Deep Cryogenic Treatment of Audio Equipment
What is Deep Cryogenic Treatment?
Deep Cryogenic Treatment (DCT) is the process of cooling an object in a low temperature vessel to a very low temperature, typically that of liquid nitrogen at -196oC, keeping the object at that temperature for a period of time and then raising the temperature back to ambient temperature.
The purpose of applying deep Cryogenic Treatment is to improve the properties of the item being treated. In the case of audio cables and other audio equipment, the justification for Deep Cryogenic Treatment is the improvement in sound quality.
The Deep Cryogenic Treatment Process
Deep Cryogenic Treatment is usually applied in three separate stages.
Cool down. The cables are very slowly cooled over several hours at a pre-defined rate to the desired temperature.
Soak at low temperature. The cables are held at low temperature for a long period with precise temperature/time profile that has been tested to deliver superior audio sound quality.Maintaining the temperature at -196oC for at least 24 hours ensures complete transformation of the full cross section of the object being processed.
Return to room temperature. The temperature is slowly and carefully returned to ambient.
Computer control. All these DCT processes are controlled by a pre-defined computer programme to ensure consistency in performance for each process.
Description of the Deep Cryogenic Treatment used for audio
The ‘dry’ treatment. The cables and connectors are cooled in nitrogen vapour. It is important that all moisture and air is removed from the cooling vessel so that all that remains is an inert Nitrogen atmosphere. If any condensation occurs during the process sensitive electrical parts and materials could be damaged. So some cryogenic processing suppliers may use different vessels for audio than for other industries.
Another factor that affects the quality of the treatment is that different vessels should be used for different materials. When automobile parts are processed, the lubrication on the tools and engine parts is dispersed throughout the cooling vessel. It is impossible to remove all the petrol based lubricants could settle on the audio grade silicone and polymers on a subsequent processing, causing premature perishing.
Types of Products that Benefit from Deep Cryogenic Treatment
Products that are formed from a molten state
Most of the materials that are used in audio such as metals, plastics and glass begin life in a molten statewill benefit. As they are formed into shape, they are then allowed to cool. In most manufacturing processes the cooling is engineered to occur as quickly as practical to keep manufacturing costs down. As some parts will cool quicker, stresses in the material will develop due to the differential cooling rate. These stresses will cause mechanical weakness and will impede electron flow in conductors. Further processing post manufacture will further change the material crystal structure. Glass and plastics may be moulded. Metals may be milled, sawn, bent or sanded to achieve their finished state. All this additional processing can cause further irregularities in the crystal structure.
Why further heat treatment is not as effective
The most common way to relieve the stresses caused during manufacture is to heat the material until the atoms can move more freely and then cool down.However there is still the danger of new stresses being created in the material as it cools down.
Deep Cryogenic Treatment relieves stresses in materials
DCT processing relieves manufacturing stresses more effectively by the removal of energy. As the material cools, the atoms are bonded more closely together, removing any distortion in the atomic structure. New material stresses are avoided by controlling the cooling in a very slow controlled manner. As the materials returns to room temperature the structure formed at low temperature will remain. This new structure has less stress and responds to energy such as the electrical signal representing a musical performance in a more accurate way. In other words, the sound quality will be improved.
Materials that do not benefit from DCT
Most materials appear to benefit from deep cryogenic treatment because the treatment changes the molecular structure of the material from one in which is irregular due to uneven cooling occurring during manufacture. Wood, for example is organic and no improvement in any if its properties is achieved by DCT.
Materials that are damaged by DCT
If the deep cryogenic treatment is carried out under carefully controlled conditions there are very few materials that can be damaged. One substance that does not react well to cryogenic processing is glue. As most loudspeaker drive units use glue in their assembly, the cryogenic processing of loudspeaker drive units cannot be recommended.
Deep Cryogenic Treatment processes applied to Black Rhodium Cables and Connectors
DCT++. The DCT process described above is applied. Before the object is removed when ambient temperature is reached, it is subjected to a normal tempering re-heat. This re-heat cannot be applied to any cables containing parts (such as many types of plastic)that might be damaged by the re-heat. In practice the re-heat is fine for all bare wires, and for wires insulated in certain high temperature insulation such as PTFE and silicone rubber. Very careful control is needed for wires plated in tin due to the low melting point of tin.
Crystal Sound Process. The process known as ‘Crystal Sound Technology’ is a proprietary technique developed by Black Rhodium’s cryogenic process supplier, Frozen Solid based on its empirical tests.
Because a continuous conductor will offer lower resistance than one with a mechanical discontinuity, electron flow is more regular. The result is that sonic distortion in the music signal flowing through the wire caused by conductor discontinuities will be reduced.
The Benefits to Audio Cables of Deep Cryogenic Treatment
Unlike most other improvements in audio, Deep Cryogenic Treatment does not change the character of the sound, but it does make the listening to music a much more pleasant experience. Each aspect of audio performance is improved by a small but audible amount. Whilst an analytical assessment might consider these improvements to be small, the sum total effect on overall listening pleasure is much more dramatic.
At Black Rhodium we find the best way to describe the benefits of DCT to audio cables as:
A very small change in the sound of each cable
A very large change in the enjoyment of music.
Many people have written about the improvements to their sound quality by DCT. Here is a list based on our own experience and on comments seen on the web.
- Expanded dynamic range
- Improved transient response
- Greater sense of ease
- Clearer and more refined higher frequencies
- More articulate bass
- Sharper stereo images
- Lower noise floor
- Quieter and blacker background
- Less distortion in vocal
- Deeper and more open soundstage
- Enhanced detail and definition
- Greater separation of musical textures
The benefits to Audio of Crystal Sound Processing
Our experience of the Crystal Sound Process is that whilst the DCT process improves almost all aspects of the sound in almost equal ways, the Crystal Sound Technology changes the sound in a way that can only be satisfactorily described by saying that the Crystal Sound Process delivers a more full-bodied and more natural sound to the music that once heard you will not wish to take away.
Other Audio Products that benefit from DCT
Stresses induced from the CD’s manufacturing process causes birefringence when the player’s laser tries to read the disk, degrading sound quality. A precisely controlled, deep cryogenic process stress-relieves the polycarbonate disk, making it more optically clear. This greatly reduces birefringence and improves audio quality.
The sound quality of thermionic valves is also improved with DCT.
Deep Treatment of audio cables is an essential ingredient of high quality audio cable design that cannot be ignored.