1x Mullard ECC83 Valve Date Code: ?3 mCA (1953) Very rare ECC83 from Copenhagen factory with long welded plate and D-getter Tested by AVO VCM Tester Ia1 = 1.2(mA), gm1 = 1.45(mA/V) Ia2 = 0.9(mA), gm2 = 1.3(mA/V) NOS specification: Ia = 1.2(mA), gm = 1.6(mA/V) *** This valve has also been tested in amplifier without any noise. *** Postage Costs I am happy to post this item to worldwide and combine postage cost on multiple purchases. 20230522L006

Mullard CV4004 M8137 Special Quality Box Plate Valve This type is a special quality robust version of the ECC83 or 12AX7 double triode.Tested on an AVO VCM MkII results are: A1: Ia 1.55mA. Gm 2.2mA/VA2: Ia 1.35mA. Gm 2.1mA/V (Avo spec. for ECC83 is 1.2mA, 1.6mA/V) On 14-May-23 at 18:34:23 BST, seller added the following information: Supplied in white box

MULLARD CV4004 M8137 12AX7 ECC83 VALVE TUBE GOOD QUALITY BRITISH

A pair of ECC83 M8137 CV4004 12AX7 special quality valves.Both made at the Mitcham factory, etch codes are R9F5 (1959 June week 5) & R4D2 (1964 April, week 2)The M8137 is characterised by a large halo getter used to increase the quality of the vacuum.Tested on an AVO CV160Results are:Valve 1 Anode 1, 1.2mA 1.8gm - Anode 2, 1.2mA 1.8gmValve 2 Anode 1, 1.2mA 2.0gm - Anode 2, 1.2mA 1.9gmBoth valves exceed the standard for ECC83Very stable and quick warming.

Mullard CV4004 M8137 Used Special Quality Box Plate Valve This type is a special quality robust version of the ECC83 or 12AX7 double triode.Tested on an AVO VCM the results are perfectly matched: A1: Ia 1.3mA. Gm 2.05mA/VA2: Ia 1.3mA. Gm 2.05mA/V (Avo spec. for ECC83 is 1.2mA, 1.6mA/V) Supplied in brown box