Absorption is usually the key.
" New Building" with no carpet and bare walls
wont be less reflective than a old one.
Carpet and drapes.
Hard surfaces are reflective regardless.
The brick building photo with concrete floor.
Has very nice atmosphere.
But the curved non parallels wall theory wont
save it. It would be incredible reverberant regardless.
Good to hear testimony from people with actual
experience in many rooms.
As mentioned a poor reflective room.
Calms down with more people.
Very dramatic.
Easy to "emulate" without having a " expert"
drain your wallet with magical acoustic panels and
overpriced materials.
It is called carpet and drapes.
" New Building" with no carpet and bare walls
wont be less reflective than a old one.
Carpet and drapes.
Hard surfaces are reflective regardless.
The brick building photo with concrete floor.
Has very nice atmosphere.
But the curved non parallels wall theory wont
save it. It would be incredible reverberant regardless.
Good to hear testimony from people with actual
experience in many rooms.
As mentioned a poor reflective room.
Calms down with more people.
Very dramatic.
Easy to "emulate" without having a " expert"
drain your wallet with magical acoustic panels and
overpriced materials.
It is called carpet and drapes.
Thanks for all the replies so far.
What I have learned so far:
Spread out room dimensions....so height is not close to a multiple of width or height, width is not close to half the length.
Prevent hard surfaces like tile, glass, concrete. For the walls I am looking at AAC block with clay/paper fiber plaster. The ceiling 3mm bamboo panel covered with rockwool. Concrete floor covered with wood parquet.
Most ideal speaker for uniform coverage is a corner line array. Should have the widest "sweet spot due to both even dispersion and slower volume decrease per distance doubling. So not being equal distance from both speakers has less L/R volume difference.
Have a flat ceiling....best for maintaining cylindrical line array wave. Make a triangle piece of ceiling and floor in the speaker corners reflective to help extend the virtual line array. I may even actually make it a mirror.....would be a cool visual......seeing the line going into the floor and ceiling to infinity.
I can build the room with a recessed corners so drivers can sit behind the wall/corner so the speaker is not in the corner but in the wall in the corner.
As much as I like to stack 20 heil AMT's that would gobble up too much budget. I am now toying with the idea of a corner loaded line array synergy horn. Wall to ceiling line array compression driver manifolds exiting exactly in the room corner with midrange and woofer holes at appropriate 1/4 wave distances also from floor to ceiling. Should cost a quarter or less than using Heils. If the bar is a raging success I can always upgrade.
What I have learned so far:
Spread out room dimensions....so height is not close to a multiple of width or height, width is not close to half the length.
Prevent hard surfaces like tile, glass, concrete. For the walls I am looking at AAC block with clay/paper fiber plaster. The ceiling 3mm bamboo panel covered with rockwool. Concrete floor covered with wood parquet.
Most ideal speaker for uniform coverage is a corner line array. Should have the widest "sweet spot due to both even dispersion and slower volume decrease per distance doubling. So not being equal distance from both speakers has less L/R volume difference.
Have a flat ceiling....best for maintaining cylindrical line array wave. Make a triangle piece of ceiling and floor in the speaker corners reflective to help extend the virtual line array. I may even actually make it a mirror.....would be a cool visual......seeing the line going into the floor and ceiling to infinity.
I can build the room with a recessed corners so drivers can sit behind the wall/corner so the speaker is not in the corner but in the wall in the corner.
As much as I like to stack 20 heil AMT's that would gobble up too much budget. I am now toying with the idea of a corner loaded line array synergy horn. Wall to ceiling line array compression driver manifolds exiting exactly in the room corner with midrange and woofer holes at appropriate 1/4 wave distances also from floor to ceiling. Should cost a quarter or less than using Heils. If the bar is a raging success I can always upgrade.
yes........you're missing everything about sound reproduction in a social multi purpose environment. Line arrays are direct sound....and DO NOT sound good in the mid field......so folks closer to the array ( less than 10x the length) will just be plain old annoyed and not having a good time at all. Wrong application.
I am not saying you're wrong but this would mean numerous people here like Wesayso who have floor to ceiling arrays in their rooms are knowingly or unknowingly subjecting themselves to sonic torture? There is no way they can be more than 3 or 4 line length removed from their speakers. And since in theory those lines are infinite due to boundary reflections they can't even be one line length distance from their arrays.
Sitting alone on a couch with your head at tweeter level and in a vice you can't do better than a point source. But don't the rules change in a very large room with 80 people?
I don't have a dog in this fight. I just don't want to pour money and time into the wrong concept. And I also don't want to go the mono route. I am looking for the best stereo solution.
Options:
Big horns a la Klipsch/JBL
Big open baffle speakers
Corner loaded infinite line arrays
Synergy / Unity speakers
Omnidirectional speakers
Basically I sneed a SWAT analysis of those options.
