NOS Mullard ECC33 (1952) Double Triode Valve
Offered here is a genuine New Old Stock (NOS) Mullard ECC33 double triode valve manufactured in 1952 and fully tested on an AVO Mk III valve tester.
The ECC33 is one of Mullard's classic British audio valves and is closely related to the 6SN7 family, offering a higher amplification factor. Original Blackburn-manufactured Mullard valves are highly regarded by audiophiles, vintage radio enthusiasts and collectors for their excellent build quality, reliability and distinctive sound characteristics.
Although this is unused old stock, every valve I sell is individually tested before listing to confirm that it remains electrically sound after many decades of storage. The valve has also been checked to ensure that both triode sections remain closely matched.
Test Results
This valve has been tested on an AVO Mk III valve tester, which measures both plate current (Ia) and mutual conductance (Gm). The measured readings are shown below alongside the published Mullard data book specification.
| Measurement | Data Book Specification | Triode 1 | Triode 2 |
|---|---|---|---|
| Plate Current: Ia (mA) | 9.0 | 8.0 | 7.2 |
| Mutual Conductance: Gm (mA/V) | 3.8 | 3.6 | 3.4 |
The readings show a strong, well-balanced valve, with both triode sections testing close to the published Mullard specification for a new ECC33.
Condition
This is genuine New Old Stock (NOS) and has not been placed into normal service. It retains its original Mullard markings and is presented in excellent cosmetic condition for its age.
Please study all photographs carefully, as they form an important part of the description and show the valve, original printing, internal electrode structure, base and getter condition.
Applications & Compatibility
The ECC33 was developed for high-quality audio amplification and is suitable for vintage British valve amplifiers, pre-amplifiers, radio receivers, communications equipment and other equipment specifically designed for the ECC33. It is also widely recognised as a premium member of the 6SN7 family where circuit compatibility permits.
Original Mullard ECC33 valves are increasingly sought after by audiophiles, collectors and restorers of classic British hi-fi equipment because of their rarity, build quality and desirable sonic characteristics. They are equally at home in restored vintage amplifiers, period radio receivers, studio equipment and historically significant electronic equipment.
Buyers intending to use the ECC33 as a substitute for a 6SN7 or equivalent valve should confirm compatibility with their own equipment before purchase, as operating conditions and substitutions vary between manufacturers and circuit designs.
Packing & Dispatch
The valve will be carefully packed using appropriate protective packaging to ensure safe delivery. Every valve is individually photographed and electrically tested before dispatch, so the purchaser will receive the exact valve shown in the listing.