Film-Tech Forum ARCHIVE: DTS Digital Sound in a Drive-In

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Posted by Robert Schultz (Member # 2301) on 06-13-2005, 01:59 PM:

I just finished installing DTS in a Drive-In in California and it sounds GREAT in Stereo over the FM. I've had the system for a few years but just never had the time to actually put it into a theatre. This last week I finally had the time and I put it to use in one of my friends Drive-Ins. Has anyone else done this?

I will have pictures on rsem.com in a day or so.

Posted by Adam Martin (Member # 641) on 06-13-2005, 03:50 PM:

Yes, a good number of drive-ins have done this, since at least the release of Star Wars Episode I.

Posted by William T. Parr (Member # 677) on 06-13-2005, 04:11 PM:

Ray Andres, my old engineer at UA in Corpus installed on of the first DTS units in his Drive In theatre in 1996 in Abilene TX.

Posted by Adam Wilbert (Member # 1184) on 06-13-2005, 04:30 PM:

I've never worked in a drive in, but here is my (probably ignorant) best idea ever.

1) Broadcast the rear surround channels on a separate station.
2) Advertise to patrons to bring a battery powered boom-box (ghetto-blaster?!)
3) patrons throw the boom-box in their back seat and tune it to the surround station.
4) patrons adjust their car radio to play to the front speakers only.
4) Patrons can now make out in their car while listening to your movies in true surround.

eh?

Posted by Mark Gulbrandsen (Member # 72) on 06-13-2005, 05:06 PM:

Jack Ondraceck's drive in, the Rodeo, up in Washington State has all CP-65's with DTS on two screens and SRD on one. Probably makes him one of the very few D.I.'s that are even able to properly decode the SR analog track.....

I installed a MOD-2 DIT processors on each screen at the Melody Drive In near Bass Lake, IN. Fred still runs speakers as well as AM, and FM stereo. We installed an eq card in both the processors to eq the speakers to make them sound half way decent.

Mark

Posted by Bruce Hansen (Member # 281) on 06-13-2005, 06:16 PM:

Do you mix the center channel into both the left and right channels, and the surrounds into the left and right? Do you use any compression because of the wide dynamic range?

Posted by Robert Schultz (Member # 2301) on 06-13-2005, 06:54 PM:

We are mixing the channels like this:

L,C,LS,Sub = Left Channel
R,C,RS,Sub = Right Channel

I am using the standard mixing formulas for making the Lt/Rt tracks on a film, but I am not using an encoder, we are simpling mixing the tracks. I did make Center Channel 1 dB hot on both Left and Right so the dialog would come through very clean and crisp. When you sit in a car with a good sound system you actually get a phantom center with dialog and it sounds quite good.

The FM unit I am using for this system has a built in Limiter and Compressor that I setup very carefully, but this did allow me to play the dynamic range of film tracks and still get a good volume level over the FM transmitter.

Posted by Gordon McLeod (Member # 33) on 06-13-2005, 11:02 PM:

quote " am using the standard mixing formulas for making the Lt/Rt tracks on a film,"
No Ls and RS in a Lt Rt Matrix are encoded out of pahse to the centre channel

Posted by Robert Schultz (Member # 2301) on 06-13-2005, 11:41 PM:

When I say "mixing formulas" I mean LEVELS. Using an encoder on this system would be overkill for a Drive-In and most cars do not have the ability to decode an encoded Lt/Rt and create all the channels. The mixed system allows for all content to be heard and it simply desingates the content to the left of right side of the car at the right level. The system sounds great as a mix and the customers love it.

Posted by Ken Layton (Member # 133) on 06-14-2005, 12:57 AM:

I've listened to the digital sound at Jack Ondracek's Rodeo 3 drive-in (Port Orchard-Bremerton, Wash.) and it's fantastic! The main screen has Dolby Digital (and 7,000 watt lamphouse for a bright picture). The other two screens are DTS Digital with 5,000 watt lamphouses.

Posted by Robert Schultz (Member # 2301) on 06-14-2005, 01:30 AM:

Ken...do you know how they are mixing the channels? Is it similar to, or the same way I am doing it?

