Microphones HELP! UNEXPLAINABLE FEEDBACK running Shure slx1 wireless! show in a few hours!

[LouR]

Hey All
So I'm posting this for a friend on the road who's in a tight spot. I won't be able to give major details but I will do what I can. He is running Shure slx1 lavalier mics, and cannot get any gain out without feeding back all over the range, and even when he pulls the freq out of his eq the problem persists. Tried using the little gray toggle switch on the side to pad it down a little. Any advice anyone can give would be MUCH appreciated.

 

[DuckJordan]

Hey All
So I'm posting this for a friend on the road who's in a tight spot. I won't be able to give major details but I will do what I can. He is running Shure slx1 lavalier mics, and cannot get any gain out without feeding back all over the range, and even when he pulls the freq out of his eq the problem persists. Tried using the little gray toggle switch on the side to pad it down a little. Any advice anyone can give would be MUCH appreciated.

Check to see if there are any loops in the signal chain (meaning is it routed back through the console creating a signal path loop) Next are the mic's in question in front or behind a set of speakers this will greatly help us decide what the issue is. Have you tried replacing batteries?

 

[LouR]

Check to see if there are any loops in the signal chain (meaning is it routed back through the console creating a signal path loop) Next are the mic's in question in front or behind a set of speakers this will greatly help us decide what the issue is. Have you tried replacing batteries?

No loops in the chain at all, he just went and re checked that. Mic's are behind speakers and he is replacing the batteries I type this.

 

[Sayen]

RF interference?

Is it every mic? Check the cables from the receivers to the console - it's unlikely, but sometimes a bad cable will make some odd things happen with a signal.

 

[LouR]

RF interference?

Is it every mic? Check the cables from the receivers to the console - it's unlikely, but sometimes a bad cable will make some odd things happen with a signal.

Yes it is every mic.
He's checking cables and RF right now.
The big weird part about it is that when he gets the mic to an acceptable volume, the 630 band feeds back. He pulls it out, and then the 315, and then he pulls that out, and then the same with 6.3k and on and on. I've been doing sound for a couple years now, and he's been doing it for longer and I am at a loss.
Granted, he mixes differently than I do. He starts with his gain at unity and then brings his fader up. But he's tried lots of different approaches with no results.

 

[museav]

Have they used this system before without problems? How many mics? The SLX1 is the wireless system but there are several options on the mics themselves or they could be using a mic from another manufacturer, so what mics are being used? If truly lavalieres, where are the mics located (tie, hairline, etc.)? The SLX receiver has 1/4" and XLR outputs and the 1/4" output is like 20dB hotter, what output are you using on the wireless mic receivers and what are they run into on the mixer?

Does the problem occur with only one wireless system turned on? Are you experiencing the same problem with all mics and regardless of where they are on stage or does it vary between mics or locations?

Oh, and a simple one to possibly differentiate RF from acoustic issues, does the problem occur if the bodypack has no mic attached?

 

[LouR]

Have they used this system before without problems? How many mics? The SLX1 is the wireless system but there are several options on the mics themselves or they could be using a mic from another manufacturer, so what mics are being used? If truly lavalieres, where are the mics located (tie, hairline, etc.)? The SLX receiver has 1/4" and XLR outputs and the 1/4" output is like 20dB hotter, what output are you using on the wireless mic receivers and what are they run into on the mixer?

Does the problem occur with only one wireless system turned on? Are you experiencing the same problem with all mics and regardless of where they are on stage or does it vary between mics or locations?

Running with Shure 93's, mic's are placed in the hairline, but right now he's just got it sitting on stage trying to make it not feedbacke. It is feeding back on every mic, no matter what systems are on or not, and it is happening everywhere any mic goes.
He has switched out every cable, going XLR out of the reciever, into a analog snake, and XLR into his console. He has tried every Db pad he has, both on console and beltpack. He has also changed out the batteries on every pack.

 

[wolf825]

Some dumb questions--but since we cannot be there to see--have to go thru the dumb or obvious ones first--so this is no insult intended...but this can help trace the problem source.. Overall it sounds like a gain structure issue...but could be an equipment problem too..so lets get some basics out of the way:

What mic elements and how many mics? Are they going thru antenna distro or not? What indications does he see on the receiver itself when he powers on the pack/receiver--does he get full signal and strength etc and see the sound indicated on the receiver? Does he get this issue with a mic element unplugged? The SLX doesn't have a headphone jack to check if I recall..but you should at least see signal strength and audio metering. Does it stay strong when the pack walks away from the receiver or does it drop out?

