Film-Tech Forum ARCHIVE: Speakers behind screen vs. around screen question.

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Posted by Ray Bernardi (Member # 1615) on 04-10-2003, 08:00 AM:

I've learned a lot here. I thank you all. I'd like to ask a question.

I own a small theatre that has a lousy sound system. I'm going to upgrade it. I have a large screen curved set into the back wall. No way to put a screen array behind it. I have room on the left, the right, above and below inside the wall for speakers.

My thought was to put the new speakers in the wall. Left and right are obvious. I'd put the center channel on top angled down at the audience. The subwoofer would go on the bottom of the screen.

I've mentioned doing this to the folks who are going to do the work for me. They suggest I put up a new sound screen in front of my old screen and place the speakers directly behind it.

I know the new screen would give me a brighter picture, but does it really matter if the speakers are directly behind it or just around it as I propose?

Please give me your feedback. I really want to do this once, and do it right. Thanks guys and gals.

Posted by Mark Gulbrandsen (Member # 72) on 04-10-2003, 08:46 AM:

AMC installs their speakers above the screen in the installations that use the curved compound screen. Its quite obvious that the sound is comming from ABOVE the screen in those places. Installing a new screen and installing the speakers behind it would be the correct way to do this....can't you just get rid of the old screen all together, or move it slightly out from the back wall? If that screen is really bad it should be replaced anyway. Your customers WILL appreciate any improvements you do there!! Generally screen frames are not "nailed in place" so to say...sometimes flown though and that might be a limitation if that is the case....or then just get rid of it.
Mark @ CLACO

Posted by Mark J. Marshall (Member # 1409) on 04-10-2003, 08:51 AM:

This may be a stupid question, but I have to ask...

Is the current screen perforated? And where are the current lousy speakers?

Posted by Ray Bernardi (Member # 1615) on 04-10-2003, 02:13 PM:

The current screen is made of sheetrock. It's curved. yes you can curve sheetrock we've already covered that in a previous thread! It's built right over the back wall - it's actually the back wall itself. There is no behind it, it's not perforated at all. The current crappy speakers are on either side of the screen. Mono - no left no right no center no sub no surround - it's basically a 20 watt PA system with two speakers hooked to it. I gotta tell ya, Chicago sounded like CRAP! I know I need to do something. Putting up the perforated sound screen adds 1K to the project. I was hoping I could cut that corner a bit.

Posted by John Pytlak (Member # 331) on 04-10-2003, 02:34 PM:

Unless the screen is really small, the sound will not seem to come from the image unless the speakers are behind a perforated screen. A unique solution might be to REFLECT the sound from the solid screen by aiming the speakers at the screen, but that is a phasing and equalization nightmare. [Roll Eyes]

Posted by Bob Koch (Member # 1062) on 04-10-2003, 03:12 PM:

If the speakers are not where the action is it`s disaster.Try closing your eyes while listening, when the speakers are not in their proper location with dialogue and you`ll see that you don`t want to use a weird location.

Posted by Mike Blakesley (Member # 26) on 04-10-2003, 05:37 PM:

I vote replacement. Your customers will be thanking you for years. People care more about sound than they let on, especially in small locations.

Posted by Don Sneed (Member # 955) on 04-10-2003, 06:42 PM:

I been to several AMC theatres using EAW speakers, with the hi-freq. located above the screen & the woofers on the floor, I was impress with the sound quailty & thought it was a good idea...but I would hate to be the poor tech that has to get up to the hi-freq. cabinet to replace the voice diapham...exspecially since I'm scare of hieghts...(I have a man to do all my speaker connections, repairs, & speaker aiming...

Posted by Jack Ondracek (Member # 1466) on 04-10-2003, 09:15 PM:

Just seems obvious that the sound should come from where the actor's mouth is, or therebouts. Don't know that one could ever get quite used to movies, featuring a cast of ventriloquists! [eyes]

Don't feel too bad about the lousy sound system... at least you've recognized you have an issue that needs dealing with. I once saw an indoor house that had reasonably good equipment right up to the amplifier.... which was a Bogen CHS series PA amp, mounted right under the observation port! [puke]

Posted by Michael Schaffer (Member # 1204) on 04-10-2003, 09:50 PM:

quote:
Just seems obvious that the sound should come from where the actor's mouth is, or therebouts.

Since we don`t get treated to directional mixing anymore, that`s what we see/hear a lot of times anyway. But that`s a different subject...
I know the technical manager of a North European chain, and they install all their cinemas with the speakers above the screen aimed steeply downwards. I will contact him about details.