Posted by Frank Angel (Member # 248) on 06-14-2005, 03:16 AM:

I may have mentioned this before, but as long as a DI is investing in DTS and obviously concerned about quality sound, I suggest they look into using Dolby's Virtual Surround technology to create a surround sound environment. This process is used in many sound cards for computers and it's applied to TV and boom boxes all the time. It creates a fairly believable surround channel from two speakers. The one drawback that makes it impractical in large invironement is that to get the proper surround sensation, you have to be sitting pretty much between the two speakers, as you do in front of a computer monitor. This would work very well in the cab of a car as pretty much the whole cab is in the sweet spot.

Sony makes a processor that will take the five channels and processes them for virtual surround. This is for headset listening, but no reason at all that it wouldn't be easily adapted for DI use after the processor. Once you got that in place, you've only got one thing left to do -- HYPE: The ONLY Drive-In in the WORLD that presents movie soundtracks in full Dolby Virtual Surround, creating a 360* soundfield that rivals anything you will find in an indoor cinema! The beauty is that I think this Sony unit (there must be lots of other manufactures out there as well who have incorporated this Dolby technology into their products) cost under $300! Small price to pay for the ability to offer surround sound.

I heard this at a Computer Expo in NYC maybe 8 years ago now and it was damn impressive -- you would swear there were speakers behind your head.

Posted by William Hooper (Member # 71) on 06-14-2005, 06:40 AM:

Wow, an untapped revenue stream for Drive-Ins.

In the early days of FM stereo, when most music stations were on AM & most cars had only AM receivers, FM stations (& the sister AM's) made a tidy little stream by selling "FM Converters" to add FM to your radio.

Go ahead & matrix it all down in the rack, & sell "Surround Sound Converters" at the snack bar.

Posted by Gordon McLeod (Member # 33) on 06-14-2005, 07:32 AM:

Actually I would look at the SRS system as a surround option for driveins
I built a cheap encoder for a drivein once and it worked very well even in a two speaker care the depth of the surround effect was still noticed as it appeared to move outside the car

Posted by Ken Layton (Member # 133) on 06-14-2005, 09:24 AM:

Jack has his digital sound system patched into a computer in the booth.

Posted by Scott Norwood (Member # 30) on 06-14-2005, 09:44 AM:

Instead of in-car heaters, perhaps drive-ins could make money by renting RTAs at the box office. They could play pink noise through the system before the film starts (maybe using the mode on the CP650 that plays it in alternating channels automatically) so that people could EQ their cars.

Perhaps the next edition of each Dolby manual should have a section on microphone placement in automobiles. Somehow, I doubt that "2/3 back, slightly off-center" would be appropriate here.

Posted by Frank Angel (Member # 248) on 06-14-2005, 01:22 PM:

MRD-DS000 Sony's Virtual Digital Surround Processor:

The processor has 6 inputs and sends the processed virtual surround two channel signal to the headsets via infrared. There is also an output 1/4in TRS jack for a corded headset which is where you can also get the processed signal. That is where you would get your L - R signal to feed the transmitter.

Sony sez:

quote:
Enjoy the surround sound equivalent to that of 6 speakers (using only two) when you listen with Sonys MDR-DS8000 Infrared Cordless® Digital Surround Headphone System.

....this system is compatible with DTS ES, Dolby Digital EX, DTS, Dolby Digital, Dolby Surround, Dolby Pro Logic II and MPEG2 AAC. ... an Optimum surround field is created anywhere (between two speakers) -- simply select Input, Effect Mode, & Output. For a more realistic surround sound experience, choose the MDR-DS8000

This unit with the infrared headset has a list on the Sony site for $799, but I know I saw it for half that street price. Again, small price to pay to give them surround sound in the car. I know if I owned a DI, you bet I would have this thing installed in the blink of an eye and then go about getting Filmack to make me a snipe proclaiming that we had Dolby Digital Surround.

Posted by Jack Ondracek (Member # 1466) on 06-14-2005, 03:37 PM:

quote: Robert Schultz
do you know how they are mixing the channels? Is it similar to, or the same way I am doing it?

Pretty much, Robert. The only real catch to this is that you are feeding two monaural sources to your stereo channels (the center and sub feeds), so you need to use mixers with active front ends to prevent the l/r channels from mixing and losing separation.

I'm using Behringer mixers in my 3 setups. They're small enough to mount in back of the rack. A friend of mine in Lockport, NY installed SRD this year. He uses a rack-mounted mixer, but his rack has a security door on it.

quote: Robert Schultz
The FM unit I am using for this system has a built in Limiter and Compressor that I setup very carefully, but this did allow me to play the dynamic range of film tracks and still get a good volume level over the FM transmitter.