Some more...
1) Has he used these packs before without issue and is this a new situation that suddenly popped up at a specific venue? OR is this his first show out with these? If he has used these before--what has changed (i.e. element, venue, location, position) from the last time he used them?
2) Did he set them up himself or were they part of a rental package set up for him to order etc?
3) Has he checked frequencies to see if they are all different and far enough apart (not so close they are stepping on each other/IMD) and properly set for each pack/receiver and sync'd each one up? Has he tried to re-sync them?
4) Has he checked the local frequencies in use to see if there are local interference or items using his current range?
5) Has he checked the output volume on the receiver? I think if I recall the SLX has their output volume on the rear--its a small recessed screw knob.. Also--is he using the XLR or the 1/4in jack on the rear--those have different output levels (mic/line)
6) Has he swapped out and tried different mic elements on the packs? Sometimes hairspray on an actors mic element if its not protected can freeze a mic element and make it sound like utter mush so you get no gain and all you get is a dull subdued mwwwooooommp...
7) Has he checked his cables and connections at the mics and the console--making sure he is not mixing line and mic level inputs/outputs etc or using a mix mash of TS cables on a balanced TRS connections or inserts by mistake etc etc?
8) Has he checked his console/channels--making sure they do not have anything inserted partially or the routing is straight and so on?

Thats a few to start...I may or may not be back shortly as I am setting a show soon but will check in...but this list with your answers should help others help you..


-w

 

[LouR]

Some dumb questions--but since we cannot be there to see--have to go thru the dumb or obvious ones first--so this is no insult intended...but this can help trace the problem source.. Overall it sounds like a gain structure issue...but could be an equipment problem too..so lets get some basics out of the way:

What mic elements and how many mics? 22
Are they going thru antenna distro or not?
yes antenna
What indications does he see on the receiver itself when he powers on the pack/receiver--does he get full signal and strength etc and see the sound indicated on the receiver?
full signal strength
Does he get this issue with a mic element unplugged? The SLX doesn't have a headphone jack to check if I recall..but you should at least see signal strength and audio metering. Does it stay strong when the pack walks away from the receiver or does it drop out?
yes/no

Some more...
1) Has he used these packs before without issue and is this a new situation that suddenly popped up at a specific venue? OR is this his first show out with these? If he has used these before--what has changed (i.e. element, venue, location, position) from the last time he used them?

2) Did he set them up himself or were they part of a rental package set up for him to order etc?

3) Has he checked frequencies to see if they are all different and far enough apart (not so close they are stepping on each other/IMD) and properly set for each pack/receiver and sync'd each one up? Has he tried to re-sync them?
4) Has he checked the local frequencies in use to see if there are local interference or items using his current range?
5) Has he checked the output volume on the receiver? I think if I recall the SLX has their output volume on the rear--its a small recessed screw knob.. Also--is he using the XLR or the 1/4in jack on the rear--those have different output levels (mic/line)
6) Has he swapped out and tried different mic elements on the packs? Sometimes hairspray on an actors mic element if its not protected can freeze a mic element and make it sound like utter mush so you get no gain and all you get is a dull subdued mwwwooooommp...
7) Has he checked his cables and connections at the mics and the console--making sure he is not mixing line and mic level inputs/outputs etc or using a mix mash of TS cables on a balanced TRS connections or inserts by mistake etc etc?
8) Has he checked his console/channels--making sure they do not have anything inserted partially or the routing is straight and so on?

Thats a few to start...I may or may not be back shortly as I am setting a show soon but will check in...but this list with your answers should help others help you..


-w

Running 22 of these receivers.
Going through antenna distro.
Full signal and strength on reciever.
Same issue when element is unplugged, no signal does not drop out.
Used them very recently, set them up himself. He did say that he had an EQ set but the EQ itself died and he had to get a new one and has yet to get it back to the same place the first one was. Same venue.
He has checked the freqs and reset them.
Checked local freqs, no problems.
Adjusted output volume knob, no results.
Changed all elements.
Checked cables.

The only thing I can think of is his console. He has set up 2 studio lives, firewired together so instead of having 2-16 input consoles it makes one 32 input console. I do not know exactly how this works but if anybody has any experience with that it might just be the problem.

 

[wolf825]

Running 22 of these receivers.
Going through antenna distro.
Full signal and strength on reciever.
Same issue when element is unplugged, no signal does not drop out.
Used them very recently, set them up himself. He did say that he had an EQ set but the EQ itself died and he had to get a new one and has yet to get it back to the same place the first one was. Same venue.
He has checked the freqs and reset them.
Checked local freqs, no problems.
Adjusted output volume knob, no results.
Changed all elements.
Checked cables.

