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Is one better than the other?
Are there calculators that will predict the acoustics of a rectangular room when given that room's dimensions, assuming that all speakers are placed appropriately? Are they using Dolby's speaker placement recommendations, or someone else's?
As in, don't have the distance from the front wall to the back wall be a multiple of the distance from the left wall to the right wall (or vice-versa)?
Hmm, I'm sensing a theme here. Is it the location of doors and windows? 😉
Previously, when I saw images of dedicated theater rooms in people's homes, with seating arranged in rows as in real movie theater auditoriums, those rooms always looked 'cold' or 'unfriendly' to me because those are single-purpose rooms; you go in there to watch TV shows and movies, and maybe play video games. You don't go in there with other people and do social activities with them, because the seating is arranged such that you can't look everyone face-to-face. So it's not like a living room, where you can all watch a TV show OR play a board game OR play Twister, for example. So I always thought that a multipurpose living room and media room was a better idea.
That would be ideal, no matter whether the room is a dedicated theater room or a multipurpose room. However, I read a little about that, and it kinda seems like if a room is not already soundproof, soundproofing is only possible by remodeling it--tearing down and rebuilding its walls, floor, and ceiling in order to put up soundproof walls, floor, and ceiling. That's not possible for people who are renting their home, are looking for a place to rent, or own their home but don't have a lot of money. I guess that if I look for a new place to live--which would mostly be for other reasons--I could try to find a place that has a soundproof room that is acoustically optimal, but I don't know how much that would increase the monthly rent price or sale price.
Can you elaborate?
Right now, only 5.0 (I don't have a subwoofer), but my system might grow.
I mean, I'm trying to find out what type of floor would be acoustically ideal. I don't have a specific type in mind yet. Same thing with other characteristics of the room.
Is this only relevant to their position in the room, or is it relevant for other reasons as well?
I'm trying to find out what characteristics would be acoustically ideal.
Right now, my TV is a 47" LED LCD TV, but that might change.
I don't know.
Depends if it is for an audience of one or for a big family but there's some stuff here which might be of interest. It's how professional laboratories design rooms for critical evaluations. Dolby Labs uses it for instance.
Correct. You don't want one speaker to "live" in a different acoustic environment than another. Speakers come in matched pairs so they "match". This is important for sounds that pan around the listening space and for imaging. For example, if you're trying to project a "phantom" sonic image from between two speakers, they both need to sound the same, or the image won't be precise or stable. If you put them into different acoustic environments, they'll no longer match. If sounds pan around from speaker to speaker, you don't want the tone of the sound to change as it moves from speaker to speaker.
A suspended floor can be made to provide tactile response. A subwoofer system, or even good full-range speakers, can acoustically couple with the floor and cause it to "shake." That causes motion energy to be transferred to the seating and the listener. Some people REALLY like that, others don't. Personally, I love it. If you're on a concrete slab, tactile response is virtually eliminated. In that case, you can add it with tactile transducers. That's what I have done in my HT: https://www.avsforum.com/forum/113-...-crowson-tactile-motion-actuators-thread.html In the subwoofer forum, there are numerous threads about adding tactile response.
There are a number of calculators that predict the "modal response" of the room. Just Google "Room Mode Calculators." However, they are predicated on rectangular rooms. If the room is not rectangular, all bets are off. Even if they are rectangular, the construction of the boundaries will impact the *actual* modal response. Therefore, the calculators are only modestly useful. There are some *theoretically * ideal room dimensions that spread the room modes out across the bandwidth, but following them is not as necessary as some claim. Just make sure the dimensions are not multiple of each other. IOW, a 12' x 24' x 12' room would not be ideal. It can still work, but 13' x 23' x 9' would work better.
Exactly.
Yes, The locations of doors and windows will impact a number of things. Ingress/Egress. Speaker placement. Placement of acoustic treatments. Light spillage onto displays. Sound leakage into adjacent spaces and/or outdoors, etc. The "ideal" room has no doors or windows. You lock yourself in and you can never leave, just like Hotel California!
No counterpoints, just different design goals. One is a dedicated Home Theater, the other is a media system in a communal living space. However, it's almost impossible to design a "living space" as an ideal acoustic and viewing space.
Yes adequate soundproofing or sound isolation is not for the feint of heart. It's pretty much an "all or nothing proposition. If you can't do it completely, there is only limited benefit to doing it "a little bit."
Speakers can have all sorts of different dispersion patterns, and their dispersion patterns can impact their placement in the room. You don't want to place a speaker that fires to the front and the rear. (bipoles/dipoles), close to the rear wall. You want some distance behind the speaker to allow it to reflect off the rear wall properly. You don't want to place a speaker with wide dispersion too close to the side walls because you'll get reflections and boundary interference effects. OTOH, some wide dispersion speakers benefit from those reflections. On-walls or in-walls have their own set of criteria. Also, acoustic treatments can modify and ameliorate the effects, (remember the doors and windows.)
Are suspended floors something that I'd only find in purpose-built home theater rooms?
So you think that carpet is better than plain hardwood or otherwise reflective flooring? That's helpful, because the room that I'm considering moving my A/V equipment to is carpeted, and when I look at other places to live, I can try to find a place with a multipurpose room or dedicated theater room that has carpeted flooring.
