Question about digital recorders causing interferrence at DVinfo.net

Eric Rogers · January 14th, 2014, 04:43 PM

Hi guys, I am not a audio guru and I have a situation/question that has come up several times lately. Hopefully someone can give me some professional insight so I can start sleeping again.

We shoot weddings and we use Olympus digital recorders w/wired lav for wiring up the podiums, priest & groom. I was told this was so we didn't cause interference with the existing church sound systems.

Everything was great but 3 or 4 times in the past few months we have been confronted by the dreaded church lady and asked what we had attached to their podium. During the service there was either an intermittent dropout, feedback or noise of some kind. I try to explain that its not our recorders because its impossible, but they swear that it has never has happened until I placed our recorder on their priest or podium.

From a professional, what is the real deal? Is it just coincidence? Is it possible for a digital recorder wired lav mic too close to theirs to cause some type of noise or dropout on their system? I didn't think it was possible.

Thanks.

Eric

Jim Andrada · January 14th, 2014, 08:05 PM

Sounds unlikely, but fundamentally anything with a wire and a source of electricity can cause interference. So even though it seems unlikely it's not impossible. If you were consistently having problems you could move the recorder further away and see if it's the culprit.

Or it could be a cell phone or a pacemaker or...well pretty much anything

Eric Rogers · January 14th, 2014, 09:34 PM

The recorders are super small 1.5 x 4" maybe. I have been wondering if it could have been the lav mic too close to the other mic. Sometimes I tape the cable to the post and have the mic right next to the podium mic.

So even though its a recorder only, your saying its possible... Have you had any experience with that happening?

Richard Crowley · January 14th, 2014, 10:20 PM

Simply, NO. Putting two mics close together DOES NOT cause feedback or any other kind of noise with the possible exception of ground-loop hum in the case of two different mains-powered systems crossing different ground systems. But since your recorders are battery powered, that completely eliminates them as suspect

And putting the typical modern, small digital voice recorder next to a microphone DOES NOT cause noise. If it, then they couldn't put a microphone inside the voice recorder case(!)

Unless you have some remote-control on-off switch for your recorders, there is no way you could place one next to a venue system microphone and then have it suddenly start generating interference at some subsequent time.

It is not clear from your question whether the "intermittent dropout, feedback or noise of some kind" was in the VENUE system, or in YOUR recording? But in either case, it is extraordinarily unlikely that it could be caused by your scheme and equipment.

Regrettably, you are dealing with completely clueless "church ladies". It is much more likely that kind of interference could be coming from a cell phone, perhaps even the officiant's own phone!

Don Bloom · January 14th, 2014, 10:48 PM

The chances of something like the supposed interference happening because of your digital recorders are to be blunt...slim and none and slim is getting on the train to leave town.
I bet if you goggled digital recorders causing interference you will find zero evidence of that happening and might even go so far as to print out the various articles to give to the "church ladies".
Man I don't miss the wedding gigs at all!

Actually don't bother. I just goggled it in 2 different ways and came up with a big fat nothing soooo....

Eric Rogers · January 14th, 2014, 11:12 PM

Well that's what I thought, but the last few incidences made me second guess myself. I hate hate hate dealing with church people when they think your screwing up their system. I had a Priest rip off our mic once during the ceremony, it seemed to quit for a bit but then the noise came back. Sheesh

Yes Richard it was coming over their system not ours. I mean there a hundred digital devices sitting not far away and we are the ones to get blamed regardless. I like how they will swear it has never happened before.

Thanks guys, I think now I can go to sleep!

Eric

Roger Gunkel · January 15th, 2014, 05:54 AM

Feed back in particular can only be caused when the sound source is being amplified and monitored, such as by a microphone through a PA system. If the church is getting feedback through their system, then their own mics are picking up the sound from their own speakers are re-amplifying it. It is quite likely that they have put new batteries in something and getting more gain than they had previously.

You cannot get feedback by placing a lav to a digital voice recorder next to a pa mic as there is no sound from the mic being played back and no wirelessly transmitted signal. The only exception to that could possibly be if the voice recorder was placed next to the PA mic with it's inbuilt monitor speaker turned up loud enough for the PA mic to pick it up and re-amplify it. Even that is pretty unlikely though.

The reaction of the Church ladies to your lav mic and recorder, is probably due to them having past experience of a videographer's radio mic being picked up through their own system and causing problems.

