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[Stephen Swaffer]

I have been fighting noise on our church sound system for months.  Very erratic sometimes very minimal other times unbearable.  I have chased it and one time it seems like it is from one mic or set of mics, the next somewhere else.  I was able to eliminate (or at least greatly reduce it) for about 2 weeks by cleaning all of the jacks on the platform with De-oxit.

Unplugging nearly all of the mics at the mixer also helps-though it defeats the purpose!

Most of the mic jacks have been in place 10 years or longer and we use special effects every year at Christmas time that I can't help but think contribute to degrading of the jacks.

I have recommended wholesale replacing the jacks, but am being asked my confidence level in this curing the problem.  The mixer is an A&H GL3800.  (Which I recently cleaned ) Could there be a problem with the mixer making it more susceptible to static, or does my approach seem reasonable?

[Lee Buckalew]

I have been fighting noise on our church sound system for months.  Very erratic sometimes very minimal other times unbearable.  I have chased it and one time it seems like it is from one mic or set of mics, the next somewhere else.  I was able to eliminate (or at least greatly reduce it) for about 2 weeks by cleaning all of the jacks on the platform with De-oxit.

Unplugging nearly all of the mics at the mixer also helps-though it defeats the purpose!

Most of the mic jacks have been in place 10 years or longer and we use special effects every year at Christmas time that I can't help but think contribute to degrading of the jacks.

I have recommended wholesale replacing the jacks, but am being asked my confidence level in this curing the problem.  The mixer is an A&H GL3800.  (Which I recently cleaned ) Could there be a problem with the mixer making it more susceptible to static, or does my approach seem reasonable?

Can you describe the "static" or do you have a recording of it that you could link to?

Does it occur only when...
Congregants present
Choir or musicians are in place
Certain days of the week or times of day
Etc.,
Etc.

Have you tried unplugging only at the stage or have you unplugged connections from the console?
Unplugged one at a time (while soloing the output to headphones) and then plugged that one back in and moved on or unplug, leave unplugged, unplug next, leave unplugged, unplug next... until all are unplugged?

More detail will help us to help you troubleshoot.

Lee

[Ivan Beaver]

Lee has given some good advice.

The whole "trick" is to divide and conquer.

Just because a console was "cleaned" does not mean anything.

What exactly was "the cleaning"?

Start with listening (solo) on each channel to see what channels are causing the problem.

Then unplug the input to that channel?  Did the problem go away?

You said that unplugging "most" of the connectors helped?  What were you listening to at that point?

You HAVE to go channel by channel.

That tells you which way to start to look-the console or the input.

If it is the jacks are on stage, then using some contact cleaner (NOT WD40!!!!!!) and spraying into the jack and working a CLEAN connector in and out can help to clean it.

 But if the problem is in the mixer-replacing the jacks on stage is a waste of time and money.

[Stephen Swaffer]

Cleaning consisted of unplugging every ribbon connector and cleaning with de-oxit followed by de-oxit gold per manufacturers recommendations.

I will try to post a recording.  Best description is a very "airy" sometimes faint, often is hardly noticed by congregation, but at times can be very harsh.

I thought maybe a CFL ballast, but on a Saturday afternoon. With all lights in building off still had the issue.

Soloing does not help-noise is present in mixer no matter what I listen too-solo any channel, main, L-R.

This last service, pastor asked me to "do something".  Choir mics have seemed to contribute most to the problem so I unplugged them at the mixer and things improved greatly-pastor's dad was preaching so he text me that got it.  About 3 minutes later more static.  His dad was using a cordless mic so, I pulled other mics.  Still had 7 wireless plugged in, as well as 3 wired mics-baptistery, pulpit and piano, but zero static for the ready of service-say 45 minutes or so.

As for doing one at a time, I'd love to - that is basic troubleshooting, but the Saturday I had the lights off I thought I had it after a change but 15 minutes later more noise.  I suppose I could spend 2 or 3 40 hour weeks but that seems like an excel is in futility.

[Lee Buckalew]

Cleaning consisted of unplugging every ribbon connector and cleaning with de-oxit followed by de-oxit gold per manufacturers recommendations.

I will try to post a recording.  Best description is a very "airy" sometimes faint, often is hardly noticed by congregation, but at times can be very harsh.

