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Author Topic: Shure QLXD next to Sennheiser ew 300 IEM G3  (Read 3595 times)

Chris Poynter

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Shure QLXD next to Sennheiser ew 300 IEM G3
« on: July 24, 2018, 12:11:49 PM »

Hello!

I have a Shure QLXD and a Sennheiser IEM unit that I use as part of my DJ rig, mostly for wedding receptions and corporate events.

The Shure QLXD is used by me, the MC, speeches, etc. Usually indoors, usually not more than 100-feet away.

The Sennheiser IEM unit is used when I want to broadcast the sound wirelessly from the booth outputs of my DJ console to remote speakers... sometimes at the back of the room... sometimes out on a patio... etc. Basically when I just need to get a bit of sound to somewhere else.

Question 1

I've been reading online that it's best to keep RX and TX units far away from each other; however, I often just put the QLXD box on top of the IEM box due to space constraints and keeping everything looking neat. I haven't had issues with it "yet", but am I likely to? Or will it not be an issue because I'm only using these two specific wireless units and not a whole bunch? They're both in roughly the same frequency range and I run a scan on them both when I set up my rig.

Question 2

Yesterday I mounted the Shure 1/2 wave antennas onto the back of my road case (I used a steel plate with dimensions of 14" x 3" and drilled a couple holes in it) and ran the BNC cables underneath my mixer to the QLXD which fits perfectly underneath.

I want to do the same with the 1/4 wave antenna from my IEM unit. I know that remote mounting of 1/4 wave antennas isn't good because they need a ground plane, but does this still hold true for a 1/4 wave antennas that are transmitting and if so, will it work fine if I mount the antenna on a 4" x 3" piece of steel?

TL;DR

I want to DIY-mount my Shure QLXD 1/2 wave antennas and my Sennheiser IEM 1/4 wave antenna on the outside of a road case so I can have my wireless mic unit and "remote speaker broadcasting unit" all wired up and ready to go for ease of setup. Can I do this?

Don Boomer

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Re: Shure QLXD next to Sennheiser ew 300 IEM G3
« Reply #1 on: July 24, 2018, 12:36:24 PM »

So what matters is the distances between antennas and not the physical Tx and Rx. Think of it like speech. If I use my normal speaking voice from 5 feet away you will hear me just fine. But if I speak at the same level 1 inch from your ear you would hear that as screaming.

I would suggest getting a helical antenna for your IEM and setting it up at some distance from the mic’s antenna
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Don Boomer
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Justin Goodman

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Re: Shure QLXD next to Sennheiser ew 300 IEM G3
« Reply #2 on: July 24, 2018, 12:53:34 PM »

First, I wonder what the impact would be of going to a digital IEM system: Lectro, Mipro, etc? 

If they're not even racked together, why the need to literally stack them on top of each other?  TX + RX only a few inches apart is a potentially more negative situation than having things look a little messy (and I work weddings, too, so I get it). 
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Chris Poynter

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Re: Shure QLXD next to Sennheiser ew 300 IEM G3
« Reply #3 on: July 24, 2018, 01:14:59 PM »

First, I wonder what the impact would be of going to a digital IEM system: Lectro, Mipro, etc? 

If they're not even racked together, why the need to literally stack them on top of each other?  TX + RX only a few inches apart is a potentially more negative situation than having things look a little messy (and I work weddings, too, so I get it).
So what matters is the distances between antennas and not the physical Tx and Rx. Think of it like speech. If I use my normal speaking voice from 5 feet away you will hear me just fine. But if I speak at the same level 1 inch from your ear you would hear that as screaming.

I would suggest getting a helical antenna for your IEM and setting it up at some distance from the mic’s antenna

So what you’re both saying is that this would be asking for issues?

https://www.dropbox.com/s/bzadxk47nt0so1o/Photo%202018-07-24%2C%209%2059%2043%20AM.jpg?dl=0

https://www.dropbox.com/s/4jgsu34s18xitwv/Photo%202018-07-24%2C%209%2059%2055%20AM.jpg?dl=0

Justin Goodman

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Re: Shure QLXD next to Sennheiser ew 300 IEM G3
« Reply #4 on: July 24, 2018, 01:16:29 PM »

If you're already drilling holes in your coffin why not put them (ETA: by "them" I mean the antennas) on opposite sides 3-4' apart?
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Chris Poynter

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Re: Shure QLXD next to Sennheiser ew 300 IEM G3
« Reply #5 on: July 24, 2018, 01:21:23 PM »

If you're already drilling holes in your coffin why not put them (ETA: by "them" I mean the antennas) on opposite sides 3-4' apart?

