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Author Topic: QLXD Dropouts  (Read 575 times)

Patrick Riley

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QLXD Dropouts
« on: October 07, 2018, 10:30:56 am »

I was coordinating a show at Mandalay Bay last week & ran into dropout issues. I had around 85 H50, 20 G50, 20J50, & 10 L50 units. Counting the outside AV companies, my total coordination consisted of 150 units. I did a fresh scan, & tuned the units using IAS.
I started getting texts from the breakout room techs right away, saying that their RF levels were intermittently dropping out. I issued new freqs, but that only helped in a couple of cases. The dropouts continued, so we ordered some 100' snakes & moved the receivers behind the stage. We also increased the transmit power from low to hi, (10mw). Again, in about half of the cases, (we had around 30 problem units), this helped. It didn't help in about 10 units. I wondered if I had defective units so I did a test. I had a room with 4 mics. 2 of the freqs were rock solid, & 2 were dropping out. I had the tech swap freqs & lo & behold, the rock solid units performed flawlessly with the freqs that were dropping out on the other 2 units. This leads me to believe that there's a possibility that there could be defects in some of the QLXD transmitter or receivers.
 I sent them back to the AV company with a big white label & an email describing my ordeal. Hopefully they can bench test them & keep the faulty ones out for future shows. Has anyone else experienced a similar situation with QLXD units??
« Last Edit: October 07, 2018, 10:35:45 am by Patrick Riley »
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Jordan Wolf

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Re: QLXD Dropouts
« Reply #1 on: October 07, 2018, 08:35:45 pm »

Hi Patrick,

Can you explain how the mics were split up physically? GS vs Breakouts, etc.

That is a LOT of single kits to piecemeal together and split antennas to when you there are dual kit of ULXD /UHF-R and quad kits of ULXD/Axient that would require less effort and have fewer points of physical connection failure.

I'm going to assume you had around 40 units in the GS and 2-3 units per breakout room.

If you lowered Tx power to squeeze in more units in close proximity, I have found that the QLXD & ULXD Low power setting of 1mW is a little too weak for my liking in anything other than smaller breakout rooms - people just suck up the RF too much. The 2mW setting on Axient is pretty much perfect, IMO.

Looking forward to more info - this intrigues me!

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Tom Bourke

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Re: QLXD Dropouts
« Reply #2 on: October 08, 2018, 12:12:08 am »

I think I had those same 10 bad units a few weeks ago. Clean RF environment and all our uhf-r and ulxd were solid.  Even after hours, with everything else off, I could get the qlxd to drop at 3ft just cupping the antenna end of a handheld. It was like I didn't have the antennas on.
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Milt Hathaway

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Re: QLXD Dropouts
« Reply #3 on: October 08, 2018, 06:36:50 am »

Is it possible they needed a firmware update, or even worse the firmware wasn't matched between transmitters and receivers?
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Jason Glass

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Re: QLXD Dropouts
« Reply #4 on: October 08, 2018, 09:37:51 am »

Quote
It was like I didn't have the antennas on.

Are you guys using antenna distribution splitters?

Are your antennas attached directly to the receivers or to splitter inputs or to panel bulkhead connectors?

Any faulty component in the antenna system including coax can cause the problems you describe.

Are you absolutely certain that your whip antenna frequency bands were appropriately matched to the freq bands of the receivers?  This is a common mix up in large deployments of various freq bands.

Are you using remote antennas on mic stands?  QLXD Doesn't provide +12VDC for active antennas.

Sent from my mobile phone using Tapatalk
« Last Edit: October 08, 2018, 09:46:10 am by Jason Glass »
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Tom Bourke

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Re: QLXD Dropouts
« Reply #5 on: October 08, 2018, 11:52:58 am »

Are you guys using antenna distribution splitters?

Are your antennas attached directly to the receivers or to splitter inputs or to panel bulkhead connectors?

Any faulty component in the antenna system including coax can cause the problems you describe.

Are you absolutely certain that your whip antenna frequency bands were appropriately matched to the freq bands of the receivers?  This is a common mix up in large deployments of various freq bands.

Are you using remote antennas on mic stands?  QLXD Doesn't provide +12VDC for active antennas.

Sent from my mobile phone using Tapatalk
Our test was just the unit on a table with stock antennas. We also tried pasive paddles. Several units had the same issue. I think we even swapped transmitters and the problem followed the receivers.
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Justin Goodman

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Re: QLXD Dropouts
« Reply #6 on: October 08, 2018, 12:31:44 pm »

This is ridiculously anecdotal - so much so that it's of questionable value - but IME, there may be QC issues with QLXD.  I've gotten 2 bad systems out of like ~20 where audio signal drops out with good line of sight indoors/outdoors/high power/low power/etc. Obviously, drop outs could be any number of things, but when I've had exactly zero dropouts with every single other system and many with the exact same 2 systems dropped out all the time, it seemed like a pattern.

Retailer exchanged them for me and took care of replacement w/ Shure.
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Patrick Riley

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Re: QLXD Dropouts
« Reply #7 on: October 09, 2018, 01:24:14 pm »

Our test was just the unit on a table with stock antennas. We also tried pasive paddles. Several units had the same issue. I think we even swapped transmitters and the problem followed the receivers.

This was similar to my situation. The receivers were spread out across a 6ft banquet table, 4 per room. In half the rooms they were stacked 2 by 2. The antennas were 45 degrees apart & not touching. We staggered the receivers to achieve this. The rooms were 1500 sq ft avg. We double checked the firmware. It was current. The antennas were the right kind. We used all whips, no distro. I have to say that I feel the same way as Justin Goodman. His 10% failure rate is in line with mine. There may be a QC issue at Shure.
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Steve Litscher

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Re: QLXD Dropouts
« Reply #8 on: October 09, 2018, 02:40:08 pm »

I'll add to the anecdotal experiences...

On 9/29, we were at an outdoor event and had six (6) QLXD receiver/transmitters deployed. Using two SWB units with the whip antennas. Close proximity between transmitters and receivers - less than 30-feet, unobstructed.

One of the units started dropping audio/connectivity at random points. We rescanned and resync'd. Changed batteries, checked for interference from other sources. Problem remained.

Then, on 10/5, same rig but different venue, had the same random audio/connectivity drop-outs, but with a different receiver/transmitter combo. Eventually got it to connect consistently, but I don't fully trust either receiver right now.

When we arrive to a new venue, we check for interference, scan/program frequencies, sync the transmitters and use freshly charged SBC900a batteries. 99.9% of the time, we're using the whip antennas (not paddles), and receivers are usually within 50 feet or less of the transmitter, with clear line of sight.

Everything had been absolutely flawless for months; this all started very recently.

Brian Jojade

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Re: QLXD Dropouts
« Reply #9 on: October 15, 2018, 06:00:51 pm »

I've seen something like that with my QLX-D mics.  It seems as though the BNC connection isn't solid.  I only see the problem when using the whip antennas. Reseating the antenna often fixes it.  Using an external antenna never seems to have a problem.  I'm wondering if maybe the BNC connector on my antenna cable fits better than the whip antenna which would certainly explain the better results.
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