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If you want stereo I thing you should make three speaker stereo, which would maintain the stereo image better keeping the center and sides still regardless of listening position.
As everyone can test at home, stereo image collapses to nearest speaker if one moves away from central axis. If room early reflections dominate this might not be so apparent though.
Depending of the place and where people will hangout corner speakers might not work, if they are too far apart. Example 10x10 room, speakers in cornera, equilateral triangle puts good lsitening positions near backwall. You might want equilateral triangle middle of the room so speakers roughly 5-10 units apart depending where rest of the growd is, front or back of the room.
OB might not be ideal either if you put three speaker stereo with identical units.
Point is, it's too early to determine the playback system. You need the room and listening position/area first, and then go after speakers that would make sound you'd like at that position. Or change initial plan if it is impossible. Context + implementation = goal.
So, draw the room in CAD with all the bar stuff so that it makes sense from business perspectove, and see how it could accommodate a playback system. If it's space you buy / rent go do that to lock it down and design a system for that.
As everyone can test at home, stereo image collapses to nearest speaker if one moves away from central axis. If room early reflections dominate this might not be so apparent though.
Depending of the place and where people will hangout corner speakers might not work, if they are too far apart. Example 10x10 room, speakers in cornera, equilateral triangle puts good lsitening positions near backwall. You might want equilateral triangle middle of the room so speakers roughly 5-10 units apart depending where rest of the growd is, front or back of the room.
OB might not be ideal either if you put three speaker stereo with identical units.
Point is, it's too early to determine the playback system. You need the room and listening position/area first, and then go after speakers that would make sound you'd like at that position. Or change initial plan if it is impossible. Context + implementation = goal.
So, draw the room in CAD with all the bar stuff so that it makes sense from business perspectove, and see how it could accommodate a playback system. If it's space you buy / rent go do that to lock it down and design a system for that.
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The beauty is that I can build a room around the speakers.
I have land, budget and a vision. The vision is optimal music experience for 80-100 people in one large space. If I think I know what kind of speaker is best in this scenario I can find our what room shape & acoustics fit this type of speaker best.
I recommend DIY defuser,it's cheap and easy, looking not bad.
I surprised for the effect when I built for my room.
https://www.diyaudio.com/community/...ot-sound-diffuser-panels-step-by-step.269366/
I visited some jazz cafes in Tokyo.
Some cafes are too loud,only few places are comfortable and want to visit again.
I prefer a pair of large speakers with good quality sound.
Just my personal opinion.
I surprised for the effect when I built for my room.
https://www.diyaudio.com/community/...ot-sound-diffuser-panels-step-by-step.269366/
I visited some jazz cafes in Tokyo.
Some cafes are too loud,only few places are comfortable and want to visit again.
I prefer a pair of large speakers with good quality sound.
Just my personal opinion.
No use in trying to reinvent the wheel here and vision won’t save you…….Keele……Toole…..Moore……these folks have done countless hours of evaluating and writing. Start there. Search the web for White Papers too on arrays, subwoofers, etc. Once you’ve absorbed enough acoustic knowledge, then as yourself the ‘could I’ or ’should I’ question. The most difficult person to be honest with is yourself……and this question stings a bit. Such questions are high contrast not unlike many of the poisonous creatures in the wild for a reason.
The foundational response range of bass won’t care what your space looks like visually…..only the displaced volume and the materials it’s made of. Long wavelengths will aggressively compete and all you can do is excite as much of the modal response of the room as possible. Two or three sources of bass in a large space will be an epic fail for starters and what happens above 100hz will never find a cohesive happy place.
I believe someone touched on diffusion here……..that’s going to be your fundamental design criteria. Many years ago, I assisted in the design of the performance sound system update for the original Hayden Planetarium at the NYC MONH where we used a combination of direct and reflected sound working with the dome and its complex metrics of reflections. The final tweaking took weeks but we achieved massive success to 95% of the final performance value right at the initial install where the space and music were one. From a seated listening position within the space, visually the transducers ( Bose btw) weren’t visible and those that were were not on any individual listening axis.
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The information on the size of the venue can help to determine the type of diffusers used (if any). With Danley-style loudspeakers--even the ones that you showed by JBL (the trough-type MEH), the loudspeakers themselves can dramatically decrease or even eliminate the need for diffusors. For instance, here is a REW measurement of the reverberation times and early decay time (RTs and EDT) taken 1m in front of my center loudspeaker (a K-402-MEH) on-axis:
And the same measurement done about 2m farther away from the left front Jubilee (fully horn loaded loudspeaker) at the main listening position:
(So it appears that where you take the RT measurements matters a lot.) My room dimensions are 40' L x 15.5' W x 9' H (5510 cubic feet), (12 x 4.7 x 2.7 metres--152 cubic metres). The listening position is about 11 feet from the front wall (~3.4m).
