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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => Pro AV Forum => Topic started by: Mike Henderson on November 07, 2020, 08:10:07 PM
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Hey guys, I would like to upgrade from old Sony surround system. Main issue in this small one car garage is the bass as I have cabinets, fridge, tool boxes, chairs e.t.c along the 3 walls.
Isn't there some option to get almost equal bass no matter where you sit? I am thinking of having the subs for bass on the walls instead of on the floor or may use 2 powered subs on the floor on opposite sides maybe, any thoughts?
Also, what is a good modern surround system which gives clean highs with which you can run and manipulate playlists from the phone and also bass and volume please?
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I thought you had an SB1000 for your garage sub??
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I have a Sonos system in my 20'x20' garage/shop (not a theatre setup)and put the sub up in one corner on a shelf.
The coverage is fairly even but, as it is with bass, the reflections from the surfaces will make nulls no matter where it is placed.
Pick a listening location and move the sub until you hear what you like.
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I thought you had an SB1000 for your garage sub??
Yes I have a DJ system and a Sony surround system. I get the part of uneven bass due to the room acoustics, just grasping at straws I guess.
One of my friends has the Sonos system in his house but my Sony with a 10" powered sub sounds better to me.
When I get rich I will get a system like this:
https://hifiheaven.net/shop/Klipsch-THX-Ultra2-Home-Theater-System?language=en¤cy=USD&gclid=Cj0KCQiAy579BRCPARIsAB6QoIb35akEE2m_Vi888u_bjr6R-wfak0ZozxErB__uFTnojkqfYfz1KRUaArMjEALw_wcB
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Acoustic treatment would help but seeking an "ideal" placement of subwoofers is not likely to produce the evenness of bass sound in many locations, as opposed to just at one single listening position, that you are asking for.
The evenness of bass sound at different locations in a room is determined mainly by the standing waves that form in the room due to sound reflecting off the walls and reinforcing or cancelling other sound at any given location. These standing waves are determined by several factors, including frequency of the bass sound, dimensions of the room, shape of the room, reflectivity/absorption of the walls, as well as the factor you are asking about, location of one or more sources of the bass sound in the room (including interactions among them around crossover frequencies). The loudness of the bass source (size of subwoofer) is not one of the main factors in determining the evenness of the sound, just the loudness at a given location. The variation in loudness is often large, tens of decibels louder and softer over several feet of change in location, due to peaks and nulls in the standing waves that form in the room. Smaller rooms tend to have much larger relative variation than large concert halls or outdoor spaces at audible bass frequencies.
Since your garage is a fixed size and shape, and you want to listen to all the audible frequencies, the only two factors you can really control are location of the subwoofers and the reflectivity/absorption of the walls. You could try to optimize the evenness of loudness of bass content of the music over the expected listening areas by moving the subwoofer(s) and main speakers around. This is complicated and not likely to produce a very even result in a small space like a garage, since the standing waves cause what works ok for one listening location to not work for other locations.
The other option is to install enough absorption in the space that the amplitudes of the standing waves will be reduced to acceptable levels. Typically studios and other listening areas use broadband bass traps that attenuate the sound level of the bass standing waves. These work best when placed one quarter wavelength out from the walls, where the peaks of the standing waves occur. Absorbers placed within a few inches of a wall do nothing to absorb low frequencies. Given the frequencies of bass sound (40-100 Hz or even lower), the speed of sound in air (1130 ft/sec) and the resulting wavelengths of the bass frequencies (11-28 feet), your bass traps would optimally be placed 3-7 feet out from the walls. To attenuate bass frequencies they would need to be many inches or feet thick of rockwool or fiberglass acoustic absorption material. Typically they are placed closer to the walls but then are less effective. One useful technique is to place them with six inches to a foot of dead space between the absorber and the wall, so the absorption is located closer to the optimal zone without wasting absorber in space close to the wall where it is ineffective.
This is all an oversimplified description of the acoustic theory that you can find in books and articles on acoustics of sound in small spaces, or that an acoustician would know and be able to apply to your space. Since you seem to be just interested in listening for enjoyment and not for critical professional purposes like mixing or mastering a recording, you can apply these principles in a partial and informal way. You basically want to create a relatively "dead" acoustic space with lots of absorption of the bass frequencies. I have had pretty good results in my basement rehearsal/recording studio from simply placing 4 bales (1ft x2ft x4 ft) of rockwool insulating boards a foot or so out from the walls, plus about 10 absorbers (4 inches x 2ft x 4ft) in strategic locations (mirror reflection points for each speaker for one listening position, clouds on the ceiling, across corners) for higher frequencies. You could probably get by with just a bunch of bales of rockwool insulation, still in its original plastic wrap, and play around with the locations such as in the rafters, across corners, or hung from the ceiling. The bales are pretty ugly and you can cover them with porous fabric to make them look a little better, but in a garage, keeping them clean will be difficult. Depending on how bad the unevenness is now, and your availability of space, time to work on it, and budget, you may want to just settle for the uneven sound.