Mine does, too. However, I take a somewhat different approach to the final dynamics of the system. In my mind, people are going to compare my sound to the (unfortunately) squished & clipped stuff they listen to on their way out (cd's notwithstanding). People are talking in their cars, so the ambient noise levels are frequently higher than you'd find in an indoor theatre. Add to this, the noise floor of many FM radios I've tested out here (generally 40-45db), and you have a system that is not compatible with the dynamic range of even SR.. much less a digital playback. In my case, I'm using Afterburners to get the range somewhat under control. Past that, everything here passes through a 6-band Behringer DSP-9024 processor, where most of the dynamics are adjusted... to a Broadcast Warehouse transmitter, which has an internal peak limiter I use very sparingly.

My booth is controlled by a Broadcast Systems "Simian" automation system, which manages our show starts (control of the automation), intermission announcements, pre-show and intermission music programming and the voiceovers I can do at the ends of our trailers. This system uses a sound card for each screen. Software-controlled mixers allow for audio inserts. I use a Broadcast Tools audio switcher to to insert the Simian sound cards into the audio chain only when needed. This allows the entire system to be operated manually, if necessary. The switcher also feeds cue inputs from the film to the Simian system to trigger the various audio functions it controls throughout the night.

As a system, the computer manages my entire presentation except the start points of each feature. With one button, the system runs through our introductory audio, starts the show, does any voiceover tags during our trailers ("Batman Begins starts Wednesday, here at the Rodeo Drive-In"), intermission inserts on the first feature's credits ("get in here and buy more stuff"), then starts the music at the end of the feature. Music plays until I go up to hit another button (lens changes and DTS disk changes are done at this point). At the end of whatever song is playing, the computer does some marketing for the drive-in then starts the second show, does any voiceovers on the trailers, then switches itself out of the audio circuit until the second feature credits hit. It then switches back in, does our "bye bye" audio (exits are at the left of the field and out the back), then plays our exit audio when the credits end. Basically, the computer does all the stuff I used to do manually, so I can spend more time cooking cheeseburgers and french fries!

When I get to it, the system can be made to trigger our 2-way radios & announce intermissions and any alarms... something like the Newmade system, though I can do any audio I want.

I'm running XL heads, SH1012 sound w/ CE readers, TA10 controllers and a 701 reader for the DA20. Lamphouses are the new 7kW Big Sky units with glass reflectors, electric dowsers & Strong switcher supplies. My automation controls the motorized dowsers, not the bulbs, which are manually switched on & stay lit throughout the nite.

Posted by Scott Norwood (Member # 30) on 06-14-2005, 05:14 PM:

Jack--that's awesome. It sounds like you have a very classy operation there. [thumbsup]

Not exactly the sort of booth that one could just walk into and run a show without having seen it before, however.

Posted by Jack Ondracek (Member # 1466) on 06-14-2005, 06:40 PM:

Well, maybe not, Scott. You could probably get things up & running in pretty short order.

While probably true that you might have to figure out how to get music to play out of the computer (maybe I should wire up a cd player to the nonsync inputs?)... the system initially boots up without any fancy stuff in the circuit. You can turn on the breakers, thread up, hit the start on the TA10 and it will work. It just won't be snazzy. On power-up, the audio switchers default to a straight-thru channel. If not separately armed, the computer will not interfere or respond to any incoming triggers. Past that, everything else is icing on the cake.

quote: Frank Angel
Sony makes a processor that will take the five channels and processes them for virtual surround. This is for headset listening

I think I've seen earlier posts about this, Frank... maybe even from you. Seems I remember a report that this unit is effective only if you have a fixed point of reference (center). In a car, with people sitting on both sides & maybe also in the back, would this still work & not be a distraction?

Posted by Mark Gulbrandsen (Member # 72) on 06-14-2005, 07:18 PM:

Nice racks Jack and good to see you back here!

Mark

Posted by Robert Schultz (Member # 2301) on 06-14-2005, 08:33 PM:

Jack...that is an absolutely phenomenal setup. I love what you've done to automate the voice overs and promotions. Great idea and excellent marketing. The cost of the system has probably already paid off through return customers, a decrease in payroll, and your ability to manage the snack area rather then make announcements.

Thanks for spending all the time to explain what you've done and show us the pictures. Some time when I'm in the area I'd love to stop by and see this in person.