The only thing I can think of is his console. He has set up 2 studio lives, firewired together so instead of having 2-16 input consoles it makes one 32 input console. I do not know exactly how this works but if anybody has any experience with that it might just be the problem.

Honestly from your answers it does not seem like its a gear problem with the mics or the reciever/transmitters then.. If all has worked fine before--and ESPECIALLY he gets the same feedback problem as you noted with the mic element removed from the pack--then it suggests to me the issue is not with his mics but is in his routing or signal path.. It could be in the firewire set up and he is somehow creating an electrical loop in how he has this linked together.. Not familiar with the StudioLive but that would be my place to look... Way to confirm--see if he gets the same issue on other channels not the wireless that he connects to the consoles directly. (i.e. do a CD or playback or plugged a regular dynamic mic into a channel from the RF he had issues with--and if you get the same gain problem or feedback issues--then its the set up or linking he has..not with the RF.)

FWIW the manual for the Studio Live is here:

http://www.presonus.com/media/manuals/presonus_studiolive16.4.2_manual_EN_1.pdf


-w

 

[LouR]

Honestly from your answers it does not seem like its a gear problem with the mics or the reciever/transmitters then.. If all has worked fine before--and ESPECIALLY he gets the same feedback problem as you noted with the mic element removed from the pack--then it suggests to me the issue is not with his mics but is in his routing or signal path.. It could be in the firewire set up and he is somehow creating an electrical loop in how he has this linked together.. Not familiar with the StudioLive but that would be my place to look... Way to confirm--see if he gets the same issue on other channels not the wireless that he connects to the consoles directly. (i.e. do a CD or playback or plugged a regular dynamic mic into a channel from the RF he had issues with--and if you get the same gain problem or feedback issues--then its the set up or linking he has..not with the RF.)

FWIW the manual for the Studio Live is here:

http://www.presonus.com/media/manuals/presonus_studiolive16.4.2_manual_EN_1.pdf


-w

I've got him checking those right now. Already started reading the manual, but at this point I don't think there is very much more I can do over the phone with him. I've got a show of my own to set up for, and I've run through this thing with him multiple times now. I'm going to work on the manual to see if I can find anything major, but that manual is over 200 pages long. Thanks very much for all of your help and ideas on this one. I'll let you know how it turns out.

 

[wolf825]

I've got him checking those right now. Already started reading the manual, but at this point I don't think there is very much more I can do over the phone with him. I've got a show of my own to set up for, and I've run through this thing with him multiple times now. I'm going to work on the manual to see if I can find anything major, but that manual is over 200 pages long. Thanks very much for all of your help and ideas on this one. I'll let you know how it turns out.

Sorry couldn't help more. Good luck man....


-w

 

[museav]

Running 22 of these receivers.

That's likely a problem right there. Shure says "up to 20" simultaneous ULX systems and that's in an ideal situation. Many times the practical number could be much less.

Same issue when element is unplugged, no signal does not drop out.

Adjusted output volume knob, no results.

So having no mic attached and turning down the receiver volume have no effect, which seems to eliminate acoustical feedback. If you are getting audio output from the receivers

He has checked the freqs and reset them.
Checked local freqs, no problems.

How has he checked local frequencies? Did he use a spectrum analyzer on site or some software? How has he set the frequencies? Is he using the automatic frequency finder of the SLX and is he leaving the one already set on as he goes to set the others?

The only thing I can think of is his console. He has set up 2 studio lives, firewired together so instead of having 2-16 input consoles it makes one 32 input console. I do not know exactly how this works but if anybody has any experience with that it might just be the problem.

So he has a sort of 32 channel console that is not real friendly to theatrical applications. How familiar is he with this setup? I won't go into all the details but there are a number of variables in how he may have the consoles configured and the signals routed, so without knowing that anything is greatly guessing. The first thing to try may be to bypass any channel processing and route the wireless mics direct to the main bus, no subgroups or effects or anything like that. Then unmute one channel. Is the problem still there?


It's easy to panic when you're on the line with a deadline looming but I think you're going to have to approach this logically. Try to eliminate or identify possible issues one at a time. For example, if you're getting any audio out of the receivers with no mics attached at the transmitters that shows something unexpected is happening there regardless of what is happening elsewhere.

For others, this is a good example of why although you may sometimes have no choice, when you have a large number of wireless systems and a complex console setup then if you have any other option you shouldn't wait until just hours before the first show to make sure everything works.