# Sennheiser wireless interference



## navy4534 (Apr 11, 2012)

I've tired everything i know how to do and still having problems.

I have 11 Sennheiser ew300 gen1( i think). This church has had them for years and are waiting for them to die out before getting new ones. 
They are all fed by Sennheiser antenna splitters. I have two ASP2 and one ASP1. I have 3 Sennheiser A 1031- U antenna 2 of which have a booster on it AB 1-A. The other one has a AB 2-A on it. And my 4th antenna is a Sennheiser A 2003 UHF with a AB 2-A on it. I either have a lot of hiss in my channels or they all seem to peak RF spike? Any Ideas? Below i listed the frequencies. Zip code is 30068.

Thanks!!!!

1- 524.100
2- 524.500
3- 522.400
4- 525.600
5- 535.900
6- 528.400
7- 530.200
8- 530.500
9- 532.400
10-539.200
11-527.200

Pastor mic( ew500 g3) - 542.900 ( not tied into ASPs- using antennas that came with it )


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## mbenonis (Apr 11, 2012)

Is the problem happening on all channels, or just some? I haven't run the numbers but I suspect you have intermodulation products running around here--and the antenna "boosters" are not helping you in the least bit in that department. A few of your transmitters are a bit closer together than I'd like to see as well--524.1/524.5, as well as 530.2/530.5. Remember that wireless mics need at least a 200 kHz bandwidth to live in, and I recommend carriers no closer together than 600 kHz.

I will try and run your frequencies tonight for IM3 products...


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## navy4534 (Apr 11, 2012)

Thanks Mike, that would be great. When I take off the boosters all my microphones seem to drop out. As for the problems it seems to be on some of them, but it seems to jump around. I will test it around 2 or 3 pm and everything will be fine but come sunday morning it goes crazy. Sorry I am much more of a lighting guy than Audio- trying to figure out this wireless issue. What is the proper way to run the ASPs?


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## Chris15 (Apr 11, 2012)

I've run the analysis for you Mike...
We have 4 IM3 issues, 2 spacing issues and 1 TV co channel, based on generic parameters...

Standby for a nice clean set of frequencies if I can create one...
View attachment Senneheiser RF in 30068 20120412.pdf


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## navy4534 (Apr 12, 2012)

Thanks Chris.

Read what you posted but not sure what the next step to take is.


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## Chris15 (Apr 12, 2012)

In part this is a discussion between Mike and I over a public channel...

As soon as I go and dig my Sennheiser settings up off the old computer I'll create a new set of frequencies to use that are free of nasties...


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## mbenonis (Apr 12, 2012)

Thanks Chris. Got busy last night and today and didn't have a chance to run it. About what I expected to find... Chris or I will come up with a clean set of frequencies for you.

In the mean time, how far from the stage to the antennas? If it's less than a few hundred feet you should not have any issues, even without the boosters. Can you take a picture of the antennas showing where they are located in the space? Also, what antennas are connected to what antenna distro's, and what receivers are on what distros? I'm basically looking for a signal flow chart here...

Also, does the problem go away when only some of the transmitters are on?


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## navy4534 (Apr 12, 2012)

Thanks guys. As for pictures I am gone for the weekend and won't be able to get pictures till next week. They are located in our balcony which is about 50 feet from the stage. As for how its wired i have tried a few different ways all with different results. As of right now ASP1 inA is house left antenna(1031). Out A of same ASP1 goes into B of ASP1 and all the outs for that go into 8 of the wireless receivers A antenna input. The ASP2 inA is House right antenna (1031).Out A of same ASP2 goes into B of ASP2 and all the outs for that go into the same 8 wireless receivers as the ASP1 but into channel B. The tired ASP 2 has a house left 1031 and house right(A 2003 UHF ) and those outs feed the remaining 3 receivers. The problem goes away mostly when the mic is on but even when on it seems to have interference, can hear hissing and it will peak quickly and startle everyone.


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## Chris15 (Apr 12, 2012)

Ta daView attachment NEW Senneheiser RF in 30068 20120412.pdf


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## navy4534 (Apr 12, 2012)

Chris15 said:


> Ta da


Awesome ! Thanks Chris! So those are ones I should be able to use ?


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## Chris15 (Apr 12, 2012)

Such is the theory...

There's a couple of spares in there.
RF being the beast that it is, sometimes, for reasons we can't explain or diagnose without proper test equipment, you just get interference on some frequencies...


