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Author Topic: IEM distribution antenna / combiner  (Read 2013 times)

Mac Kerr

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Re: IEM distribution antenna / combiner
« Reply #20 on: June 18, 2014, 04:25:16 pm »

Even if it was zero dB down, it would cause you no problems unless it fell on another frequency you are using!  If you stick to vendor recommended intermod-free channel allocations you should largely be immune from self-generated intermod problems.

While this is true, it ignores the fact that the manufacturers groups only work within that group, you cannot combine groups, nor can you combine systems from different manufacturers, including any RF comm that may be in the UHF band. The manufacturers groups are limited in the number of RF mics you can use, and AFAIK don't include any IEMs. They also do not take any DTV in the area into consideration.

Using good IM software like WWB, or IAS will let you freely choose compatible for all your systems, allowing a far greater number of mics, as well as IEM and RF comms. While it is best to do an on site RF scan with a spectrum analyzer, all the major IM software systems will block out any DTV in the FCC database.

Once you have moved on to using one of the (often free) IM programs you are no longer limited to the few channels in the manufacturers groups.

Mac
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Lyle Williams

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Re: IEM distribution antenna / combiner
« Reply #21 on: June 19, 2014, 05:27:55 am »

I agree that if you are bringing a whole rack of wireless gear then you should plan ahead.

Many low scale users of wireless products get by just fine without knowing any more than "set each unit to a different frequency".
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Jordan Wolf

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Re: IEM distribution antenna / combiner
« Reply #22 on: June 19, 2014, 09:15:15 am »

Debbie,

Sennheiser has a free software program (for Windows or Mac) that will allow you to input your various devices and calculate frequencies for them based on the number of units, bandwidth occupied, etc.  If your units have the ability to network together, you may even be able to scan the local RF environment to further refine the frequencies that are available to you.

NorthernSound has a walkthrough video of the program and here's the official user guide.

It would be good to get friendly with this software, and I think you'll find that you'll have more peace-of-mind at events when you know you've done as much as you could to ensure good wireless coordination for your gear.
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Debbie Dunkley

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Re: IEM distribution antenna / combiner
« Reply #23 on: June 19, 2014, 11:08:50 am »

Last I checked, 6-10dB is a big deal.

Debby, are you using a tool to determine your frequencies? If so, be sure to include wireless mics as well.

Sent from my iPad using Tapatalk HD

Hi Rob…no I am not using any measuring tools of any kind.
I am quite new to the wireless thing really.
Years ago when I was singing I used one of the early Nady Mics (there wasn't much choice back then) and it was such a horrible experience,  I immediately went back to wired till the very last gig I sang a few years ago. IEM's were unheard of for most of my career and to be honest, I never even used wedge monitors for the first few years back then…."The kids of today don't know they've got it made" ….  anyway- I digress….. 
For the most part this is a recent transition to the world of wireless  for me. Hubby has a wireless mic which we have not yet used WITH the iems on stage yet. I was just trying to be prepared for any issues that may arise. So far I have had none with the iems running them with separate antennas. Bear in mind right now I have 2 systems (2 transmitters, 4 receivers).
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Debbie Dunkley

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Re: IEM distribution antenna / combiner
« Reply #24 on: June 19, 2014, 04:14:36 pm »

Debbie,

Sennheiser has a free software program (for Windows or Mac) that will allow you to input your various devices and calculate frequencies for them based on the number of units, bandwidth occupied, etc.  If your units have the ability to network together, you may even be able to scan the local RF environment to further refine the frequencies that are available to you.

NorthernSound has a walkthrough video of the program and here's the official user guide.

It would be good to get friendly with this software, and I think you'll find that you'll have more peace-of-mind at events when you know you've done as much as you could to ensure good wireless coordination for your gear.

Thanks Jordan…
yes I think I need to do some research. I'd rather be prepared before and in case anything happens rather than be surprised if it does and unable to correct the problems……….don't like surprises like that!!!
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Steve.Oldridge

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Re: IEM distribution antenna / combiner
« Reply #25 on: June 19, 2014, 04:34:36 pm »

Thanks Jordan…
yes I think I need to do some research. I'd rather be prepared before and in case anything happens rather than be surprised if it does and unable to correct the problems……….don't like surprises like that!!!