I think that "boundaries" means the floor, walls, and ceiling. So you're saying that how the walls, floor, and ceiling were built, and what materials they were built with, will impact the modal response. That makes sense. What materials are best?
What are "room modes" and "bandwidth"?
Does that mean entry and exit, as in 'the location of the doors will affect where people enter and exit the room'?
Hotel California allows its residents to check out anytime they like, even though they can never leave.Speaker placement. Placement of acoustic treatments. Light spillage onto displays. Sound leakage into adjacent spaces and/or outdoors, etc. The "ideal" room has no doors or windows. You lock yourself in and you can never leave, just like Hotel California!
If I were building a room from scratch or were remodeling a room, could I design it to be acoustically perfect and still be a 'living' room? I guess that the seating is the main problem: if the seating is arranged such that everyone can see each other, then not everyone is facing the screen, and not everyone is inside of the acoustic sweet spot. What other trade-offs are there when it comes to choosing a living room over a dedicated theater room? On the other hand, what trade-offs are there when it comes to choosing a dedicated theater room instead of a living room?
Is there a general rule for how much space should exist between the front speakers and the side walls, and how much space should exist between the rear speakers (if present) and the side walls? I understand that ideally, I'd know the dispersion patterns of all of my speakers and choose the amount of space between them and the side walls accordingly, but a general rule would be helpful for those of us that don't know the dispersion patterns of our speakers.
A "suspended" floor is a floor not connected to the earth. IOW, a first floor over a basement or crawl space would be "suspended." The suspension system would be the floor joists, subfloor and flooring. Since these have no immediate contact with the foundation of the earth, they have the ability to move. "Resonate" is the correct term. "Shake" is the other correct term.
Reflective flooring causes... reflections. Those reflections of the soundwaves can combine and interfere with the direct soundwaves causing reinforcements and cancellations, which change the sound that arrives at your ears. Floor bounces are generally not considered beneficial, and absorption of them is usually desired. A thicker cut-pyle carpet will absorb more sound than a thin berber style carpet. The pad can also be sound deadening. The thicker the carpet/pad system is, the lower in frequency it will absorb.
This is a complex subject as there are many different construction techniques, even within the range of "studs and drywall." Plus, there are two dissimilar goals for wall construction techniques, sound absorption and sound proofing. Some walls flex and the flexing absorbs acoustic energy. Other don't flex nearly as much and reflect more energy. Concrete walls don't flex at all and reflect virtually all the acoustic energy that hits them. I don't want to get into all that but if you want more info, try googling "wall construction for sound absorption."
Room Modes: http://www.acousticfrontiers.com/room-modes-101/
Yes. The location of the door(s) will impact where people will enter or leave, but will also impact the acoustics, speaker placements, furniture placements, ability to place acoustic treatments, etc. Likewise with windows.
Exactly.Hotel California allows its residents to check out anytime they like, even though they can never leave.
A living room or family room is a place for socialization. A dedicated theater is a space with one and only one purpose: viewing movies and television.
Soft cushions with padding can work quite well as acoustic absorbers and be benficial for acoustics. More reflective surfaces, like leather, wood, glass, porcelin, etc, will add some reflections, and they may, or may not be diffuse. If diffuse, they're beneficial. If they cause direct reflections, like off of a wooden/glass coffee table situated between the front speakers and the listener, they can cause acoustic interference, which is not beneficial. Also, speaker mounted in "entertainment units generally don't benefit from the internal reflections off the unit. Dedicated Home Theaters would not use an entertainment console.
You've answered your own question. This will depend ENTIRELY on the speakers, so find out what the dispersion characteristics are. Having said that, there are some good guidelines in the link I posted previously summarizing Dr. Toole's book. I would encourage to read that entire website. It has the answers to most, or all of your questions.
When you blow across an empty bottle, the air in that small chamber will resonate (make that booooooh sound). If you enlarge that small chamber to the size of your room, the air inside will still resonate (of course at different frequencies than the empty bottle). These resonances will result in peaks & nulls throughout the room. That means some listeners will be sitting in quiet nulls while other listeners will be hearing loud peaks. It's mostly audible in the bass range.
Do different companies--Dolby, THX, DTS, etc.--have different speaker placement recommendations? If so, whose speaker placement do these online calculators use?
What is the ideal location for doors? I assume that ideally, the room would have no windows.
When I first read this, I figured that you meant that I should ask myself whether I want a dedicated theater room or a multipurpose room. I just realized that you maybe meant something else when you said "a room open to other spaces." I'm not sure what that means.
The online room mode calculators don't consider speaker placements. They calculate the room modes, which are independent of the speaker placements. Room modes are explained in the link I posted. Also, see Sanjay's explanation above.
Wherever a speaker, a TV, a projection screen, an equipment rack or an acoustic treatment DOESN'T need to go.
A room open to other spaces is a room with large openings, (doors, archways, open to a kitchen or hallway, etc.) The acoustics are greatly affected by large openings, and where they're located in relation to the speakers and listening position. A "sealed" room, (one not open to other spaces and "sealed" by closed doors/windows), is easier to pressurize with bass because only the air inside the sealed space needs to be pressurized, ("pressurized" as in sound pressure, not barometric pressure.) An open room needs more subwoofer acoustic input to reach the same pressurization because all the air in the adjacent spaces also needs to be pressurized in addition to the air in the room.
Anechoic chamber.