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There are two modes of thought on how to fix your issue:
1.) Place a single sub in the ideal location. In your case, this may be in the actual center of the room tucked up against the ceiling ( if your garage has one ). It will be more even, but you will have weaker bass as you get further away from the sub. Room modes will still exist, but with the many large objects and things against the wall, this will be reduced quite a bit. The problem is that it is generally not practical to place a sub in such a spot. In many cases, placing a sub in the ideal location is usually not possible due to the layout of the room and aesthetics. this leads us to option two.
2.) Use many subs placed at the locations of the highest interest. This is an old home theater trick that employs several subs placed where they are needed to fill in the holes. You start with the typical single or stereo deployed subs at the focal point and then wherever you need more sub output within the listening space, you just add another sub at or near that location. The idea is that the saturation of energy from several low-level subs, will even out the coverage ( SPL wise ) in the room and not hinder sound quality too much. I disagree with this approach and feel it is a marketing ploy to get you to buy more subs, but it does work for the purpose of adding sub content to an area that is lacking in coverage. The quality of the sub content is absolute garbage, but if you must.....
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If you're going the treatment route, This is my go-to. Rigid fiberglas panels. Easily mounted with fender washers.
If you want them pretty: a light dust of spray paint, or nicer: light wood frame with an acoustic cloth cover.
https://www.acoustimac.com/acoustic-insulation-materials/acoustic-insulation/owens-corning-acoustic-insulation
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The idea is that the saturation of energy from several low-level subs, will even out the coverage ( SPL wise ) in the room and not hinder sound quality too much. I disagree with this approach and feel it is a marketing ploy to get you to buy more subs...
Subwoofers in different locations will activate different room modes. If you do the work and testing, you can position them so that the LF response is more even as you move around the room - one subwoofer will fill in the cancellations of another.
I'd consider the above factual, so I'm a little confused about how someone might disagree.
Chris
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It works, but is less than ideal for great results. If all you care about is the boom at X location, then it fills that box, if you want true to life quality of sound, well it doesn't do that so well. Sure you have what you want, but you still don't get your cake and get to eat it. I guess it comes down to your design goals. Do you want outright quality, or do you just want to have the sound? Perhaps to some, the latter is the same as having cake and eating it too? I still think that it originated as a marketing ploy from some home theater company to sell more subs. It may one of the more realistic and semi truthful marketing schemes, but it is still snake oil.
I guess my point is that it is much more difficult to convince someone to buy lots of foam to place on their wall than it is to sell a couple of extra subs with wire that costs over $100 per foot. Or said more gracefully: It is easier to sell more subs and expensive wire than it is to get someone to engineer their listening space.
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Luke,
The distributed subwoofer method is based on solid acoustic principles, and works well for bringing a more spatially uniform response, which can then be EQ'd overall to produce the desired results.
It's not just "boom at X location". It's even response at all locations.
You seem to think physics = snake oil, and that just ain't so.
Chris
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Luke,
The distributed subwoofer method is based on solid acoustic principles, and works well for bringing a more spatially uniform response, which can then be EQ'd overall to produce the desired results.
It's not just "boom at X location". It's even response at all locations.
You seem to think physics = snake oil, and that just ain't so.
Chris
Thanks for all of the info guys. Yes Chris the ideal goal would be to get even response at all locations but if not possible with all of the things in the garage closest option would be to get "boom around where we sit". Actually I was thinking the same thing Luke mentioned and try to do some experimenting.
I can get one more sub and move it around to different spots where we sit to see if it will help. Klipsh has a wireless sub which would make this easy and should it not work I can simply send it back.
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I can get one more sub and move it around to different spots where we sit to see if it will help. Klipsh has a wireless sub which would make this easy and should it not work I can simply send it back.
