ECC83-HARMA STR CRYO ECC83-HARMA STR CRYO Click on image(s) above to view larger

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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 ECC83 STR Cryo has the most neutral and warmest sounding with the Classic vintage tone when compared to all the current production ECC83/12AX7 types.

This is our most popular valves as it has provides medium to high gain with a warm balanced vintage tone. This valve also has a low noise floor so it is ideal in high gain circuits if you want more clarity or simply calm down harsh circuit. This have also has some important features such as an internally rugged construction which is based around a frame grid design. The valve is made with thick mica supports. This has a number of advantages such as reduced microphonics and better isolation from vibration. The grids windings are all gold plated as were the original Telefunken valves.

This translates to excellent sonic and mechanical performance in high volume and guitar combo applications

This is a specially cryogenically treated version offers which offers huge improvements in top end detail giving better transparency and definition. The mid band sees improvements in detail and warmth and the bass response become sharper and more musical. The other factor that guitarist find the major reason for choosing this valve is that it has more bite and has a smoother more harmonic distortion.

This makes it a great choice for clear Fender sounds or warming up a harsh modern amp or taming a high gain circuit. This is one of the best modern ECC83 and in cryo format beats many nos valves.
These valves are all selected for low noise, low microphony and are drive tested with a gain rating of between 229 and 249 digital points give rich even sound.

All Harma 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



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