A while later, I went back to the same station, but with a Mid-Side rig instead of ORTF. Having cut my teeth working in music, I’ve had “mono compatibility” drilled into my head from the very beginning and still worry about it when doing field recordings, even though it’s not much of a concern anymore in audio-for-video contexts. Actually, that’s not quite true: there are plenty of mono assets used in games and it’s conceivable that something initially recorded in stereo would need to be mono-ized. Maybe I will keep worrying about it. (For the uninitiated: Mid-Side is mono-compatible, because when it’s summed to mono, the side channels disappear and all you’re left with is the material from one microphone, so there aren’t multiple sources to interfere with each other).

I don’t have the notes from this session, but I’m almost certain that the microphones were a Microtech Gefell M-295 (mid) and a UMT70S (side). The microphones were placed about 6′ from the tracks at a 45-60 degree angle (away from perpendicular), pointing towards the direction of approach – the idea behind this being that I wanted any bells and horns to be somewhat centered in the sound field, rather than skewed way off to one side as they would have been had the mics been aimed perpendicular to the tracks. I found that the drawback to this (as you can hear in the first clip) is that parts of the train wind up behind the plane of the microphone array, which really screws up the stereo imaging – essentially, I would up sacrificing the stereo imaging at extreme angles for the sake of mono compatibility. In hindsight, I don’t think M-S is a good idea this close to a moving subject.

Other things you may notice about these recordings: the background noise on a Saturday afternoon in September (these recordings) is considerably higher than it is at 9pm on a weeknight in January (pt 1). There’s a bit of editing in the first clip both to make the track shorter (the train was parked for a while) and to remove some weird modulating distortion in the middle of the horn blast. I was completely not ready for the amount of SPL coming off the horn (the engine was about 10′ away), and you can hear me drop the gain down a notch after the first blast, in anticipation of a second. There’s a good brake squeal in the 2nd clip: some kids weren’t paying attention and almost missed their stop, so the train stopped a 2nd time to let them off.