Speaker Placement and boundary problems

[prerich]

80skid and Lil' Louie made some good comments in another thread and I just wanted to bring it to full discussion here. The affect of boundaries and speaker placement. If it were a perfect world we would have no obstructions to our HT's - but seeing that most of our HT room's function as something else also (living room, den, ect...) or the room itself is the limitation, speaker placement becomes very critical.

I have seen speakers placed in corners (some belong there like K-Horns and Audio Note Sogons), but others actually need room to function properly like ML CLS, Mini monitors and the like. I see a lot of speakers that are set up like the BB and CC show rooms - however, they didn't take placement into consideration - they're trying to sell a box.

JJ has an excellent system with room treatments, but when I looked at his placement of his acoustic tiles - like another member, I began to question his placement. The mirror technique works (for the seated position or sweet spot - you need two people to do this, sit in the sweet spot and have another person hold a mirror an walk down the side walls - where the speakers come into view - you need a room treatment there). Bass also loads up in the corners so absorbant material is need there.

For imaging - speakers should be properly spaced apart (from each other and the front and side walls). Then if you use SDA speakers or Carver Sonic Holography a entire new realm of logistics comes into play.

The question I'm getting at is where does the trade off begin? We want our systems to sound the best - but the best stereo image would to theoretically place a wall down the center of your room to the listening point about a foot from your nose - one speaker on each side of the wall - no one is going to do that ! However we will go to some extremes to get the best sound. My setup is kinda ugly - but it sounds right (right is a subjective term by the way - the original performance is the represention of truth or right - if the original was bad - it should sound bad - think about that one for a minute). To what lenghts to we go with speaker placement? Do you use a measuring tape (I do) where do you measure from - center of the driver, outside edge of the cabinate ect..? Or do you just plop the speakers down, line them up and say I've got surround sound now. Or even worse - put the left and right speakers on the same side the center under the tv and the left and right surrounds next to each other (don't laugh I've seen this before) and proclaim you have "round sound". I think that with the combined knowlege here - we can start a serious discussion about speaker placement and boundaries (to include walls, sofas, furnishing - there effect on EQ's like the YPAO and Audussey - because they do)

OK its on, Chime in and start yappin'

[Beta Man]

I'm planning on having my local shop come out and provide a diagram of my room with an accoustical analysis.......


Also, I need bass traps and other accoustical panels still.... I want to get the "building blocks" in place before I have them do a detailed analysis



Anyone use the foam plugs for their ports? (I don't, just curious though)

[prerich]

Originally Posted by Beta Man

I'm planning on having my local shop come out and provide a diagram of my room with an accoustical analysis.......


Also, I need bass traps and other accoustical panels still.... I want to get the "building blocks" in place before I have them do a detailed analysis



Anyone use the foam plugs for their ports? (I don't, just curious though)

When you get ready to by you panels - go to Ebay - you can find studios selling this stuff cheap! Or if you want to you can make your own. I'm going to drape my entire back wall. I remember when people used to use the Golden Flute filter mod on B&W 800 series speakers - the tweeking days

None of my front speakers are ported (except for my 2 subs and they are designed that way) so I don't use the speaker plugs

[Sir Terrence]

When it comes to acoustics with most, its all just guess work. When it comes to speaker placement, its all just guess work. Consider this, how many folks have actually used a RTA and signal generator to tune their system, or judge where is a good place to put a speaker. NOBODY!!

Let's face it, I have used and tested just about every self calibrating and EQ system out there, and unless you pre-treat the room, the results are all over the place. But that is where most folks are, they just let the receiver do the work, and are satisfied with the results.

As far as boundary issues, I have seen speakers in corners, within inches of the front wall or side wall, with absolutely no acoustical control whatsoever. I know what this sounds like, because I have had to reset many a speaker position in my day. People just place their speakers without much thought(I saw somebody elses speakers placed this) and just get used to the way it sounds.

[prerich]

Originally Posted by Sir Terrence

When it comes to acoustics with most, its all just guess work. When it comes to speaker placement, its all just guess work. Consider this, how many folks have actually used a RTA and signal generator to tune their system, or judge where is a good place to put a speaker. NOBODY!!

