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

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Harma Deep Cryogenic treated valves offers improvements to the sonic character of the valves and results in sound characteristics only normally found in very expensive NOS valves such as Mullards. The process involves taking the vacuum tubes and freezing them down to -312 Fahrenheit and soaking these for a minimum of 12 hours. Then the temperature is held at this low level for 24 hours. The vacuum tubes are then slowly brought up to normal levels over the next 12 hours.

Metals respond very well to deep cryogenic process. The reasons are as follows, during the cooling or solidification phase of the manufacturing process, molecules are trapped in a haphazard pattern. This is down to stress caused in the bending and welding of the anode plate material. This random placement causes obstacles for electrons and when encountered this interference can cause noise, slow down electron flow and sound deterioration affecting the quality of the sound of the vacuum tube. .

At very cold temperatures (below -312 Fahrenheit), the molecules will align in a more uniform, compact structure through the removal of kinetic energy. When the material is returned to ambient temperature, this new uniform, compact pattern is maintained, Thus changing the structure of the nickel permanently. This process makes a permanent change and the benefits do not deteriorate over time or upon return to operating temperature, it changes the whole way the vacuum tube performs.

The biggest benefits I have found have been a dramatic improvement in the sound quality. The bass response has been clearer with reduction in microphonics and clear more transparent highs. Cryogenic treatment has now become a way for a modern valve to produce a sound quality that approaches the iconic originals.
The Harma ECC81 CRYO is a specially treated and selected valve for use in critical positions in both audio and guitar amplifiers.

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.

The valves are also well balanced and we have chosen for its exceptional sound quality and works excellently as a reverb driver.

Balanced option

The balanced item has matched triode sections for use in critical positions in tube compressors and audio amplifiers. These are matched on dB gain for the ultimate audio performance.



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