# Wireless Mics/IEMs - portable rack setup help



## darga19 (Jan 28, 2016)

Hello all,

I've been reading up on this but hoping for some help! We are trying to build a small portable rack for 6 wireless units - 3 microphones and 3 IEM systems. The units being used are: 

(2) Shure SRX wireless mics
(1) Sennheiser EW135 wireless mic
(2) Audio Technica M2 IEM systems
(1) Shure PSM IEM system

I've got all the hardware figured out to mount the boxes side-by-side in a 4U shallow SKB Roto rack using adapters/ears for the similar units, and a universal shelf for the 2 units that don't match, along with a 1U Furman power supply. So that part I feel like I'm set. My question is about the antennas. 

Up until now, we've been setting up all 6 boxes practically right on top of each other and we don't typically have any issues. We can usually place the systems on or near the stage so they're very close by, and even if line of sight drops out due to a band member walking in the way, it's so close that it doesn't really matter. We have also not seen any issues when using the mics for speaking at weddings, even when they rove around the room. I'm hoping to do the same with the rack and avoid having to use these crazy expensive antenna distribution/combiner systems. So I'm looking at a couple options:

Option 1: Use a 1U or 2U flat cover piece, mount BNC bulkheads on it for all 9 antennas (2 each for the mics, 1 each for the IEMs), extend back with BNC cables to the bulkheads, and then disconnect/reconnect all 9 antennas each gig. It'll be ugly, crowded, and a PITA to set up each time we use the system, but because of how we're used to stacking these up, I would _expect _that it would probably work OK. 

Option 2: I'm wondering if I could get away with using 5-1000 MHz CATV passive splitters with BNC adapters to cut down the number of antennas. For example, if the freq bands on the mics are all similar and I can find a 1/2 wave antenna system to match all 3, could I use a 3-way splitter and run all 3 "A-side" antennas to a single 1/2 wave, and all 3 "B-side" antennas to another 1/2 wave? That would essentially cut down from 6 antennas to 2 larger ones. And could a similar approach be taken with the IEM systems? 

Would option 2 even be worth it...? Or should we just go with option 1 and be done with it?

I know I have to dig into the exact frequency bands that each unit is operating at; I'm awaiting on that info from the rest of the band members for each of their systems. I know this isn't the full-on pro way to do this, but I'm wondering if one of these strategies will be acceptable for our use. Any advice or things to consider will be much appreciated!!!

Thanks.


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## Footer (Jan 28, 2016)

Either buy the right stuff or do separate antennas. Your playing with fire no matter how you slice it.


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## Chris15 (Jan 29, 2016)

And avoid at all costs a situation where IEM transmit antennas are in close proximity to mic receive antennas.
On the same rack panel is asking for issues.

It has been known to work using MATV components to split signal, but whether trusting your show to a coddle together solution is an acceptable risk will depend on your operating environment.
Doing the reverse with IEM is categorically NO, the impedance matching is critical in a transmission path.


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## brin831 (Jan 30, 2016)

You can get a decent combiner and splitter for under 500 each including external antenna, check out rf venue .... it comes down to what is your show and accepted level of reliability.


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## darga19 (Jul 22, 2016)

Update! Just in case anyone has been on the edge of their seat waiting LOL

We ended up skipping the hack version of combiners and just mounting a plate on the back of the rack that has 6 antennas for the 3 mics. Turns out the rack covers fit right over top...so VERY easy setup. 

For the IEMS, the 2 AT units have antennas attached at the front already, and I used the equipment that came with the Shure PSM unit to run that antenna to the front of the rack too. 

So I obviously know it isn't ideal...but at least we have the separation with the mic antennas at the top/back of the rack sticking up, and the 3 IEM antennas in front. 

We've been using this rack over a year and a half now about 4-5X per month...I can only remember maybe 1-2 times we had issues and that was pretty much our fault for going the "set and forget" route rather than doing a scan/sync operation at each venue, each time we're there. Since all 3 users of this gear are at the front of the stage, the rack has been mostly placed at the front/side of the stage behind one of the subs.

Overall we've been pretty happy with how the setup turned out. The only downside is having to have the rack at the front of the stage. Putting it in one of the back corners would be much more ideal, but then I worry about line of sight with the drums being placed between the rack and at least one of the performers. :-/


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## WVTheatre (Jul 23, 2016)

Even if you do the proper 45 degree off center tilt for the A/B antennas, you're asking for trouble. If they are all the same band, you can get away using just two 1/2 waves for all three mics, and one singular antenna for the IEM. If not, you will need an antenna distributor (which amplifies the RF signal compared to a coax splitter, where there is signal loss. You'd also need an antenna combiner for the IEM's.
RF isn't something to skimp on, if you want it to be at all reliable, start saving now.


Sent from my iPhone using Tapatalk


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## darga19 (Jul 25, 2016)

WVTheatre said:


> Even if you do the proper 45 degree off center tilt for the A/B antennas, you're asking for trouble. If they are all the same band, you can get away using just two 1/2 waves for all three mics, and one singular antenna for the IEM. If not, you will need an antenna distributor (which amplifies the RF signal compared to a coax splitter, where there is signal loss. You'd also need an antenna combiner for the IEM's.
> RF isn't something to skimp on, if you want it to be at all reliable, start saving now.
> 
> 
> Sent from my iPhone using Tapatalk



Yeah...I know. Unfortunately a couple of systems are the same and a couple are different, and at this point upgrading them all to be the same isn't an option. In the future maybe, but right now it's not going to happen. Convincing musicians to spend money to fix something that has no signs of not working properly is a losing battle, even when it's the right thing to do. 

But we've had pretty darn good reliability over the past year and a half out of this rack. Should we really expect that it won't continue to work well? After this many shows without problems...what is going to happen out of the blue that will cause it to fail? 

I know what we have isn't ideal. I know that. And I know that the true answer is...it'll work well until it doesn't. But at this point what my genuine question is what could cause it to take a dump on us?


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## WVTheatre (Jul 26, 2016)

Assuming that you're running below 600MHz you should be safe from the FCC downsizing the spectrum for us wireless users (whenever they finally get around to that). Only other thoughts are: existing RF sources in a venue (walkies, comms, video, really anything) or cellular interference. We used to have all sorts of issues because our venue is basically a concrete box where signals just love to bounce around; mitigated by relocating W/L rack to backstage, and running the audio over the dante network back to the console.


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