Powered speakers show audiophiles are confused

@phusis , The problem most of us face with subwoofers with normally sized rooms in a residential setting is SIZE. Horn loaded subwoofers would have to be huge to work correctly. Same thing goes for the enclosures required to house a 21" subwoofer. It is much easier and more cosmetically acceptable for most people, myself included, to use multiple smaller drivers is sealed enclosures. With modern drivers you can get a 12" driver into a 1.5 cubic foot sealed enclosure and with enough power and digital signal processing you can get it to do just about anything within the limits of your amplifier to work perfectly. I use 8 of them which equals 4 15" drivers or two 18" drivers. In a 16 foot wide room I have no trouble getting flat down to 18Hz where they are rolled of steeply by a digital high pass filter at 84 dB/oct so as not to waste power and piss of the turntable. They are actually boosted 6 dB or so at 20 Hz to simulate the visceral sensation you get at a live concert at more reasonable levels. They are also in perfect phase and time with the main speakers. This is critical if you cross over at 100 Hz like I do and don't want to know you are listening to subwoofers.

@mijostyn 

I use 8 of them which equals 4 15" drivers or two 18" drivers.

Does the law of diminishing returns kick in after the first 2 or 3 subs?

I fully agree with @mijostyn.

I used to work for a church doing sound that had the biggest electronic organ in the world. There were 4x 30 inch subs in separate cabinets on both the left and right sides of the main sanctuary the cabinets were not facing the same direction. The organ sounded wonderful and could keep up with the biggest real organs in the world. The speakers for the organ were not set up like a concert but looked like someone had randomly designed them, definitely more of an art than science.

My room is wonderful because it's fairly large and is not square or rectangle and doesn't have any flat parallel walls it has a 10 foot ceiling. Just last night I moved my expensive Lyngdorf 60-2 processor to my Dolby Atmos mixing system simply for it's acoustic room fixing system "Room Perfect", until now I didn't have to use any acoustic processing it simply didn't help even with powdered subs built into my main speakers and 6k watt separate subs next to the speakers. I nearly bought very expensive speakers but realized I only need very good high and mid frequencies and the low frequencies if done right will make everything smooth out. Low frequency is an art, ears are the most part of tuning the system, play a 60hz or 80hz tone and roll the phasing where it's most pleasing musically. Don't forget any latency if you have any digital devices you have latency no way around it.

My Atmos system speakers distances are not spec, newer thinking in acoustics is tending toward non symmetrical speaker placement I fully agree. Ultimately a mixing room needs above all to be standard but this room is personal and I want to experiment, a lot. In the future even 2 channel speakers will be object based and won't need to be symmetrically based. 

Also, about diminishing returns when it comes to low frequency. The best system I ever heard was at Harmon headquarters in LA when I was doing playback for a music video and the location person who was an employee of Harmon showed me there big concert system inside the room we were doing the music video in, it took a few minuets to set up but wow I didn’t expect huge speakers could sound so good. There was so much physical movement of low frequency sound that it stunned me. It wasn’t amplitude volume it felt like thunder that even at low amplitude you can feel how huge it was. Bigger is better, this Harmon (JBL etc. ) was a demo to show big concert companies how good sound can be if you want to pay for it and it was amazing. Of course all powered speakers.

@donavabdear , how do you roll phasing with subs?