It’s not easy to summarize my years of knowledge into a single page of words and images, still I can say my instructions here are more free from any commercial bias but it’s still one man’s word against another.
You could say it’s not bias free afterall.
Damn!!! Another paradox!!!! I’m getting tired of these.
The goal here would be to identify the involved parameters and develop some understanding about the auditory relationship of these parameters to the actual physical acoustics of the room itself. In other words, what’s actually needed to be taken care of when choosing the right speaker system for your room and how to place the chosen speakers in your room accounting for the acoustics of the room itself and the listening position.
Even after all the conditions are matched to provide the listeners with adequate levels from each speaker to fulfill the above requirements, the quality of the reproduced sound is another issue There are a million ways about judging quality subjectively but to actually quantify it in actionable terms is where you need a professional to guide you. Simply put , it’s the statistical understanding of the sugar and salt.
Collecting all data about the room geometry & it’s acoustical behaviour and the characteristics of the electro acoustic systems, number of seats & their listening positions etc and implying specific targeted recommendation about room furnishing and acoustical treatment for satisfactory directional, spatial impressions & quality.
A basic 5.1 channel system can be expanded to 6.1 or 7.1 channel but it all depends upon whether your source material is made for such arrangement or not. Still large number of seats can benefit from more speakers that provide adequate coverage & loudness.
Envelopment requires strong sounds delayed by 80 ms or more reproduced through suitable surround speakers. All the important sounds to reproduce the perception need to arrive at the listener ears from the sides.
Thing to remember , all this is just applicable to the sweet spot as we move away from this location various degradations increasing with distance are experienced. More speakers can’t deal with problem of propagation loss.
Bass problems can be dealt with 2 or more subwoofers.
By now you know the front speakers are required to deliver a moderate ±30° horizontal dispersion. Surround speakers require a wider coverage angle to deliver a smoother uniform response to the audience.
Speakers with propagation loss of less than -6 dB/double distance are preferred for surrounds. On wall bidirectional in phase speakers are suited best for surround requirements. Wide dispersion forward firing designs might be good enough if aimed properly for coverage.
Summarized basic needs :
Calibrating & tuning your system can be a real time consuming problem when you are not sure how to make it sound good and not just different.
Aim your mic towards the ceiling & get a C weighted measurement for approximate equal loudness. Listen to each speakers timbre & tonal characteristic facing it with pink noise playback.
Speaker that are not the same distance from the prime location must be delayed by the DSP. Remember there is only so much EQ can do below 300 HZ as well as treating the nulls would be hard. Any thrusting peaks are reduced, dips are left alone but depressions are boosted till 6 dB.
Steady state measurements are not that useful above 300 Hz. For rectangular rooms , when arranged in certain manner multiple subs yield special kind of spatial equalization which can be added as cherry on the cake.