Speaker placement formula?

[bleedink]

I asked this at another forum but got a cryptic answer that frankly went right over the three brain cells I have that work concurrently. I am trying to position a set of 5.0 speakers to get a 22 degree angle for the floor standing fronts (L and R) and get a proper arc with the center. I unfortunately didn't do that well in geometry. What I am wondering is if there is some kind of formula I might use to determine that exact placement? For example, lets say the fronts are 6 feet apart. Is there a formula that would determine the listening position from those details to get me a 22 degree angle from each speaker? Like say if x is 6 then y is __ and your speakers are at a 22-30 degree angle. I was told this formula (on the other site) is approx 1.18. However I am not sure what the reference is for this figure. Whether the listening position is 1.18 times the distance between the two speakers or the opposite. Boy I hope I explained this correctly. I am looking to make a triangle with the front speakers at 22 degree angles from my listening position without using a protractor and I was hoping there's some kind of mathematical formula I can use to figure that out. I have a feeling my fronts are spaced a bit far apart for this angle but I dont have a 7 foot protractor to help me out!

 

[Mark Powell]

Is the 22 degree angle so important to you?

 

[ted_b]

in this isosceles triangle (two equal sides, the distances from you to either speaker). So use 1.34 as your multiplier (1.34 times the distance between the center of the drivers, is the distance from you to each driver). If the speakers were at, say, 30 degrees, you'd be forming a perfect isosceles triangle and your distance from each speaker would be identical to the distance between them.

 

The ITU setup for 5.1 or 7.1 is, for the mains, 30 degrees....a bit more nearfield than your setup. Not a big deal, but yours makes it more difficult to keep the surrounds at the similar distances.

 

[bleedink]

Ted to the rescue! I knew there was a formula out there to do it I just had no idea what it was! I must have googled about 800 versions of the same question to no avail. So if we are talking say 7 feet btw the two drivers (L and R) I'd multiply 7 by 1.34 and add that to the original 7 to get my listening distance correct? Sorry to have to totally be hit over the head with this stuff! I just want to confirm I understood you correctly. If so I am actually not too far off!

 

 

As to what's so important about 22 degrees...my research and much searching on Quad forums and the like--most people seem to agree that 22 is the magic number for music surround and is an ok compromise for movies as well--though I am primarily concerned with music since film tends to me much more forgiving for various angles and such. Even most of my surround music it doesn't make much difference to be honest. But the few surround recordings I have that make extensive use of pans and the like are less forgiving if the speakers aren't spot on. Flaming Lips comes to mind. The closer I get to 22 from the approx 35 degree angle I started out with the more those same pans tend to sound more natural. My listening room is quite small for the size of the speakers so the small increments actually make a large difference.

 

Ted thanks so much! I think I'd still be googling if it weren't for you!

 

Ted-I know my rears are a bit off due to the size of the room. I'm trying to do my best with the fronts (ie use as little delay as I can-get the speakers at the closest distance relative to my receiver) as there's no way to get the rears equidistant without them being in another room. That said the distance isn't huge. The delays on the rears seem to be less of a problem than the proper placement of the fronts from my listening. At 22 degrees the rears are closer to where they should be in the set up.

 

[mitchco]

http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/4_Multichannel_Music_Mixing.pdf

 

 

[ted_b]

at 22 degrees? If your mains were, say, 30 you'd be closer to them, and thus making the distance to your surrounds (vs to your mains) less of an inequality. I'm confused.

 

[bleedink]

Im a bit confused myself, Ted. I would think that a 22 degree angle would place the speakers closer to the center right? Most diagrams I see put the surrounds out at nearly double the space. My thinking is the closer the angle with properly placed fronts (ie moving them as close to the center as possible before the sound suffers) automatically places my surrounds further apart, though my sweet spot isn't changing if that makes sense. Right now proper placement of the surrounds would put them outside my room. So I am using delays on the surrounds but trying to get the fronts as close as possible to 'correct'. These diagrams frankly are very confusing! As my listening position is fixed in this instance I was thinking it might be easy to plug in the numbers to a formula to get the desired results. I know I am getting really close to where I need to be because the pans I was referring to above have resolved themselves more clearly. Before there were some pans that were skewed incorrectly because of some mistake I'd previously made. I got some ok advice at QQ that got me close but it's not all that accurate as I am guessing the angle. Make any of this out?

