5881/HARMA-CRYO MESA BOOGIE 400 PLUS SET 5881/HARMA-CRYO MESA BOOGIE 400 PLUS SET 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.
Here is a special Cryo set for all you owners of the Mesa Boogie 400 plus bass head who want upgraded performance and clarity without taking out a second mortgage.

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.

Indeed I have seen many 400 plus which date from 1994-1996 which still have the original valves. This is simply astounding as many modern 6L6GC valves will get no where near this life span.

This is why Mesa and Marshall used this valve to power their designs thought the 1980's and 1990's.

So as I own several Mesa 400 plus bass heads I fully understand the pain involved in revalving this classic bass amp and maintaining your sound without the need for a second mortgage.

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.

In my own Boogie 400 plus subtle changes in Eq or enhancing certain frequencies with the graphic was far more noticeable with the 5881 Cryo. 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 therefore matched special sets of 12 of these 5881 Cryo with identical current draw and output gain. They have also been tested for hum and microphonics all within the parameters of our own Boogie 400 plus. With these original Military 5881-Cryo you can improve your sound with the added sonic benefits that Cryogenic treatment brings.

The set consists of
12 identically matched 5881Cryo.

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



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