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#1 unc417

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Posted 02 May 2013 - 03:27 PM

dboomer and ronmartin

 

To continue the old forum conversation

 

I finally have an update: All the line6 receivers, now going through an AD8, are on a single receptacle. All other audio equipment is sharing another receptacle. There is no difference in the strange sound.

 

I have not yet tried rf2, I will if you think that's still worth considering. An rf scan on the receivers show 1-4 clear, the rest have medium to high interference. I'm on power save and 50-70ft distance. Is this ok?

 

thanks


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#2 Sheriton

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Posted 03 May 2013 - 06:32 AM

It's perhaps worth clarifying the difference between WiFi channel numbers and Line6's transmission channel numbers - they're not the same thing at all. I've not yet looked at this in any detail yet but I'm sure Dboomer can give a definitive description.

I know the channel scan facility on the V75 receivers shows active L6 mics on their respective transmission channels numbers but what exactly is it scanning? Each transmission uses either two or four WiFi channels (depending on the RF mode) so if interference is shown on channel eight, for example, where is that interference? Is it on WiFi ch.8? Or one of the two frequencies that L6 ch.8 uses in RF2 mode? Or one (or more?) of the four frequencies it uses in RF1? Or something else?


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#3 dboomer

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Posted 03 May 2013 - 12:51 PM

I'm on power save and 50-70ft distance. Is this ok?

 

thanks

 

It all depends (doesn't it always :) )  As long as you aren't gettiing any dropouts I guess it's fine.  The tools in setup mode all work only on RF2 mode.  So channel scan won't tell you anything usefull except that transmitters are on mode mode or the other when operating in RF1 mode.  It cannot scan for RF1 channels.  Also if you are in RF2 mode you can actually track data errors which is a good way to see if your antennas are setup efficiently and whether using high or low power is working better in your venue.

 

You should definately try switching over to RF2 mode and see if it helps.  That's whay we built it.  In some cases it works better than RF1 mode and visa versa.  Just scan for channels first and pick the best ones you can find.  Usually you should be able to get 8 channels with relative ease if only a single wi-fi channel is also in operation.



#4 unc417

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Posted 04 May 2013 - 11:48 AM

I have 2 wifi channels in use.  

 

The receiver shows 1-4 clear.  It's easy to see where the wifi shows up on the scan.  In the middle and high channels there are a couple channels showing high interference, and those channels are surrounded by channels with medium interference.

 

What do you mean by rf2 being created for this? I thought it was more like the other way around. I thought rf interference from wifi was more likely in rf2, and rf1 should be more immune to any type of interference?  I'll try it next week, but I'm still trying to understand how it could make any difference at all, especially a difference to the positive.

 

thanks


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#5 dboomer

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Posted 05 May 2013 - 07:39 AM

The RF2 mode allows for interference avoidance while RF1 mode works more by interference immunity. Depending on the local interference in your venue, one method may work better than the other.  

 

If Wi-Fi is your interference then it is in a fixed, known frequency band and you can steer around it.  Scanning allows you to find clear channels and move to them. Almost every other wireless system works with a system avoidance scheme.

 

So back to your popping issue.  Does it still happen in RF2 mode?



#6 unc417

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Posted 05 May 2013 - 11:07 AM

I will change to rf2 now, next band practice is Wednesday. I left it on rf1 for today's services, I don't like to make any more changes than I have to after the Wednesday practice if I can make the change before practice. 

 

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#7 unc417

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Posted 08 May 2013 - 07:04 PM

I used rf2 today, and do not think it's going to work out.

 

Firstly, I did not notice any popping sound, but 1 practice session is not enough to convince me that the problem does not exist in rf2.  I would prefer to have a few more practices before being sure about it. I am a bit concerned about the reliability.  I tested this afternoon before the band arrived, 4 of the 7 systems had all of the green rf led's constantly going on and off, even though the rf scan showed little to no interference there. I turned off both wifi ap's, and turned the transmit power to high, and some of the systems still had rf dropouts. 

 

It isn't reliable enough to go through performances Sunday, I will have to go back to rf1.  I can continue this for a few weeks if you think it's necessary, running rf2 with no wifi on Wednesday practices. 

 

I also have new p180 paddles, I was planning to install them soon.  But wanted to troubleshoot this a step at a time. The nearest ap will be behind the paddles, but there is 1 ap directly above the stage on the 2nd level of the building. So the paddles will "see" that wifi signal. 

