This is MrZ's department, but what do you mean by good acoustics? And what is the gypsum supposed to be good for?
If money weren't an issue, I would choose concrete in the walls to stop sound from escaping, as lightweight concrete is not ideal.
Do you want to control reverberation time?
Do you want to change the reverberation time frequency selectively?
Do you want to control reflections?
Do you want to prevent sound in or out of the room?
etc.
If money weren't an issue, I would choose concrete in the walls to stop sound from escaping, as lightweight concrete is not ideal.
Do you want to control reverberation time?
Do you want to change the reverberation time frequency selectively?
Do you want to control reflections?
Do you want to prevent sound in or out of the room?
etc.
Since I've invested some money in the ceiling (suspended ceiling and then Ecophon A), I thought I'd do a bit with the walls as well. Mostly for sound insulation but behind front speakers and the like, should acoustic adjustments be made?poiu said:
Of course, you should do things to the walls. Gypsum is sound-insulating but hardly a phenomenon when it comes to room acoustics unless you use perforated boards that function as Helmholtz absorbers.
Keep it simple. Draw an exact floor plan indicating the speakers (stereo and center) and the spot you plan to sit when alone. Ideally, in section too, if you plan to tilt the speakers downwards or upwards. We make it simple by drawing straight lines from the speaker's tweeter through the center of your listening position to the wall it first encounters, whether rear or side wall, doesn't matter. Here is the first reflection, which should be addressed. However, if it hits the wall at 30 degrees, it leaves at 120 degrees. And bounces further. You should primarily aim to minimize reflections that reach the listening position within 10 milliseconds or so. I'm not sure if I remember that correctly... Address these reflections first. The treble usually reflects because people choose to have a coffee table in the way, which is a nightmare but a practical choice...
But make drawings and see what happens at the 1st, 2nd, 3rd, 4th, and 5th reflections. You don't want them entering the listening position, as mentioned... Treble is simply redirected as it behaves like light, one might say...
However, the midrange is a bit more challenging as it requires "thicker" absorbers... The thickness of the absorber should be 1/4 of the wavelength it should be most effective against... Check, for example, where you have the biggest problem with room dimensions... Where harmonics meet, etc. You should make an intervention there, and so on...
However, I would say that you should spend exactly as much money on room acoustic measures as you have on speakers and amplifiers...
A poor room makes a good system terrible, but a good room can't make a terrible system good... But better... Dimensioning is important, and you've already done that, as we've established earlier...
Now I'm not exactly sure what I've written and what is actually relevant... I'll blame it on having Friday coma
But specify more
Keep it simple. Draw an exact floor plan indicating the speakers (stereo and center) and the spot you plan to sit when alone. Ideally, in section too, if you plan to tilt the speakers downwards or upwards. We make it simple by drawing straight lines from the speaker's tweeter through the center of your listening position to the wall it first encounters, whether rear or side wall, doesn't matter. Here is the first reflection, which should be addressed. However, if it hits the wall at 30 degrees, it leaves at 120 degrees. And bounces further. You should primarily aim to minimize reflections that reach the listening position within 10 milliseconds or so. I'm not sure if I remember that correctly... Address these reflections first. The treble usually reflects because people choose to have a coffee table in the way, which is a nightmare but a practical choice...
But make drawings and see what happens at the 1st, 2nd, 3rd, 4th, and 5th reflections. You don't want them entering the listening position, as mentioned... Treble is simply redirected as it behaves like light, one might say...
However, the midrange is a bit more challenging as it requires "thicker" absorbers... The thickness of the absorber should be 1/4 of the wavelength it should be most effective against... Check, for example, where you have the biggest problem with room dimensions... Where harmonics meet, etc. You should make an intervention there, and so on...
However, I would say that you should spend exactly as much money on room acoustic measures as you have on speakers and amplifiers...
A poor room makes a good system terrible, but a good room can't make a terrible system good... But better... Dimensioning is important, and you've already done that, as we've established earlier...
