Quantcast
Holy Crap, what is THIS sound? (Countryman E2 & Sennheiser G2) - Gearspace.com
The No.1 Website for Pro Audio
Holy Crap, what is THIS sound? (Countryman E2 & Sennheiser G2)
Old 24th September 2012
  #1
Gear Maniac
 
🎧 15 years
Holy Crap, what is THIS sound? (Countryman E2 & Sennheiser G2)

Hi folks. At the synagogue I work at, we're having these crazy problems with our Countryman E2, which is connected to a Sennheiser G2 (100 series).

I THINK I've narrowed the problem down to the countryman mic!
I've tried the mic with two different Sennheiser systems, which operate in (radically) different frequency ranges. The same problem occurs with both transmitter/receiver systems.

Also, I'm sure the problem comes from the transmitter, as you can see the AF meter bounce around when these loud noises pop up.

So I don't THINK it's any type of RF interference, but for the life of me, I can't figure out what the hell is going on here!

Anyone recognize these sounds? I've attached an 30 second .mp3 where the problem occurs a couple times....This is ALL on the 1 channel, received from the Sennheiser unit.

-Stephen
Attached Files

mic probs.mp3 (639.8 KB, 1935 views)

Old 25th September 2012
  #2
Lives for gear
 
🎧 15 years
I think it could be RF interference--what I hear sounds like "noise-ups", where the RX can't find the TX for a second. Did you have a chance to watch the RF meter while this was happening? Can you walk test your gear during some down time? Is that freq clear when you turn your TX off? Anyone else using wireless in that space--like musicians w/ wireless guitar rigs? Those sounds could be due to a two way-radio being keyed nearby (like a walkie), or some other switching device. Also check the connector of the mic, and look closely at the cable where it enters the mic head. I've had some similar sounds caused by lav mics that had broken wires inside the connector, or the shield was damaged near the head. The only cure for that is a trip back to Countryman.

phil p
Old 25th September 2012
  #3
Gear Head
 
🎧 10 years
I think that noise sounds like an electrolytic capacitor going bad, or perhaps the condenser element itself in the E2.

-Keith
Old 25th September 2012
  #4
Gear Nut
 
🎧 5 years
RF interference
Old 25th September 2012
  #5
Gear Head
 
🎧 5 years
RF interference.
Old 26th September 2012
  #6
Lives for gear
 
🎧 10 years
RFI/dodgy screen.
Old 26th September 2012
  #7
Lives for gear
 
Lenzo's Avatar
 
6 Reviews written
🎧 10 years
There is a scan function on the Sennheiser receiver. Go into the menu while you have it in the room and have it scan for clear frequencies. Then set your transmitter to the same frequency. That can help sometimes.
L.
Old 26th September 2012
  #8
Gear Nut
 
🎧 5 years
IMO it is a combination of things. My earlier answer is still correct, but it's only the overview. The RF signal from a transmitter to a receiver has a lot of obstacles. First, there is absorption from the body of the wearer (especially in the case of a belt pack transmitter). Start by making sure that you are keeping the antenna away from direct contact with skin or a damp undershirt or the like. Do not let them put the transmitter in their pocket.

If possible, have the transmitter on the same side of the body as where your receiver is located, i.e. "line of sight" between transmitter and receiver.

Even with all that, if the person with the transmitter is moving around at all, the RF level at the receiver can jump up and down dramatically due to multipath nulls. This is because multiple reflected copies of the signal can arrive at the receiver out of phase from each other. This is the main reason for diversity receivers.

On the receiver end, if you have a diversity system, space your antennas as far apart as possible. Your antennas should also be parallel to the transmitter antenna, and ideally both should be vertical.

What happens during these dips in signal level is that other unwanted signals (i.e. noise) can "break through". I.e. whatever signal is stronger is what the receiver sees.

I suspect in the OPs case it was a combination of these things, resulting in the receiver taking "hits".
Old 27th September 2012
  #9
Gear Maniac
 
🎧 15 years
Thanks for your feedback, everyone!
1) I've got the transmitter clipped onto his belt (with the antenna pointed towards his shoes, not up towards his face). I don't expect his pants are damp (and if they were, there's the pocket underneath, so that would get damp first....)

2) Why would the reception drop with two different tx-rx systems, which operate on radically different frequencies (632 or so and then 564, I think)? I suppose the multipath nulls would be the same (the room is the same, and the antennas are in close to the same locations, only a foot or two apart)....

I think I've noticed the receiver occasionally receiving LESS signal as these noises happen. Like the RADIO meter on the receiver will dip a bit (thought not die). Let me see if I understand what happens at that point...What I believe PhilPer described as "noise ups."

At that point, you STILL need another signal to create noise on the frequency, right? So the noise on the recording is actually another radio signal (which sounds like nonsense to the human ear) showing up on this frequency? Or is that noise caused by something else?

