Originally Posted by Vahid Jamali
So what's the difference between the nr747 and the nr 757 that's coming out in may? Also what's the diff between the nr646 and the 747? Does the THX certified make a big difference?
Did they ever fix their previous hdmi board issues, and overheating issues?
The 747 is 2"deeper and weighs 4lbs more so evidently has a more robust power supply for managing the amps.
It is THX Select2 certified. THX Select2 Certified products are for medium sized rooms, up to 2,000 cubic feet in size, with a 10-12 foot viewing distance from the screen.
What that means is below.
THX Certified Audio products are designed to let you experience movies the way they were meant to be heard. On every THX Certified AV Receiver the “0” on the volume dial represents THX Reference Level, a setting designed to mirror the exact volume level used by moviemakers and sound artists in the studio.
When you are watching a movie with the playback volume set to “0” on a THX Certified Receiver, you experience every sound element exactly like it was produced by the filmmaker—with the same fidelity, detail and clarity.
What Is Reference Level?
Manufacturing receivers and speakers that can achieve THX Reference Level is no simple task. It requires a tremendous amount of power to drive an audio system effortlessly without clipping or distorting. To ensure the audio products can reach this peak performance, THX developed a set of standards as part of its THX Ultra2, THX Select2 and I/S Plus certifications.
Experience Studio Clarity: THX Certified Receivers reproduce studio Reference Level, 85dB SPL with 20dB of headroom.
Reference Level for your Room: THX Ultra2 Plus, THX Select2 Plus and THX I/S Plus certification categories deliver Reference Level performance in your specific room size.
Distortion-free Playback: THX Certified Receivers and speakers are designed to recreate Reference Level with minimal distortion.
Listening Below Zero
Of course, there is a downside to watching all of your films at Reference Level—it is often too loud for your neighbors. But, when you lower the volume level, bass sounds, surround effects and other sound elements can be lost or perceived differently. To correct this, THX developed a technology called THX Loudness Plus, which lets you experience the rich details of a movie or game soundtrack without driving your neighbors crazy.