Let's face it, I have used and tested just about every self calibrating and EQ system out there, and unless you pre-treat the room, the results are all over the place. But that is where most folks are, they just let the receiver do the work, and are satisfied with the results.

As far as boundary issues, I have seen speakers in corners, within inches of the front wall or side wall, with absolutely no acoustical control whatsoever. I know what this sounds like, because I have had to reset many a speaker position in my day. People just place their speakers without much thought(I saw somebody elses speakers placed this) and just get used to the way it sounds.

Whoaaaa!!!!! Excellent points - I have only used RTA'S (a real one not the one built into some outboard eq's) in specially built rooms. Basically buying an RTA is the only real way to get a room "right" and I believe (correct me if I'm wrong) you want the room as close to acoustically neutral or flat as possible. I've listened to affects of onboard receiver calibration - some are decent - some are bad - some disgusting! It also varies from speaker to speaker. You are right - its all really guess work without the proper equipment. But, can we educate ourselves to make better judgements?

Getting used to bad sound is horrible. I know people who have gotten used to bad sound. But when re-exposed to excellent sound - they want to duplicate it - but they don't want to take the time and effort to do it. I direct a local choir and I had a Pastor inform me that his choir wanted to sound as good as ours - He replied and told his director - "Do you think you're going to come in here - practice for 30 minutes and sound like that? You need to put the time and effort in before you do that". I was astonished, but the same applies here. If we would take more time and effort - we could achieve more out of our given systems - regardless of our budget.

I'm not a Bose fan - but I will give them this - They make sure their speakers are presented in the best light possible - they ensure that the acoustic conditions favors their speakers - so that the will sound the best. They are not accurate - the Acoustimass has documented flaws - but some how some way through trickery and magic (naw I'm just joking here) they make their speakers sound appealing. What did they do? They made sure that the acoustics of the room and its boundaries favored their speakers. Now if an overpriced speaker can do this - what can a well built speaker do in comparison? The room, speaker box, are sound producers and manipulators themselves - along with its boundaries. What steps are we willing to make - to ensure that the room works for us instead of against us?

The first DSP modes that I heard and actually liked were from a Yamaha DSP-1 , my living room was very dead, the affects sound very good, but you could control alot of variables with the DSP-1 (Center frequency, bandwidth, ect...I thought I was using crypto gear). I've heard other receivers in live rooms and the effects were awful!!!! The next time I was impressed by DSP modes was the Fosgate Model 3A - was iti the effects, or was it the way the room presented the effects? Totally carpeted room (to include the walls) - as dead as you could get a room. This was the total Fosgate system in this room (which I sold )!!! I have never heard multi channel music sound so good!!! It was crazy! I was convinced - bought a model 5 myself and didn't quite get the same affect. Move up to a 4 and still - lacking, then I moved up to the 3A and guess what....still lacking. My wife bought new furniture (big and plush) with heavy pillows and such - moved her glass nic-naks to another room and then it happened - sonic heaven with DSP modes. I realized that it was the room as well as the processor. Then I tweeked speaker placement - It was wonderful ! Then I found out that 2 channel music without DSP sounds even better - when set up right, my tinkering helped me discover 2 channel stereo and what it should really sound like. (I later went to work for an A/V salon - no sales experience, but the boss saw my passion - that passion sold a lot of gear )!

We may not have access to RTA's and pink/white noise generators, nor have the money for a professional to give us a diag., but can we educate ourselves and use the limited tools (albeit guess work) to get it more..."right"?

[RUR]

Originally Posted by prerich

.....The mirror technique works (for the seated position or sweet spot - you need two people to do this, sit in the sweet spot and have another person hold a mirror an walk down the side walls - where the speakers come into view - you need a room treatment there).

Or you can do it solo, using a little basic geometry:

The side wall panels will go slightly forward of the halfway point, and the exact distance is determined using the formula shown below. The panels are centered vertically on the tweeter height, which should be ear height as well.

Looking at Figure 4, this simple formula shows how to find the reflection point based on the distances from the side wall to the tweeter, and from the side wall to the listener.

etc., including diagram: http://www.realtraps.com/art_room-setup.htm
Indeed, there's plenty of good room optimization info on that page.