Deb, I don't pretend to be knowledgeably in the wireless area at all, but I'd GUESS you will NOT have any of the issue outlined in this thread unless you run MANY/multiple sets of wireless devices.

We have the following at a gig (tomorrow night is next gig) and not a lick of interference/crosstalk - I assume - because they are configured to all run on separate channels/bands:
1 wireless mic on lead vox
1 wireless acoustic gtr (G50)
2 wireless electrics  (G50's)
1 wireless bass (G90)
5 IEM devices.. (4*PSM200, 1*EM900).

That's 10 devices on stage with no issues.. I don't know where the boundaries are and I'm not saying it couldn't or wouldn't ever happen, but based on my limited exposure and impression(s) from talking with local folks "in the know", you need some level of scale to occur. Is that 12 devices, 20? idk.

We could get concerned, but we're not going to worry about it for now. We're also not likely to have any stadium gigs in the next week or 2 :)
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Tim McCulloch

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Re: IEM distribution antenna / combiner
« Reply #26 on: June 19, 2014, 04:52:44 pm »

Steve, the problems begin when the 2nd transmitter is turned on.  Just because you're not *obviously* stepping on your own signals doesn't mean that you're not creating problems.
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Mac Kerr

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Re: IEM distribution antenna / combiner
« Reply #27 on: June 19, 2014, 04:58:40 pm »

Deb, I don't pretend to be knowledgeably in the wireless area at all, but I'd GUESS you will NOT have any of the issue outlined in this thread unless you run MANY/multiple sets of wireless devices.

We have the following at a gig (tomorrow night is next gig) and not a lick of interference/crosstalk - I assume - because they are configured to all run on separate channels/bands:
1 wireless mic on lead vox
1 wireless acoustic gtr (G50)
2 wireless electrics  (G50's)
1 wireless bass (G90)
5 IEM devices.. (4*PSM200, 1*EM900).

That's 10 devices on stage with no issues.. I don't know where the boundaries are and I'm not saying it couldn't or wouldn't ever happen, but based on my limited exposure and impression(s) from talking with local folks "in the know", you need some level of scale to occur. Is that 12 devices, 20? idk.

We could get concerned, but we're not going to worry about it for now. We're also not likely to have any stadium gigs in the next week or 2 :)

Any time you run 3 or more wireless devices you run the risk of interference from intermodulation products. There are at least 2 FREE RF management programs, one from Shure, one from Sennheiser. Either one will work with Shure, Sennheiser, or Lectrosonics products. There is no excuse for not taking this simple step to help assure that you are not causing interference with your own system. There is not a point at which IM suddenly becomes a problem other than the minimum of 3 systems. Every combination of 2 or more RF transmitters causes IM products, but with only 2 they won't interfere with each other. As soon as you add more than 2 you open the possibility that one of those IM products will fall on one of your active frequencies.

The software is fairly easy to use, and can be run in advance. If you enter the ZIP code of the venue the software will look up TV stations in the area and include them in any calculations.

While it is better to have a recent scan of the RF in the venue, a combination of asking what other RF is in use, and the data the software looks up online will give you a better chance than you have now of success.

If you are running IEMs and mics you should try to keep the IEM frequencies separated from the mics as much as possible.

Mac
« Last Edit: June 19, 2014, 11:12:34 pm by Mac Kerr »
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Steve.Oldridge

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Re: IEM distribution antenna / combiner
« Reply #28 on: June 19, 2014, 05:22:55 pm »


thanks Mac.. I wasn't aware of that.. will take the recommendations and see what we end up with..    Like I said above... wonderful folks on this board !

One question... ??   I'm sure Deb is interested too..
Is it necessary to "profile" and adjust settings for each venue - assuming local radio/tv interference intensity will likely vary ?
« Last Edit: June 19, 2014, 05:27:07 pm by Steve.Oldridge »
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Steve.Oldridge

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Re: IEM distribution antenna / combiner
« Reply #29 on: June 19, 2014, 05:24:31 pm »

Steve, the problems begin when the 2nd transmitter is turned on.  Just because you're not *obviously* stepping on your own signals doesn't mean that you're not creating problems.

thanks Tim.. I'm assuming that we have enough separation with the the devices that nothing has reared it's ugly head yet...  I'm going to take Mac's advice and run the test on the band's gear and make sure it doesn't happen to us..
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