EL34-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 EL34 Retro Cryo is a specially Cryogenically treated version designed to give you enhance audio performance.

The Harma EL34 Retro Cryo is based on the famous Mullard EL34 and has a number of important features which technically set the valve apart from other EL34 types.

The grids of the valve use a block construction which enables the valve to provide smoother output and eliminating odd order harmonics. The Anode plates are constructed using a laminated alloy which gives better heat transfer under overload conditions. This results in a tight bass response, balanced warm midrange sound stage and clean clear treble response. The construction is then house in a thick glass envelope that not only adds strength but also provides lower michrophoney.

The cryogenic process offers permanent change to the metals microstructure. This results in a better sounding valve. It has clear note definition and enhanced clarity over complex musical passages.
Music has more focus and tighter note and instrument sound staging with more harmonic content.

The Cryo treatment offers an improved sound that has previously only been attainable by using rare and expensive new old stock classics.

The Cryo treatment has dramatic effect on the way the valve performs not only in clean applications but also when overdriven. The cryogenic process removes the harshness from the valves tone and imaging has more focus and bite. It has a warmer fuller sound which is pleasing to listen to, providing a clear and musical distortion. In short, many musicians, engineers and audiophiles have found that by using cryogenically treated valves it is a proven way of obtaining NOS sound quality with a great difference, an affordable price!

All Harma Output valves are Dynamically Burst tested and undergo our own unique real world burst testing under real working conditions. The valve undergoes full drive testing which involves a series of varying timed electrical signal bursts that replicate the same stress conditions that the valve will encounter in your amplifier. Note No other supplier tests valves this way and why Harma valves have been used by the top Professionals. This is designed to ensure the ultimate reliability. The Harma valves have passed all the following tests:

Gain (m/A) Drive Tested)
Variable Signal Burst(Burst 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

All output 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.



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