Building a listening room

Discussion in 'Audio Hardware' started by Emmett Scully, Mar 1, 2021.

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  1. Emmett Scully

    Emmett Scully New Member Thread Starter

    Location:
    Ireland
    Hi everyone,

    I want to have a go at making and selling boutique speakers, so I'm going to build a listening room. I wanted to ask the knowledgable people here for advice.



    The goal is to have a room which will allow for the clearest evaluation of speakers. To this end I want the walls to be reflective, but for there not to be any issues with the sound which would mask the sound quality.

    The internal dimensions in feet are 14x22.5x36.5

    The walls and floor will be concrete.

    I'm thinking the roof could just be galvanised sheets.



    My question is; how can I get a good in room frequency response, i.e. not too rolled off at the top end.

    This needs to be cost effective and non-resonant.



    Maybe Plywood over the concrete would even the response, and then the right paint over that might improve matters further.

    How should they be fixed to the concrete to avoid resonance?



    Any thoughts?
     
  2. KT88

    KT88 Senior Member

    Yeah, if you have to ask, then you are going to lose a lot of money. I'd rethink your investment strategy. Buying a great set of speakers will be way more affordable and allow for way more time to enjoy various other activities. It's a brutal industry that will not likely go in your favor. Industry trends for loudspeakers are for smaller and cheaper designs. The most notable thing to see is the number of users declining over the years. Most folks use Bluetooth speakers or headphones these days. Companies that are making large, accurate speakers are beginning to have ridiculously high price tags that rule out most of the world as customers. That's a sinking ship from this angle.
    -Bill
     
  3. Ingenieur

    Ingenieur Just a dog looking for a home...

    Location:
    Back in PA
    This has a section for building a listening room for evaluating equipment.

    You are entering a crowded market with some heavy hitters. The have anechoic chambers, test instruments, mechanical and electrical engineers, modeling software, established supply chains, manufacturing facilities, etc.

    Your $ but enter knowing what you face



    https://www.itu.int/dms_pubrec/itu-r/rec/bs/R-REC-BS.1116-1-199710-S!!PDF-E.pdf
     
    Swann36 likes this.
  4. Mike-48

    Mike-48 A shadow of my former self

    Location:
    Portland, Oregon
    In the small chance that you are serious, I'll just make this suggestion: Start by studying the ways that speakers interact with rooms and what speaker designs have been developed in the past to address that. Next, study what is known about room acoustics and their effect on sound from a hifi. Then, consider whether any customers will have a room anything like the one you propose. After the reading, you should have an idea why that matters.

    But I hope you are joking, and you don't really think the room you proposed is suitable for evaluating hifi speakers.

    In either case, I wish you well!
     
  5. mibrighton

    mibrighton Forum Resident

    Location:
    Lincolnshire , UK.
    You are not serious , are you ?

    Maybe you meant to post it next month ... April 1st !
     
    Rick58 likes this.
  6. Dillydipper

    Dillydipper Space-Age luddite

    Location:
    Central PA
    This is not just to join in the chorus of skepticism so far, but...if you don't know what you're doing, perhaps you shouldn't be in the business of convincing others you know what you're doing.

    On the other hand, consider this easy strategy for room treatments, until you get the sound you are looking for: hanging banners or some sort of fabric treatments off the ceiling towards the corners, in such a way you can move them around, and see what the results can be. These only need be as low as, say a flag, affixed to moveable points above.

    Also, consider office-type cubicle walls treated with listening insulation as well. Their benefit is the same: you can move them around to solve reflection problems...and, you can even draw them close to one another, to demonstrate near-field listening.

    I think a customer might appreciate your willingness to change your listening room environment to approximate his own home situation, and how to deal with it. And, these are inexpensive, temporary solutions.

    But, if you are starting a business from scratch, and don't even have the basics down about how to best demonstrate the products you haven't even auditioned in your own home...it might be faster to take on a knowledgeable partner...and let him rob you blind.
     
  7. Ingenieur

    Ingenieur Just a dog looking for a home...