Originally Posted by prerich

When you get ready to by you panels - go to Ebay - you can find studios selling this stuff cheap! Or if you want to you can make your own. I'm going to drape my entire back wall......

Hopefully, the stuff on eBay comes with published absorbtion data, so that you know what you're getting! Before treating your back wall with absorbtion, have you treated for corner bass absorbtion and first reflection points? Rooms can be too flat and you may find that diffractive treatment works best on the back wall. Everyone's system/room are unique, of course.

Originally Posted by Sir Terrence

When it comes to acoustics with most, its all just guess work. When it comes to speaker placement, its all just guess work. Consider this, how many folks have actually used a RTA and signal generator to tune their system, or judge where is a good place to put a speaker. NOBODY!!..........

All of which argues for education if folks are to get the most out of their systems. Will most settle due to lack of interest or aesthetics or ??? Probably, but there's always a few who'll take the plunge.

[prerich]

Originally Posted by RUR

Or you can do it solo, using a little basic geometry:

etc., including diagram: http://www.realtraps.com/art_room-setup.htm
Indeed, there's plenty of good room optimization info on that page.


Hopefully, the stuff on eBay comes with published absorbtion data, so that you know what you're getting! Before treating your back wall with absorbtion, have you treated for corner bass absorbtion and first reflection points? Rooms can be too flat and you may find that diffractive treatment works best on the back wall. Everyone's system/room are unique, of course.


All of which argues for education if folks are to get the most out of their systems. Will most settle due to lack of interest or aesthetics or ??? Probably, but there's always a few who'll take the plunge.

Excellent info "R"!!!! Yes some of the stuff (not all of it) comes with the absorbtion info. I will consider the diffractive treatment also - this is what I'm talking about - education. I love to learn

[Yeha-Noha]

Our main activity room which is pretty much the way the wife want's it to be, meaning forget pre-treatment, is very unlikely to get ideal sound, right? All I can do is get the best possible sound. For me then my Energy speakers which have rear ports should be away from room boundaries, correct? The speaker manuals say don't put them directly against the wall. I have them two feet from the front wall and the 2 surround rears are one foot from the rear wall. The two surround side speakers are about one foot from the side walls. All the surrounds on their stands are about 4 ft off the floor. The ceiling maxes out at 16 ft starting from 9 ft (cathedral ceiling). The front L/R Energy speakers sit on 3 foot high speaker stands. The center speaker is under the HDTV and about 2.5 off the floor. There is no adjacent wall on the left or right side of the front speakers because there are rooms, off to the left is a parlor, like a small living room but with no A/V media, and to the right is the main dining room.

I have a Yamaha receiver. So, is YPAO useless in such a room or should I use it an hope for the best?

[prerich]

Originally Posted by rwojtalewicz

Our main activity room which is pretty much the way the wife want's it to be, meaning forget pre-treatment, is very unlikely to get ideal sound, right? All I can do is get the best possible sound. For me then my Energy speakers which have rear ports should be away from room boundaries, correct? The speaker manuals say don't put them directly against the wall. I have them two feet from the front wall and the 2 surround rears are one foot from the rear wall. The two surround side speakers are about one foot from the side walls. All the surrounds on their stands are about 4 ft off the floor. The ceiling maxes out at 16 ft starting from 9 ft (cathedral ceiling). The front L/R Energy speakers sit on 3 foot high speaker stands. The center speaker is under the HDTV and about 2.5 off the floor. There is no adjacent wall on the left or right side of the front speakers because there are rooms, off to the left is a parlor, like a small living room but with no A/V media, and to the right is the main dining room.

I have a Yamaha receiver. So, is YPAO useless in such a room or should I use it an hope for the best?

With your present position - you sound like you've made the right desicions based on your speakers literature. You can try the YPAO and tweek it from there. The real tattle-tale on your front speakers (l/r) would be to listen to them in pure direct mode. It can tell (based on your taste) what you may want to do in your room. Just something to try - not very scientific but pure direct takes all processing out of the path - you will hear the signal form your source to your amp to your speakers. It can tell you alot.

