While there are wired solutions around that work pretty well, I looked on Amazon and found some low power (100mw-500mw) FM stereo transmitters. I figured I will give one a shot, and it worked very well, though it took some careful setup.
Here's what I did - YMMV. I posted these notes on another forum I participate in as well but I thought the community here might also like to hear.
I bought the SainSonic 0.5W Long Range (10km) Dual Mode Stereo Broadcast FM Radio Transmitter (in *Fashion Black*); there are other models but this was the only one that clearly contained all the moving parts. Wall-wart power supply, 1/4 wave antenna, transmitter. There is at least one transmitter on Amazon with switchable 100/500 mw power. This one is fixed at 500 mw (1/2 a watt).
The SainSonic was roughly seventy five dollars. Free shipping with my "prime" account.
I received the transmitter, and just like so many high quality low price items from the far east, - no manual, but it couldn't be easier to operate. Plug in the power cord, 1/4 wave antenna, a line source, select a broadcast frequency adjust the input level and you are on the air.
The line input on the SainSonic is a front panel 1/8 in stereo consumer level input and is easy to overload. My first test was to simply play some music from my tablet into the transmitter and listen with an mp3 player which also has an FM tuner (Creative Labs-Zen I had lying around) I walked around the house and this little guy was covering well over a hundred feet very well. I did not try longer distances as I don’t expect to really need more than 200 feet, conveniently the FCC limit for part 15 low power transmitter operation. I checked- The FCC part 15 rule permits low power FM broadcasting (under 200 feet). I'm no lawyer, so don’t take this as legal advice.
But what frequency to use? This thing broadcasts on the standard 88-108 MHz band all our local FM stations occupy. Fortunately radio-locator.com has a vacant frequency finder. Just put in your location and it will list the frequencies nobody in the area is licensed to broadcast on. The bad news here is for people living in highly-populated areas like New-York city. There are NO vacant frequencies there, so if you are considering this approach - check your local listings. You may still be able to over-power local stations within the building you are in, but that doesn’t mean your FM receivers will discern your signal enough to be useable, so be warned. You also don’t want to go around broadcasting on top of licensed stations your neighbors may be enjoying. A 200 foot broadcast can affect a lot of people in a densely populated area, so be considerate.
The other thing I noticed is that if this little guy is within a few feet of unbalanced cables it will easily modulate a signal onto the cable or into equipment that may not be well shielded. So much for setting this thing on the FOH console. Still, I was pleasantly surprised with the quality, so I decided to use the transmitter / mp3 player in a live setting.
Without announcing to anyone what I was trying I sent a monitor feed to the transmitter during sound check and the first part of a set I was mixing for a local band. I should say two monitor feeds as the unit is stereo and I did not have a y cable handy. The transmitter does not have a "mono" only or sum operational mode, as most pro in-ear transmitters do.
Did I mention the unit is easy to overload? You bet. If you try this using an analog mixer you'd better use a compressor between your output and the transmitter input. Fortunately I was using a digital desk with compression available everywhere, so no problem. (Yet another reason to go digital!!) I experimented with various thresholds and ratios and ended up running 2.5:1 ratio with a very low threshold (meaning everything is compressed) zero attack time, and a generously long hold/release. The whole time I was making adjustments I was listening to my Zen MP3 player FM radio receiving the mix I was broadcasting. A limiter may have worked just as well. Again, this adjustment very subjective but some compression / limiting is absolutely required.
After a few songs I brought the Mp3 player / FM radio with some cheap new skull candy ear buds to the lead singer and asked her to try them. She smiled from ear to ear the rest of the set, and through the next set. She sang better, kept in pitch, and I was able to drop her from the wedges, significantly reducing stage volume and feedback potential.
The bass player saw what I was doing and pulled out his HTC EVO phone. It has an FM radio. Now he had ears. Cool freebie.
So between the transmitter and receiver I'm in for a hundred bucks. Far less expensive than pro-wireless ears and the cost of adding another listener is minimal, zero for the bass player. Most of the bands I work with can get by on one or two monitor mixes, so I will be picking up another FM transmitter soon for the guitar players.
Is this for everybody? Absolutely not. Is this as good as pro wireless in-ear monitors? No way. FM transmitters do not have the dynamic range the pro units deliver. If your artists are very discerning, they may not like the sound. Then again, for a low budget solution this has real promise.
Again your mileage may vary, but this is pretty cool.
Don --
4x T39
2x OTOP12
2x Wh6
2x Wh8
2x cxi1531
