Rare 1972 NOS NIB MULLARD Blackburn el84 6bq5 RTC green logo super strong Vox AC2 AC4.

 This a rare NOS NIB new in box Mullard el84 6bq5 km1 model, with green RTC logo ( for french broadcast import). Fully tested.  
Made at the famous Mullard Blackburn factory in Great Britain in 197, during the third week of march.
 code : km1 B2B4

 test results 102%

Ring getter, one round hole, non copper post, copper rods.
NOS new, no scratch on pin when I got it, since, it just has been gently burnt time , prior to fresh full new tests.

These Blackburn Mullard are real gold for a vintage Vox AC2 or AC4 but also for recording studio gear using el84 6bq5 tube.

Do we need to present this magic sounding el84 ? The Rolls of el84. They have this so rich sound full of harmonics and sweet unrivaled break up to die for,

Provided in original box, with paper , . please note , see pics, that one corner of the box is a bit damaged and can't close properly.

Note the round hole in plate, ONLY real Blackburn made Mullard have this round hole in plate.
Philips Amperex Valvo Miniwatt , Mullard Canada etc have a rectangular hole in plate . So don't be fooled...

Oh ... to be complete about "el84  round hole in plate",  some very rare French made Philips Belvu have some too , it's the exception but in many details the construction differs from Mullard Blackburn. 
So I can say this is a real Blackburn no doubt for that.
                 

I COMBINE SHIPPING ,  SO PLEASE HAVE A LOOK AT MY OTHER ITEMS AND SAVE .
             

These tubes has been tested with a first tester for

Heater filament test: Short circuit
Heater filament test: Open circuit
Heater filament test: Tolerance check
Heater cathode insulation: Leakage
Heater cathode insulation: Short Circuit
Tests for heater current abnormalities
Amplification factor
Voltage gain
Power gain
Screen grid test
Mutual conductance test
Dual test for double triodes
Emission
Inter electrode leakage
Inter electrode short circuit
Flash-over (arc detection, high voltage breakdown)
Gas ionisation test

and then with a second tester ( Jackson 648S ) for

Leakage

Filament

Circuit

Shorts

Plate

Life test...

The Jackson 648. It is definitely one of my favorite tube testers. While it does not employ a mutual conductance test circuit, it does use an advanced emission circuit that applies separate element voltages to each tube element, and separate load circuits are also used. “These voltages and loads have been carefully selected for each tube to meet most ideally the normal operating condition of the tube.” (Source: 1950 Jackson catalog.)

In my experience, the Jackson circuitry is very effective, and often will surprise you with accuracy that approaches Hickok’s coveted “mutual conductance” test method. ( Source tubesound web site.)

I do my best to test and describe the tubes the best I can.

Note that test results may vary from one tester to an other so this must be taken as an indication, although my jackson is regulary tested for calibration.

 Photos are part of the description you get what you see.

Private sale so no guarantee or return please.

But if any problem (never happened yet ) please contact me first.

Thank you for your interest.