Why do we need to have the gains bottomed out?

[MillburyAuditorium]

I am not a sound guru by any meens and I am kind of noobish at wireless and frequency's and what not,
8 of our wireless mics are set for -30 on the beltpack and two newer ones, are at -60. These are the lowest they go on the belt packs. And on the board, a Mackie VLZ 24*4, the gains for the wireless channels are bottumed out and the new oens a tad above that. If we go any higher we get bad feedback and screeching until turned down. But the volume is still adiquit for the room.

We don't have any problems with it set this way, I am just wodnering why this happens.

 

[themuzicman]

Not answering your question, just saying how I work it so you don't have everything bottomed out.

I set my faders to unity (0db), and my mic packs to 0db, and then adjust the channels gain to a usable level, just so you are at a nice medium.

Having the gains bottomed out and the mic packs bottomed means you have no way to go in the event you have a problem. You can only go up, and that is not a good solution.

Try to find a happy medium!

 

[DuckJordan]

the question lies in the EQ of your venue, and also speaker placement and mic placement. We have had several issues over the years with new microphone systems that are a tad bit more sensitive than others we fix this problem with a tune up using a real time analyzer on our EQ, it has solved a lot of our problems. whats probably happened in your venue is (assuming its a school) the principal looking at two choices spend the $300 to bring some one in to do an EQ setup, or have the TD take all the gains down as far as they go. considering which was cheaper the Principal and possibly the school board decided lets just turn down the mics. we had that problem in our space until me and two other designers/directors brought it up and then they paid the money for the EQ setting.( Dang Automatic Feedback Exterminators, usesless they are.)

 

[MillburyAuditorium]

Sorry I should of mentioned this before,

Well, let my just run through our entire sound setup.

We have a 130 Foot snake with many more channels then needed, and a small 6 channel snake. About 50F long. Our four floors mics are connected to the small snake then that snake is plugged into our larger snake starting backstage, then our six hanging mics connect to the snake as well. Then the snake runs up along the side wall of the house and over to the sound board, a Mackie VLZ 24*4, all the hanging and floor mics hooked up accordingly. Then the wireless receivers, which are in two stacks of five onto of each other with the antenna arranged apart as much as possible, and the frequencies spaced accordingly. Then since we are running mono, we use the Mono main out, into our 15 band EQ, which is in a 8 space rack onto of our CD mixer, the EQ is a dual 15 Band, but we only use Channel A since we are running Mono. So out of the EQ back through the snake and out of whatever channel we are using as the main out connect another XLR wire from that channel on the snake box, then up to a 10 space wall rack that swing open plus a locking door, so, Into a processor, out to our sad single 250 watt amp, then out to the speakers.

Not sure if maybe or EQ would have anything to do with it? Through my knowlege of EQing it seems fine.

 

[DuckJordan]

the whole reason you would get a feedback noise is a loop is being created through your microphone out through your speakers then back to the microphone, the easiest way to fix a problem like this is to use the auto setup on the eq system assuming it has one, if its a lower end it probably doesn't we have a digital eq in our space so we hook up everything we need hit setup microphone and it automaticaly tunes down the freqs that cause feedback in our space. also speaker placement could be a huge issue.

 

[Chris15]

Whats the make and model of the wireless?

To me there's a mic / line selection not set right at the moment somewhere. Possibly on the back of the RF receivers and they are spitting out line level that's being fed into a mic input...

 

[SHARYNF]

I agree with Chris your wireless mics probably have a mic out and a Line out, sometimes they are externally selectable sometimes it is based on the jack connection. It looks like you have a line out set and connecting to a mic in on your mixer. I would say someone has set these wireless mics to line out thinking that was what was needed based on the distance and the snake which is not correct. Don't know what model of wireless you have. The setting on the belt pack is so not to overload the receiver, and can be independent of the setting on the Receiver output to the mixer, so Suggest you look at the output of the receiver not the beltpack.

BTW trying to use a 15 channel graphic eq for feedback control is typically not successful. The alteration of the eq is just too broad to not have a significant audible effect. An inexpensive DBX 231 dual channel 31 eq would make things much much easier (a 1231 is a better unit but a bit more money)
Really sounds like your system was sort of cobbled together by some inexperienced folks. Your setup seems to be designed by a DJ with stage sound added on to it. So every time you use the DJ cd mixer setup (probably a Numark??) you run the risk of completely altering the settings for the pa audio. Basically just from your description you should have an independant line mixer that takes the outputs of the PA feed from your Mackie, and the outputs of your DJ CD Mixer and combines these and is pretty much Set and Forget, that way, you can set up the mic system and the DJ system independantly and not have to worry about one changing the other. In setups like yours I have used a Whirlwind Matrix Mixer 44 which then allows for your to have maximum flexibility and allow you to add additional amps later on

http://www.fullcompass.com/product/290893.html

Again just some thoughts, cannot really design a system this way


Sharyn

 

[David Ashton]

You have all got it horribly wrong.
There is only one correct answer.
SET YOUR GAIN STRUCTURE
All your fiddling around trying different things is a waste of time.
You must learn how to set your gain structure or you are just wasting your time.
Sorry to be blunt but there is no other way to say it.

