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Author Topic: network hub for Senn. G3  (Read 4451 times)

garethhance

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network hub for Senn. G3
« on: November 12, 2012, 12:08:30 pm »

Hi,

Racking up our Senn. G3 receivers into 4-way racks I'd like to connect the ethernet management ports into a 5-way hub (1 in, 4 out) for quick setup.. and ideally one with a built in wireless AP like the TP-Link TL-WR743 or similar.

Should I be concerned about RF noise? .. is placing an ethernet switch or AP very close to a bunch of receivers likely to cause issues?

1  -has anyone had problems?
2 - any recommended make / models - We use Apple Airport Express in back of our M7's & LS9's for the audio port.. but obviously need something with at least 5 ports for a 4-way Senn RX rack... would a metal-cased unit like the Netgear Pro range help reduce noise?
3 - should i steer clear, use longer UTP cables and have a simple hub sat a few feet away?

Thanks

.gh
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Mark McFarlane

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Re: network hub for Senn. G3
« Reply #1 on: November 12, 2012, 10:56:01 pm »

Hi,

Racking up our Senn. G3 receivers into 4-way racks I'd like to connect the ethernet management ports into a 5-way hub (1 in, 4 out) for quick setup.. and ideally one with a built in wireless AP like the TP-Link TL-WR743 or similar.

Should I be concerned about RF noise? .. is placing an ethernet switch or AP very close to a bunch of receivers likely to cause issues?

1  -has anyone had problems?
2 - any recommended make / models - We use Apple Airport Express in back of our M7's & LS9's for the audio port.. but obviously need something with at least 5 ports for a 4-way Senn RX rack... would a metal-cased unit like the Netgear Pro range help reduce noise?
3 - should i steer clear, use longer UTP cables and have a simple hub sat a few feet away?

Thanks

.gh

I can't recommend a specific 'quiet' wireless AP, but you can determine potential problems by running the G3 RF Spectrum Analyzer with an AP turned on and then again with the AP turned off.  There have been a couple posts on this in the past 2 months. Personally I had a problem with the AP causing noise but I haven't tried repeating the tests yet so take that with a grain of salt.  Someone else said they had no noise problems using a specific AP.  Maybe next week I can re-run the test.
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Mark McFarlane
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Shawn Keck

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Re: network hub for Senn. G3
« Reply #2 on: November 13, 2012, 01:07:08 am »

I have several racks with 8 units, wireless router, and a laptop built in...not sure of the hub model...but we did notice interference when we used the whip antennas off the DA on the rack. No problems though with paddle antennas even if they are on mic stands right next to the rack.
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Mark McFarlane

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Re: network hub for Senn. G3
« Reply #3 on: November 14, 2012, 01:25:46 pm »

I re-ran some tests tonight.

Receiver is ew300-G3 with both stock antennas attached
Wireless AP is Belkin N600 DB Wireless N+ Router Model F9K1102V1

Edit: rack gear on, 01V96 off, for all tests

1) g3 and AP sitting on top of 01V96 console on top of FOH rack,
2) g3 moved to floor right next to rack (3' from AP)
3) g3 stays on floor, AP turned off
4) g3 moved 4' into next room, AP turned off
« Last Edit: November 14, 2012, 02:05:16 pm by Mark McFarlane »
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Mark McFarlane
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Mark McFarlane

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Re: network hub for Senn. G3
« Reply #4 on: November 14, 2012, 01:27:25 pm »

Here's pic 4 with AP off, g3 in 'next room' behind double-thick wallboard walls.

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Mark McFarlane
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Mac Kerr

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Re: network hub for Senn. G3
« Reply #5 on: November 14, 2012, 01:45:56 pm »

Here's pic 4 with AP off, g3 in 'next room' behind double-thick wallboard walls.

Why is there no mic transmitter on? The RF level of background noise is meaningless without a reference to what the mic transmitter is putting out. The "level" on the vertical axis does not represent normal RF type levels, which would have noise in the -100dB to -80dB range and mic transmitters in the -60dB to -20dB range. What does that scale represent?

It is clear that like most modern electronic devices your console and your access point have a certain RF noise level, but there is no way to know how important it is without knowing the level of the "good" RF.

