Hey everybody Mark Edward Lewis here with Cinema Sound and we've gotten an
awful lot of folks asking us about "Where do we put speakers?" and we've
got tons of that up there for you. But a lot of people have asked, "Look if I can't
get my speakers in exactly the right position what do I do?"
I mean not everybody, especially in the consumer world, just wants to set up a
nice home theater system, can know what to do about that. Well, it's a great
question, I just want to answer it here really briefly in the video. Yes, there
are those little devices where you stick a microphone, and it may even come with
your head unit, that you turn it on and it susses everything out and does an eq
and a balancing and all that, but let's be clear. I mean unless you can get your
speakers in exactly the same position to the listening area, all the way around,
the subwoofer, the left, the center, the right, the surrounds, if you can't do that,
whatever we have to do to fix that degrades the sound. And most of you
probably don't have treated rooms for which you can solve reflection problems.
So whatever we're gonna do is gonna degrade the sound. We
can get it close to great, but if you're like, "Wow i got this room where the my
surrounds are right here, or i got a situation where my subwoofer has to be
over here, or i want to put them on the ceiling," something like this,
you're gonna have an issue. But here's how we solve that. We don't solve it by
just turning up the speaker that's farther away. Why? Well because the way
your brain works, if a speaker is closer than another speaker, then that close
speaker is always going to sound louder to your brain than the speaker behind.
And in fact, so much so, that you're gonna have to turn this back speaker up so
much louder, that you're gonna create all kinds of problems. Not to mention phase
problems and cone filtering and then all this other stuff that's gonna happen. And
it's just gonna be late. The sound from here is going to your head is gonna be
late. Secondly, regardless of where your speakers are, you want them to be pointed
at you. You don't want to be kind of sort of at an angle, or have them this way so
it's like on a ceiling where it's just coming over your head,
or it's pointing at your navels, or it's on the floor pointing up at the
ceiling. You want those tweeters and the speaker's faces in general pointing at
the listener where their heads, not where their arms or stomachs are, right
at their heads, not over their heads. But that's really critical. If we can't do
that, it's never...there's no way to fix that. Then lastly, what we want to do
in most head units after 2009 have the ability to delay individual speakers
independent of each other. Which is super great and head manufacturers know that
nobody can get their speakers in exactly the right place, and so they put delay in
knowing that that's really the best way to solve a speaker issue. Now we have an
article on--several articles on this on Cinema Sound--as to how to fix this and
how to do it, but I'm just gonna tell you really briefly. There's also
videos about what levels you should put your speakers at, and what
distances, but let's just talk delay. Delay doesn't solve the problem of
having--like--your speakers in the right position, but it fixes it quite a bit.
Because if we can create sort of a virtual distance, where all speakers are
the same, then we can balance the room a lot easier and make changes and even EQ
it or whatever you want to do, as long as they're facing us. So what's the delay?
Well...most of the time at sea level between 72 degrees and 75 degrees Fahrenheit,
sound moves at 1.1308 milliseconds per foot
that means for every foot that sound travels, it takes 1.1308 milliseconds.
So if your room is a little bit warmer or if it's even
hot--you know--if it's cold, you're gonna want to make that number less, maybe
1.2 milliseconds per foot. But you know, to be super accurate and super fun
I just call it 1.1308 milliseconds per foot. Then you
take a measurement, and with a measuring tape--or whatever you want--and measure
each speaker, and write down how far is it from your head. Not a general space
but as accurately as possible--the middle person listening on the middle of your
couch or wherever that is. Center, left, right, sub-woofer (LFE), left- surround
right-surround, where is that? Write them all down, and then what we're gonna do is
we're gonna take the speaker that is the farthest away and that will be our
reference. Because you can't delay a speaker that's further away--the
furthest away--that's the one that has to be not delayed. So if you have a speaker
that's like--let's say--you're left surround is--call it ten feet away from
your listening position--way way back there in a situation where maybe you've
got your left and right speakers four feet apart from you in the magic
triangle. Right? Magic triangle--critical to have correct. That at least the left
and the right are the same distance from each other
that they are to you--you got to get that part right. Once that's fixed, you're like,
"Okay we're 48 inches or 4 feet from left and right, to left and right, to me--my
face--not my eyes, my ears where my ears are." Then we can go, "That speakers 10 feet." All
right that's the longest. Let's say right surround is 9 feet. That means it's a
whole foot closer. That means that you have to take the distance from the
longest distance away--of the longest speaker, in this case 10 feet from the
left surround--and subtract from that...the next closest speaker--or
whatever closer it is, in this case right surround--we'll call it 9 feet. That
leaves you with a 1 foot distance, and at 1.1308 milliseconds per foot
that means you have to delay the right surround speaker 1.1308 milliseconds.
