By John Siau
Many electronic products have a "CE" mark affixed to the product label. This mark is mandatory in European markets, but is not required on products sold elsewhere. Few people understand what this mark means and why it is important. It is often a good idea to look for this mark when purchasing a product outside of Europe.
The CE mark is the manufacturer's declaration that the product has passed a comprehensive set of tests to evaluate the ability of the product to operate in close proximity to other electronic products without causing interference. Today, our homes and offices and studios are filled with a variety of electronic gear. Some work well together, but some do not.
You are about to introduce one more piece of electronic gear to your audio system. Will it cause interference with other components? Will your existing components degrade the performance of the new component? If your new piece has a CE mark, it shows that the manufacturer has addressed some of these issues.
Advertised performance, (the performance of a product in an ideal environment) may not be possible in your environment. The ideal conditions of a manufacturer's test bench may not be replicated in your installation. If the product is a well-designed professional product it should still deliver the advertised performance. If the product is classified as a consumer product, the CE standards allow some loss of performance.
We have all experienced radio or TV interference caused by a power tool running in another room. We may be less aware of other interactions that occur between all of our electronic gadgets. Cell phones may cause bursts of low-level noise from speakers. WiFi signals may mysteriously drop out when certain devices are turned on. Your audio system may produce unexpected pops, clicks, and buzzes - all due to interactions between electrical devices. Audio products with a CE mark may be far less prone to this sort of problem, especially if they are classified as "professional audio products".
The CE test standards distinguish between professional and consumer audio equipment. Professional products must withstand high levels of interference and must do so without a loss of performance. In contrast, consumer products are held to a much lower susceptibility standard. Consumer products are exposed to lower levels of interference during testing and are even permitted to malfunction in the presence of this interference - as long as no permanent damage is sustained. The CE standards recognize that a momentary burst of noise from a desktop computer speaker may be acceptable to consumers, but a similar burst of noise from a professional studio monitor would be unacceptable to a recording engineer.
The CE standards define separate tests for "immunity" and "emissions". The immunity standards define how much radio, magnetic, electrostatic, and power-line interference a product must withstand. The emissions standards define how much radio, magnetic, and power-line interference a product can emit. The test limits vary by product type and by operating environment.
The CE standards define five distinct operating environments. Products must be tested to operate in at least one of these environments.
CE test environments are defined as follows:
Immunity standards increase as we progress from E1 to E5. In contrast, Emissions standards are more lenient as we progress from E1 to E5.
If we focus on immunity, E5 products have the toughest requirements. In contrast, if we focus on emissions, E1 products have the toughest requirements.
Products that are designed for a residential (E1) environment may fail to operate in a heavy industrial (E5) environment. Likewise, heavy industrial equipment often emits far too much interference for a home environment. Products must be designed and tested for the environment in which they will operate.
The differences between professional and consumer test standards may prompt the following questions:
The answer to all of the above questions is that the product needs to be designed for the environment in which it will be used. Benchmark products are classified as professional audio products. This classification subjects our products to much higher immunity standards than typical consumer products. But, we also test for consumer (E1) environments and this subjects us to the strictest emissions standards. This combination (professional product in an E1 to E4 environment) holds Benchmark products to the highest standards.
We could choose to only test for an E4 environment (recording studio), but we recognize that many of our professional products find applications in high-end home Hi-Fi systems. For this reason, Benchmark tests for environments E1 through E4.
Please note that Benchmark products are not rated for environment E5 (heavy industrial). Beware, the performance and longevity of your Benchmark product may suffer if you try to operate it in close proximity to an arc welder.
Products must be designed and tested for the environments in which they will be used.
Benchmark products are tested to perform to professional standards in environments E1 through E4, making them well suited to professional and home applications.
If an audio system is composed of multiple components, we may have detailed specifications for each component, but we will not know the performance of the combined system without doing some calculations. You may have questions such as these:
Use Benchmark's online audio calculators to find answers!
For example, if we know the output power of an amplifier, as well as the sensitivity and impedance of our loudspeakers, we can calculate the maximum sound pressure level that our system can produce.
This application note provides interactive examples that help to answer the questions listed above.
We have added an "Audio Calculators" section to our webpage. Click "Calculators" on the top menu to see more like these:
Secrets contributor Sumit Chawla recently caught up with Benchmark’s VP and Chief Designer, John Siau to get a little more in-depth on several subjects.
Q: "Benchmark is one of the few companies that publishes an extensive set of measurements, but you also balance that with subjective testing. Can you talk about the equipment, the listening room, and the process for subjective testing?"
Q: "Was there ever a time where you learned something from a subjective test that was not captured by measurements?"
Q: "You conducted some listening tests to determine whether distortion in the “First Watt” was audible. What test material did you use for this, and what did you find?"
Q: "The AHB2 amplifier incorporates THX Audio Achromatic Amplifier technology. When and how did the partnership with THX come about?"
Q: "Linear power supplies have been and remain quite popular in high-end devices. You favor switch-mode power supplies. When and why did you make this switch?"
... and more!