Harma Cryo / 5881-HARMA CRYO

5881-HARMA CRYO 5881-HARMA 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 5881 Cryo is the button based Russian military valve is the same valve which powered the Marshall and Mesa Boogie amps (STR 425) in the late eighties. This valve has bullet proof reliability and proven track record over decades of use in Russian military applications.

This valve was designed to withstand 3G as it was used in the servo motors of Russian fighter Jets. The valves are made with high quality military grade plate material for extended life in the most serve working conditions. Therefore have a reputation which is second to none in terms of clarity and reliability. These valves are of a much higher specification than current manufactured 5881 and each of these valves also has the Russian government stamp of approval for military applications.

So when used in Guitar amplifier applications this valve is vibration and rattle free and will give many years of excellent service.

The 5881-Cryo enhances the sound in a number of ways over the standard 5881 valve. The treble response has much more clarity and detail with more percussive attack. The valve also has a clearer midrange with a tighter more fluid bass response. The valve overall has more dynamics and a more musical response. The performance under distorted and saturated conditions transforms this valve into a valve worthy of the top division.

The Harma 5881 Cryo has a tight and dynamic lead sound with solo having a punchy and clear attack. The overdriven it sounds is warm and well balanced with excellent note definition. This will particularly suit fast players or music such as metal than involves extreme riffing. The top end has more smoothness than the standard item and this is a real benefit as some models of High gain amplifiers as can have an overly hard and bright treble. The 5881 is quite lean in this department in standard format. The good thing about the Cryo 5881 is that it maintains this leanness but just adds more clarity, thus making ideal for use in High gain circuits for Metal, Rock, Grunge and Fusion styles.
What the cryo treatment does to this valve is remove the haze that hampers the sound of the standard item. This transforms a valve known for it legendary reliability in to a valve that now sonically can compete with the best.

We have these specially selected matched pairs and quads

Here is Guitarist Paul Bacon email on fitting the Harma 5881

"I just want to say how pleased I am with the Harma 5881 valves.
I have had problems with the Mesa branded valves ever since I bought my Mesa Express 5:50 Amp. All the Mesa branded STR440 valves developed a rattle and added an annoying harmonic hum to the amplified guitar sound after a short time.
I replaced the Mesa valves each time but the problem would repeat.

I spoke to Watford valves who were very helpful, and suggested some Harma 5881 valves as a replacement.
I have used the new Harma 5881 valves in my amp for many months now and the amp remains free of any tube rattle and harmonic interference. ****Problem solved.****"

Thank you

Paul Bacon

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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