I had a little bit of open time yesterday afternoon and I decided to work on some fine tuning of the home theater. The need to tune the environment was driven by the arrival of my Christmas gift. I had received a pair of surround speakers for my gift and they finally arrived last week.
The speaker system consists of matched 600 series B&W speakers — 683 towers for the left and right position, HTM61 for the centre, 685s for the left and right surrounds — and the SVS PB13 Ultra subwoofer. The speaker system is powered by a THX certified Pioneer Elite VSX-94TXH receiver. The front projector is a hi-def Panasonic AE3000U and the media player is a Sony Blu-Ray. The screen is 120 inch diagonal. And the throw from the project to the screen is 14 feet. Native resolution is 1920 by 1080. Display is 1080p.
I opted to layout the speaker grid in a classic fashion: front left and front right speakers 30 degrees from centre of the sweet spot. Rear surrounds at 90 degrees from the centre of the sweet spot. Centre speaker in the centre and the subwoofer placed just to the right of the speaker grid.
Due to a column placement in the home theater space, I had a choice to move the prime seats back to roughly 15 feet of the screen or forward to about 12 feet of the screen.
It turns out that the speaker placement and fine tuning was much easier than determining the optimum viewing distance.
There are numerous calculators on the web like this one. And the range of prime viewing is about 12 feet from the screen — as recommended by THX to support a 40 degree view angle. By my calculations, I was close at 39.9. Other calculators suggest a prime range of just under 13 feet 6 inches.
We watched a movie last night with the tuned sound and it was terrific. Not just to my ears. My wife heard the difference as well. However, I think 12 feet to the screen is too close and I am going to move things back by a foot.
It does mean recalibrating the speakers. I use a laser pointer to align the tweeters to the prime listening position and I have to enter precise measurements from the tweeter cones to the prime listening position to ensure time accurate delivery of sound. I then use an SPL meter to measure the amplitude of each speaker to the prime listening position and calibrate the test tones to 75dB (C weighted, slow) for all speakers except the sub. The sub gets 80. Even a slight adjustment to the seating position requires retuning the sound.
Sometimes it is just a curse to be a geek.