Lets talk about improving wireless mic performance

B

Brian Frost

Sophomore
Jan 11, 2011
132
2
18
Chicago
www.narniaproductions.com
I had 2 gigs this week using shure slx. Ive used these same shures near stage and never had a dropout. Ive used them far from stage and if I auto search channels, Ive had them consistently clean to 200 ft. This week I had random dropouts in rehearsal so I pulled up wireless workbench and put in channels as suggested. This cleared things up til 400 guests arrived with 400 ipads (dont know if this had any bering on the situation). I had occasional dropouts. I know the slx arent the top shelf of wireless but they have never given me problems before.

I cant tell if it was RF interference or if my signal just wasnt strong enough I was getting dropouts as close as 30 ft away. Problems improved with new channels but were never completely solved. Do I want to consider an antenna distro with a paddle antenna? Do I just need to pony up and buy higher end wireless? What might I want to purchase to improve my signal and prevent dropouts in these corporate events with talent that wanders a very large area pretty far from FOH.
Frost
 
Re: Lets talk about improving wireless mic performance

whats odd is Ive never had a problem all over chicago on music stages but i had quick dropouts on every frequency channel including those suggested by wireless workbench in a chicago venue, milwaukee venue and cleveland venue. shure says 300 ipads shouldnt cause any problem as the freq is totally different but maybe that many caused intermod problems?
 
Re: Lets talk about improving wireless mic performance

Hi Frost,

Shure is correct, iPads don't usually interfere with SLX systems. iPads operate in the 2.4GHz ISM band (WIFI), while SLX operate somewhere in the 470MHz to 698MHz UHF TV band.

Since you mentioned that you used Wireless Workbench to avoid local TV station interference, there are a some other sources of interference to consider. For example, if your gig was in a hotel ballroom, a likely culprit is that someone turned on other wireless mics or IEMs in another nearby ballroom, or perhaps a local TV mobile crew showed up and fired up their mics.

Please read my article about this very subject here on SoundForums; http://soundforums.net/hub/1157-fundamentals-rf-coordination-live-sound-part-1-rf-environment.html. The article outlines some reasons for the problems you might be having and ways to deal with them.

Karl Winkler's series of articles about configuring your equipment for best performance are also excellent reading:
http://soundforums.net/hub/290-optimizing-wireless-microphone-systems-real-world-part-1.html
http://soundforums.net/hub/397-optimizing-wireless-microphone-systems-real-world-pt-2.html
http://soundforums.net/hub/453-optimizing-wireless-microphone-systems-real-world-pt-3.html
 
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Re: Lets talk about improving wireless mic performance

Hi again Frost,

I hope you've had a chance to read those articles. I did a little more digging into your problem and I'd like to share a few things with you that I found.

The first thing to address is that you must be as accurate as possible with your location info when searching the TV channels function in WWB. Chicago is a big place with lots of RF on the air and it's different everywhere you go, so you want to use your location zip code at minimum. When I do big RF coordinations I use exact latitude and longitude, but that is probably overkill for your situation.

We don't know which version of WWB you're using, but you must be sure that you have the latest update for your version, since the updates contain the latest TV database info. I did the testing shown below with WWB6. I also don't know your exact location, so I did this simulation with data collected at Wrigley Field on Sept. 6.

We also don't know how many SLX systems you were running or what frequency band each was in, so I did the simulation with four units in each of these bands:
G4, G5, G8, H5, J3, L4. I set up each band in a separate zone for this experiment.

There are public safety licenses issued in TV channels 14 and 15 (470 to 482 MHz) across the entire Chicago area. At the Wrigley Field location, there are 85 specific licensed frequencies within that range which we are prohibited from using or interfering with. You can see in the first image that many of these are showing as peaks in the spectrum analysis, but not all are visible. At any time, any of those other licensed transmissions can pop up and cause interference (which is their privilege and right as licensees). So, no mics can operate from 470 to 482 MHz at Wrigley. This covers a big chunk of the SLX G4 band.

Wrigley Field 470-505.png

The second image shows the entire UHF spectrum and all of the RF that was detected on the air at Wrigley during the scan. I used that data to calculate as many usable channels as possible for each of the SLX frequency bands.

Wrigley Field 470-952.png

Even when I set up the parameters to be as generous as possible (Shure's "more frequencies" setting and SLX's set to "master list" mode) the results are bleak, with the exception of the H5 band:
G4 - 3 frequencies available
G5 - 0 frequencies available
G8 - 0 frequencies available
H5 - 4 frequencies available + 4 backups
J3 - 4 frequencies available + 0 backups
L4 - 2 frequencies available

Wrigley Field 470-700.png

Please keep in mind that this is specifically for the Wrigley location. If you're on the other side of town the results could be very different.
 
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Re: Lets talk about improving wireless mic performance

I read them closely and will repeat. Being that I have friends in the wireless dept of shure, I have H5 and was only using 4 channels. Thats why I was surprised that the wwb 6 and the scans both came up with sporadic interference. I might have to spend a day at shure or borrow an antenna distro and a paddle or two or maybe I just need to own the new ulxd quad that I keep looking at. Thank you for your help and the articles. I welcome any additional information you think of.
 
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