ECC83-HARMA RETRO CRYO ECC83-HARMA RETRO 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 Retro Cryo is a true sounding recreation of the famous Mullard ECC83.

The valve produces a harmonically rich and detailed sound with clear 3D midrange warmth. It has a very open and clear top end chime that gives the amplifier a rich sustaining tone when overdriven.

The valve has been specially designed to give a smooth harmonic slope which gives a warm crunch in guitar amplifiers when overdriven. To replicate the Mullard sound, the Harma ECC83 Retro has a mid boost which produces the warm detail and harmonically rich midrange that made the Mullard sound so famous. This design feature also has the benefit of reducing the upper end fizz and hardness that occurs in many modern day High gains pre amp circuits.

The Cryo treatment gives greater depth and clarity to the valve sound, sweetening the highs and tightening the lows .The Cryo also adds bite to the valves sound making this the ideal choice to add crunch and punch to your sound.

You will get improvements such as a crystal clear top end with more extension and clarity when used clean. When using the overdriven settings the valves characteristics and mid boost provide a warm sustaining sound with plenty of upper harmonics with excellent projection on solos.

This Cryo valve provides glassy smooth highs with a more musical midrange than the untreated item, with the added bite that you need. This is the perfect valve to upgrade all ECC83/12AX7 types in all applications.

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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