    Location:
    Back in PA
    I agree. If you don't have the knowledge and education to research this on your own, you are in over your head. We could never convey the knowledge you need for this endeavor. There are literally dozens (if not more) on the subject of acoustics and listening spaces.

    In addition there are as many Engineering/Architectural/Consulting firms that do this very design work, and many others that build them.


    No harm meant, just an observation.
     
    bever70 likes this.
  8. JCRW

    JCRW Forum Resident

    Can't really begin to help unless you have an overall budget in mind and are willing to disclose an estimate. If you're looking for cost effective solutions to build an entire listening room then you're going to be running into trouble from the start. The way you are describing things I would recommend searching for an acoustic engineer who can at least provide you consultation and a potential starting point on the goal you have set.

    If you already have the room built and you just want to make cost effective improvements to improve the room sound there's certainly options out there. If this is the case I would look into acoustic panels and some consultation from a company like GIK Acoustics.
     
    Ingenieur likes this.
  9. Emmett Scully

    Emmett Scully New Member Thread Starter

    Location:
    Ireland
    Thanks for the replies.

    I plan to start off doing it all myself. I'll be using a 7-axis CNC machine to do much of the work. Start up cost should not be that much, the listening room is going on my parents farm land. If I just sell a few each year that would be enough, after that I can get some one else on board.

    I think I can do without an anechoic chamber, a free space measurment should be fine.

    I have read Sound Reproduction by Floyd E. Toole, it's very illuminating.

    I have full confidence in my speaker engineering capabilities, I just want to get some help on the listening room.

    How can I make it sound better?
     
    timind likes this.
  10. Dillydipper

    Dillydipper Space-Age luddite

    Location:
    Central PA
    Like I said, easily-portable and repositionable elements that you can adjust according to the room's needs, and the customer's interests.

    Also, zealously-cautious electrical wiring (conditioners at the electrical box, separate circuits for different zones within the room itself*, good UPS boxes, and grounding, grounding, grounding). You want as clean an electrical signal as you can deliver to power your products.

    (*for instance, having electricity free of interference from either video setups or computer systems, by running those on separate circuits)
     
    Last edited: Mar 1, 2021
  11. Emmett Scully

    Emmett Scully New Member Thread Starter

    Location:
    Ireland
    Oh yes. But I'm pretty convinced after reading Tooles book that room corection is bad. The only correct on axis frequency response of a speaker is one that's flat when placed in ananechoic chamber. So I don't think a changable room is really helpfull.

    Really I'm just trying to improve the sound from bare concrete. Given the room dimentions, and how far the speakers would be from the side walls(6 feet), bare concrete might not even sound that bad. But is there anything that can be done with Plywood?
     
  12. Dillydipper

    Dillydipper Space-Age luddite

    Location:
    Central PA
    Pretty sure the last thing you want to use to demonstrate a speaker to a customer is an ananechoic chamber.
     
  13. Emmett Scully

    Emmett Scully New Member Thread Starter

    Location:
    Ireland
    Yes, you want a room with reflections. I'm saying there is only one correct on-axis frequency response, although you could add some bass
     
  14. mibrighton

    mibrighton Forum Resident

    Location:
    Lincolnshire , UK.
    So how are you going to control the bass.

    What is your current room and equipment details.
     
    Last edited: Mar 1, 2021
  15. John76

    John76 Forum Resident

    Location:
    Midwest
  16. The Pinhead

    The Pinhead KING OF BOOM AND SIZZLE IN HELL

    Good luck with that !:laugh: Bare concrete floor and walls and tin roof; a recipe for sonic disaster !
     
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  17. mibrighton

    mibrighton Forum Resident

    Location:
    Lincolnshire , UK.
    Was thinking the same , wonder if its an old milking parlour or pig sty ?

    REALLY !!!!
    I cant think of a much worse designed listening room. The best of luck.
     
    The Pinhead likes this.
  18. Ingenieur

    Ingenieur Just a dog looking for a home...

    Location:
    Back in PA
    Bare rough unpainted block is a good absorber over a pretty wide range. I imagine split face would be even better.
    Both may offer diffraction too at higher freqs.