[Yeha-Noha]

I haven't really listened to any of my BD movies in pure direct mode yet mainly because there's no video. Also pure direct sends all the 5.1 or 7.1 audio downmixed to the front L/R speakers. As I understand it, YPAO and all its settings are disabled. I will try different L/R front speaker placement if the wife doesn't object to where I put them.

[ambientcafe]

Originally Posted by Beta Man

I need bass traps and other accoustical panels still....

Excuse my ignorance, but I've heard of bass traps but am unsure of the theory and their utilization. I'm using 3 Velodyne subs (15", 12", & 10") across my front soundstage (1 in each corner & 1 in the center, coupled w/my center channel), and yet, I'm not happy w/the results. The amount of bass greatly diminishes from the subs location to my seated position, which is about 9 feet away. The original reason I went with multiple subs was for better coverage and not to overwhelm the audience. The dimensions of my room are W=14' / L=20' / H=8'. Would bass traps help in my case? Thanks for in advance for any input.

[Big Daddy]

Originally Posted by ambientcafe

Excuse my ignorance, but I've heard of bass traps but am unsure of the theory and their utilization. I'm using 3 Velodyne subs (15", 12", & 10") across my front soundstage (1 in each corner & 1 in the center, coupled w/my center channel), and yet, I'm not happy w/the results. The amount of bass greatly diminishes from the subs location to my seated position, which is about 9 feet away. The original reason I went with multiple subs was for better coverage and not to overwhelm the audience. The dimensions of my room are W=14' / L=20' / H=8'. Would bass traps help in my case? Thanks for in advance for any input.

Studies at National Research Council of Canada have concluded that an even number of identical subwoofers is the best alternative. To get better results from your subwoofers, read A Guide to Subwoofers , A Guide to Subwoofers (Part II): Standing Waves & Room Modes, and Acoustic Treatment Research Material.

EDIT: Part II of A Guide to Subwoofers should help you the most as far as subwoofer placement is concerned.

[ambientcafe]

Originally Posted by Big Daddy

Studies at National Research Council of Canada have concluded that an even number of identical subwoofers is the best alternative. To get better results from your subwoofers, read A Guide to Subwoofers , A Guide to Subwoofers (Part II): Standing Waves & Room Modes, and Acoustic Treatment Research Material.
EDIT: Part II of A Guide to Subwoofers should help you the most as far as subwoofer placement is concerned.

Many thanks BigDaddy....some very comprehensive articles of which I'll have to set aside some time to thoroughly digest. BTW, a perusal of your sig suggests that those fortunate enough to experience your A/V setup are usually in for a real treat....cheers

[STARKILLER--1138]

Originally Posted by ambientcafe

Excuse my ignorance, but I've heard of bass traps but am unsure of the theory and their utilization. I'm using 3 Velodyne subs (15", 12", & 10") across my front soundstage (1 in each corner & 1 in the center, coupled w/my center channel), and yet, I'm not happy w/the results. The amount of bass greatly diminishes from the subs location to my seated position, which is about 9 feet away. The original reason I went with multiple subs was for better coverage and not to overwhelm the audience. The dimensions of my room are W=14' / L=20' / H=8'. Would bass traps help in my case? Thanks for in advance for any input.

I've had great success with a 12", 10", and two 8" subs in my Lounge, but they were all stacked in the same corner. All were from the same manufacturer (DefTech) and decided to try it when I read that multiple subs, used in an HT, had to be the same size to see if that were true. In my room, it wasn't. The 12, 10, and two 8's worked perfectly. My best sub configuration was an M&K MX-350 w/ and MX-150 stacked on top of it. Anyway, I haven't tried an odd number of subs stacked in the same corner; but, give stacking in the same corner a shot.

BTW, thanks to prerich for starting the thread.

[ambientcafe]

Originally Posted by Lil' Louie

give stacking in the same corner a shot.

That thought had crossed my mind, but wouldn't the coverage be somewhat uneven? Depending on the side of the room one was seated, would they experience differing amounts of bass? Although having both the subs located in one corner might alleviate cancellations problems. In any event Lil' Louie, I may give the stacking concept a try -- thanx.

