Podcast #1038: What does Reference Level Mean?

On today’s show we define “Reference Level” and what it means for your home theater and we look at the 9 things you need to consider if you are in the market for a new TV. We also read your emails and look at the news stories of the week.

News: Sonos acquisition fuels new headphone rumors The cheapest 2022 Samsung MicroLED TV will reportedly cost $80,000 Samsung Display apparently struggling with QD-OLED production Streaming device wars: Smart TV viewing time surges, dongles see first-ever decline Other: Join the Neat Exchange - Social Media for Whiskey Drinkers Ara's Woodworking Join the Flaviar Whisky Club and get a free bottle Mike's Star Wars Inspired Home Theater Reference Level

Reference level is a calibrated volume setting used for movie production, Sound and dubbing stages, and movie theaters (and now the home theater)

A reference is critical if the mix is to translate from one production house to another and audiences are to hear the director’s intent in terms of the balance in the soundtrack between dialog, effects and ambiance.

So how do we set up a theater for Reference?

Reference level for all channels except the subwoofer is calibrated by adjusting the gain of each channel when a pink noise signal recorded at -20dB relative to full scale (0dB) is played through the system and measures 85dB with a C weighted sound pressure meter at the seating locations. This is what your receiver's auto calibration tries to do. 

What is Pink Noise? To answer that we have to tell you what white noise is. White noise consists of an equal amount of every frequency, all played at once. If you are old enough to remember “snow” on TVs that had no signal. That was white noise. Pink noise is essentially bass-boosted white noise, where the amplitude decreases as the frequencies get higher. It got its name thanks to the pink / violet hues present at the lowest frequencies of light. This is the perceptually ‘balanced’ white noise that many of us are comfortable with;

After each channel is individually adjusted until they read 85dB. The master volume control setting associated with this playback level is then set to a nominal 0dB, or reference level. The history behind this is that sound engineers and producers generally work so that the average recording level for dialog in movie soundtrack is -20dB. This allows for 20dB of dynamic range in the soundtrack. The Subwoofer is calibrated higher, so that a -20dB signal reaches 95dBC at the seating locations.

In the home it works slightly differently. Most receivers have calibration test tones used for level setting that are recorded at -30dB relative to full scale. Using these tones the level of individual speakers are adjusted to 75dB at the seating position.  That is 10db less than movie theaters and sound stages.

Can my speakers and subwoofer support reference levels?

If your system is properly calibrated to output 85dB for a -20dB signal at the seats then the speakers and amplifiers could be asked to produce 105dB for a 0dB signal.  The Subwoofer is handled slightly differently and has a 10dB boost relative to the other channels. The maximum SPL that subwoofers could be asked to reproduce from the low frequency effects track is therefore 115dB at the seats.  More than likely the typical home theater setup will not handle reference levels. But that is OK. Most of us don’t need that level of sound. If you have a theater with a large volume you should look for a set of highly efficient speakers specifically designed to handle reference levels. You may also need a better receiver to achieve this as well. 

TV buying guide: 9 things you need to know

In the market for a new TV, and feeling overwhelmed? This TV buying guide is here to help. 

If you've been browsing in-store or online for a new TV, you might have found yourself a bit confused by huge selection of different technologies, features and functionality that come with buying a TV in 2022. And that’s before we get started on the acronyms… Full article here…

Screen size: Finding the sweet spot - A good rule of thumb is that you should sit at a distance from the TV that is three times more than the height of the screen for HD and just 1.5 times the screen height for 4K Ultra HD. In other words, you can sit twice as close to a 4K UHD TV. Don’t buy a TV with less than 4K resolution. Avoid full HD or 1080p sets. You can skip 8K TVs (for now). 8K TVs are super expensive, and 8K movies and shows aren't available yet. Expect to pay about $500 for a good budget 55-inch 4K TV. And at least $900 for a 65-inch model. Models with a better picture, upgraded speakers and next-gen features will cost more. Look for 60 Hz or 120 Hz refresh rate: When it comes to refresh rates, 60 Hz is good, but 120 Hz is better. A higher refresh rate provides smoother motion for everything from movies and shows, to live sports and gaming. Look for an HDR-compatible set: This offers more realistic colors and better contrast. Preferably consider a TV that supports the more advanced formats, namely HDR10+ or Dolby Vision. Some will support both. OLED TVs look much better than most LCD sets: But QLED TVs from Samsung, Vizio and TCL are an affordable middle ground. Look for at least four HDMI ports. And opt for the newer HDMI 2.1 format if you can. Plan to buy a soundbar. TV speakers are worse nowadays because the screens are thinner. Avoid extended warranties. Your credit card company may already provide purchase protection