 

[ted_b]

Draw or describe a picture of your room (very basic) and put squares where you want mains and surrounds, and a circle where you sit. Also, are you gonna use a center channel (important to note, cuz closer spaced mains could hurt a center, but benefit you if you have no center)? All i was trying to say is that if you sit closer to the fronts, you ipsofacto have them further apart than 22 degrees. And by sitting closer to your fronts means you have less of a dramatic delta of your front distance vs your surround distance....but this is only really an issue without good delay capabilities (as you've stated).

 

The other concern of yours is literally the spacing of the surrounds vs the fronts (i.e the distance the sound pans to get from front to rear). If you can only get your surrounds to say, 100 degrees, then having your mains at 30 degrees is only a 70 degree pan from front to rear.....I understand your tradeoffs. Let's look at them.

 

[bleedink]

Ha! You're probably right. I'll get the basics of the room and show you my spot ect. It will likely be much easier to understand. I'll put it up after some errands. No hurry. I won't be doing any moving until at least tomorrow. Thanks! It's one of those things that can drive you batty if it isn't perfect on unforgiving tracks. The delays work well when I place the speakers relative to the receivers limitations (1/2 ft increments). Be back later!

 

[bleedink]

Ted here is a copy of what my listening area is like. As you see it is SMALL. The futon and the rear surrounds are as far out as they can go. The listening position is basically going to be fixed as well. I can move the couch out a half foot. I am not concerned about the wall placement (I know they are too close but this near field it just doesn't impact the bass that much as I am not listening that loud given it's about 7.5-8.5 feet from center to listening position. Again about 5 foot for the rears.) I hope that helps.

 

PS I see obviously I am going to be using some kind of delays--like I said I am trying to get close as possible since my listening position and the rears really cannot be changed. I'm figuring I stand a good fighting chance of getting closer to correct if I get at least the fronts in proper order and use delays on the rears. That was the plan. I'm definitely open to suggestions and the like if you see something obvious that might help.

 

[ted_b]

more in line with ITU (i.e what the surround mixer intended), but would put you quite nearfield (good for removing the room effects) for 2 channel.

 

[mayhem13]

It AMAZES me that there even exists a formula for speaker placement as there's no way a formula can account for polar response and the accompanying nulls that are part of every speakers radiation pattern.....not to mention power response.

 

Place them wherever sounds best to you. If you need to be analytical in your approach, purchase a measuring rig so you can 'see' what's going on.

 

[ted_b]

have thought of that, Bleed.

 

[Mark Powell]

Why the 22 degrees is such a matter of life and death.

 

We have not been told....

 

[bleedink]

I didn't realize when Chris created this site that it was for those who own certain kind of gear. My apologies. It seemed to be a place where people could ask questions and not be attacked or belittled. Thank you gentlemen for your input and your elitist attitudes. Seriously did you guys have a bad day or something? If you're not adding anything to the discussion I assume you just want to troll. We get that. Thanks so much for your time.

 

Ted--Yeah I guess the first thing I should have done was buy a new receiver rather than set up my speakers correctly. Apparently you can put them anywhere unless you own a particular kind of receiver. Thanks again for that input!

If I move them up aren't I going to have to set up another delay for the center? Dolby site and a couple trade papers suggest anywhere from 22-30 degrees. The one suggestion for the front speakers that keeps coming up is to swing a piece of string or what not from the listening position to make sure the center and the fronts are in a circular arrangement, which I've done. Maybe I should concentrate on 30 degrees for the moment and if it's still too far apart I can probably come pretty close from that point? So if I go that way Ted the distance from me to the center is going to be the distance between the L and R right?

Ted thank you so much for answering my question without a hint of elitism, sarcasm, or anything that just doesn't have it's place here. Or perhaps I misunderstood the reasons for this site.

 

[ted_b]

and then only make concessions if it doesn't destroy the 2 channel soundstage. Applying a center delay (actually a delay everywhere else to make the center catch up) is no big deal in my priority list, but if you have a delay scheme (like the Oppos prior to July 11 firmware) that says the furthest speaker must be the mains then my idea is not useable, for the center won't be in spec.

 

[bleedink]

I have a delay scheme a la Oppo. LOL! Well hey at least I know how to get a 30 degree angle now!

 

[ted_b]

You can, indeed, now have a center that is further away from you than either l or r (same with surrounds).