Posted by Philippe Laude (Member # 79) on 04-11-2003, 02:21 AM:

I totally agree with Mark.
Ray don't forget that when you bring your essential new screen closer to the projector, you"ll need to change your lenses too. Another unexpected expense! Your audience will just love you. [Smile]

Philippe

Posted by Lindsay Morris (Member # 1430) on 04-11-2003, 05:07 AM:

Ray,
I have a similar problem being an outdoor screen, made of steel and certainly NOT perforated so when I set my system up I followed what an dear friend of mine did some years ago at his outdoor which had a brick screen and was about 45feet wide.
He put his HF unit on top and his Bass boxes, a pair of 15" drivers either side of the screen. Sound was magic but of course that was in mono days.
I am basically mono with a bit of simulated stereo fed into a column speaker unit hung on either side of the screen.
In my case I have mounted the HF Horn (which is now a Raycophone unit and has a field coil requiring 10volts to energise it... so it is VERY old) right on top of the screen angled down so the centre of the multi-cellular throat points into the middle of the audience.
The bass unit with 2 x 15" drivers, powered 80watt subwoofer, 400Hz Crossover plus HF field coil power supply are all in the one big "W" bin at the base of the screen. It is something like 7 metres from bass unit up to HF horn and the sound is quite OK. It all blends nicely and there is no perception that the sound is coming from the top or the bottom of the screen it seems to spread out and merge very well. The original horn, a Vitavox had 8 throats and for 6 years that worked OK until zapped by lightning one night. The replacement Raycophone is probably a 1940's era of manufacture and has 16 throats and if anything is far superior to the Vitavox in terms of spreading the sound and the clarity of its output.
We seat 310 and have had 500 some nights for Big Fat Greek Wedding and if I feed about 5watts down the line it is VERY loud.(Very efficient units they made in those days)
So if your setup is phased OK I do not think you will have much problem having the HF unit on top. When I set mine up I wired a reversing switch into the HF line and with some music going had a helper at the base of the screen switch the reversing switch each time I raised my hand. I was really battling to pick which way round was the best in terms of phasing between the HF and LF units. Even going to voice from a radio source still did not alter the clarity which ever way I set the connections. I think phasing is more important for LF efficiencies as due to the frequency those cones have to shift more air for people to hear it effectively and if you connect a couple of woofers out of phase you soon can pick that up.
Possibly the phasing of the HF to LF units is more critical indoors than outdoors... never had to tinker with indoor setups.
I hire a cherry picker to check and service the HF horn each season as it sits up there all year round, rain hail or shine but it's driver is well covered in plastic and canvas to waterproof it and has a heavy duty gauze over the face to prevent insects building nests in the throats.. wasps love those little tunnels.
I would just try it out and see what works best... shifting that screen would be like me having to shift mine... not likely with 3 x 100mm steel legs set in concrete.
I may be in for a surprise this winter as I upgrade to stereo and surround sound but I have nowhere else to put the speakers so it will an interesting when I get "true" stereo going to see what it all sounds like then!
Lindsay

Posted by Daryl C. W. O'Shea (Member # 1303) on 04-11-2003, 07:30 AM:

quote:
Ray don't forget that when you bring your essential new screen closer to the projector, you"ll need to change your lenses too. Another unexpected expense!

Just get a bigger screen when you move it forward! [Smile]

edit: Now that I'm awake... your moving the screen back towards the lens, not forward. It's going to get smaller.

You know, new lenses would be nice though. [Smile]

[ 04-11-2003, 10:31 AM: Message edited by: Daryl C. W. O'Shea ]

Posted by Ray Bernardi (Member # 1615) on 04-11-2003, 07:33 AM:

New lenses? I didn't think the screen was going to move that far. The new screen would only be about 20 inches closer. It would make that big a difference? Hmmmm.

How much bigger a screen would that require? I like the idea of a bit bigger picture....... but......

I'm starting to think that I'll try it with the old screen first. Put the speakers in the wall and do the best that I can with it. If I'm not happy with it when it's all done, I can always put up the sound screen later.

What should I paint the old screen with to make it really reflective? Any suggestions?

+++++++

Scratch all above ----

+++++++

Here we go -

I'm going to do the new screen. I'll make it bigger so I don't need to change the lenses. I'll mask it doing a pipe and drape deal around it. All material up to fire code. The screen array goes behind it. I'll have a center, left, right and a single subwoofer back there. Two surround sounds on the left wall two on the right wall. All new in the booth, processor, amps, sound head, reader etc....

