Sennheiser G2 Lav System issue at DVinfo.net

Chris Christensen · January 13th, 2009, 11:27 AM

I have been using a Sennheiser G2 wireless system for 2 years now. I had access to 2 sets in school where I shot 2 documentaries and many random interviews. I purchased one when I got out of school and have used it a couple of times with no issues. Now for the past 5 months at work I have used the same two systems EVERY OTHER day. I have logged HUNDREDS of hours with this system, and for the price and what it does, i love it.

That said, I was on location 2 weeks ago and had some minor interference issues on one of the systems. It was a really "white noise" type sound about 6 times in my 30 min shoot... One time I could almost here a voice with the white noise. I didn't have my headphones on at the time but when I heard it in post, I immediately changed the frequencies for the next day's shoot. The next day, it happened again, I changed the frequencies again and I am going to be watching the footage from the day after that this afternoon, so we will be seeing if it happens (in our studio where it has never happened before).

Has anyone had issues with these lavs? Should I keep experimenting with different frequencies, and is there a way for me to detect interference before I start shooting and hear it in the phones, having to cut and back track. I will try to put up some audible examples soon...

Thanks in advance for the help!

Chris Leone · January 13th, 2009, 11:44 AM

When you are powering up, turn on the receiver while keeping the transmitter off. If you see rf levels then you know you are picking up some interference, try another channel. Sometimes you have to keep channel surfing throughout the day depending your location.

Paul R Johnson · January 13th, 2009, 11:51 AM

The reality is that you could turn the receiver on, without the transmitter and listen for a while and hear nothing, only to turn on yiur tx and have problems. Sometimes it isn't that you have somebody on your channel at all, but it's a combination of two transmitters that together appear to be on your channel. Sennheisers are actually pretty good on the interference front. If you can quickly turn off your transmitter when you hear the problem and then you hear the interference signal properly - maybe then you can see what it is?

Depending on if you are on the free channels (often bad news) or proper licensed ones some are noticably empty in certain parts of the country.

White noise interference is often due to being near something powerful on a close, but not exactly the same channel. So the problem could be location based. Look for obvious transmitter sites, but not the familiar cellphone ones. Amateur radio users are very common in the 433MHz band, sometimes running BAGS of power, and they do have some output (although usually small) at double this, on 866MHz - which could desensitise your receiver. Unlikely, but possible.

Things to check are the obvious ones - received signal strength - does the noise come suddenly when both the receiver and transmitter are stationary? If it does, then an external influence is possible. If the system has been pretty stable before, and you know what it can do and what it can't, I'd look for an external problem source. Has this location been ok before? if so, has anything physical changed? That kind of thing?

If we can hear the noise, it could help?

Michael Liebergot · January 13th, 2009, 12:46 PM

Also remember when using multiple Sennheiser wireless systems, to make sure that you are using the same Frequency Bank on both sets, but have them set to different channels.

The reason being that Sennhesier has grouped sets of channels in each bank that are spaced enough as to not interfere with each other.

Even though you might be using different channels on each wireless set, they still might be close enough in frequency proximity to case some audio bleeding on a set.

But, the advice given here is a good one.
Always do a frequency sweep when you get to a venue to avoid problems while shooting.

Also of not, that I just thought of...
If you are not shooting on a closed set, you might be getting interference from a cell phone or PDA nearby. Or even on the talent.

Chris Christensen · January 13th, 2009, 02:53 PM

I will try the same frequency with different channels. Also, they are both on the frequency range 626 - 662 Mhz.

Michael Liebergot · January 13th, 2009, 02:58 PM

Quote:

Originally Posted by Chris Christensen

I will try the same frequency with different channels. Also, they are both on the frequency range 626 - 662 Mhz.

You don't want the same frequency, but you do want the same "BANK" for both units.
So let's say for example, you have both units set to "BANK1" and then select 2 different "CHANNELS" in that BANK.

But make sure that you do a sweep for the available channels in a given BANK. This if you do a sweep and have 4 free channels in a given BANK, then if you happen to have interference suddenly come up while shooting, you can quickly switch the receiver and transmitter to another channel in that BANK that not being used by the other system.

Chris Christensen · January 13th, 2009, 03:03 PM

Quote:

Originally Posted by Michael Liebergot

You don't want the same frequency, but you do want the same "BANK" for both units.
So let's say for example, you have both units set to "BANK1" and then select 2 different "CHANNELS" in that BANK.

But make sure that you do a sweep for the available channels in a given BANK. This if you do a sweep and have 4 free channels in a given BANK, then if you happen to have interference suddenly come up while shooting, you can quickly switch the receiver and transmitter to another channel in that BANK that not being used by the other system.

Ok that makes sense, i am sitting with the lavs in my hand right now and I was confused about that... thanks for clearing it up, I will do that now!

