A couple of art cars want to standardize on FM transmitting of our sound. I wonder if there is an ‘industry standard’ / ‘best practices’ way to broadcast the output of our system over a short distance?
The idea is that UNAVERZ could be rolling around the playa and anyone who wanted to transmit our sound could simply go to an FM station and then play what they hear.
The flip side is equally important. UNAVERZ could pull up next to someone broadcasting and play what they are creating through our sound system.
SainSonic AX-05B Long Range Stereo Broadcast
It looks like the SainSonic will allow us to broadcast about 300 meters for $65. This would solve the transmissions side of the problem.
To receive, I believe I can simply run an FM radio application on my iPhone (or other device) and then plug it into the system by using the headphone jack.
If anyone has comments, I sure would like to hear them.
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JoeJoe the Clown
August 4, 2014 at 10:36 am (UTC -8) Link to this comment
The FM route is the way most people usually go, but available spectrum on the playa is “controlled” by a radio group that makes sure that FM broadcast on the playa doesn’t interfere with any actual stations in the 100 miles or so around the desert. This is important so that everything is Part 15 compliant and the FCC doesn’t swoop in and shut things down.
Technically, you should hit up Gary and see if there’s any open allocation left, or if it’s only for one night you can “team up” with an existing station and have them stop broadcasting and give you their spectrum for the event.
http://bmfreqs.wordpress.com/
It being burning man, there are a bunch of amateur radio nuts that make it a fun task to triangulate and go track down FM broadcast that is stepping on the official allocation or using the prohibited bands. If you are just broadcasting to a small area using one of those home FM transmitters through a small antenna you should be fine. If you are trying to broadcast for the larger playa, you’d need to talk to Gary and go the legit route. People often drop out at the last minute freeing up channels.
For a point of reference on transmit power, we used one of these 7W transmitters with a large 1/4 wave antenna on a 20ft mast last year at VBC. Our coverage was basically to the gate road on our side of the city.
http://www.amazon.com/gp/product/B008BF9B1A/ref=wms_ohs_product?ie=UTF8&psc=1
The antenna is what you need to pay attention to..
Pay attention to which antennae & how high it is. That’ll dictate your range, instead of the wattage of the amplifier.
Any FM transmitter would work, as long as you have a good omnidirectional antenna that is well placed up high.
Then run your RCA’s into the back of wherever your audio signal is coming from.
You have to tweak on your transmitter a bit, because on your gain you’ll start clipping your signal and that’ll ruin your sound. So, based on the type of antenna & the hotness of the signal coming in, you’ll have to make that tuning.
Lots of other details, but this is really all you need. There are tunable antennas & different types of coax cable you can use, but none of that really matters when you’re interested in transmitting only up to a couple of hundred feet away.
jj
Smash
August 4, 2014 at 12:25 pm (UTC -8) Link to this comment
I say go for it!
Also, when choosing a FM reciever, some folks like to use the stereo head units designed for hot tubs and spa’s because they are sealed for water and dust. There are also common marine head units for sport boats. They are good for a general purpose CD player.
We can plumb a generic input pair just for the head unit to the X32 that would be ALL it does with it’s own cables as well as set up the FM transmitter to transmit it’s own special signal that is “full bandwidth” without any copression limiters, or any modification so the receiving art cars get the best possible copy o the DJ’s mix for UNAVERZ.
– Smash
Gary Taylor
August 4, 2014 at 12:26 pm (UTC -8) Link to this comment
I can help you get an assigned frequency for the project. It is important you run a limiter between your audio source and the transmitter. DJ’s will always overdrive any FM transmitter that has no limiter and make it splatter out of it assigned frequency. A simple $100.00 stereo limiter compressor by Behringer or Alesis will work fine for what you need.
I can give you 91.9FM
let me know if that works.
– Gary
Bill Fuller
August 4, 2014 at 12:33 pm (UTC -8) Link to this comment
Space Cowboys use an FM transmitter for their Hoedown event on the playa. Easy and receivers are cheap.
JoeJoe the Clown
August 5, 2014 at 7:17 pm (UTC -8) Link to this comment
To add on also, we have in past years used the small car transmitters meant to transmit to a car without an Aux input. They suck. FM usually sounds like shit through a large sound system, and often there is a bit of a delay.
Also getting all the input levels to the transmitter sorted for optimum sound quality is kind of a pain. For a small roundup of art cars that aren’t going to be moving, we’ve found just XLR cabling them together is the smartest.
jj