Updated: Apr 6, 2022
Principle 12 (ISO 9000): Produce Systems of Intrinsic Stability
Good systems may be impacted by fast-paced changes in technology, but that doesn't mean that they should be designed for obsolescence. On the contrary, a well-designed system will last for decades, perhaps with elements updated or upgraded as needed. If the basic system was installed correctly, the microphones and loudspeakers are in the same place they were when the system was first installed, but certain items of equipment may have been changed. Ceiling mounted projectors may have given way to flat screens, for example. In any case, you generally do not have to rip everything out for an upgrade.
AV9000 points to the fact that good design means doing so with the service technician in mind, not the designer or installer. By the "service technician", I mean the person(s) who need to maintain the system for years, well after the last installer left the building.
Is each item of equipment accessible?
Are the cables adequately labeled, so if an item of equipment is pulled for repair or replaced, is it obvious how all the different cables were connected?
Are frequently accessed terminals, such as the output terminals of power amplifiers, readily accessible or at least available on an I/O panel, so measurements can be taken (S/N, THD, normal operating levels)?
Are cables tie-wrapped so that it makes it nearly impossible to pull something for repair?
Is the equipment well ventilated?
Is the equipment inventoried and documentation complete and includes make, model, serial number, firmware version, software version, IP and subnet addresses, passwords, and all the other database elements in the AV9000 requirements so that when a replacement is necessary, it can quickly be configured?
If something needs to be recalled, do you know
(1) if you have it in the system, and
(2) where it is?
Answers to questions such as these still determine if there is a high Mean Time Between Failures (MTBF), and the least Mean Time During Failures (MTDF), both critical elements of a well-installed system.
“Quality means doing it right when no one is looking.” ― Henry Ford
“I am enthusiastic over humanity’s extraordinary and sometimes very timely ingenuity. If you are in a shipwreck and all the boats are gone, a piano top buoyant enough to keep you afloat that comes along makes a fortuitous life preserver. But this is not to say that the best way to design a life preserver is in the form of a piano top. I think that we are clinging to a great many piano tops in accepting yesterday’s fortuitous contrivings as constituting the only means for solving a given problem.” ― Richard Buckminster Fuller
"People forget how fast you did a job – but they remember how well you did it” ― Howard Newton