Battle Vaughan · January 13th, 2009, 03:35 PM

You may find that setting the pilot tone on will help, as it keeps the receiver from opening squelch to anything but it's matching transmitter. I still get a little passing white noise from time to time; btw a weak battery sounds just like that....I have found some kind of intermodulation interference when several G2's are operating in the same area...once when one was a b-band unit and ours a c-band, completely unrelated frequency ranges....you might go to this site: Find Available Frequencies
and check for open freqs in your area..../Battle Vaughan/Miamiherald.com video team

Chris Christensen · January 13th, 2009, 04:48 PM

I put together a few clips: Sennheiser G2 Wireless Glitches on Vimeo

Michael Liebergot · January 13th, 2009, 07:29 PM

Quote:

Originally Posted by Chris Christensen

I put together a few clips: Sennheiser G2 Wireless Glitches on Vimeo

Chris this is definitely RF interference that you are getting.
Try the methods mentioned here next time you're shooting.

But to me it sounds like you're getting a local station interfering, or possibly something else nearby.

Maybe next time you could bypass the wireless and use some boom micing directly into the camera.

Chris Christensen · January 14th, 2009, 10:14 AM

Thanks so much, I have a shoot this afternoon, but its in our studio so i don't forsee any problems anyways... I will let you guys know next time i shoot on location and hopefully all will be well!

Battle Vaughan · January 14th, 2009, 11:54 AM

See pages 31 and 32 of your G2 user manual for procedure to scan and lock out conflicting frequencies...need to do it, of course, near where you will be working. Best of luck! / Battle Vaughan

Guy Cochran · January 14th, 2009, 07:33 PM

Tips on getting optimum results from your Sennheiser Wireless:

1. With the Transmitter in the off position, perform an Autoscan on the receiver and make sure you get "4 channels Free" if you get less than 4, move to a different Bank and repeat the Autoscan. If unsure of how to do this watch Sennheiser Wireless Tutorial on Vimeo

2. If you're close, within 20', turn the Squelch setting to "High" - you'll lose range but reject more stray RF.

3. Try to make sure the antennas "see" each other - line of sight - not always possible. Do not put the transmitter in a coat pocket and bend the antenna. If anything, flip the Transmitter's clip upside down and attach it to their belt. I have a vid showing how here Sennheiser Wireless G2 hot shoe set-up on Vimeo

4. Face the antennas directly up or directly down. Do not lay them horizontal if you want maximum range.

5. If possible, put the Receiver on a long XLR cable and position the Receiver close to the talent.

One last vid with the Rackmount version - a great investment if you want the additional features - including true diversity, battery monitoring on the Receiver and the ultra cool "Red" somethings wrong or "Green" everythings groovy LED display. Super high quality Wireless microphone set-up for church, school, corporate, or live event on Vimeo

January 13th, 2009, 11:27 AM	#1
Chris Christensen Regular Crew Join Date: Oct 2008 Location: Rochester, MN Posts: 29	Sennheiser G2 Lav System issue I have been using a Sennheiser G2 wireless system for 2 years now. I had access to 2 sets in school where I shot 2 documentaries and many random interviews. I purchased one when I got out of school and have used it a couple of times with no issues. Now for the past 5 months at work I have used the same two systems EVERY OTHER day. I have logged HUNDREDS of hours with this system, and for the price and what it does, i love it. That said, I was on location 2 weeks ago and had some minor interference issues on one of the systems. It was a really "white noise" type sound about 6 times in my 30 min shoot... One time I could almost here a voice with the white noise. I didn't have my headphones on at the time but when I heard it in post, I immediately changed the frequencies for the next day's shoot. The next day, it happened again, I changed the frequencies again and I am going to be watching the footage from the day after that this afternoon, so we will be seeing if it happens (in our studio where it has never happened before). Has anyone had issues with these lavs? Should I keep experimenting with different frequencies, and is there a way for me to detect interference before I start shooting and hear it in the phones, having to cut and back track. I will try to put up some audible examples soon... Thanks in advance for the help! __________________ Chris/Final Cut Pro Certified/Apple is my life. Canon XH-A1, SGpro

January 13th, 2009, 12:46 PM	#4
Michael Liebergot Trustee Join Date: Jan 2005 Location: Maryland Posts: 1,505	Also remember when using multiple Sennheiser wireless systems, to make sure that you are using the same Frequency Bank on both sets, but have them set to different channels. The reason being that Sennhesier has grouped sets of channels in each bank that are spaced enough as to not interfere with each other. Even though you might be using different channels on each wireless set, they still might be close enough in frequency proximity to case some audio bleeding on a set. But, the advice given here is a good one. Always do a frequency sweep when you get to a venue to avoid problems while shooting. Also of not, that I just thought of... If you are not shooting on a closed set, you might be getting interference from a cell phone or PDA nearby. Or even on the talent. __________________ Michael www.lvpvideo.com

January 13th, 2009, 02:53 PM	#5
Chris Christensen Regular Crew Join Date: Oct 2008 Location: Rochester, MN Posts: 29	I will try the same frequency with different channels. Also, they are both on the frequency range 626 - 662 Mhz. __________________ Chris/Final Cut Pro Certified/Apple is my life. Canon XH-A1, SGpro