Roger

Steve House · January 15th, 2014, 08:56 AM

Cell phones are notorious for interfering with wireless systems or even hardwired PA systems when close enough to a component. That's the most likely cause of the noise in the venue system.

Eric Rogers · January 15th, 2014, 04:19 PM

I really appreciate the help and the thorough explanation from people who really know whats going on. It makes me feel at ease and it makes sense.

Your right about their reaction to us is probably because of past experiences with others. Regardless my stomach drops when I hear something in church now because I know what their thinking when they give us the little crappy looks.

Much appreciation to all!

Eric

Roger Gunkel · January 16th, 2014, 06:10 AM

Don't feel anxious when you hear a noise through their system that they think is caused by you. The best form of defence is attack, so take the initiative and politely ask them to sort out their system as it is interfering with your ability to record the sound for your clients. You could even offer to look at their system for them if you have time. It's worked well for me on occasion.

You can demonstrate instantly that it isn't you, by turning off your sound recorder while they watch, if it is before the ceremony start.

Roger

Ty Ford · January 22nd, 2014, 11:54 PM

Can you post a sample of the noise? Some of us are used to hearing various weird noises.

And, BTW, the Sound Devices 744T recorder does spray rf through the rear-side battery cavity AT CERTAIN FREQUENCIES ONLY. It can get into wireless mics if the receivers are bag mounted. It can also reduce the range of wireless systems.

If the 744T can, I'm guessing others may as well.

However, if your recorder were at fault, I doubt it would be an intermittent problem.

Regards,

Ty Ford

January 14th, 2014, 04:43 PM	#1
Eric Rogers Tourist Join Date: Jan 2014 Location: United States Posts: 4	Question about digital recorders causing interferrence Hi guys, I am not a audio guru and I have a situation/question that has come up several times lately. Hopefully someone can give me some professional insight so I can start sleeping again. We shoot weddings and we use Olympus digital recorders w/wired lav for wiring up the podiums, priest & groom. I was told this was so we didn't cause interference with the existing church sound systems. Everything was great but 3 or 4 times in the past few months we have been confronted by the dreaded church lady and asked what we had attached to their podium. During the service there was either an intermittent dropout, feedback or noise of some kind. I try to explain that its not our recorders because its impossible, but they swear that it has never has happened until I placed our recorder on their priest or podium. From a professional, what is the real deal? Is it just coincidence? Is it possible for a digital recorder wired lav mic too close to theirs to cause some type of noise or dropout on their system? I didn't think it was possible. Thanks. Eric

January 14th, 2014, 08:05 PM	#2
Jim Andrada Inner Circle Join Date: Feb 2007 Location: Tucson AZ Posts: 2,211	Re: Question about digital recorders causing interferrence Sounds unlikely, but fundamentally anything with a wire and a source of electricity can cause interference. So even though it seems unlikely it's not impossible. If you were consistently having problems you could move the recorder further away and see if it's the culprit. Or it could be a cell phone or a pacemaker or...well pretty much anything

January 14th, 2014, 09:34 PM	#3
Eric Rogers Tourist Join Date: Jan 2014 Location: United States Posts: 4	Re: Question about digital recorders causing interferrence The recorders are super small 1.5 x 4" maybe. I have been wondering if it could have been the lav mic too close to the other mic. Sometimes I tape the cable to the post and have the mic right next to the podium mic. So even though its a recorder only, your saying its possible... Have you had any experience with that happening?

January 14th, 2014, 10:20 PM	#4
Richard Crowley Trustee Join Date: Aug 2007 Location: Portland, Oregon Posts: 1,238	Re: Question about digital recorders causing interferrence Simply, NO. Putting two mics close together DOES NOT cause feedback or any other kind of noise with the possible exception of ground-loop hum in the case of two different mains-powered systems crossing different ground systems. But since your recorders are battery powered, that completely eliminates them as suspect And putting the typical modern, small digital voice recorder next to a microphone DOES NOT cause noise. If it, then they couldn't put a microphone inside the voice recorder case(!) Unless you have some remote-control on-off switch for your recorders, there is no way you could place one next to a venue system microphone and then have it suddenly start generating interference at some subsequent time. It is not clear from your question whether the "intermittent dropout, feedback or noise of some kind" was in the VENUE system, or in YOUR recording? But in either case, it is extraordinarily unlikely that it could be caused by your scheme and equipment. Regrettably, you are dealing with completely clueless "church ladies". It is much more likely that kind of interference could be coming from a cell phone, perhaps even the officiant's own phone!