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## navy4534 (Apr 13, 2012)

Chris15 said:


> Such is the theory...
> 
> There's a couple of spares in there.
> RF being the beast that it is, sometimes, for reasons we can't explain or diagnose without proper test equipment, you just get interference on some frequencies...



My room is about 70 feet wide. FOH and antennas are on front row of balcony about 40-50 from stage. Board and receivers sit in middle of the balcony. Where should i put my antennas?


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## mbenonis (Apr 14, 2012)

Put the "A" antennas one one side of FOH, and the "B" antennas on the other side. Make sure they're separated by 8' or so (more is fine). Here's an additional trick: turn either the A or B (but not both) antennas on their side if it's possible to do so. This gives you polarization diversity in addition to spaced antenna diversity.


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## navy4534 (Apr 14, 2012)

Did you get my picture ?


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## mbenonis (Apr 16, 2012)

navy4534 said:


> Did you get my picture ?



Yep. Recommendations above based on that picture.


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## mbenonis (Apr 20, 2012)

Did you get it all to work?


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## navy4534 (May 7, 2012)

Yep everything worked perfectly and no interference for the first time in awhile. THANKS. Recently moved to a gym for services while worship center is getting renovated and am now having a few drop out issues. Just using 8 of the same mics and the asp2's with 2 of the A 1031- U and boosters on the opposite side of the gym up on a track. Not a ton of drop outs but it doesn't like the floor in front of the stage for some reason- line of sight is there for sure. but i'll take drop outs over interference right now . Thanks so much, I really appreciate y'all.


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## mbenonis (May 7, 2012)

navy4534 said:


> Yep everything worked perfectly and no interference for the first time in awhile. THANKS. Recently moved to a gym for services while worship center is getting renovated and am now having a few drop out issues. Just using 8 of the same mics and the asp2's with 2 of the A 1031- U and boosters on the opposite side of the gym up on a track. Not a ton of drop outs but it doesn't like the floor in front of the stage for some reason- line of sight is there for sure. but i'll take drop outs over interference right now . Thanks so much, I really appreciate y'all.



Still shouldn't be getting dropouts if you're within a few hundred feet of the transmitters. Could well be multipath reflections in the space. Are both antennas oriented the same way or is one perpendicular to the other? How far apart are the antennas spaced? If they are above the stage area, are they pointed roughly down or straight ahead?


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## navy4534 (May 13, 2012)

they are prob 90 feet at most. both are sitting on straight mic stands pointing straight up . i turned one so the flat part is facing the stage and the other antenna is turned so the side is facing the the stage. They are separated by about 15-20 ft.


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## mbenonis (May 13, 2012)

navy4534 said:


> they are prob 90 feet at most. both are sitting on straight mic stands pointing straight up . i turned one so the flat part is facing the stage and the other antenna is turned so the side is facing the the stage. They are separated by about 15-20 ft.



LPDA antennas (shark fin antennas) are directional antennas, and they pick up from their shorter edge. The antenna connector is at the back on the longer edge. So, you want to point the shorter edge toward the stage, with one antenna oriented vertically and one oriented horizontally. Flat part is parallel to the walls (vertical) and ceiling/floor (horizontal). That make sense at all? It's a bit hard to explain without a picture...


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## navy4534 (May 13, 2012)

the antennas are Omnidirectional tho. It's 2 of the Sennheiser A 1031


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## mbenonis (May 13, 2012)

navy4534 said:


> the antennas are Omnidirectional tho. It's 2 of the Sennheiser A 1031



My bad! Then what you did is fine.


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## navy4534 (May 14, 2012)

Still having drop outs tho. Any other ideas ? Starting to think a lot of these problems have to do with age of the equipment but gotta make it a few more months till I can get new ones


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## mbenonis (May 14, 2012)

navy4534 said:


> Still having drop outs tho. Any other ideas ? Starting to think a lot of these problems have to do with age of the equipment but gotta make it a few more months till I can get new ones



Hmm. Should not. You are using the frequencies that Chris15 gave you, correct? Also, where is the new venue you mentioned? Same building, or is it across town?

Can you describe the "dropouts" any further? Static, loss of audio, something else? Can you be sure it is an RF issue and not bad audio connections, for example?

Hey--what kind of coax between the antennas and the receiver, and are you using the signal amplifiers ("boosters"). If you are using the boosters, are they at the antenna end or the receiver end of the coax?

Passive or active antenna distro?

Trying to narrow this down some more...


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