I already had holes there from my old Sennheiser EWD1 mic antennas. I had to put the half waves where they are now accommodate my two laptop stands.

I could theoretically put the IEM antenna on the side of the case, rather than the back? Would that make any difference or is this just a dumb idea to begin with?

Justin Goodman

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Re: Shure QLXD next to Sennheiser ew 300 IEM G3
« Reply #6 on: July 24, 2018, 01:30:30 PM »

I already had holes there from my old Sennheiser EWD1 mic antennas. I had to put the half waves where they are now accommodate my two laptop stands.

I could theoretically put the IEM antenna on the side of the case, rather than the back? Would that make any difference or is this just a dumb idea to begin with?

One of the biggest issues IMO is that you're using an IEM system with a fixed 30mw output -- there's no low power option.  Farther the better -- see what happens? I'm not the expert that some on here are, but I don't think anyone can tell you that you definitely will or definitely won't have issues. Just that you wouldn't be following "best practices."

If I were you, I'd probably just run coax to your speaker stand with your signal cable. Clamp on something like a Shure UA860 which will look fairly inconspicuous and get the tx antenna several wavelengths away from your rx antennas. 
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Chris Poynter

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Re: Shure QLXD next to Sennheiser ew 300 IEM G3
« Reply #7 on: July 24, 2018, 01:39:37 PM »

One of the biggest issues IMO is that you're using an IEM system with a fixed 30mw output -- there's no low power option.  Farther the better -- see what happens? I'm not the expert that some on here are, but I don't think anyone can tell you that you definitely will or definitely won't have issues. Just that you wouldn't be following "best practices."

If I were you, I'd probably just run coax to your speaker stand with your signal cable. Clamp on something like a Shure UA860 which will look fairly inconspicuous and get the tx antenna several wavelengths away from your rx antennas.

Okay, thanks for the tip! If I have the coax cable wired up to that second metal plate in the photo so I can just plug in a longer coax on the outside of the case (to run to an external antenna) would I potentially run into issues having the metal plate with the half waves mounted right beside it? Like, because they’re both unshielded metal plates?

Henry Cohen

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Re: Shure QLXD next to Sennheiser ew 300 IEM G3
« Reply #8 on: July 24, 2018, 06:59:10 PM »

So what matters is the distances between antennas and not the physical Tx and Rx.

If by "not the physical Tx and Rx" you mean frequency separation, then this statement is not entirely accurate. In general, the greater the frequency separation, the less spatial separation is needed. There are other factors involved of course (receive selectivity; transmitter power, transmission scheme, occupied channel bandwidth; antenna patterns; etc.), and thus it's a balancing act.

Using your speech analogy, if one were speaking at a very high frequency, and the listener had poor hearing in the upper octaves, the talker would have to scream that much louder to really interfere with the listener's reception of lower octave sounds.
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brian maddox

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Re: Shure QLXD next to Sennheiser ew 300 IEM G3
« Reply #9 on: July 24, 2018, 08:37:00 PM »

If by "not the physical Tx and Rx" you mean frequency separation, then this statement is not entirely accurate. In general, the greater the frequency separation, the less spatial separation is needed. There are other factors involved of course (receive selectivity; transmitter power, transmission scheme, occupied channel bandwidth; antenna patterns; etc.), and thus it's a balancing act.

Using your speech analogy, if one were speaking at a very high frequency, and the listener had poor hearing in the upper octaves, the talker would have to scream that much louder to really interfere with the listener's reception of lower octave sounds.

This is super good^^
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brian maddox
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Re: Shure QLXD next to Sennheiser ew 300 IEM G3
« Reply #9 on: July 24, 2018, 08:37:00 PM »


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