Harma Valves / ECC81-HARMA STR

ECC81-HARMA STR ECC81-HARMA STR Click on image(s) above to view larger
Select Test Options
  • Factory Tested
  • Balanced (Triodes)

All prices contained on this page are exclusive of VAT. This is currently charged at 20% and is payable by the UK only.

Harma valves consist of a selected range of valves that are chosen after meeting stringent standards for sound quality and reliability. These valves are sourced from current production as well as some of the finest Nos valves available. Unlike our competitors no Harma valves, past or present has been made in China. Harma valves represent the finest available items of their type available.

Harma valves are tested using a range of custom designed and built test rigs which are unique to Watford valves.These unique tests are not offered by any other valve supplier in the world.

All Harma pre amp valves undergo the drive rating system; the valve undergoes a series of through tests under full operational conditions. This involves a controlled burn in process to ensure perfect stability and correct ageing. A shock and vibration test, microphoney, hum, and a balance and symmetry test.

All Harma output valves undergo our own unique real world burst testing. No other supplier tests valves this way. The burst testing process involves a series of varying timed electrical signal bursts. This runs the valves under the same stress conditions that they will meet in your amplifier especially when overdriven. All out put valves are then dual matched by us on anode current and gain. This will ensure that you get the best selected valves available anywhere in the world.
The HARMA ECC81 STR is a German manufactured valve that has been specially chosen for its outstanding performance and sound quality.

The ECC81 is as direct replacement for a 12AT7, 6201 and CV4024. The Harma ECC81-STR has a number of important features that set this valve apart from the current production items.

The German engineers used the military designed half flange anode plate. This has 3 support rods which run through the anode plate this design was used by all the military as it reduces vibration and shock. This valve has a 22mm glass envelope which makes it very resilient to micro phonics and outperforms all modern ECC81/12AT7 in this regard.

The ECC81/12AT7 has somewhat lower voltage gain than the 12AX7, 60 mu as opposed to 100 mu of the 12AX7. So this is ideal to reduce the gain in V1 positions should you wish to clean up your amp.

We offer a balanced option:

1) Balanced -matched triode sections for Phase splitter, Audio & Tube microphones

All Balanced preamp valves are Dynamically Drive tested under real working condition have passed the following tests:

Gain (db) Drive Tested
Transconductance (gm) Drive Tested
Output Drive Tested
Noise 1 (signal to noise)
Noise 2 (Aural)
Microphonics Test 1(Ambient)
Microphonic Test 2 (Shock)
Cathode Test
Grid Leakage Test

If you want a matched pair then by ordering 2 of the balanced valves you will get a matched pair



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