 

Thanks


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#8 RonMarton

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Posted 24 May 2013 - 04:23 AM

Line 6's revamp of these forums initially seemed to have dropped all of us "old hands" (and all the past posts) into limbo, hence this delayed reply...

 

I've just a couple of comments.

 

From memory, the sample I heard really didn't sound like anything I would expect from RF interference to my XD-V systems, so I remain uncertain as to the actual cause.

 

Nonetheless, the sooner you can arrange good locations for your P180 antennae, the better.

 

If at all possible, it would be great if one of your diversity pair was able to look "down from above", (even if only slightly) in order to back-reject that overhead wireless access point (above your stage) as much as possible.

 

My nine XD-V systems are regularly required to work quite close to heavy 2.4GHz traffic, which is when I almost invariably operate using the RF1 scheme, with my transmitters often (but not always) set for maximum (10mW) power. 

 

In this mode, I can honestly report consistent, trouble-free and simultaneous operation of my nine channels, with no interruptions to my green "RF" LED columns, given that my transmitters are being received via my P180s with their inbuilt amplification correctly configured for up to 100 feet of LMR-195 coax. 


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#9 unc417

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Posted 24 May 2013 - 05:21 AM

Thanks for the response. 

 

I really do not understand the rf2 mode not working. I have used it briefly in the past without major issue. Also I noticed last Wed at practice that even on rf1, a couple of my mics had a few brief dropouts. I've never had a dropout in rf1 before. I was using rf1 low power like I always have. The only new thing right now is the addition of the AD8, whereas previously I had 2 antenna chains using the built in distro ability.  I'm not sure if that's of any relevance or if something else has changed that I'm not aware of.

 

I will get the paddles installed soon. Though I'm not sure how to work out the look-down-from-above position.  I have 2 25 ft cables, and was planning on mounting the paddles on my camera platform that is sitting next to the foh platform and is elevated higher. I think I have just enough cable to do it such that they can be mounted a few feet apart. They will be mounted about 7-8ft off the ground, putting them above the congregations heads. The stage is elevated 2 ft off the main floor, so line of sight shouldn't be an issue. But I don't think this will get the 2nd level wifi ap out of sight.  I don't know if that's even possible without putting an antenna on stage.  I can turn the 2nd level ap off temporarily for troubleshooting purposes, but long term I need to find a way to make everything work together nicely.

 

Thanks


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#10 RonMarton

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Posted 24 May 2013 - 05:59 AM

As you say that this latest RF dropout problem only arrived with the XD-AD8, it may be worth double-checking the correctness of every single connection made, ...both from your pair of antennae to the XD-AD8 ...and via the short LMR-195 cables from each of the XD-AD8's RF outputs into each of your receivers' antenna inputs.

 

I don't remember whether you've got V70 receivers, V75 receivers or a mixture of both.

 

So another vital point is that, when individually feeding receivers from an XD-AD8,  the older V70s must have their supplied terminator plugs on their individual "RF Out" BNC connectors, whereas on no account should the newer V75s have anything connected to their "RF Out" BNCs.

 

Given the greater distance from the 2nd level overhead access point to your receivers, my experience leads me to think that (provided the above wiring is correct) a pair of P180 paddles facing the stage as you describe really should give rock-solid and trouble-free RF1 performance for all the receivers you have running from your XD-AD8, with high transmitter power generally only being needed to "tread on" such 2.4GHz traffic as might "walk in".


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#11 unc417

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Posted 24 May 2013 - 06:40 AM

I have all v70's. They do all have terminators.

 

I'll let you know how the paddles work out.

Thanks


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#12 unc417

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Posted 29 May 2013 - 11:25 AM

I have the paddles installed.

 

A couple of small questions.

 

Using rf1 and either hi or low power, a couple mics show slightly fluctuating signal in the led column, while the A-B indicators are solid. This is with 60 ft line of sight..

 

Also, according to the L6 docs I found, the 3db gain is for 16ft cable length while the 12db gain is for 65ft cable. I'm using 25 ft cables. Does it make any meaningful difference which gain I choose? 3db because it's closer, or 12 db because it's the lowest value that is made to cover for 25 cable?

 

Thanks


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#13 RonMarton

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Posted 29 May 2013 - 12:35 PM

"...a couple mics show slightly fluctuating signal in the led column..."

 

That's perfectly normal ...and I'd guess that the slight RF fluctuations for the two receivers in question are the only remaining effects of whatever RF was giving you huge grief with the previously inadequate rig ...and that the previous inadequacy probably arose from those whip antennae being attenuated by some physical aspect of (and/or metal-induced contribution from) their rigging.