January 14th, 2014, 10:48 PM	#5
Don Bloom Inner Circle Join Date: Jan 2003 Location: Chicago, IL Posts: 6,609	Re: Question about digital recorders causing interferrence The chances of something like the supposed interference happening because of your digital recorders are to be blunt...slim and none and slim is getting on the train to leave town. I bet if you goggled digital recorders causing interference you will find zero evidence of that happening and might even go so far as to print out the various articles to give to the "church ladies". Man I don't miss the wedding gigs at all! Actually don't bother. I just goggled it in 2 different ways and came up with a big fat nothing soooo.... __________________ What do I know? I'm just a video-O-grafer. Don

January 14th, 2014, 11:12 PM	#6
Eric Rogers Tourist Join Date: Jan 2014 Location: United States Posts: 4	Re: Question about digital recorders causing interferrence Well that's what I thought, but the last few incidences made me second guess myself. I hate hate hate dealing with church people when they think your screwing up their system. I had a Priest rip off our mic once during the ceremony, it seemed to quit for a bit but then the noise came back. Sheesh Yes Richard it was coming over their system not ours. I mean there a hundred digital devices sitting not far away and we are the ones to get blamed regardless. I like how they will swear it has never happened before. Thanks guys, I think now I can go to sleep! Eric

January 15th, 2014, 05:54 AM	#7
Roger Gunkel Inner Circle Join Date: Feb 2013 Location: LIncolnshire, UK Posts: 2,213	Re: Question about digital recorders causing interferrence Feed back in particular can only be caused when the sound source is being amplified and monitored, such as by a microphone through a PA system. If the church is getting feedback through their system, then their own mics are picking up the sound from their own speakers are re-amplifying it. It is quite likely that they have put new batteries in something and getting more gain than they had previously. You cannot get feedback by placing a lav to a digital voice recorder next to a pa mic as there is no sound from the mic being played back and no wirelessly transmitted signal. The only exception to that could possibly be if the voice recorder was placed next to the PA mic with it's inbuilt monitor speaker turned up loud enough for the PA mic to pick it up and re-amplify it. Even that is pretty unlikely though. The reaction of the Church ladies to your lav mic and recorder, is probably due to them having past experience of a videographer's radio mic being picked up through their own system and causing problems. Roger

January 15th, 2014, 08:56 AM	#8
Steve House Inner Circle Join Date: Mar 2005 Location: Hamilton, Ontario, Canada Posts: 5,742	Re: Question about digital recorders causing interferrence Cell phones are notorious for interfering with wireless systems or even hardwired PA systems when close enough to a component. That's the most likely cause of the noise in the venue system. __________________ Good news, Cousins! This week's chocolate ration is 15 grams!

January 15th, 2014, 04:19 PM	#9
Eric Rogers Tourist Join Date: Jan 2014 Location: United States Posts: 4	Re: Question about digital recorders causing interferrence I really appreciate the help and the thorough explanation from people who really know whats going on. It makes me feel at ease and it makes sense. Your right about their reaction to us is probably because of past experiences with others. Regardless my stomach drops when I hear something in church now because I know what their thinking when they give us the little crappy looks. Much appreciation to all! Eric

January 16th, 2014, 06:10 AM	#10
Roger Gunkel Inner Circle Join Date: Feb 2013 Location: LIncolnshire, UK Posts: 2,213	Re: Question about digital recorders causing interferrence Don't feel anxious when you hear a noise through their system that they think is caused by you. The best form of defence is attack, so take the initiative and politely ask them to sort out their system as it is interfering with your ability to record the sound for your clients. You could even offer to look at their system for them if you have time. It's worked well for me on occasion. You can demonstrate instantly that it isn't you, by turning off your sound recorder while they watch, if it is before the ceremony start. Roger

January 22nd, 2014, 11:54 PM	#11
Ty Ford Inner Circle Join Date: Nov 2004 Location: Baltimore, MD USA Posts: 2,337	Re: Question about digital recorders causing interferrence Can you post a sample of the noise? Some of us are used to hearing various weird noises. And, BTW, the Sound Devices 744T recorder does spray rf through the rear-side battery cavity AT CERTAIN FREQUENCIES ONLY. It can get into wireless mics if the receivers are bag mounted. It can also reduce the range of wireless systems. If the 744T can, I'm guessing others may as well. However, if your recorder were at fault, I doubt it would be an intermittent problem. Regards, Ty Ford __________________ Ty Ford's Audio Bootcamp Field Guide Ty Ford's Audio Video Blog