Wireless mic (senny g2) issues

[James Strange]

Hi all, not sure if this would be better served in the audio forum, but here goes.

My setup audio wise for the past umpteen years has centered around 2 pairs of sennheiser G2 wireless lavs.

One on the groom, one on the person conducting the ceremony.

This has served me well, without fail, until recently.

On 2 separate occasions, at 2 entirely different locations, I got constant interference (not sure if 'interference' is the correct word, but that's what I'll use)

At today's shoot, the interference disappeared at some point, as I watched back the clip from today, I found the point where the 'clean' audio signal returned.
(20 mins prior to this, when I hooked up the groom, everything was fine, it wasn't until literally 30 seconds before the bride was about to start walking down the aisle the interference started / got noticed)


For the ceremony, I was only about 4 feet from the bride, groom and registrar (too close, not by choice, at this venue, there is no where else to go)

So I was close enough that my shotgun mic picked up the sound fine.

As I walked to the back of the room (about 20 feet from the bride and groom) that's when the signal became clean)

Can the proximity of the transmitter to the receiver cause interference?

I'm aware that the senny g2's in the UK became an issue last year with the 'digital switchover' etc, but I am not convinced that this is the reason.

I have been using the same g2 kit, on the same (albeit reduced range of 863-865) for years, and never encountered this issue.

The only change in my set up, is instead of the g2s feeding into a tascam DR100, they now feed into a canon c100, could this be the issue?


Honestly, this has me perplexed, moving further away from the groom (increasing the distance of the mic from the receiver) seemed to solve the problem today, although that could be a coincidence


It's got me considering switching to using something like a h1 and slipping that in the grooms pocket (with a lav mic), but that would mean synching sound, and no way of monitoring the sound (monitoring the sound isn't that big an issue, because even if I'm monitoring sound, if something goes wrong, I can't just stop the ceremony to try and fix the grooms mic)



The previous time this issue occurred, was on a corporate shoot, and another shooter had a senny g3 kit with them, we swapped my interference riddled g2 for her g3, and all was OK. So my immediate thought is to just upgrade to g3 kits.



As always, any help or advice is much appreciated.

James

[Chris Harding]

Hi James

I have Azdens and their "blurb" says that tramsmitters should be at least 2m apart but I also use (purely for convenience) a receiver on the camera on my shoulder and the transmitter on my belt so they are closer than 1m apart and never had an issue so it seems that TX and RX close together shouldn't be a problem at all. (My close setup is for Realty reports with a running commentary not weddings)

I'm wondering if maybe your Sennies are oldish and have the older frequency bands that digital radio and TV are going to use? Check the Sennie website and check which frequencies are legal??

Chris

[Andy Wilkinson]

James,

I see that you are aware that you can now only legally use Bank 8 channels with the Sennheiser G2 radiomic system in the UK. All the other frequencies (channels) were sold off in 2012 for other uses, radio astronomy etc.

Only the very few options the Sennheiser G2 radio mic system has, those above 862Mhz, should be used in the UK. Assuming that was the Bank you were using then I suspect it is the close proximity you mentioned as I had something like that happen with my G2s a few years ago.

[Paul R Johnson]

Two transmitters together can be bad news

have a look at this topic on a back stage forum - where radio issues are always a hot topic.
Radiomic antennas height vs. RF noise issue - Blue Room technical forum
The important part of the topic is copied here

I had a situation this week, using 6 channels of Trantec S5.3, lavs on 606.60, 607.500, 608.150, 609.150 and handhelds on 611.250 and 612.300. All fine for the first hour or so, then for no more than 5 minutes loud occasional splats across 607.500, 608.150 and 612.300.

At the time this happened, two of the RX packs were with me at FOH, monitoring them gave what I can only describe as a clipped, reverbed version of the FOH PA signal.

The response was

I don't know if it's time to get a SA to look at the RF environment, but it's really time to get some intermod software to help you choose frequencies. Among your 6 frequencies, 608.150 and 606.600 have an intermod frequency on 611.250, and 611.250 and 612.300 have one on 609.500. If any of those packs were close together they could have been causing the interference you experienced. The symptoms seem to fit that scenario.

Probably a bit heavy for some, but the frequencies Sennheiser (and others) put in the preset banks are carefully tested and chosen. The topic I linked to mentions inter mod - intermodulation. Put two radio transmitters together and the two different frequencies will interact with each other and generate spurious outputs that can produce very odd noises and interference. In theatre, we often get this when helpful people return unused body packs and handhelds and leave them on top of the receiver rack. Add a few actors and all these operating devices can combine in very unpredicted ways and interfere with the weaker, but critical transmitter a bit further away.

The imminent arrival of 4G phone kit in the pockets of people close too also means that it's not just channel 69 that could be a mess - it's likely that interference will spread into the channel 70 band, where most casual users are moving too - or will, once they get their first pile of interference. In the topic above, you'll see frequencies that are in channel 38 - the new 'professional' band in the UK - but the post also shows that interference is still perfectly possible. The person has accidentally selected frequencies that are mathematically related, not ones suggested by the manufacturers - and although it worked well in one case, all hell breaks loose when circumstances conspire against you. Systems that scan for empty channels might sound good, but finding an empty channel does not mean that using it will be trouble free. People treat RF systems as just like an invisible cable - it really is much more than that.