 

 "Does it make any meaningful difference which gain I choose?"

 

It certainly does.

 

Too little cable-compensating head amp gain is the easier to diagnose by dint of the low RF indications that show on receivers' front panels that often coincide with muting,

 

...whereas...

 

Too much will not only yield falsely high RF readings, (probably because it's "forcing" more undesirable 2.4GHz traffic down the cables, along with the targeted signals) but also generate muting that's then a lot harder to diagnose.

 

My rule of thumb for a given installation is to set and stick with the least head amp gain that's proven to be "safe" on a walk test in "battery save" mode ...and I suspect that the 3dB setting may be all you'll need.

 

As for then deciding the transmitters' power levels, ...if it's not practical to arrange a backstage "all mics on" pre-show test in the presence of a "sold out, standing room only" audience, I arrive at a "full power" or "battery save" decision based on another test with a single mic's transmission antenna being deliberately attenuated to "simulate" such problems as may later arrive.

 

If an assistant is available for the "walk", they provide the attenuation by deliberately "cupping" the antenna in their free hand, while orientating themselves at maximum range so that their entire body "blocks" the line of sight from transmitter to receiving antennae.

 

In the absence of an assistant, a reasonable "worst case simulation" can often be achieved by attenuating transmission through placement of the test transmitter inside a metal receptacle, such as a trash can or (moisture free) ice bucket that's located at maximum range.

 

Once you've optimised the rig we've been discussing, I'd now expect RF1 to yield a performance from your handhelds that will be rock solid in the direction you've aimed the P180s, seemingly all the way to the boundary of your suburb's zip code!   :)


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#14 dboomer

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Posted 30 May 2013 - 07:20 AM

The RF LEDs on the front panel are not RF strength (RSSI) but rather more an indicator of packet quality.  As long as you have any, you still have audio.  But you should experiment with antenna placement though to get the best you can.

 

The A & B triangles are RSSI meters.



#15 unc417

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Posted 06 June 2013 - 10:00 AM

Thanks for the info.

 

I'll give a short update.

 

After having more rf dropouts than ever before, I've removed the paddles and am back to using the standard 1/2 wave antennas on the AD8.  Though I still seem to be having a few dropouts. It seems as if this started when I added the AD8. I may try going back to the built in distro system if I continue to have rf issues.  

 

Back to the original problem, I'm still hearing the unexplained clicking type sound in the audio.  Any other ideas?

 

I'm considering buying a Shure GLX-D to try out.  


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#16 dboomer

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Posted 06 June 2013 - 10:58 AM

If you can send me a wav file recording I can analyze it for you.

 

Also ... do you have dropouts if only one transmitter is running and then get more if you turn on other units?

 

Where are you located?

 

Not sure I ever answered your question about paddle gain ... use the lowest first



#17 unc417

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Posted 06 June 2013 - 11:15 AM

Here is the sample I linked to in the original post.

https://dl.dropboxus...gital noise.wav

 

3 of the 7 transmitters were on at my last practice.  1 was solid. One another unit, the rf column varied but never completely dropped. The 3rd system dropped numerous times.  Granted, turning around backwards so that the singers back was towards me made it worse, but it also dropped when the singer was directly facing me, and to be honest before I added the AD8, I never had any rf issues of any kind regardless of position.  The AD8 addition may be a coincidence, but I don't know of anything else that has changed.

 

I was using the lowest setting on the paddles from your recommendation.  I still experienced pretty iffy rf performance after switching back to the standard whip antennas part of the way through practice. Though it didn't seem quite as bad, didn't have enough time for a more precise comparison though.

 

I'm in NC. 

 

Thanks


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#18 RonMarton

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Posted 06 June 2013 - 12:53 PM

...And Don, more "environmental" details along with of our previous laborious canvassing of this issue can be found here http://line6.com/sup.../91299?tstart=0.


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#19 dboomer

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Posted 07 June 2013 - 02:08 PM

Forgive me because I've probably asked before.  It's hard to keep track with the forum change ...

 

Does the "popping" sound change if you switch back and forth between high and low power on the transmitter?

 

Has the popping always been there or did it start after you had used the systems for a while?

 

Are you using LMR-195  coax cable with the AD-8?



#20 unc417

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Posted 07 June 2013 - 04:16 PM

No the sound does not change based on power.

 

It's always been there.  It must be something environmental, all 7 systems were purchased at different times, from multiple sources. I doubt that they would all have the same defect.

 

Yes on the cable.


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