Posted by Jack Ondracek (Member # 1466) on 06-14-2005, 09:07 PM:

quote: Robert Schultz
Some time when I'm in the area I'd love to stop by and see this in person.

Any time!

Oh, by the way... I need to pass along my appreciation to Mark for the way he (and his company) approach their business.

About 2 weeks ago, my DA20 started acting a bit wierd. Over about 7 days, it got worse, then eventually died altogether... reasonable error rates, but no audio. A long conversation with Dolby resulted in no clear answers. One of their people actually suggested I pull the cards and "lightly tap the relays" (???????)!

After a chat with Mark, it became clear, this problem was going to be an unusual one.

Mark sent me a complete DA20, which I initially used intact to eliminate my reader (which scoped out ok) and anything else external (it worked fine). Simple card substitution after that pointed to the single card that was causing all the trouble (it was the 673 board).

Fixing this could have been much more complicated... possibly requiring me to send the whole box out (I didn't have another one here to compare it to). Mark's approach had me back up in a couple of days.

So, my thanks to Mark & the rest of the folks at Claco. With Vern being gone, it's good to find people who really know this stuff when I do get stumped.

Posted by Frank Angel (Member # 248) on 06-15-2005, 10:48 AM:

Jack, that's a spectacular setup....love that computer monitor sitting there ruling the world. Me, I would try to automate the hamburger grill so I would have more time to work the booth. [Wink]

As for that Sony processor, I did post about it when I first saw it a couple of years ago because I was blown away when I heard the Dolby Virtual Surround --there is something about hearing a sound coming from behind you, but you turn around and there are no speakers, that fascinates me. Then when Sony incorporated the technology into a unit that seemed to be an easy way to get it into a DI sound system, being the DI lover I am, well like I said, if I ran a DI, I would try this thing out.

And yes, ideally it wants you to be equidistant between the two speakers. But I saw the technology when it was demonstrated using speakers (not headphones) and even at a ten feet distance from the speakers, and quite off-center (it was at Computer Expo in a demo of a sound card where the Dolby Virtual Surround was incorporated -- about 10 of us standing around the computer speakers) the effect was still very impressive.

As for being distracting, if you are not dead center, then the perspective shift that would ocurr wouldn't be any more distracting than what happens in two channel stereo when you are not sitting dead center -- the stereo perspective shifts slightly. Same here, the entire multi-channel soundstage shifts slightly, but you still hear audio that is supposed to come from behind you coming from behind, maybe only a bit to the left or a bit to the right, depending on you off-center position.

This technology is used in lots of TV sets and like a car, people aren't sitting exactly dead center and it seems to work. I guess the only way to see what it does would be to install it and do some testing. Just get it from a place that has a 30 day return policy.

Posted by John Pytlak (Member # 331) on 06-15-2005, 12:43 PM:

My 48-inch Sony rear projection television has Trusurround-SRS, which seems to use the same technology. When we are just using the two in-set speakers with over-the-air material, it does really seem to "spread" the sound through the room with some programs. It's certainly not true surround or multichannel, but it is effective for casual listening.

Posted by Mark Gulbrandsen (Member # 72) on 06-15-2005, 12:55 PM:

quote: Frank Angel
I would try to automate the hamburger grill so I would have more time to work the booth.

MacDonalds has done just the with their Soda Dispensers that are behind counter. They have aded a cup carousel to them making fully automated Coke fills a reality. The thng works pretty good too!

Mark

Posted by John Vincent, Jr. (Member # 1791) on 06-16-2005, 09:05 AM:

A couple of years ago I bought a Lake Techologies Dolby Headphone unit and tried that at our drive-in (hooked up to a CP-55), worked great over FM if you used a walkman, not so great if you used your car speakers.

Still may go digital next year, if for anything but having a inherent backup in extracting the soundtrack. The only thing that would prevent us from using the new virutal surround technologies, is that I have to apply compression via a Beherenger unit (700 cars with a dynamic soundtrack does not bode well with my close neighbors), and the compression ruins the encoding for the virtual surround.

Another option I'm considering is providing a different frequency for FM Walkmans and the Dolby Headphone, that way if you wanted to hear it in Dolby Digital with Dolby Headphone, you could, without compression.

For our current setup, we use a CP-55 with the 150 card removed and Lt and Rt bypassing the 150 slot via the DB 25 test port in back. On to the compressor and FM transmitter, as well as a active mixer combining Lt and Rt for field speakers.

John - Wellfleet DI