Let's say that the subwoofer is 6 feet away--somewhere, you got it on a wall
somewhere...somewhere not really close let's call it 6 feet away.
Well...in the same way, we're gonna take the 10 foot from left surround
subtract it from--subtract from it--the subwoofer which is 6 feet leaves us 4
feet. So then you'd multiply 1.1308 by 4 milliseconds--by 4--and that
will give you the milliseconds that you want. Let's say the left and right are in
the correct position but they still need to be delayed. That means they are 4
feet from us. Again 10 feet minus the 4 feet for both of them,
even though they're in the right position--because we're delaying all
speakers except for the one farthest away--they all have to be delayed.
So left and right are going to be delayed 10 feet minus 4 which is 6, 6 times 1.1308
milliseconds--that's how much that delay is. And let's say you've
done what most people do, and that is you put left, center, right in a straight line.
And even though you're like, "Well then they're all the same distance." No they're
not. If you've done geometry at all, you know in a circle that means that the
center channel is closer to you. Bummer. And let's say maybe it's 6 inches
closer to you than the left and right, which isn't that unusual when you put
them in a straight line like that. But what do you do then? Same thing. 10 feet
from the left-surround minus--well this would be now 6 inches too close--which would be
then 3 1/2 feet subtracted-- whatever that is--6 1/2 (is that
right?) 6 1/2 times 1.1308 milliseconds, that's how far those
have to be delayed. Now, do you have to be perfectly accurate with this down to the
decimal? No, just round of this nearest millisecond and you're probably gonna be
okay. Since you know, the amount of measuring--you weren't doing it with a
laser tool--I mean unless you were--and you can be as accurate as you want.
Especially if your head unit will let you get down into the decimals of
milliseconds, but that's how you delay your speakers so that you get everything
sort of in a virtual same distance. Yeah? So once you have that in place, then--and
only then--do you do your volume balancing with pink noise or tones or
whatever that is. And you store that as a preset--don't let anybody mess around
with it--and you're gonna see a lot more efficient use and a lot better
recreation of the surrounds that you have. Now last thing, if you do everything
you can to not--N.O.T., not--put speakers on your ceiling it's just for so many
reasons. First of all, you're putting them on a wall which makes speakers sound
terrible. And then you're putting it on...sometimes up on a corner of...the
ceiling with the wall. So now you're actually putting it on two walls. Plus
it's up in a corner like this sometimes where that creates its own horrible
ambiences. And usually people forget to tilt them down--we just saw a member
do that and say "Hey look at my new ceiling mounting!" we're all like, "Oh what?"
and actually pointing straight across the ceiling, which then creates further
reflection issues. You're actually hearing the speaker off the ceiling
itself, more than you're actually hearing the speaker, which is like the worst
possible thing. Not to mention that it's very likely now way far away. So far away
from a listening position in comparison to the other speakers, that you're gonna
have to drive those speakers really, really hard. And you know most surround
speakers are teeny in home systems, and it's gonna overdrive them. They're just
not designed for that. So please don't put them on the ceiling if you can avoid
it. Put it somewhere else. If you must put them on the ceiling, don't buy cheap
speakers. Buy robust speakers because they're gonna have to really drive in
order to reach you at the same volume that your left, center, right, and your
subwoofers are gonna be. So hopefully this helps you with your your consumer
systems, figure out how to deal with delays, and if you're doing this in the
studio don't delay them. Just do everything you can to get them in the
exact right p osition. You'll be very happy you did, and your mixes will
translate. For home studio systems it's a little less important, but if you want to
recreate what the original mixers wanted in their films and their television, and
you can't get the speakers in the right places, use the delays, then tune your
rooms, and don't put anything on the ceiling. Hopefully this has been very
helpful and we've got all kinds of articles for you about this on Cinema
Sound and go avail yourselves. Until then we'll see you at home, in the home theater.