    NOISE CONTROL WITH CONCRETE MASONRY - NCMA
    Concrete masonry is an ideal noisecontrol material for both properties: it can act as a barrier by diffusing incident noiseover a wide range of frequencies; and it can be an effective sound absorption material for absorbing noise generated within a room.

    tin/metal, another matter

    [​IMG]
     
    Last edited: Mar 1, 2021
  19. aorecords

    aorecords Forum Resident

    You might consider hiring an acoustician to consult. Otherwise, I'm sure there's tons of material on the internet or in book form to check.
     
  20. Doctor Fine

    Doctor Fine "So Hip It Would Blister Your Brain"

    Concrete floor is OK with a thick pad and thick wall to wall carpet over that.
    You don't need to go nuts with special treatments as your goal should just be a "typical NORMAL somewhat treated environment."
    Not some high tech room that nobody else will own.
    You want your designs to work out in the ugly world where things are not perfect.
    But you WILL need to be able to CONTROL that room and KNOW everything positive you are doing to it!

    Your room needs to allow you to experiment with different placement locations to mimic all the basic problems in getting speakers that sound great in-room in different scenarios, not in a lab.
    If it was me I would use both long and short walls to learn what happens in both scenarios with MY setup.
    And I would NOT put anything in between my tested speakers like a rack or junki that makes it impossible to hear just the speakers.
    You do NOT want to "hear" your rack diffusing all the sound and messing you up!
    The tricky part is getting EVERYTHING set up to produce flat enough response to not fool you and for that you will just have to "learn the room" and perhaps come back a second time to clean up any problems you discover after it is built.

    Perhaps a pair of great headphones (I use Sennheiser HD650s) with an amp (I use the Monoprice THX amp), EQed to the Harmon Curve (I use a DBX 1215) could be used as a baseline to mimic that sort of flat response out in the room in different locations typical of what a consumer might use for speaker placement.
    I don't want my finished setup to be too far out of whack tone wise and response wise and there is nothing better than HEARING good response and then going about MIMICKING it in-room.
    You can also actually measure your progress with room measuring microphone setups, test tones off Youtube and so forth.
    My guess is you will find various parts of the room are totally out of whack but a few will work pretty well at producing flat response (just like MOST rooms in the real world) ---FIND THEM.

    You will need accessories to quiet down standing waves and to treat first reflections that screw up your speaker response for no good reason.
    You should assume the consumer will make some kind of effort to have a decent room but not perfection---and that should also be YOUR goal.
    So TUNE IT WITH ACCESORIES to clear it up to decent levels and leave it at that.
    When you are all done you can go over to various friends pads and set them up and see how well they work in typical homes...

    Sonex makes portable 2X4 sound absorbent Sonex panels with eyelets to hang wherever you wish.
    I own a dozen and use them to quiet a room so I can just hear the actual room without all the reverb going off.
    Then I remove them one by one and listen for the best combination of live/dead reflected energy.
    You should also consider making home made adjustable diffuser panels sort of like venetian blinds.
    Or simply buy venetian blinds on hooks and hang them on the walls as needed for testing purposes.
    These will kill flutter echo without deadening the room to anechoic weirdness levels.

    I like to kill SOME of the reflections on the wall behind the front where the speakers go but not get too dead up front as that is un natural and not likely to be what the consumer has at their disposal.
    I typically leave an adjustable reflective space in the center to dial in just how much strong "center phantom speaker' sound is appropriate.
    So perhaps heavy closable draperies across all four walls would give you lots of tuning options.
    Open and close them depending on how large you want the center image to be.
    Open and close them to see just how lively a room you need in which to hear clearly.
    I LOVE drapes!

    What you want to find out is how the room actually works so your testing will be repeatable over at someone's home.
    To do that you will need to live in that room until you learn every weird quirk it possesses.
    You'll need to learn where the nulls and modes live so you can avoid them.

    Probably put bass traps in all four corners.
    Armed with a non reflective floor, tunable reflective or damped walls and portable panels you can place around looking for sound control plus diffusion "blinds'" you should be able to get pretty consistent energy control.
    The variety will allow you to hear how your designs work on short walls and long walls and even perhaps try them in wacky setups to see if they are "forgiving" or tweaky and twitchy.

