Harma Cryo / 6GK5/6FQ5-HARMA CRYO

6GK5/6FQ5-HARMA CRYO 6GK5/6FQ5-HARMA CRYO Click on image(s) above to view larger

All prices contained on this page are exclusive of VAT. This is currently charged at 20% and is payable by the UK only.

A test report is available click here to view

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.
These specially treated cryo 6GK5 offer the Conrad Johnson owners the ultimate performance. They provide a more detailed mid-range, sharper detail and clarity over the untreated version.

The valve has a supported structure which makes then very low in microphonics. The Cryo version reduces the noise floor dramatically. We have tested these for noise, hum and output gain. Stocks are low on this item so we may not be unable to offer these again. Matched items are available by request and will incur the matching fee.

Here is what one of our German customers said in an actual email after fitting the Cryo Harma 6GK5

Thank you Tubes arrived yesterday.
I`ve put them right into my CJ Premier 14.
What a sound!! What a performance!! What a soundstage.These are the best tubes for this Pre-amp, I`ve ever had!!

kind regards

Ulrich Szesniak

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



Facebook Twitter Follow us on Instagram