I've recently been introduced to sniffing in-ear-monitor transmissions as a taping option, and while I'm still researching the post-recording remastering fracas that inevitably follows, I wanted to solicit recommendations for good general IEM receiver equipment that can 1) scan frequencies from multiple IEM manufacturers 2) separate the L/R channels correctly, and 3) collect as much (non-noise) background data as possible 4) Besides, I was leaning toward being outside the venue anyway.
1) IEM receivers are specific to models for a designated band of frequencies from a manufacturer. what you are looking for does not exist in practice or even as a theoretical model as far as I know - if you do find such a (sexy) beast, please let me know, as we would love to adopt such a versatile system when we're on tour!
2) See 1). I guess the closest gizmo would perhaps be a scanner capable of stereo decoding. It would not sound good though as it would have a noisy, frequency-limited audio stage, as this gear is not intended for audio applications. More pertinently, scanners would not have the appropriate RF expansion algorithm for the companded signal which is different for every manufacturer and even varies with the model.
3) Sorry, don't understand what is meant by "background data" here.
4) Unlike radio transmissions in the kW range, in-ear transmitters typically put out 10-100 mW at best, and are quite directional. So trying to get this intentionally weak signal from outside would be a pointless exercise. At the very best you will get so many dropouts and RF interference that the recording would not be all that listenable. Besides, wouldn't you feel a pang of conscience for stealing a show without even having supported the artist? And what's the point of recording a live gig if you are not actually there to enjoy the whole visceral experience?!
Stick to audience recordings if you must tape - the FOH crew has put a lot of time and effort into presenting a sound intended for the audience with the proper balance and mix, so why mess around with an unrepresentative, unbalanced monitor feed that has most of the band missing from it?
btw, I'm speaking here as an audio enthusiast and fan of live music of course, and not from my work perspective where even stealth audience recordings would be severely frowned upon, especially with all the illegal bootlegging for profit happening on ebay these days (not accusing anyone here of this practice, just stating how management and the record labels feel about this issue).
And I think enough has already been discussed here about the legalities and morals of snooping in on private conversations not intended for public ears...
btw, all receivers do leak out a weak but definite IF signature that can be triangulated with the appropriate gear - and we don't have to have the budget and resources of the NSA to implement such a detection capability - just ask a couple of my colleagues who have worked with Shure on this...so be forewarned!
DP