NOS 1974 MULLARD e88cc 6922 Mitcham Dimple DISC getter Special quality like CV2492 ecc88 6dj8 CCA perfectly balanced and very strong, gold pins best audio tube, for EMI redd 47

Here for sale a perfect and very rare Mullard e88cc CV2492 matched pair, like 6922 special quality ecc88 6dj8 equals CCA.
This is a very sought after model, the 7L1 with dimpled disc getter. They have the Brimar label and were made both in 1974 in the special quality Mullard factory of Mitcham. Dimple disc getter, double stage single getter post and and gold pins. They have very closed serial number.

Tests results

tube 1:   106 %   106 %  

tube2: 107 % 108%

Code 7L1 R4G2 and 7L1 R4I2

One made the second week of July 1974 and the second only 2 month later the second week of septembre may 1974 ( so very close production)  

This pair is super strong and perfectly balanced and matched, ideal  for stereo use.

One of the very best sounding e88cc type tube ever made, very warm and realistic. Highly musical tube.
Best phono stage tube, high end Hifi without speaking of studio gear like EMI Redd 47.

Top condition NOS new, used only for testing.

I COMBINE SHIPPING ,

 SO PLEASE HAVE A LOOK AT MY OTHER INTEMS AND SAVE .

Shipping price includes tracking and insurance

This tube has been tested 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 with a first tester
and then with a second tester ( Jackson 648S ) for
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 regularly tested for calibration.

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