What's the most sensible way to set up sound in a 35mm drive in theater?

[Jesse Crooks]

With their need for live commentary you can't use the DTS non-sync because you need both sources live simultaneously.

They have a pretty complicated setup (at least for me, as a cinema-only guy). There is a whole DJ booth that I believe has its own mixing board. Then there is one additional standalone mic at one of the sound racks for announcements. They added a DSP to the righthand rack on Saturday that I inferred from the discussion was for maintaining an even level between sources (I was only there for 35mm so I was not paying close attention to the aux audio stuff). Not sure where that falls in terms of the signal path. There was also a dinky Radio Shack switcher (Realistic Tape Control Center) that seemed to be where the different sources were landing immediately before being output to the FM transmitter. That seems like a potential weak link to me.

[Tim Reed]

Starscope? Yep, that's the Mahoning. They also have Ultra 80s behind E-7s. They believe that the E-7s and Starscope are somehow special and deserve to be used as living history. I suggested to them years ago to get a pair of Centurys or XLs and a CP-65. At the time, there was all kinds of used equipment that they could have gotten for little cash or for free. Unfortunately, some folks become emotionally attached to a notion, and reject sound advice.

They don't have mag capability that I'm aware of. I just saw a recent photo of their booth and there were no penthouses.

[Gordon McLeod]

For 35mm you should try to find a SMART Mod2b Drivein processor

[Tony Bandiera Jr]

This is all great info. While there's some great resources online (like manuals etc.) there is no substitute for the knowledge of people who have experience with the gear.

It is at Mahoning. Print sources vary, and they do run some things digital. But they're committed to keeping 35mm alive as a drive in experience. It's a great place with a lot of really dedicated people pitching in to make it happen.

I guess the thing I was most confused about was why decode the surround when it's just going back to stereo. But I see now that the decoders do a lot more than just decoding. I read a bunch about A chain and B chain processing. I'm curious about that QSYS down mixer or the JSD 60 and will look more into it.

There were a variety of issues, one of which was that the sound levels between the two projectors were uneven. The overall signal was also fairly noisy. I think these were addressed by recalibrating the projectors. The only concern I have going forward is that they've been branching out into events with live components, and as of yet I still don't think there's a clean reliable way to get an outside signal into the transmitter feed. I provided live gear for and event we ran with John Waters doing commentary over a film last year, and I had to patch in at a point that made no sense to me, caused a horrible buzz, and gave me no control over relative volume level. I'm hoping to have a cleaner option in the future.

The best way is to use any open channels on the mixer. It will allow gain and some eq to take place (Usually just lo-mid-hi, but better than nothing.) If the mixer has no channels left then simply upgrade to a bigger mixer. I would go no less than 12 channels of line level and 4 more mic level, so 16 channels total. (If the digital sound is currently sent separate from the film sound to the mixer, make the mixer 32 channels minimum.) Behringer and Mackey make good units that are not too expensive. Stay away from Peavey.

If the FM transmitter doesn't have built in compressor/limiters, it is extremely important to install that externally, set it up properly and lock the controls. Overdriving an transmitter will cause all kinds of nasty problems that could possibly (though rare) bring a visit from the FCC. Josh would know more about that.

As for the why decode the surround only to downmix it back in, there is sometimes audio information in the surrounds that needs to be heard even in just a stereo downmix. That varies wildly from one movie to the other, or even within the same movie.

[Brad Miller]

For 35mm you should try to find a SMART Mod2b Drivein processor

[Ryan Gallagher]

The best way is to use any open channels on the mixer. It will allow gain and some eq to take place (Usually just lo-mid-hi, but better than nothing.) If the mixer has no channels left then simply upgrade to a bigger mixer. I would go no less than 12 channels of line level and 4 more mic level, so 16 channels total. (If the digital sound is currently sent separate from the film sound to the mixer, make the mixer 32 channels minimum.) Behringer and Mackey make good units that are not too expensive. Stay away from Peavey.

My main concern with just enlarging the mixer is now you’ve got a hard to tune film down-mix sitting alongside a bunch of live event channels operated by who knows?

if sticking with mixers, I’d suggest the one everyone gets to touch be separate and feed a couple channels or aux inputs on the film critical one.

no easy way to “restore” settings on those cheap analog jobbies. Put the film mix one up high on a shelf and leave on. ;-)

[Justin Roman]

They have a pretty complicated setup (at least for me, as a cinema-only guy). There is a whole DJ booth that I believe has its own mixing board. Then there is one additional standalone mic at one of the sound racks for announcements. They added a DSP to the righthand rack on Saturday that I inferred from the discussion was for maintaining an even level between sources (I was only there for 35mm so I was not paying close attention to the aux audio stuff). Not sure where that falls in terms of the signal path. There was also a dinky Radio Shack switcher (Realistic Tape Control Center) that seemed to be where the different sources were landing immediately before being output to the FM transmitter. That seems like a potential weak link to me.

