Friday, November 4, 2011

Dave Rat Blog - Getting Stepped On!

Well we had great time on the first tour leg.
I was way busier than expected so lagged a bit blogging, though I do keep up on facebook and twitter posts. Will try and focus more on mini blog posts and see how that works for me.
So as we start up leg two and looking at my notes, thought I'd share how we handled a wireless reception issue for the band in-ears we encountered.
It first showed up at the prouction rehearsals and we dived in to solving it in Cologne early October.
Turns out that video stages with LED video embedded, make RF noise. Lots of noise. So much noise that if you do an in-ear belt pack scan while standing on the stage while is powered on, there are 0 frequencies open, power down the stage and we get tons of open frequencies. Plus the artists are standing on the video screen so they are way closer to it than they are to the transmission antenna's.
We were able to make the jump from total bummer to pretty good and here is what we did:
Switched from 500mhz 25mw transmitter Senn G3 units to 700mhz 50mw 2000 series units - we measures the RF from the stage and is a bit worse at lower frequencies, the higher frequency units run at a higher power helps a bit.
Moved the transmitter antenna closer to the stage as every bit of distance reduction helps.
We scan for clear frequencies from the middle of the venue, away from the stage, so the units can actually see give us more than 0 open channels.
Swapped out to a lower loss cable between the transmitters and antenna
What is still on the list if issues recur:
Obtain the shortest possible 50ohm super low loss cable that will reach.
Eliminate the BNC to Coax adapter we now need to hit the antenna by getting cables with the proper ends. Every connection has loss we can not afford to have.
Add a higher power 100mw antenna power booster in line
Possibly put an antenna o the far side of stage dedicated to Flea.
When we get to the US, we will re address but for not we seem to be stable.
The pic of the spikey antenna is from when Tait Towers send a tech (other pic) out to analyze and help address the issues. Thank you Tait! Its cool to see the company that makes the stage interested in tackling the issue and helping.
Oh, and hello Dublin tonigh, the shows here always rock!
Dave Rat


  1. Have you tried any of the new Shure PSM IEM's (900's or 1000's)? The RF in those seems to be a little bit more robust, and I think there are more frequency options, But I'm not sure how much it would help if they're standing on LED screens.

  2. The o2 is a great venue! I wish I could have seen you guys there tonight, apparently my mate Harry met you Dave! He was the guy with dreads, I'm totally jealous

  3. Have you considered putting a thin mesh in front of the video screen connected to earth? Like a faraday cage. Maybe not a first choice for the video guys...

  4. Try to shield the LED controllers and earth the signal cables to the controllers. I could not imagine that the PWM switching frequency is high enough to let the harmonics interferer with the wireless.

    Had once likely the same issues. A Bosch building evacuation system was producing frequency products around 390Mhz. Exactly the same frequency's where the local police radio's where at. No problem except that the system was running at a soccer stadium in the same room where the police repeaters where located :)

  5. The Senn 2000' can actually do 100mW. Trick is to go to transmit power in the menu and keep holding the dial you will go from "high" to "maximum" transmit power