ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: 1 [2]  All   Go Down

Author Topic: Very Loud Noise From Church Soundsystem - Cause Unknown  (Read 8207 times)

Justin Buttelmann

  • Newbie
  • *
  • Offline Offline
  • Posts: 7
Re: Very Loud Noise From Church Soundsystem - Cause Unknown
« Reply #10 on: December 07, 2016, 10:45:53 AM »

Don,
Thanks for the feedback.  I'm wondering what it could be.  At least I have a few things I can test.
Hopefully, I'll be able to get over there tomorrow or Friday to leave the system on for an hour or so.
Logged
Justin Buttelmann

Kevin Maxwell

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1790
  • USA SW CT 46miles from MidTown Manhattan ATCF
Re: Very Loud Noise From Church Soundsystem - Cause Unknown
« Reply #11 on: December 07, 2016, 12:05:56 PM »

Don,
Thanks for the feedback.  I'm wondering what it could be.  At least I have a few things I can test.
Hopefully, I'll be able to get over there tomorrow or Friday to leave the system on for an hour or so.

Were you by any chance recording the service at the time? If you were please post the part with the noise on it if not I would suggest that you record the entire service including before the service when the sound system is on. Even record when you are testing the system so if the noise happens again you can post a bit of it here. Are there instruments that are plugged into the console and not just a mic in front of an amp? Is a digital board or an analog board?

Wiggle cables even where you think they couldn’t have been moved. Don’t try to break the cables just a little bit of wiggling. Tap on the top of the mixer and other gear with your fingers. Intermittent problems are the hardest things to find but if you approach it systematically you may find the cause. Try to only change one thing at a time. Was it hot in the room when this happened? Sometimes if heat is the issue you can use a hair drier to heat things up carefully and see if the problem shows up again.

What wireless things are used in the system? Brands model numbers and frequencies tuned to.
Logged

Justin Buttelmann

  • Newbie
  • *
  • Offline Offline
  • Posts: 7
Re: Very Loud Noise From Church Soundsystem - Cause Unknown
« Reply #12 on: December 09, 2016, 12:13:05 AM »

Yep, the sermon was recorded, and the recording has the noise in it.  I'm not entirely sure if the source of the noise was on an input to the mixer, or if the pastor's mic just picked it up.  I was going to download that file and post it, but I completely forgot.  It basically looks like normal talking and then a block where volume is maxed out.
I will be back at the church on Sunday and can post the file then.

We don't have any instruments plugged into the mixer, but we have several mics that run through an analog snake.  We place a mic in front of an acoustic guitar when needed.
There is a computer with the headphone out plugged into a mixer channel.  There are also two Shure wireless receivers plugged into different channels on the mixer.  I believe these receivers are on the same wireless channel and talk to each other so that only one produces output at a time.  We occasionally lost reception in the past using only one receiver.

Here are some model numbers of our equipment:
RackRider RR-15 Power Conditioner
Mackie CFX16 Mixer
DBX 1531X Graphic Equalizer
QSC USA850 Amp (sanctuary)
QSC USA370 Amp (nursery and narthex)
Monoprice Pro Audio Series snake

I tried jiggling cables today and was not able to reproduce the problem.  I haven't tried with a hairdryer yet, but did notice that the sanctuary amp is quite dusty on the inside and needs to be cleaned.
Also, there was a 1/4" phone jack cable plugged into a mixer input and unplugged on the other end.  Our other sound guy was using it for playing audio from a laptop.  I wonder if it's possible this cable was picking up RF from my cellphone looking for cellsites.  I believe the cable is shielded, but even the tip could pick up some noise.

I'll get the model numbers and frequencies of our wireless equipment this weekend.
Logged
Justin Buttelmann

Kevin Maxwell

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1790
  • USA SW CT 46miles from MidTown Manhattan ATCF
Re: Very Loud Noise From Church Soundsystem - Cause Unknown
« Reply #13 on: December 09, 2016, 12:33:27 AM »

Yep, the sermon was recorded, and the recording has the noise in it.  I'm not entirely sure if the source of the noise was on an input to the mixer, or if the pastor's mic just picked it up.  I was going to download that file and post it, but I completely forgot.  It basically looks like normal talking and then a block where volume is maxed out.
I will be back at the church on Sunday and can post the file then.

We don't have any instruments plugged into the mixer, but we have several mics that run through an analog snake.  We place a mic in front of an acoustic guitar when needed.
There is a computer with the headphone out plugged into a mixer channel.  There are also two Shure wireless receivers plugged into different channels on the mixer.  I believe these receivers are on the same wireless channel and talk to each other so that only one produces output at a time.  We occasionally lost reception in the past using only one receiver.

Here are some model numbers of our equipment:
RackRider RR-15 Power Conditioner
Mackie CFX16 Mixer
DBX 1531X Graphic Equalizer
QSC USA850 Amp (sanctuary)
QSC USA370 Amp (nursery and narthex)
Monoprice Pro Audio Series snake

I tried jiggling cables today and was not able to reproduce the problem.  I haven't tried with a hairdryer yet, but did notice that the sanctuary amp is quite dusty on the inside and needs to be cleaned.
Also, there was a 1/4" phone jack cable plugged into a mixer input and unplugged on the other end.  Our other sound guy was using it for playing audio from a laptop.  I wonder if it's possible this cable was picking up RF from my cellphone looking for cellsites.  I believe the cable is shielded, but even the tip could pick up some noise.