The plan is to have this accomplished within 3 weeks from now without stopping business to do it.

Keep giving me ideas please. You've all been very helpful.

I'll be taking some before and after pictures of the auditorium and the booth as I do this. I'll post them when I can so you can see how much fun I'm having.

Who the hell knew this much went into showing a damn movie? I sure didn't when I got this business.

It's been an education I tell ya.......

Posted by John Pytlak (Member # 331) on 04-11-2003, 08:45 AM:

Moving the screen closer to the projector will result in a SMALLER image, or require a shorter focal length lens to keep the same image size.

Use one of the on-line lens calculators:

http://www.schneideroptics.com/software/

http://www.iscooptic.de/english/downloads/indexdown.php

Posted by Ray Bernardi (Member # 1615) on 04-11-2003, 09:06 AM:

That sounds logical. A slightly smaller image would be okay here. I'm only 95 seats. I can't imagine that the screen 20 inches closer would make a huge difference.

Posted by John Pytlak (Member # 331) on 04-11-2003, 09:09 AM:

Just be sure to "Care About Composition" and mask the image to the correct aspect ratio:

http://www.kodak.com/US/en/motion/newsletters/pytlak/spring2001.shtml

Posted by Ray Bernardi (Member # 1615) on 04-11-2003, 10:14 AM:

Yes I understand that. We show scope and flat differently. At the moment we do not mask the flat image, we leave the extra screen on either side. The plans are to have a set of curtains that can be adjusted to suit the type of film being shown. I can't imagine cutting a scope down to the size of a flat. My God, you'd lose half the movie!

By the way, I was going to leave the old screen intact behind the new screen. That was the plan. I'm going to change that and take it down (cut into it for the new speakers). That way the speakers can set back farther and the new screen will only be about 10 inches closer that the old screen. The difference should not be that noticable.

Posted by Mark J. Marshall (Member # 1409) on 04-11-2003, 10:29 AM:

quote:
I can't imagine cutting a scope down to the size of a flat. My God, you'd lose half the movie!

Oh, that's ok. We do it all the time.
[Roll Eyes]

Posted by Daryl C. W. O'Shea (Member # 1303) on 04-11-2003, 10:29 AM:

Dope! [Embarrassed]

Remind me not to post immediately after dragging my arse outta bed!

Posted by John Pytlak (Member # 331) on 04-11-2003, 11:06 AM:

Mark J. Marshall wrote:

quote:
Oh, that's ok. We do it (severely cropping the image) all the time.

So, what are YOU doing about it?

Remember, "Film Done Right" means never having to say you're sorry. [Wink]

Posted by Frank Angel (Member # 248) on 04-11-2003, 05:18 PM:

There are always physical limitations that impact on how you need to approach each situation. In our big theatre where the stage is used for all manner of live shows, the screen must fly. There is no way around it so we just have to deal with it -- it prevents us from placing speakers directly behind the screen. I can state unequivically (I've had to live with this for years), unless you happen to be sitting way over to the side or in the first three or four rows, the illusion that the sound is coming from the actors mouths is not lost because of the speaker placement (center channel directly above the top of the screen and left & right on either side). The further back you sit, the less of an issue it becomes. Hey, live shows NEVER have speakers located behind the singers or actors; in most live venues they are hung stories above the stage or the stacks sit on the sides of the proscenium -- your brain is able to make the connection and it easily joins the image and the sound. It has never been even a small problem for us.

Naturally a perf screen with speakers located behind it where the sound IS coming from the screen, is ideal (you don't have to rely on an illusion to make it work), but the brain seems to do a fine job melding sound and picture for most patrons.

As for your existing screen, if cost simply will not allow you to replace it, look at it this way....it does have an up-side -- it's CURVED! Some of us experiece ecstasy and levitate when we see a curved screen. Curved screens were part of the original CinemaScope spec then later abandoned because of cost. Using a curved screen adds great panoramic impact to any presentation.

If you need to refinish the surface, you can do it to very good advantage by doing what the Drive-ins do -- get the whitest flat white paint that you can find -- paint that has a high titanium content -- and give it a first coat, let it dry. Then get silver paint and spray it carefully so as not to cause any dripping (not an easy feat, but it can be done with a good spray painting system). There are a few companies that still can supply silver paint for spraying a screen so it can be used for 3D. When the silver coat dries, it is then sprayed with another light coat of white paint again over silver. This method will produce a fairly high gain screen without the downside of hotspots. And it will be C U R V E D ! [thumbsup]

Frank

Posted by Peter Schoell (Member # 919) on 04-11-2003, 07:06 PM:

Ya know, Ray, you don't have to do everything at once. If you put in the new sound system, it will be an great improvment in your presintation. Next year you can put in the screen and get new lenses.
I always improve on a budget too.