 

[arjaytee]

is about 15.43363 feet (approximatley).

 

BUT like the previous answer I wonder why - my understanding is that the the "best " rsults come when the distance between the speakers is about 83% of the distance to the listener So for example if you are 10 feet from the speakers they should be 8.3 feet apart and at a listening distance of 15 feet from the speakers the speakers should be 12.45 feet apart i.e. about twice as far apart as you are suggesting.

 

This is not rock solid and some speakers work better slightly closer and some slightly further apart and there is also the factor of personal opinion or feelings in this but its a good place to start from.

 

[Mark Powell]

Bought at an even lower cost because it had been replaced by an 'improved' version. Works fine.

 

The usual set up for front speakers is to toe them in to the extent that you can just see the side of the inside face. IE:, so that the triangle they make has its point a bit behind you. The actual 'degrees' don't really matter. Then, forget surround sound, just listen on two channel stereo only, and adjust the toe in so you like them the best and don't touch them again. Only then do the surround sound part.

 

My speakers are a mix up. Large expensive Tannoys at the front (my main interest is two channel stereo), a cheap Monitor Audio centre, and a pair of cheap Mordaunt-Short (though very well reviewed) for the surround. If your front speakers are pretty big then you don't need a subwoofer.

 

I used the Yamaha's auto-setup for the speaker 'equalisation' and the delays. This process should not alter your front speakers at all, as the equalisation process uses the front pair as the fixed reference for the others. It may however, mess up the 'balance', so manually adjust that on the attached screen so they are equal. You might have to do this with the 'distance' as well, if it has decided that one is further away than the other, which they should not be in reality. Works pretty well, though not ideal because of the mixed speakers.

 

If the auto set up has altered the size of any speakers, manually set them back to 'large' All your speakers, regardless of their actual size, should be set to 'large' This is important.

 

Did not think the surround was quite loud enough, so I turned them up a bit.

 

That's about all there is.

 

[bleedink]

Thanks for the additional comments. I think the divergence of opinions suggest the issue isn't as cut and dried as it appears.

@arjaytee--That's very interesting. The reason for the 'formula' is that I am using a tape measure only. I'm also on a limited income due to a disability so just going out and buying a laser pointer on my income isn't possible at the moment. Thus I was hoping for something I could plug dimensions into in order to extract particular angles. I will of course try a few of these combinations to see which sounds best.

Mark I also have a Yamaha. It's set up on my unit allows for a flat response not based on the fronts. I've found it's a bit better than relying on the fronts on my system, but overall leaves much to be desired. I never felt anything was corrected. It felt like it was changed, added to, subtracted from, just not corrected. I since have found that just turning off the EQ (and because the room is small enough that the volume usually doesn't get to the point where the room dynamics really come into huge play) provides a much better presentation. Unfortunately it just doesn't do as good a job as I've been able to do myself. It does sometimes point me in the right direction for levels. I wish I'd have been as satisfied.

Again, this is not impacting every disc. For the most part, all but the most unforgiving stuff comes through just fine. Most outside pans and phantoms are present and well defined. It's just the odd disc that actually makes imaginative use of the format (perhaps um 3) that even shows a hint of something amiss. So yeah it would be nice to get those 3 to sound great. Mainly it's about dealing with my limitations in terms of tools and seeking out something mathematical that I can be reasonably sure will give me correct results. It doesn't have to be 22 but most things I've read suggest 22-30. I won't claim to be correct. Otherwise I wouldn't be here soliciting help and advice. There seem to be lots of correct answers!

 

[Mark Powell]

You don't need a laser, it's just a gimmick. You can do it just as accurately with a tape measure.

 

You are absolutely right about 'changing' rather than 'correcting'.

 

Some say that is it best to leave out the centre speaker entirely, as it never equalises properly with the two fronts. Have not tried it myself.

 

Interesting, this talk about Oppo. There was a thread about their dropping some firmware feature or another recently, and not telling anyone about it. It is not Oppo at all, they just buy the platform from a company in Taiwan, firmware and all, and put it in their own box. Cambridge Audio, Primare, and others do the same, and the firmware feature no longer appears in theirs either. Some even said it is because Oppo supplies the others. No they don't, they just all happen to buy, Oppo included, from the same place. So it is not Oppo dropping any features, it's the guys in Taiwan.

