If you own a top-end home cinema system, you’ve probably noticed the impressive “dynamic range” (also known as “contrast”) that can be created by the room’s lighting. Provided by suppliers such as Custom Microwave, the level system is the mechanism that enables light to be emitted and directed where it is needed. The key is that our eyes are highly tuned to light with a wide spectrum of contrast. So the more precise you can make the distribution of the light in a space, the more finely tuned your eyes are to detect details.
For this reason, speakers are often set at a high level (sometimes called “high level” or “hardtop”) to achieve this precisely. A level set attenuator is a device used to reduce the high levels of light that may come into a room and adversely affect your enjoyment. It is a mechanical device that will vary the level of light in the room. A level set attenuator is used to prevent light from coming into a space that might make you ill.
What is an Anti-Crawling Siren?
I feel I must clarify something now. In this video I will be using the word “siren” in a technical sense, to describe any loud emergency warning system. I am not saying that the person in the video is a “siren” as you and I would think of the word. This was just the best video I could find at the time of writing.
So what is a level set attenuator? It’s a complicated bit of technology that allows light to be directed as precisely as desired, without excessive amounts of it hitting walls and bouncing off of surfaces, with the result being a significant reduction in the amount of light.
The most common level set devices used in front speakers are called “rabbit ears” because their apparent output is similar to that of rabbit ears on a television set. The device consists of a single tube of relatively thick glass that is threaded through the front panel of your home cinema speaker and a small detector at one end, which sits within a light-tight box. This detector detects light that is passed through the light-tight box into the tube. It then outputs the amount of light (or brightening) required by the level-set device. This detector is often a small transistor in a lampshade.
The level set device is generally fixed permanently to the front speaker but can be relocated in some home cinema enclosures if desired. Some models will auto-detect when the front of the speaker is oriented vertically (as in our examples). The detector bulb of the level-set device is connected to the LED and/or a multicolour on/off switch on the front of the speaker so that the level-set device is always switched on if the bulb is lit. This is done to prevent the light level from fluctuating wildly if the volume control is momentarily set to maximum or during a power failure (due to short-circuit) and to prevent interference with other components (like amplifiers) connected to the speakers.
There is usually a resistor in the tube of the detector that increases when the volume is at low levels.