Posted by Mike Blakesley (Member # 26) on 04-11-2003, 07:10 PM:

Our screen is curved. But the damn thing is 15x30. The screen is wall to wall, so our scope image is cropped somewhat, which bothers me to no end. But the upside is, I've been here for nearly 25 years and have yet to have a single complaint about it, so I guess I can live with it.

Posted by Ray Bernardi (Member # 1615) on 04-14-2003, 05:41 AM:

I wrote the check. We're going with the new screen and new sound equipment. I need to start taking some pictures for you all. It looks like we'll be ready to install in about two to three weeks. The rack is going to be pre wired, and I need to run all the speaker cable and be ready to move fast. My plan is to put up the new screen and sounds in a day and not disrupt business. I think I can, I think I can.....

Oh boy - here we go......

Posted by John Pytlak (Member # 331) on 04-14-2003, 06:07 AM:

Ray --- thanks for investing in "Film Done Right". Your customers will really appreciate the improvements. [Smile]

Posted by Ray Bernardi (Member # 1615) on 04-14-2003, 08:52 AM:

John, there's no other way is there? Ya gotta do it right! I agree that people will notice and I think this will be a big boost for my little business. I'm pretty excited about it all.

It looks like we will premiere the new sound system with the Matrix Reloaded premiere. That should give us some bang for the buck. We are green green green for May 15!!!!!!

Posted by Mark Seaton (Member # 1398) on 04-14-2003, 12:56 PM:

Hi guys,

One point to keep in mind when weighing the trade offs being discussed is our sensitivity to these directional cues. Our hearing is very sensitive in the horizontal plane, but MUCH less so in the vertical. From my own casual observation, strong floor or ceiling reflections and very directional speakers (wide band) are required to have the image shift significantly. You have to have a pretty steep vertical angle to get the sense of speakers above you.

Posted by Gordon McLeod (Member # 33) on 04-14-2003, 02:03 PM:

A steep verticle angle will be found for people seated in the front third of the theatre normally

Posted by Richard Hamilton (Member # 321) on 04-14-2003, 08:56 PM:

quote:
At the moment we do not mask the flat image, we leave the extra screen on either side. The plans are to have a set of curtains that can be adjusted to suit the type of film being shown. I can't imagine cutting a scope down to the size of a flat. My God, you'd lose half the movie!

Be careful. If you are planning on side curtains to mask the image, dont cover the left and right speakers unless you have sound transparent masking material!!

Rick

Posted by Chris Markiewicz (Member # 1415) on 04-14-2003, 09:09 PM:

Ray, I know I'm not alone in wishing you the very best for your grand opening! [beer]

Posted by Ray Bernardi (Member # 1615) on 04-15-2003, 05:06 AM:

Rick - I had not even thought of that. You're right. The way I was going to do this would cover the left and right speaker with curtain! YIKES! Better to find out now I guess.

Chris - Thanks. I'm a bit nervous. I really hope I can pull this off.

Posted by Ray Derrick (Member # 1001) on 04-15-2003, 06:56 AM:

One solution to this little problem is to mount TWO centre speakers, one above the screen and one below and run them in parallel. This creates a phantom image near the vertical centre of the screen. The top speaker should be mounted further out from the wall so that the distance from each speaker to a point half way towards the back of the audience seating area is the same for each speaker. Of course, the actual perceived vertical position of the phantom image will vary somewhat, depending on how far foward or back each audient is sitting, but none the less, I recommended someone try this years ago and it did work surprisingly well.

Posted by Jim Spohn (Member # 1547) on 04-15-2003, 09:52 AM:

At the Granada Theatre in Bakersfield, we have the same problem with no room for speakers behind the screen (the screen being on the back wall of the stage). We placed the L C R speakers above and below the screen and balanced with "L Pads" for optimum for the seats in the Orchestria section of the auditorium.Altec A-4s provide sub-bass from box seat areas located high on either side of the procenium. Our sound is quite good and has evoked compliments from several sound experts. (there is more than one way to get the job done.)Have fun........Jim

Posted by John Pytlak (Member # 331) on 04-15-2003, 09:52 AM:

Ray -- could properly placed speakers both above and below a solid screen be used for multiple channels to give "phantom" left, center, and right sound placement within the projected image? Has it ever been done?

Edit: Just saw Jim Spohn's simultaneous posting -- it HAS been done!