[STARKILLER--1138]

Originally Posted by ambientcafe

That thought had crossed my mind, but wouldn't the coverage be somewhat uneven? Depending on the side of the room one was seated, would they experience differing amounts of bass? Although having both the subs located in one corner might alleviate cancellations problems. In any event Lil' Louie, I may give the stacking concept a try -- thanx.

Well, even with just one sub, one can experience different amounts of bass from one end of the couch to the other. As for stacking subs, I was first turned on to this when I was at a seminar with Ken Kreisel (M&K). The company I worked for has used it in their own design center, and in many home applications. Not saying that it is going to be the end all solution for you; but, it wouldn't hurt to give it a shot. Definitely let us know your thoughts.

[Sir Terrence]

Originally Posted by Lil' Louie

I've had great success with a 12", 10", and two 8" subs in my Lounge, but they were all stacked in the same corner. All were from the same manufacturer (DefTech) and decided to try it when I read that multiple subs, used in an HT, had to be the same size to see if that were true. In my room, it wasn't. The 12, 10, and two 8's worked perfectly. My best sub configuration was an M&K MX-350 w/ and MX-150 stacked on top of it. Anyway, I haven't tried an odd number of subs stacked in the same corner; but, give stacking in the same corner a shot.

BTW, thanks to prerich for starting the thread.

Stacking two subs in one corner will only provide satisfactory results from one point in the room. A sub in each left/right corner will provide satisfactory results over the entire width of the room, but will have some problems with room length, especially along the back wall.

I would love to measure the distortion and frequency response of your stacked subs. I would have loved to measure your 12, 10, and two stacked 8's as well. I bet it sounded good to your ears, but it would measure very poorly over most of the room, with some areas getting a ton of bass, and others having it sucked out. You would be surprised how forgiving our ears are in the deep bass, and how measurements are not so forgiving.

[STARKILLER--1138]

Originally Posted by Sir Terrence

Stacking two subs in one corner will only provide satisfactory results from one point in the room. A sub in each left/right corner will provide satisfactory results over the entire width of the room, but will have some problems with room length, especially along the back wall.

I would love to measure the distortion and frequency response of your stacked subs. I would have loved to measure your 12, 10, and two stacked 8's as well. I bet it sounded good to your ears, but it would measure very poorly over most of the room, with some areas getting a ton of bass, and others having it sucked out. You would be surprised how forgiving our ears are in the deep bass, and how measurements are not so forgiving.

Anytime you are up in my area, let me know. I'd be more than happy to have you come and do some bass measurements. For me, having two subs stacked has me very pleased with the results from my listening area. I'm not going to say that this WILL work for anyone else, but it doesn't hurt to give it a shot. Have you tried it?

[midrange]

There is a lot to read here and probably a lot of detail but here is just an easy quick tip to always have perfect stereo sound to each ear.

The Distance you are from the TV/RECEIVER, that is the distance the speakers should be spread apart.in all corners.

The sub, bass freq. travels where ever it wants. That you just move around till you find whats best. I have always found the sub towards rear facing tv in corner or behind couch throuws the best bass sound that spreads the whole room. (also depends on the room)

[Sir Terrence]

Originally Posted by midrange

There is a lot to read here and probably a lot of detail but here is just an easy quick tip to always have perfect stereo sound to each ear.

The Distance you are from the TV/RECEIVER, that is the distance the speakers should be spread apart.in all corners.

The problem with this advice is folks sit further away from the television than the required sitting distance for 1080p. Most folks sit anywhere from 9-12 ft away from their television, and spreading the speakers 9-12ft apart will cause the sound field to develope holes between channels. And you NEVER want to place main speakers anywhere near corners if you like a balanced overall output. Corner placement for the mains increases the bass too much and destroys the overall balance of the speaker itself. If possible, speakers should be at least 4ft away from any walls to reduce speaker/wall interaction to the bass frequencies. The further they are away, the more improved imaging will be as well.

The sub, bass freq. travels where ever it wants. That you just move around till you find whats best. I have always found the sub towards rear facing tv in corner or behind couch throuws the best bass sound that spreads the whole room. (also depends on the room)

A BIG caveat with that last set of words.