Serious use of self-recorded IR's

Question

I use reverbs all the time on dialogue, no matter what the project. There may be the occasional voiceover that gets away completely dry, but everything else gets a little bit (or a lot) of reverb. I use reverbs as a kind of glue, that ties the dialogue tracks together. Most of the time it sounds realistic, often a bit larger than real life and sometimes a lot larger than life. The film itself kind of dictates what is appropriate...

I use all kinds of reverbs, and often I use Altiverb or TL-Space if I want that realistic feeling of convolution reverbs.

I have been the supervising sound editor on 10 feature films and on 5 of them I have also been the sound mixer on set. I have recorded tons of dialogue and lots and lots of ambient atmospheres to get as much sound as possible from the set. But I have not yet recorded any IR's.

To me it is very important to be able to work quickly on set and almost instantly adapt to changes. I don't want to be the guy who slows down the production, and I think it is a lot more fun to be a little busy on set than just to be waiting all of the time. I also try to make the recording gear as small and light as possible. The boomer is working with a wireless transmitter and I am running everything on batteries most of the time as I generally wear my recording equipment.

After a 2 year break from being on set, I am probably going to record one or two feature films this fall. And I would like to try recording som IR's.

I am wondering what the general experience is with recording IR's. Especially feature film experience, where you are recording for 6-7 weeks with changing locations. Is anybody using starter guns? Or do you use speakers? How often do you do IR's?

And I would also like to know about the post production side of IR's. Are they useful to you? Do you end up using them, or do you end up using another kind of reverb, because film often creates its own space, which isn't necessarily realistic? Again, actual feature film experience is what i am searching for...

Thanks in advance!

Answer 1

I'm a post-guy: in 10 years of working on sound, I've never been on set before! But I was lucky enough to be sent on location to do some ADR last week, as an actor was leaving the country and the producers wanted to get as much stuff done as possible to make things simpler down the track (without the need for Dolbyfax/ISDN/Sourceconnect headaches)

I packed up my laptop (& portable studio), and whilst there had the thought to record some IRs to make the dialogue & foley mixes a little easier. The production was being shot on two different stages, so whilst they were shooting on the first stage, I set up my gear on the second and vice versa, so the set was as quiet as possible.

To record the IRs, I used a Genelec 8030 to playback the sweep tones, and recorded into a 744 with a few different mics and perspectives. I've been using Altiverb for years now, but never actually recorded my own IRs before, and I was paranoid about the noise on set: generators in the background, buzz from the lights (I did record as often as possible with the lights off), exhaust/extraction fans in the walls. I recorded take after take (or sweep after sweep) trying to get the perfect/cleanest IR.

I then painstakingly cut the different sweeps and ran them through the preprocessor them (as an aside - the preprocessing/naming process for Altiverb is ABSOLUTELY RIDICULOUS!) to see how they turned out. I was amazed. Nearly every single one turned out great. I had recorded 1 second sweeps, 10 second sweeps, and 30 second sweeps and I expected that I would mostly end up using the 1 & 10 sec sweeps because the noise in the 30 was just too much - but in every case but 2, I ended up using the 30 seconders! The reverbs form the 30 second sweeps were marginally fuller/richer than the shorter sweeps, and the noise that I was so worried about was inaudible.

And then when I put Altiverb over the ADR tracks, the session literally mixed itself - so much easier than using a stock reverb or preset, and lessened the need for drastic EQing as well. Sure - these reverbs don't sound as good as the factory supplied IRs, but that is not the purpose. The purpose is to make post-recordings match location recordings, and for this they were perfect. I may not end up using these reverbs on later projects, but they are without question invaluable for this specific project.

In short, I'd strongly recommend recording IRs if you have the chance - if there is a full crew on set, then it might not be possible to get 30 sec sweeps, but if you can record two takes of 10 sec sweeps, it will save you so much messing around later on. (I don't think you need any more than two takes - I recorded upwards of 6 or 7 takes sometimes, and by the time I'd run them through the preprocessor, I couldn't tell the difference. Record two - pick the cleanest in your DAW, and only run the best one through the preprocessor - should be a no brainer)

Good luck!

Answer 2

Hello, Morten, IR's are just great, Logic has its own IR's utility, so tehre you can have an easy way of creating your own. For recording setup maybe this can be useful:

http://www.megaupload.com/?d=OGGN4YDM

P.S. Your work is really great

Answer 3

Somebody should make an Iphone app for IR capturing.

Answer 4

I would never pretend to have much experience with this on film sets, I have recoreded a couple of my own just for Ss and Gs.

I found that they would never come out quite the way I wanted them to, or remembered the space sounding. I did some reading to figure out why and came across this article which details how to go about doing it: Acting on Impulse. The one thing that the author really stressed, and that I think may interfere with any IRs you try to do on set, is that you really need the space to be dead still when you're making your recording. Any kind of background sound that isn't the natural response of the room (i.e. lights buzzing, people breathing/scuffin their feet in impatience, &tc.) will be interpreted by your reverb unit as part of the natural RT60 of your room. I also assume that 30-60 people standing in whatver space you're shooting in will affect the sound somewhat as well, giving you a slightly skewed version of the space you were actually trying to emulate.

But again, I'm not an expert on these things. Do check out the article though. It's a good read, very informative.