There isn't much to be done here with EDT and RT20--they are quite low already due to the full range directivity of the loudspeakers. The story here changes dramatically if you try to use loudspeakers that basically lose their directivity below 1-2 kHz (i.e., virtually all cone and dome loudspeakers). I don't think that you'll be able to play music for 80-100 people using something as low efficiency as electrostatics or other non-cone dipoles, so the choices are either loudspeakers having full-range directivity control, and those that don't have it (i.e., direct radiating woofers, etc.).
So it looks like you can really control the diffusion problem simply by good choice of loudspeaker type--i.e., full range directivity. Certainly, if you want to add convex-type diffusors to the side walls and ceiling (if that ceiling is below 10-12 feet [2=3m]), you can do that and further decrease the EDT and RT20 times toward the back of the room.
Chris
Wouldn't open baffle also qualify? Especially in the bass region it has little side radiation.
An open baffle is a cone-type dipole--with loss of directivity control determined by the diameter of the baffle. So if you want to control directivity down to 200 Hz (like the full-range MEH and horn-loaded loudspeaker RTs and EDT plots above), you're talking about a baffle that is something approaching 34 inches diameter. That's fairly large for an open baffle.
In a room the size that could entertain 80-100 people, you probably would want to control directivity down to ~100 Hz, so the baffle diameter would need to be increased to something like 72 inches/1.8m. It's probably better to use an infinite baffle arrangement with the loudspeaker front baffle being coincident with the front wall surface,
The problem with open baffle designs is "what do I do with the backwave?" which generally needs an incredible amount of diffusion on the front wall to break up the specular reflections, as well as at least 11 feet/3,4m of standoff distance from the front wall to get enough backwave arrival delay relative to the direct arrivals to be outside Haas integration period of the human hearing system (i.e., at least 20 ms,,,and that really isn't enough delay).
I'm not a fan of dipoles, having had a pair of Magnepan MG-IIIa's for many years, and never being able to integrate them into the room acoustics in anything other than a "head in a vise" configuration. This isn't a good starting place for a room that has to entertain 80-100 people doing critical listening while scattered about in it.
Chris
In a room the size that could entertain 80-100 people, you probably would want to control directivity down to ~100 Hz, so the baffle diameter would need to be increased to something like 72 inches/1.8m. It's probably better to use an infinite baffle arrangement with the loudspeaker front baffle being coincident with the front wall surface,
The problem with open baffle designs is "what do I do with the backwave?" which generally needs an incredible amount of diffusion on the front wall to break up the specular reflections, as well as at least 11 feet/3,4m of standoff distance from the front wall to get enough backwave arrival delay relative to the direct arrivals to be outside Haas integration period of the human hearing system (i.e., at least 20 ms,,,and that really isn't enough delay).
I'm not a fan of dipoles, having had a pair of Magnepan MG-IIIa's for many years, and never being able to integrate them into the room acoustics in anything other than a "head in a vise" configuration. This isn't a good starting place for a room that has to entertain 80-100 people doing critical listening while scattered about in it.
Chris
Ha, I forgot about infinite baffle in my list of possible configurations.
What about a hybrid solution? Imagine a long listening room where you put very large open baffles in the middle, like partial room division walls. So maybe the room is 24 meters long and 7 meters wide but is divided by two 2m wide floor to ceiling baffles with a 3m opening between them.
Not sure if the baffles should touch the sidewall or there needs to be a gap?
Quite a few listening bars have TAD 2404/Altec A5 type speakers. If you want to ride a speaker brand for advertising your venture, refurbish some Altecs. If on a budget, consider an Econowave. The diy MEHs discussed here and on other forums can easily energise a room with 100 people but need bass bins. Open baffles and omnis will struggle, I don’t think they work for a room with 100 people talking.
Could you break down why something like a big Altec can and open baffle cannot work well? And assume we are comparing to 3-way floor to ceiling open baffles with large heil AMT tweeters and multiple 21" bass drivers.
Hi Cask05,
I think you have mistake. Pattern of OB would be good down to DC, and it typically gets better the longer the wavelength as asymmetric construct of cone driver gets small compared to wavelength. However, SPL drops like a stone, which is related to baffle size. The dipole peak, usable bandwidth, comes down in frequency with baffle size.
Here ideal 1" driver in ideal 1" OB and pattern is ideal down to DC.
Hi ErikNils,
this seems nice option, but it's odds with "good stereo sound" which you said you'd like to provide for people, and it's due to following reason: you can't have toe-in if you want both sides symmetric like in the quote.