That is the recommended way to locate a sub for home theater applications. At least, that's the first step in several subwoofer manuals that I've read recently. I've added subwoofers to two systems in my house recently. In both cases, the sub's location was more or less pre-determined. For the basement workout tunes, the sub is in a corner behind the TV stand. I can hear room modes, but since I'm moving around when I exercise, it sort of evens out. I flat out got lucky with the sub's placement in the living room / home theater. It's between the TV and the right speaker and it rattles the room. It probably helps that my listening position is almost against the opposite wall, so I'm likely sitting in a nice room boundary mode. And that leads me to my suggestion; if you can locate your listening position near a wall it may help you get a nice full sub sound. FWIW I wish that I'd added a sub to my home theater years ago. I thought my full size L+R speakers were good enough, but boy was I wrong about that.
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And that leads me to my suggestion; if you can locate your listening position near a wall it may help you get a nice full sub sound. FWIW I wish that I'd added a sub to my home theater years ago.
In my experience with subs for Surround, placing it in a corner has always produced best results but since all corners have stuff in them I am first going to try placing the 2nd sub in the middle of the room along the opposite wall. Since we all sit in the middle of the room, this should be best placement.
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Subwoofers in different locations will activate different room modes. If you do the work and testing, you can position them so that the LF response is more even as you move around the room - one subwoofer will fill in the cancellations of another.
I'd consider the above factual, so I'm a little confused about how someone might disagree.
Chris
Happy to disagree. Room nodes are a function of the room, and are source independent. When the room resonances cancel out a specific frequency at a particular point, it doesn't matter how big your subs are or where they're located. +1 -1 is exactly the same as +1000 -1000.
The correct answer to the OP is appropriate bass traps. REW is a solid, free, tool for checking your work.
https://www.hometheatershack.com/forums/rew-forum.8/ (https://www.hometheatershack.com/forums/rew-forum.8/)
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Dan,
It looks like you've missed my point. Allow me to try again:
When you put a subwoofer in a room, you get a bunch of nulls at different frequencies and locations in the room..
If you move that subwoofer to another location in that room, you'll get a different set of nulls. Some of those nulls will coincide with the first set, but most will not.
If you use two subwoofers, one in each location:
- In the cases where the nulls coincide, the combined response will still have a null.
- In the places where one subwoofer would have a null but the other would not, you'll still have the output of the other subwoofer: the null hasn't been eradicated completely, but it's a huge improvement as there'll still be some output.
By using a few subwoofers (diminishing returns apply - three or four is usually a good point to stop, but some people go further), and optimising with DSP, it's possible to get an in-room response that's spatially uniform.
Chris
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I think perhaps you mixed the concepts of even response and linear response? While Even response does work with distributed sound, it does not bode well for a linear response. When is say linear, I literally mean 1:1, what goes in is what comes out. As we know, if you are not equidistant between two sound sources you get phase interaction. So a PA is " fixed " to achieve the best compromise and achieve as close as is practical, a 1:1 at any given location. When you start loading a room up with subs and speakers with no regard to phase relationship and only to even coverage, you solve one problem and create another. For me, the acoustic principles and physics of distributed subs in a room is bogus snake oil BS, designed to sell you speakers. Does it work, YES, is it right, NO. It cannot ever potentially be 1:1.
Physics cannot be a snake oil, there is nothing to sell from it. It is what it is no matter what you want it to be. So while physics allows you to solve a problem in one way, it doesn't allow you to have your cake and eat it too. Even response is not a linear response. PERIOD. Solid acoustic principles aside, it doesn't defy physics, it simply fills the holes left due to physics. It doesn't solve the phase issues though and it can NEVER be a 1:1, what goes in is what comes out scenario. I would say that with enough processing and time, you could make it so that very specific points in the room could be made to have a linear response, but honestly, with enough time and money, you could do anything you wanted anyway.
As you can tell I am not a fan of the whole Audiophile ideology. When you have people that actually try and justify the cost of speaker cable, power cables, cables risers, and concrete bases 8' thick with unobtanium pyramid point feet and $100 per foot RCA cable, I only see snake oil, because physics don't care bout no $ amount, it is what it is.
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Luke,
When you have a setup which has the same frequency response at each listening position, it's trivial to EQ that to give it any response you like, including a linear one.
You have to remember, though, that we're talking about speakers operating in the room's modal region. The standard time-of-flight stuff that you speak of simply doesn't apply here. We're not outdoors - we're in an acoustically small space, and the operating principles are very different.
Chris
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As you can tell I am not a fan of the whole Audiophile ideology. When you have people that actually try and justify the cost of speaker cable, power cables, cables risers, and concrete bases 8' thick with unobtanium pyramid point feet and $100 per foot RCA cable, I only see snake oil, because physics don't care bout no $ amount, it is what it is.
definitely agree, however those people are not the ones worrying about home theater subwoofer(s) placement.