I thought maybe a CFL ballast, but on a Saturday afternoon. With all lights in building off still had the issue.

Soloing does not help-noise is present in mixer no matter what I listen too-solo any channel, main, L-R.

This last service, pastor asked me to "do something".  Choir mics have seemed to contribute most to the problem so I unplugged them at the mixer and things improved greatly-pastor's dad was preaching so he text me that got it.  About 3 minutes later more static.  His dad was using a cordless mic so, I pulled other mics.  Still had 7 wireless plugged in, as well as 3 wired mics-baptistery, pulpit and piano, but zero static for the ready of service-say 45 minutes or so.

As for doing one at a time, I'd love to - that is basic troubleshooting, but the Saturday I had the lights off I thought I had it after a change but 15 minutes later more noise.  I suppose I could spend 2 or 3 40 hour weeks but that seems like an excel is in futility.

You have not yet described the noise.
Is it like bacon frying?
Is it like the background noise of a vinyl record?
Is it like pink noise?
Is it like white noise?
Is it a constant sound (when it is occurring) or does it change?
In what way does it change?
Is there a noticeable pattern?

Does it only happen when other people are present (along with their electronic devices) or does it also happen with no one else around?

Are you saying that the noise is present through headphones no matter what you have soloed?

What is the sound console?

Lee

[John Roberts {JR}]

Cleaning consisted of unplugging every ribbon connector and cleaning with de-oxit followed by de-oxit gold per manufacturers recommendations.

I will try to post a recording.  Best description is a very "airy" sometimes faint, often is hardly noticed by congregation, but at times can be very harsh.

I thought maybe a CFL ballast, but on a Saturday afternoon. With all lights in building off still had the issue.

Soloing does not help-noise is present in mixer no matter what I listen too-solo any channel, main, L-R.

This suggests noise is output related. So stop wasting time cleaning input jacks.

This last service, pastor asked me to "do something".  Choir mics have seemed to contribute most to the problem so I unplugged them at the mixer and things improved greatly-pastor's dad was preaching so he text me that got it.  About 3 minutes later more static.  His dad was using a cordless mic so, I pulled other mics.  Still had 7 wireless plugged in, as well as 3 wired mics-baptistery, pulpit and piano, but zero static for the ready of service-say 45 minutes or so.

inputs? this disagrees with earlier statement.

As for doing one at a time, I'd love to - that is basic troubleshooting, but the Saturday I had the lights off I thought I had it after a change but 15 minutes later more noise.  I suppose I could spend 2 or 3 40 hour weeks but that seems like an excel is in futility.

You must divide and conquer, otherwise you are just hoping to get lucky,

It may not be one simple connection, could be an external noise source getting in through one of multiple vectors.

Start by isolating all the things it isn't. When finished what's left is what it is. (sorry about the cliche).

Does the noise fall and go away when you drop the main fader?

You will find it eventually but it will take some time and effort.

JR

PS Noise can come in through outputs and even through power cords, so keep looking at everything.

[Ivan Beaver]

Soloing does not help-noise is present in mixer no matter what I listen too-solo any channel, main, L-R.

Please don't take what I am going to say the wrong way.

I have dealing with "other people troubleshooting" over the phone for many years.

VERY often people say things that simply are not true-or they don't know the answer to and they "give an answer" even though they don't know the answer.

This seemingly innocent statement can cake somebody who actually knows what is going to chasing off in a wrong direction.

This is true when talking to your doctor, auto mechanic etc.

It is FAR FAR better to simply say "I don't know" rather than give a  wrong answer.

First of all-am I to "assume" that you are "properly soloing?"

Meaning listening to ONLY ONE channel at a time? Making sure ALL OTHERS are NOT engaged?

And by "soloing" I am again assuming you are listening on headphones and not just pressing solo button while listening to the speaker system.

There are all kinds of people who say things that we assume are being done properly, but they are not doing that

All that being said-with the statement I copied above from your post, there are only 2 places the problem could be.

Either the power supply in the console-or a something in a "master board" (I don't know how your console is electrically/physically laid out) that is on a "master board" that also has the solo amp on it.

Have you tried simply "beating on the console? dropping it a couple of inches and such?

You could have an intermittant in the console.

It DOES NOT sound like it would be outside the console.

But it could be-but I would not even begin to look there-BASED on the statement I copied.