Now I'm not exactly sure what I've written and what is actually relevant... I'll blame it on having Friday coma
But specify more
;D Thank you so much.mr Z said:Of course, you should do something about the walls. The gypsum is sound-insulating but hardly anything phenomenal when it comes to room acoustics unless you use perforated panels that work as Helmholtz absorbers.
Make it simple. Draw an exact floor plan over the speakers (stereo and center) and where you intend to sit when you're alone. And preferably in section too if you plan to angle the speakers downwards or upwards. We keep it simple and draw straight lines from the speaker's tweeter through the center of your listening position to the wall it meets first, back or sidewall doesn't matter. This is the first reflection, and it should be addressed. But if it hits the wall at 30 degrees, it exits at 120 degrees. And it continues to bounce. You should primarily ensure that reflections that enter the listening position within 10 milliseconds are minimized. Not sure if I remember that correctly. Address these reflections first. The tweeter usually gets reflected because people choose to have a coffee table in the way, which is a nightmare but a practical choice...
But make drawings and see what happens at the 1st, 2nd, 3rd, 4th, and 5th reflection. You don't want them entering the listening position as mentioned...
Tweeter sounds are easy to deflect since they behave like light, you could say...
However, midrange is a bit harder as it requires "thicker" absorbers. The absorber's thickness should be 1/4 of the wavelength it should be most effective against... Check where you have the biggest problem with room dimensions... Where do overtones meet, etc. That's where you should make an intervention, and so on...
However, I would argue that you should spend exactly as much money on room acoustic measures as you have on speakers and amplifiers...
A lousy room makes a good system terrible, but a good room can't make a terrible system good... However, it can make it better...
Dimensioning is important, and you've already done that as we've previously established...
Now I'm not exactly sure what I've written or what's really relevant... I'll blame it on Friday coma
But specify more
Let's start with the gypsum boards, do they do any good, or should I just plaster the walls as I initially intended? Perhaps it's not suitable to mount gypsum directly against a basement wall?
Then I'm running electrical and speaker cables now (well, at least when I'm not working on the facade...) so my dilemma is that I need to get the speakers in the right listening position, how high should the surround speakers be, and where? I have 2 Plackpearls that should be at the back since they're large and 2 others that should be on the left and right walls.
A drawing of how it should look is available here...
http://www.minhembio.com/Knystahall
Polish the walls.
I'm not particularly good at this, so I'm asking:
Do you want a listening room that colors the listening experience, or do you want a "dead" room when it comes to a surround system?
It makes a big difference depending on what you put on the walls.
If you build a dead room, the first reflection issue is solved right away.
Then I'm a bit curious about what Mr. Z means by the first reflection.
What I've learned is that it's reflections that occur after 10 ms? that are disturbing if they are strong in relation to the "first wavefront".
Then you can experiment as much as you want.
Different types of hollow bricks, with or without an absorber behind them.
Prisms on the walls (diffuser).
Selective absorbers, such as Helmholtz without damping.
Regarding absorbers, you can tweak a bit (if you build them yourself); most damping occurs on the surfaces and almost none at the wall.
Therefore, you can place them at an angle in the ceiling corner or hang them as free-hanging panels where they are less in the way.
(This naturally only applies to the overall reverberation time, not for specific reflections, but in that case, a reflector/diffuser could be an alternative)
I'm not particularly good at this, so I'm asking:
Do you want a listening room that colors the listening experience, or do you want a "dead" room when it comes to a surround system?
It makes a big difference depending on what you put on the walls.
If you build a dead room, the first reflection issue is solved right away.
Then I'm a bit curious about what Mr. Z means by the first reflection.
What I've learned is that it's reflections that occur after 10 ms? that are disturbing if they are strong in relation to the "first wavefront".
Then you can experiment as much as you want.
Different types of hollow bricks, with or without an absorber behind them.
Prisms on the walls (diffuser).
Selective absorbers, such as Helmholtz without damping.