I ask that because the channels seem TOTALLY clear. I can sit and watch the meter on the Receiver when the transmitter is off, and it is totally clear...I've also compared the frequency to TV stations, etc in the area, and I think the only TV stations on this frequency are way out in the desert (60 miles away)?

ROLO: What do you mean by a "dodgy screen?" The ground wire in the mic cable, or the wind screen on the mic element?

Thanks, folks...I feel pretty dumb needing to ask these questions, but to be honest I've not had a lot of problems with wireless mics before...I've tried to do basic troubleshooting, but this seems to be beyond my knowledge!

-Stephen
Old 27th September 2012 | Show parent
  #10
Gear Nut
 
🎧 5 years
Quote:
Originally Posted by Elsteve9 ➑️
Thanks for your feedback, everyone!
1) I've got the transmitter clipped onto his belt (with the antenna pointed towards his shoes, not up towards his face). I don't expect his pants are damp (and if they were, there's the pocket underneath, so that would get damp first....)
You should be in good shape there.

Quote:
2) Why would the reception drop with two different tx-rx systems, which operate on radically different frequencies (632 or so and then 564, I think)? I suppose the multipath nulls would be the same (the room is the same, and the antennas are in close to the same locations, only a foot or two apart)....
Multipath would not be the same, actually. First, they are not exactly in the same place, either at the transmitter or the receiver. Second, the difference in frequency means that even if they were in the same exact place, the phase cancellations would happen differently. Think of standing waves in a room - with the speakers in the same place, different frequencies have modes and nodes in different positions in the room. This is not exactly the same concept, but you get the idea.

Quote:
I think I've noticed the receiver occasionally receiving LESS signal as these noises happen. Like the RADIO meter on the receiver will dip a bit (thought not die). Let me see if I understand what happens at that point...What I believe PhilPer described as "noise ups."

At that point, you STILL need another signal to create noise on the frequency, right? So the noise on the recording is actually another radio signal (which sounds like nonsense to the human ear) showing up on this frequency? Or is that noise caused by something else?
The fact that you see dips in RF level at the receiver when you hear those noises lends support to the idea that the noises are either interference, or that the receiver is not properly responding the dips in level.

Quote:
I ask that because the channels seem TOTALLY clear. I can sit and watch the meter on the Receiver when the transmitter is off, and it is totally clear...I've also compared the frequency to TV stations, etc in the area, and I think the only TV stations on this frequency are way out in the desert (60 miles away)?
This may lend support to the latter idea - that the receiver needs to be examined. Another idea, between these, is intermods. These are phantom frequencies generated inside the transmitters or the receivers, but can cause interference just like external signals. Based on your careful description, this would be my guess. What happens is that intermod frequencies come up and down depending on the proximity of the transmitters to each other. The closer they are to each other, the stronger the IM signals. The only way to be sure you are avoiding these is to run a calculation using specialized software. There are free versions available from Sennheiser & Shure, for instance, and some non-free versions from 3rd parties. It is not common to worry much about intermods with a low channel count, but these days, who knows. Can't hurt.

Quote:
ROLO: What do you mean by a "dodgy screen?" The ground wire in the mic cable, or the wind screen on the mic element?

Thanks, folks...I feel pretty dumb needing to ask these questions, but to be honest I've not had a lot of problems with wireless mics before...I've tried to do basic troubleshooting, but this seems to be beyond my knowledge!

-Stephen
Old 27th September 2012
  #11
Lives for gear
 
🎧 10 years
Screen as in cable
Not puff gag
Electrets for radios are unbalanced mics,good screen is essential.
Old 27th February 2016 | Show parent
  #12
Here for the gear
 
🎧 5 years
Quote:
Originally Posted by Rolo 46 ➑️
Screen as in cable
Not puff gag
Electrets for radios are unbalanced mics,good screen is essential.
SAME PROBLEM FOR ME ALSO. HELP!!!
https://www.youtube.com/watch?v=tZDA6guy5QA
Old 2nd March 2016
  #13
Gear Guru
 
jwh1192's Avatar
 
2 Reviews written
🎧 15 years
RF interference, Dropouts, Bad mic placement causing clothing noise, Multi-Path, take your pic .... are these Diversity Systems or single channel units you have ???
πŸ“ Reply
Topic:
Post Reply

Welcome to the Gearspace Pro Audio Community!

Registration benefits include:
  • The ability to reply to and create new discussions
  • Access to members-only giveaways & competitions
  • Interact with VIP industry experts in our guest Q&As
  • Access to members-only sub forum discussions
  • Access to members-only Chat Room
  • Get INSTANT ACCESS to the world's best private pro audio Classifieds for only USD $20/year
  • Promote your eBay auctions and Reverb.com listings for free
  • Remove this message!
You need an account to post a reply. Create a username and password below and an account will be created and your post entered.


 
 
Slide to join now Processing…

Forum Jump
Forum Jump