[Stephen Swaffer]

It may not be one simple connection, could be an external noise source getting in through one of multiple vectors.

Start by isolating all the things it isn't. When finished what's left is what it is. (sorry about the cliche).

Does the noise fall and go away when you drop the main fader?

PS Noise can come in through outputs and even through power cords,

This is what I feel like is happening-external noise coming in through multiple vectors.

Perhaps a better description would be like the static you hear on an AM radio during a distance thunderstorm.  Completely random fades in and out then stops completely then comes back-or not!  The only thing that seems to affect it is disconnecting inputs-or in some cases shutting off phantom power to mics seems to help.  Disconnecting something seems to be a definite cure-noise stops instantly, then it r-occurs at some random time even with that stil disconnected.  Makes me think I am disconnecting the "antenna"-or one of them.

The console is an A&H GL3800.  The Saturday I was working in it, I had the building to myself.  I did have my phone on me-not a smart phone.  Turning off the console did completely eliminate the noise. 

Yes, I hear the noise no matter what is soloed.

So it is not the amps/outboard gear-definitely getting into the mixer.
It is not an isolated channel-at least not on signal wires because it happens even with everything muted.

Ivan, I understand. My background is troubleshooting industrial machinery.  I was the go to guy in a facility for a number years until I got tired of factory life, so I am usually very thorough and have experience on the receiving end of tech support.

Yes, I am soloing as you describe.

If console repair/removal and substitution for repair and jack replacement were anywhere near the same amount of "pain and suffering", I'd likely lean towards the console for something to try.  If I could consistently re create the problem I would.

[Lee Buckalew]

So, with all inputs and all outputs disconnected you still get the noise through the headphones either when any individual input or output is soloed?

Does this also occur when your phone is off (not silent, off)?

If all of this is the case and you have thoroughly isolated the problem to the console/PS and eliminated the possibility of RF then you know what needs to be tested.

Lee

[John Roberts {JR}]

This is what I feel like is happening-external noise coming in through multiple vectors.

Even if noise is entering from multiple vectors it is probably being rectified or made audible in only one isolated section or block.

Perhaps a better description would be like the static you hear on an AM radio during a distance thunderstorm.  Completely random fades in and out then stops completely then comes back-or not!  The only thing that seems to affect it is disconnecting inputs-or in some cases shutting off phantom power to mics seems to help.  Disconnecting something seems to be a definite cure-noise stops instantly, then it r-occurs at some random time even with that stil disconnected.  Makes me think I am disconnecting the "antenna"-or one of them.

perhaps... If cumulative antenna effect it would vary in intensity maybe reaching as threshold amount with X number of mic channels, doesn't matter which just how many.

The console is an A&H GL3800.  The Saturday I was working in it, I had the building to myself.  I did have my phone on me-not a smart phone.  Turning off the console did completely eliminate the noise. 

That only confirms problem is not the power amp/speakers/speaker wires... while these need to be ruled out.

Yes, I hear the noise no matter what is soloed.

are we talking about same thing... Solo isolates just one input so you hear the noise  in every input, even just listening to one at a time?

That points toward the master section of console, ASSuming there is no other source feeding the master out. Some consoles have additional line inputs (or alarm feeds) that hit the master even with inputs muted. Does the noise go away when you drop the master fader? (I ASKED THIS ONCE BEFORE BUT DO NOT SEE AN ANSWER).

So it is not the amps/outboard gear-definitely getting into the mixer.
It is not an isolated channel-at least not on signal wires because it happens even with everything muted.

Does everything "muted" include the master fader output?

Ivan, I understand. My background is troubleshooting industrial machinery.  I was the go to guy in a facility for a number years until I got tired of factory life, so I am usually very thorough and have experience on the receiving end of tech support.

does the noise go away when you drop the master fader?

Yes, I am soloing as you describe.

If console repair/removal and substitution for repair and jack replacement were anywhere near the same amount of "pain and suffering", I'd likely lean towards the console for something to try.  If I could consistently re create the problem I would.

Not crazy to swap in a small mixer just to test and confirm no larger systemic issue.

I may need to look at that console routing to understand master section logic. If you get it with inputs muted, it isn't an input.

Do you get noise with master fader pulled down?