Regarding absorbers, you can tweak a bit (if you build them yourself); most damping occurs on the surfaces and almost none at the wall.
Therefore, you can place them at an angle in the ceiling corner or hang them as free-hanging panels where they are less in the way.
(This naturally only applies to the overall reverberation time, not for specific reflections, but in that case, a reflector/diffuser could be an alternative)
Of course, strong late reflections should be removed. But what I mean is that strong early reflections are perceived as the same signal by the ear, which is a distorted signal like a phaser, which is not very fun unless you like psychedelics
By first reflection, I mean where the sound is reflected for the first time. In a home studio, this is usually on the mixer or table you sit at, which can be solved with a piece of fabric.. in a home theater system, it's the damn coffee table... However, I mean the reflection that is easiest to handle. The one that is first reflected by a wall.. However, one should probably not dampen it too hard to end up with a dead room.. You want some controlled reverberation; otherwise, the sound becomes too dry. It can be moistened up with effects that are often found on some receivers, but these are more or less useless, I would say...
A dead room is also not fun to have since the surround speakers should have minimal directionality but create diffuse sound fields from their position. Therefore, the surround should preferably be aimed at the wall with a diffuser behind it. That's what I've heard, whether it's correct, I don't know, there are probably a thousand theories here... However, I would argue that this is the right conclusion... You can build your room according to the LEDE principle (LiveEndDeadEnd), but I don't know if it's so good in a surround system. Studios are usually built this way, where you deaden the front half and open up the rear with diffusers. Sure, it's clever to kill reflections behind the front speakers, but you don't want to kill it as markedly as in a studio where you don't want the entire room acoustics. The room should color the sound but not destroy it.
However, the biggest culprit is usually the subwoofer, as people tend to like bass for some reason. Now, I'm not an expert on the placement of subwoofers, but corners are a classic if you want to create a large bass effect... However, the bass usually becomes the biggest problem in smaller rooms as it doesn't quite fit. The ceiling height often sets the worst limit. So personally, I would probably use heavy curtains on rails around the entire room in two layers to have the ability to easily influence room acoustics without permanent measures... And possibly 2 tube traps in corners, maybe 4 depending on how booming the bass is... Because no matter how much theory you recite, it's ultimately the listener's experience that is number one... And I definitely don't live as I preach
By first reflection, I mean where the sound is reflected for the first time. In a home studio, this is usually on the mixer or table you sit at, which can be solved with a piece of fabric.. in a home theater system, it's the damn coffee table... However, I mean the reflection that is easiest to handle. The one that is first reflected by a wall.. However, one should probably not dampen it too hard to end up with a dead room.. You want some controlled reverberation; otherwise, the sound becomes too dry. It can be moistened up with effects that are often found on some receivers, but these are more or less useless, I would say...
A dead room is also not fun to have since the surround speakers should have minimal directionality but create diffuse sound fields from their position. Therefore, the surround should preferably be aimed at the wall with a diffuser behind it. That's what I've heard, whether it's correct, I don't know, there are probably a thousand theories here... However, I would argue that this is the right conclusion... You can build your room according to the LEDE principle (LiveEndDeadEnd), but I don't know if it's so good in a surround system. Studios are usually built this way, where you deaden the front half and open up the rear with diffusers. Sure, it's clever to kill reflections behind the front speakers, but you don't want to kill it as markedly as in a studio where you don't want the entire room acoustics. The room should color the sound but not destroy it.
However, the biggest culprit is usually the subwoofer, as people tend to like bass for some reason. Now, I'm not an expert on the placement of subwoofers, but corners are a classic if you want to create a large bass effect... However, the bass usually becomes the biggest problem in smaller rooms as it doesn't quite fit. The ceiling height often sets the worst limit. So personally, I would probably use heavy curtains on rails around the entire room in two layers to have the ability to easily influence room acoustics without permanent measures... And possibly 2 tube traps in corners, maybe 4 depending on how booming the bass is... Because no matter how much theory you recite, it's ultimately the listener's experience that is number one... And I definitely don't live as I preach
In Hififorum, you can surely find a lot of information about acoustic treatments.
http://www.hififorum.nu
I would probably first just build the room and primarily consider the possible need for sound damping from the room out to the rest of the house. I would see to it that framed walls are reduced in "box sound" by, for example, using double gypsum.