Mac
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Mark McFarlane

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Re: network hub for Senn. G3
« Reply #6 on: November 14, 2012, 02:03:51 pm »

Why is there no mic transmitter on? The RF level of background noise is meaningless without a reference to what the mic transmitter is putting out. The "level" on the vertical axis does not represent normal RF type levels, which would have noise in the -100dB to -80dB range and mic transmitters in the -60dB to -20dB range. What does that scale represent?

...

Thanks Mac,

5. is the same as 1. but with the transmitter turned on.

6. is just a repeat of 1, as a control (over time)

Also, I made a mistake earlier, the 01V96 was not on for any of the tests, just the rest of the rack was on (DSP, 24 preamps, HD24, DEQ830, Lex verb, ADA8000)

My 'interpretation' still remains pretty much the same, I want to keep the ew300 away from the Belkin N600.

« Last Edit: November 14, 2012, 02:07:52 pm by Mark McFarlane »
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Mark McFarlane

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Re: network hub for Senn. G3
« Reply #7 on: November 14, 2012, 02:39:11 pm »

And 3 more tests with 01V off, rack on, ew300 and AP sitting on top of 01V.

7. is using an Airport Extreme (~ 4 years old) sitting right next to g3
8. is using an Airport Express (~3 years old) sitting right next to g3
9. is same as 8 after unplugging the Airport express

So 9 is similar to 3, except 3 was with transmitter off and ew300 on floor next to rack. 9 is with transmitter on and ew300 on top of rack.

The Airport Express looks pretty good except 1) I need a switch for other ethernet devices in the rack, and 2) The Belkin lets me connect a laptop wirelessly to the 01V96 using the USB port on the Belkin.

Wireless laptop isn't so important now that I have Stereoscope working fairly reliably to control the 01V96 from an iPad.
« Last Edit: November 14, 2012, 02:51:07 pm by Mark McFarlane »
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Mac Kerr

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Re: network hub for Senn. G3
« Reply #8 on: November 14, 2012, 02:49:45 pm »

My 'interpretation' still remains pretty much the same, I want to keep the ew300 away from the Belkin N600.

In every case the mic is off scale. you need to set the vertical scale so the entire trace for the mic frequency is visible. There is still no way to see the difference between the mic level and the noise level.

Mac
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Mark McFarlane

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Re: network hub for Senn. G3
« Reply #9 on: November 14, 2012, 03:07:41 pm »

In every case the mic is off scale. you need to set the vertical scale so the entire trace for the mic frequency is visible. There is still no way to see the difference between the mic level and the noise level.

Mac

I don't see any way to change the vertical scale in WSM. 

I'm also not convinced that the RF scale is relative between graphs. This is based on the repeatability of 'peaks' in measurements taken close to each other (in time) and the fact that the squelch line (yellow line) stays at 5db which is where I have it currently set.

It looks to me like WSM is using 'absolute numbers' , albeit they may not be referenced to some existing standard, they still appear consistent between all graphs. 

Therefore using these graphs to compare the noise (relative to the fixed squelch setting) introduced by the three different AP devices , and to compare the different physical positions (console, floor, next room) appears to be a valid analysis.
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Jens Palm Bacher

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Re: network hub for Senn. G3
« Reply #10 on: November 14, 2012, 03:34:35 pm »

Why is there no mic transmitter on? The RF level of background noise is meaningless without a reference to what the mic transmitter is putting out. The "level" on the vertical axis does not represent normal RF type levels, which would have noise in the -100dB to -80dB range and mic transmitters in the -60dB to -20dB range. What does that scale represent?
Mac
A competent RF tech would easily spot that the Sennheiser G3 and 2000 systems use dBuV in their rf signal strengt metres, why is that not normal rf type levels?

The top of the scale is 40dBuV = 100uV = -67 dBm in a 50 ohm system.

I agree that the scale should go higher, at least 50 dBuV
« Last Edit: November 14, 2012, 03:46:17 pm by Jens Palm Bacher »
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Mac Kerr

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Re: network hub for Senn. G3
« Reply #11 on: November 14, 2012, 03:56:17 pm »

It looks to me like WSM is using 'absolute numbers' , albeit they may not be referenced to some existing standard, they still appear consistent between all graphs. 

Therefore using these graphs to compare the noise (relative to the fixed squelch setting) introduced by the three different AP devices , and to compare the different physical positions (console, floor, next room) appears to be a valid analysis.

