nice.
do you happen to know what is the tuning frequency of your helmholtz resonator?

nice.
looks mighty expensive. hope it doesn't cost you an arm & a leg.

believe it or not, it's not mighty expensive nor complicated to enjoy 18hz well built sub.
though you might be led to believe otherwise.

only if the speakers are capable of handling 80hz (and probably one octave lower).
if the receiver can't independently set the surround channels to higher crossover point, it's probably better to set the xover point to something like 180hz-250hz.

better to post here so that everyone can read. i'm also interested in your thoughts.
we all could learn from each other.

there's no absolute golden ratio. there's a suggested ratio, which is to avoid any of the sides to be in exact multiples from each other.
the tip is to avoid exact multiples of 1/4, 1/2, 1, 2, 4, and other multiplication of that.

so avoid 10 x 20, 5 x 20 or stuff like that. hence arriving to the suggested ratio of 1.67 and 2.67. because it's not an exact multiplication of anything.
your 27/16 = 1.6875. a freckin good ratio.
opt for a 9.5 feet ceiling and you'll hit very near the recommended ratio.
16'/9.5' = 1.68
27'/9.5' = 2.84

the suggested way is to multiply your ceiling height x 1.67 = room width. ceiling height x 2.67 = room length.
so for your case the best size would be 9.5' x 15.86' x 25.36'. pretty near your size.

the suggestion is to avoid frequency bounce issue in quarter and half wavelength because it'll introduce comb filtering to the final output. better to avoid the issue altogether rather than introducing correction later.

double bricked ala DIY style IMHO is only necessary for the connecting walls to the other room.
rather than using just double brick or arranging the bricks lengthwise to make a wide wall, i think it's better to put up a double brick wall with an air gap ala diy style to help attenuate the sound penetration to the other room.

but it doesn't have to be on all 4 sides. you could refer to my house plan if you like. i only put it up on 1 side of the room.

avoid plaster ceiling if ever planning on introducing a good sub into the room. it'll crack the ceiling. my room currently using the old asbestos ceiling with wood structure. it still creaks and rattle because of the sub.

go for acoustic gypsum board/acoustic gypsum ceiling. heard that even normal gypsum board is also rattle free.

the best material would be fully carpeted. with the insulation rubber or plastic underneath. more materials underneath the floor is even better.
wood laminate won't do a thing to the floor bounce. but carpet helps. tile is even worse than wood.

windows is essential IMHO if you're planning to use the room for something else than watching movies. to soundproof the windows, you could go for double glazed or laminated window with good locking mechanism to avoid them rattling. cover them with thick curtains with rubber layer like the ones used in hospitals. the curtains is better than just a plain wall.

just don't make the glasses too wide tho.

there's so many question. i'm tired of typing. maybe later.

depends mostly on your budget. if you're targeting for a huge screen, then you need quite a high output projector, sharp output/lens that will retain sharpness for a large screen. i'm not an expert in this field but i think it's best not to go above 120" diagonal with a projector less than <RM10k.

some people opt for a large screen, but sit far far away. calculating the field of view, you could achieve similar result with a smaller screen, but sitting closer to the screen. so why waste precious light output and reduce sharpness by sitting far far away?
anyway it's a personal opinion so others with more experience could provide better insight.

some people like to mount the screen up high high in the sky. and watch while looking up. causes neck pain to me. you could mount the screen higher than your floorstander and put it underneath the screen.
or you could opt for a smaller screen and put it at the side of the screen. 120" diagonal is only 8.75' apart. if you don't believe all that 'it must be 6 feet apart or it'll sound bad' crap rule then can consider mounting the screen lower and put the floorstanders at the sides.

dedicating 1 phase entirely for the HT is a bad thing to do. IMO.
you're supposed to distribute the entire 3 phase of the line evenly to the entire house. best if it the load is even during any given time. if 1 phase is dedicated just for the HT then it'll be unused most of the time. a waste of the 3 phase wiring.

main problem isn't from dedicated wiring or not, but from the return line (neutral) wire. if you put a large current return together with the live wire to your HT phase, then when the large current return happen, it'll go through the shared neutral line and dumped inside your equipment. separating the phase to your HT will isolate the live wire, but won't isolate the neutral wire as it's still shared by all 3 phase.
voltage transient will be isolated from the other phase (good thing) but unless you have a large motor on the same phase, the transient will be mainly from the TNB station. which there's nothing you could do even if you dedicate a phase for it.

my kid is nagging me to go to sleep. later.
put it at the ceiling. your wall is too far. you'll lose light output and sharpness if you put it at the wall.

i freckin love this sketchup thingy.

if you put up a 92" projector screen, but sit 10 feet away, you'll only have 36.9 degrees of FOV.
it's the same as watching a 50" TV from 5.5 feet away.

in which case, why bother with a projector setup if you wanna sit far far away?

distribute the phases evenly. don't waste by dedicating a single phase just for HT. just isolate the aircond through a dedicated wire to the DB.

if i were you, i'll avoid motor pump/microwave/induction cooker or any other high current switching on/off from the HT phase. use inverter aircond if it's shared with the HT phase. lamps/downlights/fans/tv/computer is ok if it needs to be shared with the HT phase.