JR

[Hal Bissinger/COMSYSTEC]

Not crazy to swap in a small mixer just to test and confirm no larger systemic issue.

I agree. This really sounds like a problem with the mixer. How old is it?

-Hal

[Stephen Swaffer]

Mixer is around 8-9 years old.

I haven't answered the fader question because I can't give an accurate answer. This afternoon,  I have to go put things back together after the disassembly I did during The Wednesday evening service. From thoughts on here, sounds like I will finish disconnecting everything and see what results I get. I will also experiment with master fader.

I have also located a 16 channel mixer that is available for our use that might give me a window of opportunity for repair.  We can get by with that if we have to.

The biggest conundrum I see is that IF external sources are acting as antenna and that noise is being rectified in the mixer, then either removing the antenna or repairing the mixer potentially eliminates the problem-and repair is the only action with usable results. 

Update: For once an intermittent problem cooperated.  With everything disconnected except a pair of headphones we still have static.  The static does respond to main fader and main mute-but it is still discernible with the headphones.

So topic swerve.  We also have 4 noisy channels we no longer use (48 channel mixer).  Repair or replace?

[Lee Buckalew]

Mixer is around 8-9 years old.

I haven't answered the fader question because I can't give an accurate answer. This afternoon,  I have to go put things back together after the disassembly I did during The Wednesday evening service. From thoughts on here, sounds like I will finish disconnecting everything and see what results I get. I will also experiment with master fader.

I have also located a 16 channel mixer that is available for our use that might give me a window of opportunity for repair.  We can get by with that if we have to.

The biggest conundrum I see is that IF external sources are acting as antenna and that noise is being rectified in the mixer, then either removing the antenna or repairing the mixer potentially eliminates the problem-and repair is the only action with usable results. 

Update: For once an intermittent problem cooperated.  With everything disconnected except a pair of headphones we still have static.  The static does respond to main fader and main mute-but it is still discernible with the headphones.

So topic swerve.  We also have 4 noisy channels we no longer use (48 channel mixer).  Repair or replace?

Well...that depends on other troubleshooting.
The noise is still present even with all input (don't forget the talkback mic if you have one) and output connections disconnected from the console AND with all input channels, aux returns, groups, etc. muted and faders at infinity?
There are no cables connected to the console except the headphone cord and the power supply cable, correct?
There are no insert connections from the console either correct?
No signal was routed to the master?
The pink noise generator is turned off and potted town and unassigned?
Have you excersised all of the buttons and knobs at some point when soloing each channel (EQ in/out, mic/line, HPF, polarity/phase switch, phantom power, etc.)?  Sometimes analogue controls can develop a portion of their travel that produces static. 

Does the power supply have a properly wired IEC power cord and is there a known good outlet/circuit feeding it?

Does the same noise appear and behave the same way with only left main fader up and only L-R selected in the Monitor section?
Does the same thing occur if you pull down the left main fader and push up the right main?
Again with mono but deselect L-R and select M in the monitor section, any difference?
If with all busses unassigned and nothing even being routed to the master (even all the little extra bits in the master section that could route external signal or the internal generator to it) you still have noise in headphones when soloing the output masters then I would say the board needs service.

As has been suggested by others a quick swap to a different console would tell you if the problem stayed or went away.

Lee

[Nicholas Quek]

Had a problem exactly similar to yours before on an old mixer,  replacing the power supply filter caps fixed the problem... 

Noise came back after about another 8 years and then did the same thing to fix it again.


Sent from my iPhone using Tapatalk

[Stephen Swaffer]

There are no cables connected to the console except the headphone cord and the power supply cable, correct?

Does the power supply have a properly wired IEC power cord and is there a known good outlet/circuit feeding it?

 

Update: For once an intermittent problem cooperated.  With everything disconnected except a pair of headphones we still have static.

I guess I should be precise and state power was connected-but assumed that listening to a board with power disconnected would be a waste of time.  I also made sure nothing was even touching the console.

Power is a known good circuit wired by myself with the help of another licensed electrician-and both of us happen to be pretty picky about our work.  We have another system in another building physically about 200 feet away, power comes from same overhead drop as our main system and it is having no issues.  Power would be the only thing that swapping in another mixer would test, given that the testing I did was a stand alone test?