With the level of the mic transmitter off scale at the top of the chart there is no way to compare that level to the noise level. There is always noise at some level, what is important is how far above the noise the desired signal is.

It is always good practice to keep your RF mic receivers separated from other equipment that has RF output. This includes both intentional output, like your AP, or IEM transmitters, as well as unintended output, like the spurious output of other devices like computers and other electronics. If you have the AP in the rack with the receivers you should have remote antennas for the mics. Better yet you should also have a remote location for the AP that connects with cable to a small basic switch in the rack.

If as Jens mentions, the 40dB is really representative of -67dBm, that puts the noise level in your first graph (highest noise level) at about 20dB below that, or -87dBm, a slightly high, but not unreasonable noise level considering you are measuring near a transmitter and a digital console.

Whether or not that is a workable noise level depends on what the RF level of the mic is in normal operating conditions.

Mac
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Matt Tudor

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Re: network hub for Senn. G3
« Reply #12 on: November 14, 2012, 05:54:30 pm »

Hi,

Racking up our Senn. G3 receivers into 4-way racks I'd like to connect the ethernet management ports into a 5-way hub (1 in, 4 out) for quick setup.. and ideally one with a built in wireless AP like the TP-Link TL-WR743 or similar.

Should I be concerned about RF noise? .. is placing an ethernet switch or AP very close to a bunch of receivers likely to cause issues?

1  -has anyone had problems?
2 - any recommended make / models - We use Apple Airport Express in back of our M7's & LS9's for the audio port.. but obviously need something with at least 5 ports for a 4-way Senn RX rack... would a metal-cased unit like the Netgear Pro range help reduce noise?
3 - should i steer clear, use longer UTP cables and have a simple hub sat a few feet away?

Thanks

.gh

I have a wireless rack including 4 300G3 units with an ASA-1 splitter. I put a small 5 port Belkin router in the back of the rack. The antennas for the splitter are the little whips that came with it, mounted on the front of the rack. Never had a problem. 4 short Ethernet runs from the router to the receivers, 1 short run to an EtherCon jack on the back of the rack to get to the outside world.
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Mac Kerr

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Re: network hub for Senn. G3
« Reply #13 on: November 14, 2012, 06:01:32 pm »

I put a small 5 port Belkin router in the back of the rack. The antennas for the splitter are the little whips that came with it, mounted on the front of the rack. Never had a problem. 4 short Ethernet runs from the router to the receivers, 1 short run to an EtherCon jack on the back of the rack to get to the outside world.

That's not the same as the wireless access point Mark is dealing with.

Mac
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Jason Glass

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Re: network hub for Senn. G3
« Reply #14 on: November 15, 2012, 11:39:03 am »

A competent RF tech would easily spot that the Sennheiser G3 and 2000 systems use dBuV in their rf signal strengt metres, why is that not normal rf type levels?

The top of the scale is 40dBuV = 100uV = -67 dBm in a 50 ohm system.

I agree that the scale should go higher, at least 50 dBuV

A competent RF Tech doesn't make assumptions based on the look of the scale.  For example: WinRadio's SA window shows the same scale reference as WSM, yet when you look in the WinRadio manual, it says, "dB above the noise floor of the hardware."  If the user made the same assumption you described, his measurements would be inaccurate.
« Last Edit: November 15, 2012, 11:42:04 am by Jason Glass »
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Jens Palm Bacher

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Re: network hub for Senn. G3
« Reply #15 on: November 15, 2012, 02:06:24 pm »

A competent RF Tech doesn't make assumptions based on the look of the scale.  For example: WinRadio's SA window shows the same scale reference as WSM, yet when you look in the WinRadio manual, it says, "dB above the noise floor of the hardware."  If the user made the same assumption you described, his measurements would be inaccurate.
I didnt guess it by looking at the scale, but by seeing the tech data, that show the squelch to be adjustable from 5-25 dBuV, which corresponds with how the squelch treshold is displayed on the meter.
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Jason Glass

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Re: network hub for Senn. G3
« Reply #16 on: November 15, 2012, 06:59:20 pm »

I didnt guess it by looking at the scale, but by seeing the tech data, that show the squelch to be adjustable from 5-25 dBuV, which corresponds with how the squelch treshold is displayed on the meter.

I humbly stand corrected.  ;)
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