Thread: 5.1 or 7.1 or 9.1, etc.

Long ago, I was sitting in a local restaurant (Deewar) in Pune sipping an evening cup of chai just after college with my friends. The restaurant had a rather long narrow hall with the cash counter at the center (just in front of the entrance). The two halves were 20 feet by 10 feet each. At the end of each section, there was one speaker. Very amusing really. The two stereo speaker system was divided into the two sections so both sections had some music. All were happy.

Somewhat different but today we are faced with a different issue. The (true) home theater started with 4.1 and quickly evolved to 5.1. And today we have 7.1 and 9.1 and perhaps more. Many people do not know what to do and naturally everyone assumes that 7.1 must be better than 5.1 and 9.1 better than 7.1.

Yes and no.

First let us consider the source. If watching TV with plain stereo sound, even 5.1 is useless. Stereo sound can simulate to 5.1 using Dolby Prologic but that is about it. It is still a simulation. DVDs are sources of 5.1 sound and having a 7.1 sound system is not going to make it sound better. You will get the same channel/sound from Side-Surround and Back-Surround speakers. True 7.1 will is available in Dolby TrueHD and DTS HD Master Audio only and these soundtracks are available in Blu-ray only.

Next consider the room size. From setting the 7.1 speakers, the rear (back) surround speakers must at least be 1 to 1.5 meters behind you. Assuming a normal viewing distance of 10 feet or 3.3 meters, this means that your room must be at least 5 meters (16.5 feet) long. If the rear surrounds cannot be placed behind you, then forget about 7.1 speaker system.

Finally 9.1. True 9.1 sound source is not yet available in any format for home video. 9.1 surround sound is generated by Dolby Prologix IIz. The 'z' stands for 'z' axis or height. Most receivers have speaker connections for 5.1 or 7.1 main system (Zone A) and an auxillary 2 channel stereo for alternate room (Zone B). Modern receivers with Dolby Prologic IIz will allow configuring the Zone B speakers as Front Height speakers for Zone A. This adds an extra dimension to the system. The front height speakers must be places near the ceiling and not at ear level.

I have not tried this out as yet. But from what I read, these front height speakers do not add any discernable difference to the listening mode.

Picture below shows the front height speakers (installed above the TV):

Nice info.
Those front height speakers deliver 245-280Hz range. This range is used by instruments such as santur, cello, detuned sitar etc. For a layman, these speakers will add no better listening experience. But if you are into music recording, orchestra etc, you will then know its importance.
My logic-
Normal listeners-2.0 setup
Audiophile grade listeners-2.1
Movie buffs-5.1
Movie buff who are likely to buy Blu-ray discs-7.1
9.1 setup-wait for some time more.