I'll get the model numbers and frequencies of our wireless equipment this weekend.

Is your cell phone an iPhone? Did the noise sound at all like a lawn water sprinkler? Please confirm the model number of the 2 Shure wireless receivers and the exact frequencies that they are tuned to. And are they really used with both channels of it up at the same time? Can you also take a picture of the back of the wireless receivers and post it here? 
Logged

Tim Weaver

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3689
  • College Station, Texas
    • Daniela Weaver Photography
Re: Very Loud Noise From Church Soundsystem - Cause Unknown
« Reply #14 on: December 09, 2016, 02:47:32 PM »

Is your cell phone an iPhone? Did the noise sound at all like a lawn water sprinkler? Please confirm the model number of the 2 Shure wireless receivers and the exact frequencies that they are tuned to. And are they really used with both channels of it up at the same time? Can you also take a picture of the back of the wireless receivers and post it here?

Its not just iPhones that do this. What you're hearing is the radio broadcasting over GSM, GPRS, or Edge. It causes that dut do dut dut dut noise we hear when the phone is close to just about anything with circuits in it and a speaker attached to it.
Logged
Bullwinkle: This is the amplifier, which amplifies the sound. This is the Preamplifier which, of course, amplifies the pree's.

Jonathan Johnson

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3209
  • Southwest Washington (state, not DC)
Re: Very Loud Noise From Church Soundsystem - Cause Unknown
« Reply #15 on: December 12, 2016, 08:17:44 PM »

Yep, the sermon was recorded, and the recording has the noise in it.  I'm not entirely sure if the source of the noise was on an input to the mixer, or if the pastor's mic just picked it up.  I was going to download that file and post it, but I completely forgot.  It basically looks like normal talking and then a block where volume is maxed out.
I will be back at the church on Sunday and can post the file then.

As you have probably figured, anytime you've got a loud noise in the room, any open mic is going to pick it up. So having a separate recording of each mic input probably isn't going to help identify the source.

Every time you hear the noise, make a note of which inputs are NOT muted. You can pretty safely eliminate muted inputs as the source of the noise. (It's still possible for a significant voltage spike to occur on a muted input and cause a noise, but unlikely.)

Each time it happens, if different inputs are muted, you'll be able to narrow it down to just a few inputs as a possible source. (Pay attention to any repatches between occurrences.) If you can eliminate something because it is not in use at the time that will help troubleshooting tremendously.

Do you have access to a multitrack recorder? You can use the "insert" jacks as a direct out (see page 8 of the manual) to a multitrack recorder. By recording each input separately, you'll be able to see which inputs register the noise. Most likely, all of the mics will register it, so we can ignore them as "inconclusive". As for other instruments, a guitar with a pickup *might* register it, even if it's not the source. If some other source registers the sound on the multitrack recording, there's high likelihood that channel is the source. (Note that with some recording devices, if you have the output connected to a mixer channel, you might register the noise because the output of the recorder mirrors the recorder's input.)

You can also use the multitrack as a troubleshooting device by tapping off each connection in the signal chain (between mixer and EQ/Processor, between EQ and crossover, between crossover and amp, etc.). Because of open mics, it will probably register on every "tap." But if, say, the EQ is causing the problem, you'll notice a difference in the sound (or waveform appearance) of the noise before and after the EQ.
Logged
Stop confusing the issue with facts and logic!

Jonathan Johnson

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3209
  • Southwest Washington (state, not DC)
Re: Very Loud Noise From Church Soundsystem - Cause Unknown
« Reply #16 on: December 12, 2016, 08:23:48 PM »

Also, there was a 1/4" phone jack cable plugged into a mixer input and unplugged on the other end.  Our other sound guy was using it for playing audio from a laptop.  I wonder if it's possible this cable was picking up RF from my cellphone looking for cellsites.  I believe the cable is shielded, but even the tip could pick up some noise.

Not necessarily RF, but if a cable is plugged into an input but not plugged into an output, anything contacting the tip of the cable can cause very loud noise in the channel to the point of clipping that channel. I've had this issue with my Mackie mixer (Onyx 1640) where even a muted channel can bleed into the main mix when this happens.

On second thought, I believe there was a DI box in the line (1/4" guitar cable to active DI to XLR to mixer; guitar cable laying on the ground) so maybe it was more an issue with the DI than with the mixer. Even so, a disconnected cable plugged into an input can cause problems if the tip touches something.
Logged
Stop confusing the issue with facts and logic!

Don T. Williams

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1058
  • Midas Pro 1 & 2, M32, dbTech T12, T8, S30, DM12
    • Q Systems Music & Sound
Re: Very Loud Noise From Church Soundsystem - Cause Unknown
« Reply #17 on: December 12, 2016, 11:12:51 PM »

This may (or may not) be out there, but is it possible that someone with a hearing aid could be near an open mic.  Hearing aids tend to have upper mid-range feedback frequencies.

I have spent considerable time soloing channels and output busses trying to find the elusive mic feeding back on stage only to discover it was an audience member's hearing aid 20 rows in front of the house mix position.  The persons wearing the hearing aids really don't know they are feeding back!
Logged

ProSoundWeb Community

Re: Very Loud Noise From Church Soundsystem - Cause Unknown
« Reply #17 on: December 12, 2016, 11:12:51 PM »


Pages: 1 [2]  All   Go Up
 



Site Hosted By Ashdown Technologies, Inc.

Page created in 0.032 seconds with 26 queries.