[John Estcourt]

Hi James,

This is why I very rarely use our Sennheiser radio microphones any more. I now use Yamaha C24 pocket recorders.
saves a lot of stress over issues like that, sync perfectly to the video footage, saves on batteries and stops any worries about being on the same frequency as the venue..
I've also got a few Olympus digital voice recorders and they work very well apart from the sync issues.
cheers john

[Jeff Harper]

John, do your Yahmahas sync up? I need a second recorder, zoom is wonderful but too thick for groom's pocket.

[John Estcourt]

yes Jeff, perfectly. they sound great two.

[Jeff Harper]

Thanks John!

[Jeff Harper]

John, how do you execute the hold function on the recorder so it cannot be accidentally shut off by someone handling it? Is it a menu function? Looked at images can't see a hold switch.

On the topic at hand, I have largely given up on wireless. I still use mine, but I really depend now on my zoom H1.

I had trouble with my G2 also, even though so many loved it, I found it to be unreliable. It is definitely better to not be too close to it to maintain your signal.

[John Estcourt]

Jeff, on the rear of the C24 there is the power button.
The button is a slider with 3 positions. On, Off and Hold.
Best wishes John

[Nigel Barker]

I use the Yamaha C24s & they are great. They come with a clothes peg affair that fixes on the USB connector that allows you to easily clip it on a lectern or table decoration. The auto setting has a lot of noisy 'pumping' so I set the recording level at about 20 or 25 (out of 100) & boost levels in post.

Once you start using the C24s the Zoom H1 looks enormous.

[Jeff Harper]

John, Nigel, thanks bunches. The only drawback I've found using these recorders is I once forgot to download it after a wedding. I guess I was so caught up with video I forgot the audio. I had the priest on a wireless, so it worked out fine, but was very disconcerting!

I am excited to have a model selected, thanks again for the recommendation!

[James Strange]

Hi guys, thanks for the quick replies,


Andy - I was using the legal frequencies (863-865) never been an issue before in this range.


As I understand it (and please correct me if I am wrong) the new G3 (GB band) requires you to buy a license (yearly fee) if you want to use any other frequencies other than the above free ones ?

The new g3 'GB' band is 606-648, am I right in saying that even if I upgrade to this kit, I'll need to pay a yearly fee, and there is still a chance I'll have the same problems as I am having with the g2s?

If upgrading to the G3s would solve my issues, I would probably go for it.


For those that use pocket recorders, what's your procedure for setting levels? Auto or set it for the average level of people speaking, which at weddings, can vary quite a bit from groom to groom.
(speaking about the zoomh1 really, I just re read and see that John details his settings for the yamaha - thanks John)


I don't think the zoom h1 would be to thick for the grooms pocket, looking at it right now, side by side with a G2 TX, it's the same thickness, the zoom is taller, but narrower.

Might give using the zoom with a lav a few tests. Using the mic form the G2 kit should be fine ?
(I'm sure I saw a recent thread about lav mics so I'll give that a read also)


How does the audio quality of the Yamaha C24s compare to the zoom h1?


Would be a shame to give up on wireless systems....but if needs must.


Thanks again for all the quick responses.

[Paul R Johnson]

Yes - a move to ch 38 means you need to pay a license, and in theory have a little protection, but in practice, there aren't any vans with rotating roof racks any longer, so unless you are a big high profile user, JFMG won't be able to offer any practical protection. Channel 38 equipment is now totally different from kit designed for the free and unregulated channel 70 equipment.

Upgrading to G3 from G2 in channel 70 would in theory give you an extra workable channel - but other users could wreck this very easily.

I've had excellent results with digital kit in the 2.4GHz band - but as yet only mains powered receivers. I think that reliability wise, separate recorders would offer the most trainwreck free method of operation.

I'm also in my regular work, quite destructive to other users. My 2.4 kit wipes out local wifi networks, and because I have plenty of it, I'm using the entire licence free unregulated ch 70 band for wireless in ears. The transmitters in a rack stage side - going just a few metres to the musicians - and with clear line of site, and the results are 100% solid. However, anyone nearby using the systems with rack receivers and hand held mics at a greater distances hears my system, and often NOT their own. The systems I'm running seems pretty reliable - but a bit unfriendly to anyone else.

[Jeff Harper]

Sennheiser mic might not work, but don't rely on me, I could be wrong.

For audio levels I am not the type that monitors audio much. I set and forget. On the Zoom 75 or so is perfect for the groom, never an issue.

The Zoom is fat and it will work, but as many others who have used have said, it is just not a good fit for a jacket pocket. With a form-fitting suit it is too bulky. Yesterday the groom wore a dress uniform and it made too much of a bulge anywhere but his pants pocket.

I know that if John and Nigel recommend the Yamaha, they have already done the research, so I'm taking advantage of it. I just ordered my Yamaha.

I'm going to use the Zoom H1 for the lecturn where it belongs!