Then I would test out different acoustic treatments once the system and seating are in place. Then I think you can already plan for the need for diffusers/absorbers in the places where you get first reflections. These places are the spots on the floor, ceiling, and walls where you see the speakers if you place a mirror there. First reflections are disturbing because they are the strongest.
Diffusers are probably easiest; a bit of everything can be used, like egg cartons and such. A bookshelf where the books aren't perfectly lined up works well too, and IKEA's wooden blinds/shades. I have thought about making a wooden box, about 15 cm high, with glass wool cut into studs, lighting, and then a beautiful fabric on each sidewall. It becomes both a lighting ceiling, absorber, and decoration at the same time. On the floor, a carpet usually works wonders. In the ceiling, some kind of perforated suspended ceiling with insulation behind it would probably be the nicest, and it might be best to build that from the start.
These were some _thoughts_ from me, for I am hardly any acoustics expert, just because I've built some speakers myself.
http://www.hififorum.nu
I would probably first just build the room and primarily consider the possible need for sound damping from the room out to the rest of the house. I would see to it that framed walls are reduced in "box sound" by, for example, using double gypsum.
Then I would test out different acoustic treatments once the system and seating are in place. Then I think you can already plan for the need for diffusers/absorbers in the places where you get first reflections. These places are the spots on the floor, ceiling, and walls where you see the speakers if you place a mirror there. First reflections are disturbing because they are the strongest.
Diffusers are probably easiest; a bit of everything can be used, like egg cartons and such. A bookshelf where the books aren't perfectly lined up works well too, and IKEA's wooden blinds/shades. I have thought about making a wooden box, about 15 cm high, with glass wool cut into studs, lighting, and then a beautiful fabric on each sidewall. It becomes both a lighting ceiling, absorber, and decoration at the same time. On the floor, a carpet usually works wonders. In the ceiling, some kind of perforated suspended ceiling with insulation behind it would probably be the nicest, and it might be best to build that from the start.
These were some _thoughts_ from me, for I am hardly any acoustics expert, just because I've built some speakers myself.
Now I think I'm with you.
It's more likely filter effects/interference between the signals we're talking about.
(Otherwise, you usually talk about the first wavefront and that it doesn't matter if a new even stronger signal comes within 10 ms? It is perceived as the same as the first. Used with, for example, speaker systems outdoors.)
It really is important to put a diffuser on the wall if you direct it towards the wall. Even with the speaker directed towards the room, you risk comb filter effects.
I don't believe at all in replacing reverberation with "echo effects", not in a listening room.
Placement of ordinary speakers towards the wall is usually not recommended if I remember correctly.
Apparently, there is a significant risk of filter effects because nulls and nodes become very pronounced with that placement.
The subwoofer might work with wavelengths so its dimensions don't create that problem, I wouldn't know.
Shouldn't you take care of the room's bass modes from the beginning?
Higher up in frequency, most things become statistically distributed, and you don't have to worry as much about standing waves.
Tube traps, I assume, are Helmholtz resonators, but are they tuned for each room?
It's more likely filter effects/interference between the signals we're talking about.
(Otherwise, you usually talk about the first wavefront and that it doesn't matter if a new even stronger signal comes within 10 ms? It is perceived as the same as the first. Used with, for example, speaker systems outdoors.)
It really is important to put a diffuser on the wall if you direct it towards the wall. Even with the speaker directed towards the room, you risk comb filter effects.
I don't believe at all in replacing reverberation with "echo effects", not in a listening room.
Placement of ordinary speakers towards the wall is usually not recommended if I remember correctly.
Apparently, there is a significant risk of filter effects because nulls and nodes become very pronounced with that placement.