This is all correct. I think ideally the various sources (DJ mix, DTS mix, Starscope mix, Announcement mic) would all feed a mixer used basically just for switching. (I'd probably pull the knobs off the faders I don't want people to touch.) The output from that would go through a DSP to the transmitter. Presently there's some sort of manual switchover system to go between the DTS and Starscope. Right now the DJ (and potential voiceover) are only patched in to the DTS side of things.

I'm not opposed to keeping around old or non-ideal gear if that's what folks there want. I'd just like it to be upstream as a source and not downstream as something other systems need to rely on. (I do find the vintage radio DJ mixer, an LPB Signature II Model S13-C, rather charming despite it needing a bunch of pots replaced.)

[Ryan Gallagher]

This is all correct. I think ideally the various sources (DJ mix, DTS mix, Starscope mix, Announcement mic) would all feed a mixer used basically just for switching. (I'd probably pull the knobs off the faders I don't want people to touch.) The output from that would go through a DSP to the transmitter. Presently there's some sort of manual switchover system to go between the DTS and Starscope. Right now the DJ (and potential voiceover) are only patched in to the DTS side of things.

I'm not opposed to keeping around old or non-ideal gear if that's what folks there want. I'd just like it to be upstream as a source and not downstream as something other systems need to rely on. (I do find the vintage radio DJ mixer, an LPB Signature II Model S13-C, rather charming despite it needing a bunch of pots replaced.)

Once you start considering enough channels for TWO film processors (that don't do stereo mix down natively), that is a pretty big mixer, especially if there is Digital/DCP involved too ("technically" 16 channels for 5.1/7.1 with all the accessibility stuff). Since they won't be used concurrently, another route would be a patch bay for selecting which processor, and a smaller digital mixer (that permits you to save and recall scenes). Having scene store ability would also be some insurance against errant fingers mucking up the stereo mix-down. Plus the ability for you to have different mixes per format, as each format sends you signal on the same set of outputs from the processor.

Patch bay is not as elegant a backup changeover as their existing switch, but neither is a large analog mixer... (bunch of mute buttons to hit concurrently etc unless it has enough sub-mix faders).

But once you start budgeting for a decent digital mixer... looking anew at QSYS for system processing and programmable "presets" starts to get more appealing.

Really their setup is not that different than ours, being a mixed live/cinema venue. We tend to keep both systems totally separate (own PA/consoles and signal paths), but often times have to use both on a film show to accommodate the activity before the film starts, including DJs, dance groups, introduction speakers, yada yada.

If we summed both our systems into a FM transmitter at a final mix, it would basically be the same thing.

Edit: For reference our system includes 3 film processors. A master that is also the Digital/DCP processor. One for 35/70 Optical that feeds into the master. One for 35/70 Mag that also feeds the master (although we only have 70 Mag capacity). We too have a little analog mixer on the film side, but it is just to switch to another format for preshow music and a single stage microphone for when the Audio crew is not involved and using the live PA. If we needed talking OVER a film, it would have to be from the separate Live PA, the booth has no aux channels active when film formats are selected.

[Tony Bandiera Jr]

My main concern with just enlarging the mixer is now you’ve got a hard to tune film down-mix sitting alongside a bunch of live event channels operated by who knows?

if sticking with mixers, I’d suggest the one everyone gets to touch be separate and feed a couple channels or aux inputs on the film critical one.

no easy way to “restore” settings on those cheap analog jobbies. Put the film mix one up high on a shelf and leave on. ;-)

C'mon Ryan, you should know better than that.

Every analog mixer I dealt with at a certain theme park famous for chicken dinners where settings had to be preserved used a very simple (and very accurate) repeatable method: artist tape with a fine line marking the presets (or tiny adhesive dots on our rotary fader mixers.) We never had issues for several years..until we DID start using digital mixers, and people would go in and mess with the memory settings (accidentally or on purpose) which in many cases weren't recoverable.

Now tell me again which was easier?

[Scott Norwood]

There is/was some Ultra-Stereo processor (one of the digital models from ~2010, I think) that was sepcifically designed to have a two-channel output for drive-in use. That seems like it would be the most straightforward approach here....

[Scott Norwood]

Follow-up to the above: it is the JSD-60. Which is for D-cinema, but has a 6-channel analog input. That plus something like a CP65 (for the optical preamp, changeover circuit, and NR) might be a good option. Another thought: there is a bypass card (110L?) that can replace the cat. 150 in the CP50/55/65/200. This would give left/right (well, Lt/Rt) directly. Sam Chavez posted about that a while ago. Either setup could feed two channels into whatever switcher or mixer feeds the transmitter.

Agreed with Brad on launching the Starscope in to orbit.