    You need to learn setup techniques and get an idea how to experiment with your gear.
    Buy Jim Smith's book and CD on "Get Better Sound."
    Study the Sumiko method of speaker setup and placement.
    Use test tones available on Youtube to check for nulls and modes so you know what is real and what is being screwed up by your room dimensions.
    If you do all this stuff and test it with some typical speakers you'll have a decent idea how your own designs perform---or don't.
    Best of luck.
     
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  21. Emmett Scully

    Emmett Scully New Member Thread Starter

    Location:
    Ireland
    Thanks doctor fine. I think I might just stick to my original idea of putting Plywood up. I bet by choosing the right thickness, and the right gap from the wall, I could get an okay frequency response, It would improve the look of the room any way. Plywood for the ceiling too.
    I'm not sure about the stud spacing, maybe 12".
    Although with that many studs, maybe it's better to have a timber frame?
    If bass is too much, I will have doors at either end which could be opened.

    mrbrighton, your insane outbursts are most amusing.
     
  22. Larry I

    Larry I Senior Member

    Location:
    Washington, D.C.
    It is pretty hard to guess how a room will sound like and what it will take to get acceptable performance even when one is standing in the room, much less from the rough design specification offered up in this thread. One of the better rooms I have been in at a dealership was in an industrial park and all four walls were concrete block and the floor was poured concrete. The room had NO obvious acoustical treatment--there was carpeting and rugs on the floor, and textile wall hangings in a few spots that looked nice (stealth treatment). At the other end of the spectrum, I've heard rooms that were designed by acoustical engineers where every inch of the walls and ceiling were treated that sounded like crap-VERY dead. I know that this does not offer much help to you about designing your dedicated room/building. I would say build a solid structure and then work with what you have by experimenting with room treatment. I would consider going with a lower ceiling than 14 feet. I've helped with setting up a number of systems and the most troublesome setups involved rooms with high ceilings--it is hard to get the bass right and high ceilings tend to require playing the system at higher volume levels to get the sound to come alive; I like it when systems sound lively at lower volume levels.

    Start with minimal treatment and do a lot of listening. There is a tendency to overtreat rooms so go slow in the process. Also bear in mind that proper placement of the speaker and the listening position is far more important than the specific acoustic properties of the room--it is possible to get great sound out of almost any room with proper placement. Consider the use of things like houseplants (either real or artificial), like fig trees, located near the corners of the room as a form of room treatment. I would make the room as comfortable, nice to look at, and as true to a regular room in an upscale home as possible; if you can get good sound in a room that is not filled with ugly treatment, it will be much easier to sell customers on your speakers.

    If you want to go really fancy with the build, consider building corner traps into the walls that are hidden from view. A friend has a dedicated room that was designed by acoustic architects and it has hidden bass traps and acoustic diffusion built into the walls and ceiling that look like decorative features rather than acoustic treatment. While some wall diffusors can be sort of decorative, the best look is to build the diffusors into the walls and have acoustically transparent fabric wall coverings hiding the diffusors.

    Good luck on your project.
     
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  23. Mike-48

    Mike-48 A shadow of my former self

    Location:
    Portland, Oregon
    Got to say, I learned something from that!
     
  24. Doctor Fine

    Doctor Fine "So Hip It Would Blister Your Brain"

    Yes but I'm thinking it has to be BLACK paint---right?
     
  25. Mike from NYC

    Mike from NYC Senior Member

    Location:
    Surprise, AZ
    That is why I started designing my own speakers!!!!! Stupid High Prices!!!!!!!

    It should be noted that my less than $1000 2.1 way speakers blew away my Revel Ultima Studios!! 2 audio buddies who came over for a listen said the same thing - better bottom, clearer high frequencies and a considerably larger sound stage in terms of width and depth. Pictures to come but it should be noted I am using a pretty big Fountek Neo 3 Ribbon that I cross at 2500 Hz - a truly amazing driver.
     
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