It does sound like we may have people interested in springing for a new mixer-probably as good a time for us to make the jump to digital as any and something that is already on our radar.  If that flies, we will either sell board as is or have serviced and sell.  It is too nice to scrap-it has lived in our sound booth its entire life covered when not in use primarily used by myself and one or two others.

Powers supply caps sound plausible-while they wouldn't necessarily be suspect (in my mind anyway) if the wiring is acting as antennae.  I haven't had the opportunity to do as thorough a test as Lee has suggested, but it sounds like a challenging project for some cold winter evenings.

[Lee Buckalew]

I haven't had the opportunity to do as thorough a test as Lee has suggested, but it sounds like a challenging project for some cold winter evenings.

Most of what I suggested can be done standing at the console with headphones on (and it sounds like you have done much of it).  It's just divide and conquer. 
Testing with another temporary console would be a very good option before trying to isolate the problem to a section of the console.

Lee

[Jim Thorn]

Stephen,

I had a noise problem with a GL4800 a few years ago.  As with yours, the noise was intermittent, and would occur without regard to the input I was soloing.  Noise appeared in headphones and at mixer outputs.  After months of chasing it without being able to reliably duplicate it, I finally got lucky.  A user reported that every input channel to the right of the master section went dead during a rehearsal, but by the time I got a look at it they were working.  Lifting the mixer an inch off the table and letting it drop would now trigger the noise, which the users had described as sounding like thunder.  When I opened the mixer up to check ribbon cables, I found discoloration of the insulation on two conductors of the ribbon cable at the insulation displacement connector of the Master section's board.

It turns out that the multi pin connector from the external power supply has fairly heavy-gauge wires feeding the Master board, but the voltages are then sent from there out to all the other boards on small-gauge conductors of the ribbon cable that runs the entire width of the mixer.  Two adjacent conductors are used for each voltage (+/- 17 volts IIRC).  Apparently the insulation displacement connection for +17 was imperfect, and over time began to heat up, discoloring the insulation and oxidizing the copper, making the problem steadily worse.  I was able to cut out a few inches of the damaged conductors, clean up the connector with Deoxit, and punch down fresh pieces of 20 gauge hookup wire, which I then spliced to the cut ends of the ribbon cable.  It wasn't very pretty, but it worked well until I was able to get a new ribbon cable assembly.

If this is what is happening with your mixer, you may be able to see a light tan or brownish cast on the light gray insulation of the ribbon cable at the master module, since that is the only place where the total current feeding all other boards must pass through two small IDC connections. 

I'm hoping that this is your answer -- it would be great if someone else could benefit from my hard-won knowledge!

Jim Thorn

I have been fighting noise on our church sound system for months.  Very erratic sometimes very minimal other times unbearable.  I have chased it and one time it seems like it is from one mic or set of mics, the next somewhere else.  I was able to eliminate (or at least greatly reduce it) for about 2 weeks by cleaning all of the jacks on the platform with De-oxit.

Unplugging nearly all of the mics at the mixer also helps-though it defeats the purpose!

Most of the mic jacks have been in place 10 years or longer and we use special effects every year at Christmas time that I can't help but think contribute to degrading of the jacks.

I have recommended wholesale replacing the jacks, but am being asked my confidence level in this curing the problem.  The mixer is an A&H GL3800.  (Which I recently cleaned ) Could there be a problem with the mixer making it more susceptible to static, or does my approach seem reasonable?

[John Roberts {JR}]

Yup ribbon cables can be problematic. If you isolate it to inside the mixer, an obvious thing to check.

JR

[Stephen Swaffer]

I often wonder the conclusion of the matter in some threads, to that end I give this update.

Installed a QU-32 last Saturday (we decided an upgrade/conversion to digital made sense in the big picture anyway and we had a couple people write checks to facilitate).  A couple hours of testing and setup, services on Sunday and Wednesday and no noise/static.  A number of compliments in the clarity/quality of sound.  Not sure if that is to be blamed on going digital, or if there was another less obvious problem lurking as well.  In any case, all is good now.  Thanks to all who took time to weigh in.

Jim, I will give the ribbon cables a thorough going over after the first of the year when (I hope anyway) things calm down a bit.  Day job is slamming me with a big deadline the same week as our annual Christmas play-both 6 weeks out so pretty much putting optional stuff on hold for a while.

[ProSoundWeb Community]