For most of them more than 2 channels is blasphemy.
Many of them also have issues with crossovers in general -read up on the single-driver fullrange fad.
-and then if you can stomach that then move on to the open-baffle concept.
Eventually that would lead you to the few who are convinced that a mono, full-range speaker mounted in a board with no enclosure and powered by output transformerless single-ended tube amp of less than a watt output is the ultimate audio panacea. (after spending more than we would spend on a whole new PA and the truck to haul it in!)
Back to the HT bass issue,
To me it seems like the whole industry is making the "subwoofer obsession" a little too much like a thrill-ride. Impact and a sense of power when playing back blu-ray soundtracks is all that matters and musicality and accuracy don't really matter.
Most of the things I hear in the LFE channel are artificial and synthesized noises manufactured by the film sound creators -and actually gets too monotonous after a while. (Shutting it off brings a sigh of relief sometimes!) -I just sat through a transformers movie where it seemed like the LFE went from "cool look what we can do" to "for the love of god just make it stop!"
At least an amusement park thrill ride is over and done in a few minutes! (and you can stumble your pummeled ass to the nearest overpriced drink stand to recuperate)
So if TLDR, just fasten some bass shaker transducers to your couch and quit bothering with trying to recreate non-musical thuds and thumps acoustically!
I understand this thread was more about music listening, so with that in mind why are we trying to achieve good accuracy and coverage with equipment from an industry that's more impressed with a dinosaur foot-thump making water ripples?
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That is the recommended way to locate a sub for home theater applications. At least, that's the first step in several subwoofer manuals that I've read recently. I've added subwoofers to two systems in my house recently. In both cases, the sub's location was more or less pre-determined. For the basement workout tunes, the sub is in a corner behind the TV stand. I can hear room modes, but since I'm moving around when I exercise, it sort of evens out. I flat out got lucky with the sub's placement in the living room / home theater. It's between the TV and the right speaker and it rattles the room. It probably helps that my listening position is almost against the opposite wall, so I'm likely sitting in a nice room boundary mode. And that leads me to my suggestion; if you can locate your listening position near a wall it may help you get a nice full sub sound. FWIW I wish that I'd added a sub to my home theater years ago. I thought my full size L+R speakers were good enough, but boy was I wrong about that.
A "trick" I have used a few times.
Put the sub at your seating position, and walk the room.
Where is it "strongest"?
Put the sub there, and go have a listen.
Chris.
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The modal region, indoor-outdoor stuff is trivial. You can make your room be close enough to an anechoic space to make it a non-issue if you spend enough time and money. If you have a room treated well enough, most of the issues with room modes and modal regions are eliminated. You see where this is going.
Room treatment is not a very practical solution for a garage though. This is why I mentioned the dispersed sub concept. It is a solution to his problem. I also pointed out my reasons for not employing that solution.
As it pertains to the audiophile world, there are only a few concepts that they lean on which are truly supported by physics. The rest of it is clever nomenclature and weird science that physics doesn't substantiate. I'm not saying it sounds bad, I'm saying that for a significant amount less, you can have the same and perhaps even better. Bias confirmation aside of course.
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Many of them also have issues with crossovers in general -read up on the single-driver fullrange fad.
-and then if you can stomach that then move on to the open-baffle concept.
Eventually that would lead you to the few who are convinced that a mono, full-range speaker mounted in a board with no enclosure and powered by output transformerless single-ended tube amp of less than a watt output is the ultimate audio panacea. (after spending more than we would spend on a whole new PA and the truck to haul it in!)
Some notes:
- Full-range drivers do have advantages: no crossover in the midrange (ie, nice flat phase response) and point-source behaviour being the main ones. There are, of course, disadvantages, and those should be balanced when designing a speaker.
- Open baffle systems provide a figure-of-8 radiation pattern, which can be very useful in some situations. Side wall reflections can be eliminated, in exchange for some longer room reflections (from the rearward radiation pattern) which can be beneficial if you look into the psychoacoustics operating in the background.
- I don't think anyone would claim the system you've described is the most accurate system in the world. However, if someone's found they particularly like the sound of their music in mono through a vintage 12" unit, then more power to 'em. It's not for me, and apparently not for you, but that doesn't mean they shouldn't enjoy their system.
Luke, it's certainly non-trivial to make a room anechoic into the low-frequency range.
Chris