Screen Gain - The Awkward Truth

• Testing Acoustic Performance Factors
• Transmission Loss
• Smell / Off-Gassing
• Testing Visual Performance Factors
• Screen Gain
• Screen Gain - The Awkward Truth
• Screen Gain Data
• Surface Texture
• Light Bleed
• Welcome
• Image Surface Performance Factors
• Visual Performance Factors
• Acoustic Performance Factors
• Environmental Performance Factors

In our benchmarking of competitive surfaces, we have yet to measure a single image surface that exceeded 95% of the claimed screen gain. Indeed, it is typical to measure 75-80% of the claimed gain.

There is an apparent misconception among consumers that a higher gain number translates to a better product. Given the inaccurate data posted by so many companies, we can clearly understand the temptation to exaggerate this data. After all, it is expensive and time-consuming to measure accurately for yourself.

We have identified three types of image surfaces. Based on their construction, the gain of these image surfaces can be easily estimated from our testing.

1. White PVC-type image surfaces - 0.8 to 0.9

2. Fibreglass-type image surfaces - 0.7 to 0.8

3. Polyester-type image surfaces - 0.6 to 0.8

How can we claim this when others state gains over 1 for their image surfaces? These white surfaces behave close to a Lambertian reflector, where light falling on them is perfectly diffuse. There are no optical techniques in play to better focus the reflected light nor any particular tricks that increase the reflectivity of the base material. 

A perfect Lambertian reflector has a gain of 1. Therefore, we must treat with scepticism any claim for a screen gain greater than one on a white surface. It is possible to push this a little with PVC manufacturing techniques but not with the fibreglass or polyester types. Our reference reflector, costing over £1000 for a 5cm diameter sample, can not quite meet this standard without additional calibration.

We are interested in image surfaces that deliver acoustical transparency in this whitepaper. An open area that allows sound to pass through as required allows light to pass through and be lost. Microperforated white PVC screens have the lowest open area, greatest acoustic insertion loss, and, therefore, slightly higher typical gain. Fibreglass is more reflective than polyester; thus, it tends to have a marginally higher gain at the expense of more surface texture.

When the image surface has good AT properties, there is no chance that the screen gain will be 1. A screen gain of 0.6 to 0.8 is the more typical range from all suppliers.