You’ve probably already noticed that some speakers come with something called THX Ultra2 certification, or THX Select2. Although it might be clear to you that THX is some kind of standard for audio and video receivers and speakers, the meaning of the designation following the standard - the Ultra2 and Select2 pars - is not that easy to figure out. So, if you’re looking for THX certified speakers online, for example, and you don’t have a store clerk to ask about the different types of certifications, you can read here everything you need to know.

These different types of certifications are called performance categories, and they are used to tell you what is the optimum environment for reproduction using the components that belong to those performance categories. If the environment is paired with the a product in the right performance category, you should experience audio reproduction at the quality level intended by the sound engineers that made the content you’re listening. So, no cracking, no losses, just the pure audio reproduced the way it was meant to be reproduced.

There are four types of THX performance categories - Ultra2, Select2, I/S Plus Systems, and Certified Multimedia. THX Ultra2 certified devices are the most powerful of the bunch - they are made for large home theaters, up to 3000 cubic feet. The viewing distance for Ultra2 devices should be at least 12 feet. Select2 devices work best at medium home theaters - up to 2000 cubic feet large, and with a viewing distance of 10 to 12 feet. I/S Plus Systems are best used at small home theaters where you can view the content at the distance of 6 to 8 feet. Certified Multimedia is a category designated to desktop products that are used in conjunction with personal computers.

So, if you know the size of the room you plan to make into a home theater room, or if you know that you don’t have enough room for a home theater but you still need high quality audio for watching movies, all you need to do is pick the speakers and receivers in the appropriate performance category. You are guaranteed to have the best possible listening experience, and you know you’ll get it regardless of the maker of the gear.