 

[bleedink]

Hey all I just wanted to let you all know that I ended up following some of the suggestions here and there and tried to follow the things that came up most often across the spectrum. There were some similarities that seemed to come up even with very different diagrams and ways of setting up speakers. The 22-30 degree R and L placement came up very frequently and I think mine are around the middle of the two. This was done somewhat by 'guesstimation'-rather than put the speakers as far apart as they are from me would produce a 30 degree angle. That seemed a bit wide for my room. I went with an 80% distance between the two as per someone's suggestion above and a few other 'agreements' across the web. The rears are basically in the same place, approximately at 110-120 degrees from listening position, which is a bit further back than some recommend at 90 degrees. They are not as far back distance wise because of constraints with respect to the walls. However if they were placed about a foot or two further back (were the walls not there) they would make a nearly perfect circle. Just to recap, I thought the best approach was starting with the fronts and getting them in the correct positions before concentrating on the rears. I think for whatever reason their placement was far more important than the rears for resolving multichannel music. So, my bit of OCD actually paid off quite a bit. I am now relying less on delays and the like. The music seems to be resolving so much better. I listened to The AIX All Star Band Moonlight Acoustica Stage Mix and was really blown away by the phantoms between the front and rear which was always a hard spot to get right with the dimensions of the room (something I believe Ted hit on earlier). The phantoms are there between the front L and surround L and for the R as well--a particularly hard area for phantoms IMHO. I really appreciate all the opinions, suggestions, and help. It really makes a huge difference on PCM recordings in particular. Believe it or not, given the size of the room, a half a foot to a foot can make a pretty big difference. Anyway I just wanted to thank everyone who didn't immediately start attacking the entire premise of my post. Just putting them wherever they 'sounded best' would not have been a good choice. One notable interesting effect from this was actually from a movie soundtrack that was heavily invested in using each speaker to pan a particular sound around the room throughout the periods where the soundtrack was audible. One of the better surround effects I've heard--movie or music oriented. It was definitely not a subtle effect. I usually don't care much for surround stuff in movies--it tends to be more forgiving than music in any event. This was a bit different and I gravitated toward my sweet spot and was blown away at the geometry of the audio signals I was hearing. It was almost like seeing a circle with my ears. I don't think the effect would be very convincing if there were phasing issues or if the speakers were just totally wonkily placed willy nilly. Alas that was one of the least expensive things I've done to improve the sound of my system. That (proper placement) and Pure Direct have been real tangible improvements for me and again I appreciate all the help and wanted to report my results after living with them a while. I'm glad it gave a few people reason to chuckle but the results to my ears suggest that the effort was well worth it. It was revelatory to hear a more perfect circular pan, as well as some odd pans from front to opposite rear. As I said above it was like hearing geometry-before my circles were a bit oblong! Also as per Marks suggestion I 'toed in' the fronts very slightly to put their convergence just a bit behind my listening position. B&W's for whatever reason don't do well with large toe ins. Good suggestion, Mark. What you said about the center is very true for these particular speakers. The quad material I've listened to invariably makes me double check which speakers are active so strong is the phantom center. I could likely make do without it for music but frankly it is useful for watching movies/TV as well, allowing one to crank up the vocals which can get drowned out easily. But that's TV...There don't seem to be many recordings which make imaginative use of the center for anything but vocals.

@Mark--I believe you are correct about Oppo. According to some things I've read it seems it was a chip manufacturers decision (Mediatek I think) to eliminate that feature after some pressure from outside. I agree with you that it likely wasn't something Oppo came up with as it would seem to go against the grain of the bottom line...but that's a bit off topic.

 

[Miska]

For multichannel, if you don't use speaker processing, the most important part is to make sure you have equal distance to all speakers from the listening position.

 

Angles are not as important, especially for rear channels. Front channels should be somewhat close to 30 degrees from the center line.

 

 

[bleedink]

Thanks Miska. I meant in terms of delays (Since most delay UI's these days just measure the distance of each speaker) trying to sync more closely with what my AVR has to work with. The main thing was tuning up the levels so that the rears didn't overpower. As I said so far so good. Stereo listening is a bit better as well since I had the speakers toed in a bit much for my particular models. I would say I am closer to the middle of the range of the two, probably slightly toward the latter. Anyway bass management takes care of most of the problems associated with the smaller room. Great suggestions.