A very nice EX EQUIPMENT device Brimar white print badged GZ34 although Mullard Manufactured carrying the date code of f32 B9L2 The black base is tight to the envelope and the pins are clean and uncorroded, . The device tests as FULL EMISSION using our AVO VCM163 valve tester.
On offer today we have a superb ECC31, wartime manufacture showing superb white print and full emission and excellent matching from each section of this medium output power triode - superb in every way.
On offer today we have a lovely matched pair of Mullard EL37.
Against the nominal AVO specification for 100% emission of :-
Ia =100 mA; gm = 11.0mA/V @ Va = 250V; Vg = -15V
Obtained results were:-
y10: Ia = 72 mA; gm = 9.0 mA/V
Y24: Ia = 70 mA; gm = 9.0 mA/V
As you can see, these results are slightly lower than nominal but should give superlative performance in Push-Pull output applications as the matching of both gm and Ia is superb.
A very nice EX EQUIPMENT device Mullard white print Blackburn manufactured carrying the date code of f32 B9L3 The black base is tight to the envelope and the pins are clean and uncorroded, . The device tests as FULL EMISSION using our AVO VCM163 valve tester.
We have on offer today, one of these high performance triodes which presents the sound stage with a lush midrange and top bass registers whilst the top end remains silkysmooth without headroom roll-off. A signature characteristic of these is supreme female voice reproduction. This 1.75" height glass envelope sports the Mullard old shield and 6SN7GT notation in white ink. This device shows good emission and close matching for each triode section within each envelope - a hallmark of a good valve.
On offer today we have a matched pair of Mullard old shield white print ECC83 .
Using our AVO VCM163 for conditions of or Va = 250 V Vg = -2.0V against a nominal specification of anode current Ia = 1.2 mA and mutual conductance gm = 1.6 mA/V, the following results were obtained:-
Valve C1, A1 Ia = 1.0 mA gm = 1.4 mA/V
Valve C1, A2 Ia = 1.0 mA gm = 1.5 mA/V
Valve C2, A1 Ia = 1.0 mA gm = 1.4 mA/V
Valve C2, A2 Ia = 1.0 mA gm = 1.3 mA/V
As you can appreciate this represents excellent matching of each triode section within each envelope and superb inter valve matching such that this represents and excellent matched pair.