Shure SLX wireless range problem


Hi all.
Interesting problem here. We recently got 6 brand-new Shure SLX wireless body mics and are breaking them in on our current show (Urinetown). Through a full week of tech and opening night they all worked beautifully, then came last night. Two of the six started exhibiting the exact same problem. The four good ones work perfectly with the receivers in our booth window approximately seventy feet from the performers with a totally clear line of sight. The other two, with the same line of sight, completely lose signal after twenty feet of distance.
We swapped batteries and changed channels (all you can really do on these units) all to no avail. We even moved the receivers to just behind the proscenium wall (action is on the apron) and we lose signal anytime the packs move to the opposite half of the stage.
These units have "quarter-wave antennas" on the receivers, i.e. dinky little things that looks like toys. They are tuned through the use of preprogrammed "channels" and "groups" and there're no gain settings on the units. These are the low-end, I'm sure.
Is there anything I can do, short of shipping them off for repair, to have them useful again for this week's shows? I'm handy with a soldering iron if need be. Would fabricating longer receiver antennas help?
We switched working packs to those frequencies, and they came in loud and clear, so I'm fairly sure whatever it is is in the transmitters. Possibly broken antenna wires on the packs? I unscrewed one pack and the soldering on the antenna lead (about a six-inch long antenna) was just fine. Reassembled it, same issue--twenty feet, signal's gone.
This is frustrating. We need all six up and running for our rear-placed orchestra to be able to monitor and sync up with the performers. Any thoughts?
I can also fabricate transmitter antenna wires and solder them in, if need be.

Also, dunno if this would affect 'em, but we practice safe sound, i.e. the packs are set up, sound-checked and wrapped in unlubed Trojans before mounting on the performers--very sweaty show.
Although it probably won't be this because you have tried them off the actors I have one thing to try. When they are put on the actors are the aerials being scrunched up, this can cause problems. Try them with the anntena's straight out and see if you get the same problem. Worth a try if only to rule it out.
Excellent idea, thank you, but unfortunately already been tried, one of the first things. I grabbed the packs and walked up to the stage holding them in my hand, talking into the mics, wiggling the antennas all about, curved, straight, all to no avail.

We've also ruled out EM interference, by moving the receivers from the booth to backstage, patching them into our snake and the snake into the board. We thought it might have been EM from the HVAC blower motor (we had to leave the system running through the show--fairly quiet in the house, but like a freight train in the booth) but the problem existed with it on and off, and only on those two out of the six units, regardless of frequency setting. Seems to be no transient cause, as if suddenly the packs decided they only wanted to transmit short-range.
Ring up Shure's distributor and get them fixed.

This has happened to our UT systems, except our problems got worse.
That's the annoying thing with these units--no squelch, no fine tuning adjustments, just channel select buttons, a mute button on the transmitter and a sound level 5-LED meter on the receiver. Still searching for the answer, but thank you for the suggestion.
First off, do you have any other wireless going in the space (including radios, wireless video links, etc)? Any major TV transmitters nearby (within a few miles)? Any other facilities nearby that might be using wireless (i.e., football stadium with Referee mic)?

Second, have you checked your wireless channels for intermod? If you're using Shure's presets, you should be OK IF AND ONLY IF you are not running any other wireless in the vicinity.

If all of the above check out, then I would lean towards a hardware problem. See if you can narrow the problem down to the transmitter OR the receiver. Try setting the "bad" transmitter to that of a "good " receiver and see if there is a problem, and vice versa. If you can narrow it down this far, and are absolutely sure it's a hardware issue and not user error, give Shure a call and explain the situation to them. They might have some ideas, or be willing to ship out new units to get the show up and running.

BTW, do NOT attempt to fix the units yourself. Doing so will void the warranty and ruin any chance of Shure fixing the products themselves.

Good luck, and keep us updated as to what happens!
I've had the same problem with a couple SLX's in a batch of ten. The problem was the frequencies overlapped and, in some cases, coincided with the RF junk in the air. Same problem you described; working close, but losing signal further away. Like mbenonis said, try switching the groups and channels on them. As-setup (i.e., factory presets) the way we had them, the few had these problems. If it's not that, definitly switch packs and see if it is hardware related.

p.s. sorry mbenonis for just restating what you said, had to add personal experience in.
p.s. sorry mbenonis for just restating what you said, had to add personal experience in.

It's all good. I too will admit that I have had trouble with the SLX series personally. We bought two a while back, and they have never performed to the level of the LX and ULX wireless in the same space. I'm thinking they simply need better antennas compared to the 1/4 wave whips they come with, but antennas cost money and placing the receiver closer to the stage doesn't.

'Course my current wireless system consists of 16 Vega units, which are constantly breaking and getting fixed. The problem is that the two companies that fix 'em are running out of spare parts. I'm pushing for a new system, but hell will freeze over before that happens...
Call Shure technical support & ask for a wireless applications engineer. In my experience, they've been very helpful tracking down weird wireless problems. You can find the number on the Shure web site. With their help, we finally tracked down the source of interference on one of our LX units as stray RF generated by a Lexicon digital effects box (Lexicon still has not offered a solution to the problem, even though the two co-existed for two years before the interference began). They should also be able to authorize some sort of expedited replacement, if that's necessary.
I just found the frequency finder today on Shure's site--will no doubt come in helpful around here.

I decided to do some brute-force troubleshooting today to remove all doubt and assumptions.

The protocol:

1) set up a receiver just behind the proscenium (through the snake) and set the channel, set a mike pack to the same channel as the receiver, walk all around the stage and to the back of the house listening for dead spots or dropouts or short ranges.

2) repeat 72 times. (6 mike packs, 12 channels each)

I made three discoveries in that 3 hour period--

First, I need to lose weight.

Second, all the packs work.

Third and most importantly, of the twelve channels on the receiver, we're losing 7, 8 and 9 to ranges of ten feet or less. This affects all packs. The only possibility is someone else using something more powerful in the neighborhood on those same frequencies. My best guestimate is that something else got turned on on Saturday, when the mayhem started, and blanked out our channels 3 and 4 (we tried swapping batteries and then switching to 7 and 8, and stopped there out of frustration and already holding the house for ten minutes--the drop-outs were noticed at "places", not at mic-check, as mic-check was done very close to the receivers--not any more!). Stopping there, the only assumption we could make, since the other four units were working on 1, 2, 5 and 6, was that something had happened to the packs.

Well, we all know about assumptions, don't we?

We procured a backup unit, in a different freq band, so if we have seven channels to play with for six units, plus a backup unit as need be, I think we're okay system-wise.

Thank you all, though, for suggestions and ideas--I'm keeping 'em in mind should we run into more issues.

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