Stray Click

B

Bill Hart

Freshman
Mar 13, 2014
4
0
0
Hi everyone,

I'm looking for input on tracking down a stray intermittent click.

I've got a client that I sold a simple small analog system to that started sending me clips of a click that was occurring on 2 different recording devices as well as the house PA.

The basic sic set up is a Shure ULXP lav split into 2 channels of a Midas Venice U24. There's a dbx compressor inserted on one of the lav channels and the other feeds the 2 recording devices (tascam flash recorder and a zoom flash recorder via 2 different auxes. The house loudspeakers are mackie SRM450 or similar. They're also using a Hear Technologies self mix type system. I've got a Furman power conditioner distributing AC.

The click doesn't sound like RF interference, bad cable, or clipping. It's a single click that looks similar to an impulse trace. I have not been able to replicate it on demand, but I have positively ruled out a few elements:

- it's not the ULXP. I've swapped that out.
- the XLR cable and the XLR Y cable have been changed
- the compressor and the insert cables have been removed
- static is not likely because it's a tile environment.

What I have not been able to try:
- a different mixer.
- confirm phantom is off
- rule out the PA
- bumping to different inputs

i don't have easy access to the system, so I'm brainstorming and trying a little at a time. I hate to think it's the mixer, but it's looking more and more like it. I've never had a problem using a Y cable to split an input either. It has to be something that ties back to the Y though, since it's coming through both RF inputs. I doubt it's the Y itself since (A) it got changed and (B) it sounds like an electronically generated click.

Does anyone have any brilliant ideas? This is a stumper. I could see phantom being problematic, but I have to wait to see if it's on.

Im standing by to get it back in the shop to test it further, but I would appreciate any ideas anyone may have.

Thanks,
Bill
 
Re: Stray Click

Phantom power on the inputs or something coming in on the RF. To check for something coming in via RF, unplug the RF receiver from the console and put it straight into a recorder (checking that the recorder is not supplying phantom on the input) and record the RF for a day and see what you end up with.
 
Re: Stray Click

Hi Andrew,

Thanks for chiming in. I've got the client double checking the phantom, just in case already, but I won't know until Monday. I have tried removing the RF system from the rest and recording it for a day. I didn't find anything. While I was doing that, he was using a back up (known good) RF system and experienced the click again. That's why I ruled out the RF.

Thanks
Bill
 
Re: Stray Click

Bill Hart said:
Hi Andrew,

Thanks for chiming in. I've got the client double checking the phantom, just in case already, but I won't know until Monday. I have tried removing the RF system from the rest and recording it for a day. I didn't find anything. While I was doing that, he was using a back up (known good) RF system and experienced the click again. That's why I ruled out the RF.

Thanks
Bill
Click to expand...
When you recorded the RF, was it in the same room? I'm not saying that the RF receiver has a problem, but that there might be something in that room that's sending spurious RF hash once in a while that's producing a click.
 
Re: Stray Click

Unfortunately, I don't have access to the client's room, so I had to test it back at our shop. The client is a church that sets up in a middle school on Sundays. He never experienced the click using his older (now back up) wireless and his original system. I set him up with the new mixer, RF, comp, EQ and recorder and has suddenly started getting the click.
 
Re: Stray Click

This is probably a long shot but few years ago I had experienced a similar problem with an AT wireless system and it turned out to be the cheap off brand batteries the were using.
doug j.
 
Re: Stray Click

Bill Hart said:
The basic sic set up is a Shure ULXP lav split into 2 channels of a Midas Venice U24. There's a dbx compressor inserted on one of the lav channels and the other feeds the 2 recording devices (tascam flash recorder and a zoom flash recorder via 2 different auxes. The house loudspeakers are mackie SRM450 or similar. They're also using a Hear Technologies self mix type system. I've got a Furman power conditioner distributing AC.

The click doesn't sound like RF interference, bad cable, or clipping. It's a single click that looks similar to an impulse trace. I have not been able to replicate it on demand, but I have positively ruled out a few elements:
Click to expand...

You don't mention whether or not anything is connected to the USB digital input. Random intermittent clicks is a common symptom of digital clocks not in sync.

Mac
 
Re: Stray Click

Digital clock mismatch was an early thought, but nothing is connected digitally. The USB Buss is not used at all.
Tried changing frequencies. No difference.
Havent tried different batteries yet.
Full on troubleshooting onsite unfortunately is not an option. It's a school. They get enough time to get in and get out.

Thanks for the suggestions!
 
Re: Stray Click

Bill Hart said:
Digital clock mismatch was an early thought, but nothing is connected digitally. The USB Buss is not used at all.
Tried changing frequencies. No difference.
Havent tried different batteries yet.
Full on troubleshooting onsite unfortunately is not an option. It's a school. They get enough time to get in and get out.

Thanks for the suggestions!
Click to expand...

Then neither is a solution to the problem if it's an RF issue. I think you're going to spend a Sunday morning attending to their service at FOH or you'll end up eating this sale.
 
Re: Stray Click

Bill Hart said:
Digital clock mismatch was an early thought, but nothing is connected digitally. The USB Buss is not used at all.
Tried changing frequencies. No difference.
Havent tried different batteries yet.
Full on troubleshooting onsite unfortunately is not an option. It's a school. They get enough time to get in and get out.

Thanks for the suggestions!
Click to expand...

Tim McCulloch said:
Then neither is a solution to the problem if it's an RF issue. I think you're going to spend a Sunday morning attending to their service at FOH or you'll end up eating this sale.
Click to expand...

+1

When you cannot reproduce a recurring problem offsite that you suspect is caused by RF or EMI, you must test onsite because many of the most critical variables are site-specific.

Keep in mind that transient broadband RF and EMI can cause problems in non-RF gear. For example, a bug zapper on the loading dock, on the other side of a venue wall, can cause all kinds of problems with the system. Motor-startup capacitors on HVAC, faulty lighting ballasts, and many other common devices can generate harmful signals.
 
Re: Stray Click

Yep, there's tons of things that could cause an occasional click. I've got a couple ulxp's in an install that seem to occasionally cause a super fast little click, I noticed it seemed to sort of line up only with when they were unmuted and hot, and when the cheap UPS that my client had, that the units were plugged into, would kick in during a quick voltage drop or something. I switched the units over to a much better UPS (2-4 millisecond transfer time). I must confess that I have not heard from my client yet if that fixed the problem or not. I'll find out if it worked or not this weekend when I do an event there actually.
 
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