The subwoofer might work with wavelengths so its dimensions don't create that problem, I wouldn't know.
Shouldn't you take care of the room's bass modes from the beginning?
Higher up in frequency, most things become statistically distributed, and you don't have to worry as much about standing waves.
Tube traps, I assume, are Helmholtz resonators, but are they tuned for each room?
He he now we're moving up a notch
You should try to address the base modes already in the design stage, but this requires some angles and stuff, which unfortunately you don't have room for in 99 cases out of 100, I would say.
Speakers against the wall are sometimes a necessity as there are a few that require just that. However, this is quite uninteresting if you haven't acquired such a pair
The subwoofer becomes more noticeable when placed in a corner or if it's too close to a wall. I believe it should ideally be 1.5 m from the wall, but this depends on the size of the box, the elements, etc. You could probably calculate it if you have too much free time.
Tube traps are Helmholtz resonators, but they don't need to be tuned, although it doesn't hurt if they are. You can relatively easily get the resonance frequency in the room and calculate nodes and the whole package. I seem to remember seeing a small Excel sheet for this. It's reasonably simplified but probably precise enough that an "ordinary" listener won't get annoyed by it. Personally, I would use my ears until I was satisfied, but of course, first, you would likely do a little math exercise to have some theory to rely on and something to start from...
Then, I remember there is an exact program for measurements where you input a model file and then enter speaker coordinates and other data for the speakers, and you get a nice overview drawing of nodes, reflections, and the whole kit... However, I believe you also need to calibrate this with test signals in the room as well....
If you are a hardcore audiophile on the verge of being perverse... But as Uncle Barbro said, "There are no shortcuts to perfect sound."
You should try to address the base modes already in the design stage, but this requires some angles and stuff, which unfortunately you don't have room for in 99 cases out of 100, I would say.
Speakers against the wall are sometimes a necessity as there are a few that require just that. However, this is quite uninteresting if you haven't acquired such a pair
The subwoofer becomes more noticeable when placed in a corner or if it's too close to a wall. I believe it should ideally be 1.5 m from the wall, but this depends on the size of the box, the elements, etc. You could probably calculate it if you have too much free time.
Tube traps are Helmholtz resonators, but they don't need to be tuned, although it doesn't hurt if they are. You can relatively easily get the resonance frequency in the room and calculate nodes and the whole package. I seem to remember seeing a small Excel sheet for this. It's reasonably simplified but probably precise enough that an "ordinary" listener won't get annoyed by it. Personally, I would use my ears until I was satisfied, but of course, first, you would likely do a little math exercise to have some theory to rely on and something to start from...
Then, I remember there is an exact program for measurements where you input a model file and then enter speaker coordinates and other data for the speakers, and you get a nice overview drawing of nodes, reflections, and the whole kit... However, I believe you also need to calibrate this with test signals in the room as well....
If you are a hardcore audiophile on the verge of being perverse... But as Uncle Barbro said, "There are no shortcuts to perfect sound."
Ok but where should the speakers be placed, the center above or below the screen? The fronts right next to the screen? Surrounds 2 on each side? 2 in the back each? And the subwoofer 1.5 m from the wall, you said hmm, that might be a problem? As I said, I'm going to run all the cables now and it would be good if everything had a placement so I don't have to move it later = since I'm running pipes in the walls :-/
The center and stereo pair should ideally be at the same height, that's the first requirement. Then, from the primary listening position, the distance to the center between the stereo pair should be the same as between the stereo pair's tweeters. That is, if you have 4 meters between the tweeters on your front stereo speakers, you should imagine a straight line between them. Exactly centered between them, it should then be 4 meters to your listening position.Draven said:
I'm less sure about the placement of the surround speakers since I'm not directly knowledgeable about surround placement, but the rear speakers should create diffuse sound and don't really cause much trouble as the fronts handle 90% of the sound, so I can imagine that it's quite open really. But I could be horribly wrong...