rather than isolating the DB just for the HT, isolate a single DB to the farthest place in your house. it might be kitchen or wiring for rooms. it's easier if you need to pull another live wire from the DB. if the HT happens to be the farthest place, then isolate it.
there's a few way to wire the 3 phase, but i think this is the most proper and most beneficial way:

(refer above diagram) even if the entire wiring is in the same large, single DB box, it's still fundamentally isolated from each other. all the phases and current return are isolated from each other. this way it's even easy to add surge protection to the entire circuit or to specific phase.

usually the rule is 2.5mm wires for 18A applications. and 4mm for anything up to 30A.


you could use 2.5mm as HT current draw will never (ever) be more than 18A continuous. but if you got quoted nearly the same for 4mm then just go with 4mm. but remember there's an awful lot of bad quality wires on the market currently. bad quality 4mm is still bad compared to a good 2.5mm wire.

just don't get smaller than 2.5mm for the HT wiring.

there might be some typo. sorry.

bro your proposed room size, the 16'x27' issit already built?

120" screen, 15 feet away will only give you 32.7 degrees fov at the first row and only 24.8 degrees at the second row. that is if you're planning on introducing a second row. i would, especially with that length.

thx suggestion that i've read around is to keep 36 degrees for the last row. and like skeelee pointed, sweet spot should be around 45 degrees and 50 degrees maximum for the front rows.

it's a good idea. i'm planning such an implementation.
rough drawing in sketchup i think you could separate the HT setup and audio setup in the same room. just ngam ngan fit for separate audio speakers without blocking the view.

to calculate a good ceiling height, put your nett room dimension into this to calculate room modal distribution:
http://www.bobgolds.com/Mode/RoomModes.htm

you might wanna put your room dimension and listening position into REW room simulator.
it's so accurate, it's scary.

my current room:

the actual measured response:


read around on the net, people are also saying the simulator is pretty darn accurate.
it accurately predicted the peak at 35hz, the null at 40 and 50hz and the large peak at 60-70hz.
null at 80, peak at 90, then null at 100.

overlaid. not to scale.
but check the pattern.

focus on the <120hz because i've implement an lpf filter on the sub.

pretty darn accurate i'd say. because there's a large closet at the back of the room. the simulator needs a rectangular room for calculation.

not as bad as i thought it would be.
let's say 10'x12' as per most second room in most houses would be. with 9' ceiling.
92" screen, mounted at the wall, listening position 9 feet away, 40.6 degrees field of view.

single sub, center of the room


dual sub co located at the corner. improved the room response somewhat.


the null at ~100hz is because of the listening position 3 feet away from the wall.
1130/(3*4) = 94.16, room mode plus boundary reflection at that area causing a huge null that's hard to correct.

wow. so many speakers.
does it sound good?

common misconception.
even if the loudspeaker is capable of reaching say, 30Hz, you must understand that a loudspeaker driver is never intended to sustain that low of a frequency.
it's a fallacy at best, considering that it takes so much movement and a specially designed driver to be able to output that low. special driver in which sense, a subwoofer driver.

a loudspeaker is never (ever) intended to reach that low. while it might play that low, it will have lots of distortion which is usually audible since movies mixes will have bass surges over 100db.
manufacturer specs will show that their products have a flat response, usually close-mic-ed response at 75db. misleading at best since nobody listen to their speakers 30cm away from the baffle.

it's one thing to have a flat response 30cm away from the baffle at 75db.
and another thing altogether to maintain that flat response 4 meters away at the listening position at 100db.

a good sub will go a long way. as with one you're removing the low frequency from being played by the speakers, allowing the loudspeaker to perform better handling midrange and high frequency.

most people are mislead by the manufacturer specs saying that their speakers will do something like "±2dB from 42 Hz - 22 kHz".
this is what a manufacturer spec-ed "±2dB from 86 Hz - 22 kHz" looks like in real life:


that jagged line doesn't look anything like ±2dB.

frankly it's not for him.
there are others which believe that loudspeakers could substitute the need for a sub. or the use of multiple loudspeakers with large drivers will affectively take over the role of a sub in their system.
for stereo listening it won't matter much. because 80db is plenty loud. but for movie playback is a different game.

and even if the loudspeakers is indeed capable of low frequency playback and have no problem reaching 20hz at 120db, there will be issues regarding the timing and overlapping of bass frequencies that will play havoc to the room.


i've pursued this issue previously and my finding is in line with the result from harman.
it's explored quite a bit in their
Subwoofers: Optimum Number
and Locations
by
Todd Welti
Research Acoustician,
Harman International Industries, Inc.

move the listening position, don't sit at the middle of the room.
because for an 11x13 room, with 9' ceiling, you're gonna have a huge null at the middle of the room no matter where you move the sub to.

the null is nice nice at the 55hz, causing the response to sound like no omphh, no midbass punch, lacking in where it's mostly needed.

good room ratio won't directly translate to good response at the listening position.

measure the exact dimension of the room. measure the arrangement of the furniture, measure and mark the listening position. draw the current speaker arrangement and position.
and post a photo of the room. it'll help with the suggestion.

plan ahead for dolby atmos/dts mda. in case it becomes mainstream.
which it almost certainly will, judging from the amount of new movies mixed to the format.