January 13th, 2009, 04:48 PM	#9
Chris Christensen Regular Crew Join Date: Oct 2008 Location: Rochester, MN Posts: 29	I put together a few clips: Sennheiser G2 Wireless Glitches on Vimeo __________________ Chris/Final Cut Pro Certified/Apple is my life. Canon XH-A1, SGpro

January 14th, 2009, 10:14 AM	#11
Chris Christensen Regular Crew Join Date: Oct 2008 Location: Rochester, MN Posts: 29	Thanks so much, I have a shoot this afternoon, but its in our studio so i don't forsee any problems anyways... I will let you guys know next time i shoot on location and hopefully all will be well! __________________ Chris/Final Cut Pro Certified/Apple is my life. Canon XH-A1, SGpro

January 13th, 2009, 11:44 AM	#2
Chris Leone New Boot Join Date: Feb 2008 Location: New York, NY Posts: 12	When you are powering up, turn on the receiver while keeping the transmitter off. If you see rf levels then you know you are picking up some interference, try another channel. Sometimes you have to keep channel surfing throughout the day depending your location.

January 13th, 2009, 11:51 AM	#3
Paul R Johnson Inner Circle Join Date: Nov 2005 Location: Lowestoft - UK Posts: 4,045	The reality is that you could turn the receiver on, without the transmitter and listen for a while and hear nothing, only to turn on yiur tx and have problems. Sometimes it isn't that you have somebody on your channel at all, but it's a combination of two transmitters that together appear to be on your channel. Sennheisers are actually pretty good on the interference front. If you can quickly turn off your transmitter when you hear the problem and then you hear the interference signal properly - maybe then you can see what it is? Depending on if you are on the free channels (often bad news) or proper licensed ones some are noticably empty in certain parts of the country. White noise interference is often due to being near something powerful on a close, but not exactly the same channel. So the problem could be location based. Look for obvious transmitter sites, but not the familiar cellphone ones. Amateur radio users are very common in the 433MHz band, sometimes running BAGS of power, and they do have some output (although usually small) at double this, on 866MHz - which could desensitise your receiver. Unlikely, but possible. Things to check are the obvious ones - received signal strength - does the noise come suddenly when both the receiver and transmitter are stationary? If it does, then an external influence is possible. If the system has been pretty stable before, and you know what it can do and what it can't, I'd look for an external problem source. Has this location been ok before? if so, has anything physical changed? That kind of thing? If we can hear the noise, it could help?

January 13th, 2009, 03:35 PM	#8
Battle Vaughan Trustee Join Date: Nov 2008 Location: Miami, FL USA Posts: 1,505	You may find that setting the pilot tone on will help, as it keeps the receiver from opening squelch to anything but it's matching transmitter. I still get a little passing white noise from time to time; btw a weak battery sounds just like that....I have found some kind of intermodulation interference when several G2's are operating in the same area...once when one was a b-band unit and ours a c-band, completely unrelated frequency ranges....you might go to this site: Find Available Frequencies and check for open freqs in your area..../Battle Vaughan/Miamiherald.com video team

January 14th, 2009, 11:54 AM	#12
Battle Vaughan Trustee Join Date: Nov 2008 Location: Miami, FL USA Posts: 1,505	See pages 31 and 32 of your G2 user manual for procedure to scan and lock out conflicting frequencies...need to do it, of course, near where you will be working. Best of luck! / Battle Vaughan

January 14th, 2009, 07:33 PM	#13
Guy Cochran DVCreators.Net Join Date: Oct 2001 Location: Seattle, WA Posts: 892	Tips on getting optimum results from your Sennheiser Wireless: 1. With the Transmitter in the off position, perform an Autoscan on the receiver and make sure you get "4 channels Free" if you get less than 4, move to a different Bank and repeat the Autoscan. If unsure of how to do this watch Sennheiser Wireless Tutorial on Vimeo 2. If you're close, within 20', turn the Squelch setting to "High" - you'll lose range but reject more stray RF. 3. Try to make sure the antennas "see" each other - line of sight - not always possible. Do not put the transmitter in a coat pocket and bend the antenna. If anything, flip the Transmitter's clip upside down and attach it to their belt. I have a vid showing how here Sennheiser Wireless G2 hot shoe set-up on Vimeo 4. Face the antennas directly up or directly down. Do not lay them horizontal if you want maximum range. 5. If possible, put the Receiver on a long XLR cable and position the Receiver close to the talent. One last vid with the Rackmount version - a great investment if you want the additional features - including true diversity, battery monitoring on the Receiver and the ultra cool "Red" somethings wrong or "Green" everythings groovy LED display. Super high quality Wireless microphone set-up for church, school, corporate, or live event on Vimeo __________________ Guy Cochran DVinfo Sponsor, Cool Gear - DVeStore!