If you have good level control on the sub, you can place it in a corner, but be prepared to keep it much lower in volume... Because you'll likely get a pretty strong response from it... But everything can be solved... right...
If you have a "square" room, i.e., all walls and ceiling and floor parallel to opposing surfaces, you will obtain a frequency response that is uneven in the lower frequency ranges.
Between the flat surfaces, standing waves will form with a frequency that is 1/2 the wavelength of the distance between the walls. + multiples of this frequency, but it's the fundamental frequency that causes the most issues.
The result can be a very "boomy" and imprecise bass.
The (theoretically) ideal situation is to let two walls and the ceiling be slightly slanted.
Another problem is the one mrZ has mentioned quite a bit, speakers placed by a wall or in a corner receive strong reinforcement in the lower registers, sometimes desirable, sometimes not. If I remember the theory correctly, wavelengths up to the driver diameter are reproduced without room reinforcement, and lower frequencies than that are amplified/weakened by surrounding walls and the like. (A bit simplified)
But I actually have no practical experience with this myself; it's mostly acquired knowledge, so I recommend, among others, the following threads in another forum:
http://www.hififorum.nu/forum/topic.asp?TOPIC_ID=12431
http://www.hififorum.nu/forum/topic.asp?TOPIC_ID=54652
There you can read quite a bit about acoustics and the room.
//ML
Between the flat surfaces, standing waves will form with a frequency that is 1/2 the wavelength of the distance between the walls. + multiples of this frequency, but it's the fundamental frequency that causes the most issues.
The result can be a very "boomy" and imprecise bass.
The (theoretically) ideal situation is to let two walls and the ceiling be slightly slanted.
Another problem is the one mrZ has mentioned quite a bit, speakers placed by a wall or in a corner receive strong reinforcement in the lower registers, sometimes desirable, sometimes not. If I remember the theory correctly, wavelengths up to the driver diameter are reproduced without room reinforcement, and lower frequencies than that are amplified/weakened by surrounding walls and the like. (A bit simplified)
But I actually have no practical experience with this myself; it's mostly acquired knowledge, so I recommend, among others, the following threads in another forum:
http://www.hififorum.nu/forum/topic.asp?TOPIC_ID=12431
http://www.hififorum.nu/forum/topic.asp?TOPIC_ID=54652
There you can read quite a bit about acoustics and the room.
//ML
How big things are you planning, Draven?
There is a huge difference between subwoofers like a drink crate and bass boxes like a shoebox, compared to subwoofers like an oil tank and bass boxes like an oil drum.
The former mentioned ones tend to handle more midrange than bass.
If you have the latter things, you need to fix the acoustics in the bass range, maybe you even need to use electrical band-stop filters to not output too much in certain modes.
But now it's starting to become a bit "state of the art".
There is a huge difference between subwoofers like a drink crate and bass boxes like a shoebox, compared to subwoofers like an oil tank and bass boxes like an oil drum.
The former mentioned ones tend to handle more midrange than bass.
If you have the latter things, you need to fix the acoustics in the bass range, maybe you even need to use electrical band-stop filters to not output too much in certain modes.
But now it's starting to become a bit "state of the art".
Well, I was thinking of keeping what I have depending on how it sounds in the new home theater room :-/poiu said:How big are the things you've planned, Draven?
There's a huge difference between a subwoofer like a crate of drinks and speaker boxes like a shoebox, or a subwoofer like an oil tank and speaker boxes like an oil drum.
The first ones mentioned handle more midrange than bass.
If you have the latter, you must fix the acoustics in the bass range, and you might even need to use electronic band-pass filters to avoid outputting too much in certain modes.
But now it's starting to become a bit "state of the art."
Amplifier HK avr-430
The entire Blackdiamond series from audiopro (2 fronts, 1 center, 2 surrounds)
Then two low-budget Sony surrounds to get the 7.1 sound
Then a 12" Proson subwoofer. Possibly adding 1 more subwoofer... maybe?
So no oil tanks, I think...