Briefly, Atma-Sphere expects its products to be used for at least 20 years before needing major service (e.g., new capacitors). With that in mind, Atma-Sphere chooses parts and tubes that can reasonably be expected to be available - or to have appropriate equivalents - 20 years down the road. Long tube life is expected -- Karsten estimates at least 10,000 hours from the power tubes and 10-50,000 hours from the input/driver tubes. Atma-Sphere's two-year general warranty also warranties the tubes for one full year, a welcome departure from the typical 90 days.

“The Twenty Year Rule has been our guide over the years for quality. The idea is that our equipment will run for twenty years without major service (other than tube replacement). It has several aspects:

  • Only in-production tubes can be used, to help insure availability in 20 years
  • All parts used are rated using military reliability curves to insure long life
  • Parts choice will be such that in event of failure of the company, parts are not impossible to find

The original idea was simple enough. One of the most important aspects of good audio gear is reliability. Twenty years is a practical measure of reliability, since after that time, the likely service issues are going to be filter capacitors and connectors (including sockets). Thus the voltages chosen in the equipment are such that it is a good bet that, the filter capacitors required for replacement in 20 years, will still be available. This was a concern back in the 1970s when we got started, since higher voltage capacitors were getting harder to find. Further, tube types were becoming less diverse. So, it was apparent that, tube types for our designs, had to be limited to available tubes, and even then limited to tube types that have extremely common applications.

A further issue was that of reliability of the company itself. What would happen if the company failed? Would parts be available if service issues arose? These concerns were raised, as I have serviced many types of equipment over the years, and this has always been a problem servicing any older equipment. Usually the issues are related to transformers in audio equipment; thus we set up the transformer designs in an effort to improve aftermarket possibilities should we not be around to provide parts in the future.

This practice reduces the customer's risk. It also helps insure the viability of the company, since it makes replacement parts a lot easier for us to provide.

Barring parts availability issues, the other concern would be simple survival of the parts installed. This issue has been well addressed by the military, which has developed de-rating curves to insure maximum reliability of parts. Resistors are rated to 100% over the actual dissipations encountered in the circuit. Tube ratings are well within maximum ratings and often well below maximums for long life. Capacitors are also de-rated along military curves. Careful selection of solder, connectors and sockets are based on similar concerns.

For both performance and reliability issues, custom wire was developed, although it is not essential to the operation of our equipment.

At this point the Twenty Year Rule has served us well. It has already been in place for over twenty years. We have seen plenty of examples elsewhere in the audio community, where competing manufacturers have broken tenants of this rule, and have suffered or vanished as a result. The Twenty Year rule has helped us improve reliability in general, meaning that we don't spend a lot of time dealing with service issues (of course, a solid design helps with that also...). And as mentioned before, it makes our equipment a more sound (no pun intended) investment.”