Imagine sitting off-center, like 90% off the people in the room would, and all you hear is the closest speaker because: you are closer to it's on-axis so SPL is higher than the other speaker which you are increasingly off-axis. Also, the close speaker is closer so direct sound comes earlier so it's louder for that reason as well, and ahead in time of course. Basically you'd localize most of the sound, all phantom images, to the closest speaker, so basically mono. Some sounds, fully panned to other side, would come through some. This might be fine though, but I think it's odds with your current ideas so I want to let you know 🙂 You can do what you want of course.
If you want to give stereo for the whole growd you really need three speakers, make the phantom center a real center. Phantom images collapse sooner or later to nearest speaker listener. Three speaker stereo could work with your OB middle of the room idea as well, no necessity to toe-in I think, real center keeps the image not collapsing to one speaker only.
If it must be two speaker stereo, then you should use time intensity trading for stereo perception in a bigger area in the room. Basically, with time intensity trading phantom images are more stable so that the image doesn't collapse to nearest speaker as soon as it does without toe-in. Time intensity trading works with ~high smooth DI speakers such as dipoles, or cardioidish, or just typical ¨big speakers, but not with ideal omnis as they do not reduce SPL toward off-axis which is requirement for time intensity trading to work.
Mono sounds perfectly nice and fine, in some respects better than stereo even. So, perhaps just do stereo as you like and accept the fact that not all seats get best stereo sounds but only those who are equidistant to both speakers as long as the sound is comfortable it's likely fine. Too loud, or noticeably distorting sound is your worst enemy, much worse than collapsed stereo, or mono, sound.
Key thing here is that remember to think how auditory system works. You cannot get best sound by engineering room and speakers, you must take account how auditory system works, how perception of stereo happens.
ps. you'll have to evaluate million ideas and choises with your project, as it progresses. I encourage you to look into trade-offs of any particular idea or choice. Every choice has trade-offs, so if you cannot think one it means you should perhaps study a bit in order to avoid bad trade-offs that do not align with your goal but prevent you achieving it. Point is, to get very good sound you must know what the trade-offs of every choice are, and be able to take only those that do not reduce performance of the system but aligns with it, aligns with your goals what you have in mind. Example: you likely want stereo sound for big audience and nice bass and are wondering whether good OB system would do it. Now traditionally OB bass is done with increasing baffle size, but if you do not think what trade-offs increased baffle size brings you could ruin your good stereo sound by introducing bad edge diffraction. This could be fine trade-off for single seat listening, but not for crowd. So, know your trade-offs and take those that align with your goal. Know your goal to be able to do this in the first place.
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There are a number of golden dimensions which I'll post later for rectangular rooms. These space the room modes 'evenly' ... and more importantly, the modes don't form a 'series'.
If you have a rectangular room, DON'T have opposite walls parallel. This is DEATH to the sound and you will end up putting so much damping on the walls to kill flutter echoes that the room will sound dead.
Just 2 degrees out of parallel is enough. You could have the walls zig zag slightly. The ceiling / floor is more difficult.
Have SOLID walls, floor & ceiling; brick, stone or concrete.
Best is open bookshelves with books. This gives a good blend of absorption & diffusion. There's a good reason why music rooms in grand houses were often the library
Thanks for your valuable contribution. I do think a 3 speaker open baffle configuration is something to look at.
I'll make three small test baffles with full range drivers next weekend to hear the effect of a center channel for myself.
You might also want to experiment with how the center channel signal is derived, there are multiple "algorithms" to do it. See this:
https://www.elias.altervista.org/html/3_speaker_matrix.html
Here some remarks https://www.elias.altervista.org/html/2_vs_3_stereo_high_freq.html
And search the forums as well, I think at least mark100 has experimented with this stuff quite recently.
https://www.elias.altervista.org/html/3_speaker_matrix.html
Here some remarks https://www.elias.altervista.org/html/2_vs_3_stereo_high_freq.html
And search the forums as well, I think at least mark100 has experimented with this stuff quite recently.
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Hmm I can’t give you a scientific reply:
- A floor to ceiling array of any kind, with different drivers, will need quite a bit of listening distance for the sound to come integrate. It did not sound like you had so much space.
- The open baffle system I once heard at a show had a soft sound, it would never have been able to energise a room with people talking. You are not designing a living room, your audience will not be audiophiles who will keep their mouths shut. A home system has to sound good, a PA system has to be able reach people. Your system needs to be a blend of both worlds. In my experience with open baffle and omnidirectional speakers, at audio shows, they did not have the sound pressure or whatever the metric is required for PA purposes. But Perry Marshall described his grander open baffle designs here on this forum as if they could possibly do the job, although it was in the living room context. The strength of open baffle is their holographic presentation, but is still really the strength needed in this context?
- MEHs and Altec-type speakers were designed for PA purposes, they have great presence and dynamics, and they have modest minimum listening distances and amplifier requirements.
- Is humidity an issue given Thailand’s climate? If yes, you’ll need to rely on drivers that are designed for such an environment, afaik that means PA drivers.