Very rare earlier construction 1956 NOS TELEFUNKEN ecc81 12at7 perfect, fully tested. Rounded plate with no hole.

Here for sale a super rare 1956 earliest model perfect, perfectly balanced genuine Telefunken ecc81 12at7 made in Germany in 1956 during December in Berlin Telefunken factory.

Tests results     126 %   132 %

Code Bhh04

Fully tested, super strong, perfectly balanced within 1 % so excellent  for most regarding stereo use, or as a phase inverter.
Super early rarer model with rounded plate with no hole model, highly sought after...
and with the thick Telefunken halo getter.

Fully checked and auditioned. Best sounding tube. THE Telefunken sound.

Tests ok for noise and microphony . .

The white ink label as well as the Date factory code are in excellent shape.

Take care when handling the tube the Telefunken white ink of the label is super fragile.

NOS, Perfect condition. Sold as new or very few use

A real reference for audiophile , pro recording studio and some guitar player wanting a fat, warm, super super clean, musical, full bandwidth and balanced sound. All this with an extremely high fidelity to the source.
Great for anyone looking for high linearity response.

And a perfect choice for studio mastering tube gear, without speaking of tube mics or tube mic preamps.

These Telefunken have HUGE HEADROOM ! In the whole tube making History, Telefunken are probably the tubes that can handle the most before starting to distord. So if you need the cleanest whatever happpens, here's your tube.
. .
Tips*** Concerning guitar amps, these Telefunken are great option as phase inverter.. It really help to preserve the integrity of your V1 and also to enhance your beloved V1 and previous stages tubes tone allowing them also to have an incredible dynamic and response under the pick.

Hear and feel the difference of tube golden age era production.

I COMBINE SHIPPING ,

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

Shipping cost includes tracking and full price 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

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 regularly tested for calibration.

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

Thank you for your interest.