7591, 6SL7, 6SN7, 6SC7, 5AR4/GZ34, 5U4GB, 5Y3. Also: EL37, 6F6, 6K6, 6B4G, 6AS7G, 6080, 6SJ7, 6J5, GZ32, GZ37, 5R4, 5Z4, 5V4, 6146 (top cap).

Shop all 8-pin sockets

Noval 9-pin B9A

9 pins with a gap between pins 1 and 9. The standard preamp socket, also used by EL84 power tubes and EZ81 rectifiers. Chassis-mount types suit an 18mm or 22mm hole.

Fits: 12AX7, ECC83, E83CC, 5751, 12AT7, 12AU7, 12AY7, 12BH7, 12DW7, 6AQ8, 6BM8, 6CG7, 6H30pi, 6N1P, E88CC/6922, ECC823, ECC99, EF86, SV83, EL84, 6973, 6CA4/EZ81. Also: ECC88, 6DJ8, 6BQ7, ECC85, ECF82/6U8A, ECL86/6GW8, EL86/6CW5, EF80, EF184, EZ80, 12BY7, PCC88. Note: EL504 and EL509 are Magnoval, not noval.

Shop all 9-pin sockets

Magnoval 9-pin B9D

A larger, heavier-pinned 9-pin socket for high-power European types. It looks like a big noval, but noval tubes will not fit it.

Fits: 7868 (current production, e.g. Electro-Harmonix). Also: EL509, PL509, EL519, PL519, 6KG6, 40KG6, EL500, PL500, EL504, PL504, E55L / 8233, EL5070 / 8608, 6P45S, 6P42S.

Current-production 7868s have heavier pins made for Magnoval sockets. Vintage NOS 7868s have thinner Novar pins and can sit loosely in a Magnoval socket. See Novar.

EL509, EL519, PL509 and EL500 / EL504 types have a top anode cap. See anode and grid caps.

Miniature 7-pin B7G

The small 7-pin socket used in older radios, test gear, reverb drivers and some hi-fi preamps.

Fits: 6AQ5 / EL90, 6C4 / EC90, 6AU6 / EF94, 6BA6, 6BE6, 6AL5 / EB91, 6AV6, 6AK5 / 5654, 6X4 / EZ90, 6CB6, 12AU6, OA2, OB2. Tubes not stocked

Shop all 7-pin sockets

UX4 4-pin UX4 / B4 (US)

Two thick filament pins and two thinner pins. The classic direct-heated triode socket for single-ended hi-fi.

Fits: 300B, 2A3. Also: 45, 50, 5Z3, 80, 83.

Shop all 4-pin sockets

Jumbo 4-pin Jumbo / Giant 4

An oversized 4-pin socket for large transmitting triodes used in high-power SET amps.

Fits: 211 / VT-4-C, 845. Tubes not stocked

UX5 5-pin UX5

The American 5-pin socket, best known for the 807 beam tetrode (which also needs a top cap).

Fits: 807. Also: 27, 56, 76, 47. Tubes not stocked

Shop all 5-pin sockets

British 4 and 5-pin B4 / B5

Pre-war British bases for vintage triodes and rectifiers, now popular in boutique hi-fi.

Fits: DA30, PX4, PX25, ML6, U18/20, U20, 1701 and similar. Tubes not stocked

6C33C 7-pin Special

One large pin and six smaller pins, made for the Russian 6C33C high-current triode used in OTL amps.

Fits: 6C33C, 6C33C-B, 829B, 3E29. Tubes not stocked

Jumbo 7-pin 813

Two large and five small pins for the 813 transmitting tetrode. Bottom mount, needs a 1¼" chassis hole. The 813 also needs an anode cap.

Fits: 813. Tubes not stocked

Novar 9-pin B9E

A larger 9-pin base with a wider pin circle than noval. Same pin circle as Magnoval, but with thinner pins.

Fits: vintage NOS 7868, plus some 1960s American TV and hi-fi types.

Novar and Magnoval share the same pin circle, but Novar pins are thinner. Don't push a current-production 7868 into a true Novar socket, as its heavier pins will stretch the contacts. For current-production 7868s, use a Magnoval socket.

We don't currently list a Novar socket. Contact us and we'll help you source one.

Loctal 8-pin B8G

8 pins with a locking metal spigot, common in 1940s US radios.

Fits: 7A4, 7B4, 7C5, 7F7, 7N7, 7Y4.

Reference only. Not currently stocked.

Rimlock 8-pin B8A

European 8-pin miniature base with a locating pip on the glass.

Fits: EL41, EF40, EF41, ECC40, AZ41, UCH42.

Reference only. Not currently stocked.

Compactron and Nuvistor B12C / Nuvistor

12-pin compactrons (6LF6, 6KD6) and tiny metal-can nuvistors (6CW4, 7586, 7895).

Reference only. Not currently stocked.

Choosing the Right Socket

Mounting style

Chassis-mount sockets sit on top of the chassis, under-chassis types mount from below, and PCB sockets solder straight to a circuit board. Match what your amp already uses.

Hole size

Noval chassis sockets come for 18mm or 22mm holes. Measure the existing hole before ordering a replacement.

Ceramic vs phenolic

Ceramic sockets handle heat and high voltage better and are the safer pick for power and rectifier tubes. Belton and micalex types are proven, quality alternatives.

Gold pins

Gold-plated contacts resist corrosion and give a reliable connection, which suits hi-fi and tubes that are swapped often.

Big bottles

KT120, KT150 and KT170 tubes are physically larger. Check spacing and clearance, and fit a tube retainer in combos.

Top caps

807, 813, 6146 and EL509-type tubes have an anode connection on the top of the bulb. You need an anode cap as well as the socket.

Not sure which socket you need?

Send us the tube type and a photo of your old socket and we'll point you to the right part. Contact Evatco or browse all tube sockets.