 

[gpforet]

My guess is that the wireless recievers are putting out line-level, and are patched into mic inputs on the console. I suspect all will be well if the receivers are plugged into the LINE input of the channel, rather than the MIC input.

I am not a sound guru by any meens and I am kind of noobish at wireless and frequency's and what not,
8 of our wireless mics are set for -30 on the beltpack and two newer ones, are at -60. These are the lowest they go on the belt packs. And on the board, a Mackie VLZ 24*4, the gains for the wireless channels are bottumed out and the new oens a tad above that. If we go any higher we get bad feedback and screeching until turned down. But the volume is still adiquit for the room.

We don't have any problems with it set this way, I am just wodnering why this happens.

 

[gpforet]

David, I've preached this until I've given up the fight. There's still people talking about setting the fader to 0db and then using trim to get volume up. In fact, some schools are now teaching this approach. I've challenged anyone to refer me to a console operation manual which promotes this approach. Of course, no one has stepped forward. I've checked out the Mackie manual for the console mentioned and guess what, a complete section on IMPORTANT SENSITIVITY ADJUSTMENT PROCEDURE, directing the user to solo the channel, set trim so meters indicate 0, etc, etc. As you and I both know, gain structure begins at the input, not at the fader.

You have all got it horribly wrong.
There is only one correct answer.
SET YOUR GAIN STRUCTURE
All your fiddling around trying different things is a waste of time.
You must learn how to set your gain structure or you are just wasting your time.
Sorry to be blunt but there is no other way to say it.

 

[hsaunier]

I'm counting 10 area mics.... which if all are condensers and all are open, then introduce another slew of wireless mics into the mix...... let the ringing begin. The stage space is being amplified and reamplified so many times there WILL be problems. (Unless the stage is 100'X100')

 

[SHARYNF]

David, I've preached this until I've given up the fight. There's still people talking about setting the fader to 0db and then using trim to get volume up. In fact, some schools are now teaching this approach. I've challenged anyone to refer me to a console operation manual which promotes this approach. Of course, no one has stepped forward. I've checked out the Mackie manual for the console mentioned and guess what, a complete section on IMPORTANT SENSITIVITY ADJUSTMENT PROCEDURE, directing the user to solo the channel, set trim so meters indicate 0, etc, etc. As you and I both know, gain structure begins at the input, not at the fader.

The reason some schools are teaching this method is that when the faders are set to unity, then the output meter is reading the input level since by definition unity gain means neither attenuating or boosting the signal level.

using a PFL (Pre Fader Level) signal sent to the meter does the same thing of course, BUT if you use the SOLO BUTTON your signal is POST FADER level (ON MANY MIXERS, Mackie combines SOLO AND PFL) so if the faders are not set to Unity, if THAT signal is sent to the meter the Fader setting is effecting the reading. Most Mixers Send the signal from the PFL button to the Monitor ONLY but Solo is sent to the Main outputs.
Because Mackie SOLO/PFL is combined, the Left Meter reads the signal, and of course the level in your headphones if you were using them to monitor then may go up significantly if previous to this you were monitoring with the fader set below unity.

Sharyn

Sharyn

 

[gpforet]

The console referred to allows you select whether you want SOLO to be PFL or not...and yes, PFL is the way to set gain. Setting the fader to zero does not provide you with knowledge of the input gain hitting the aux busses unless all eq is trimmed to zero as well so it won't help you here. It will also capture any gain aquired thru channel inserted devices, so, again, it's a false reading. The goal is not to get zero out, the goal is to ensure that the gain is properly staged at every point in the path....PFL to meter is the only way to see what the first gain stage is doing to the input signal. This sets the condition of the signal for all subsequent points where the signal is split.

PFL the channel, trim to near zero, use the fader to mix. Still waiting for someone to show me an operation manual which says otherwise.

By the way, I haven't run across a console that sends the SOLO to the main outputs, everyone I've used sent SOLO to MONITOR and/or PHONES out.

The reason some schools are teaching this method is that when the faders are set to unity, then the output meter is reading the input level since by definition unity gain means neither attenuating or boosting the signal level.

using a PFL (Pre Fader Level) signal sent to the meter does the same thing of course, BUT if you use the SOLO BUTTON your signal is POST FADER level (ON MANY MIXERS, Mackie combines SOLO AND PFL) so if the faders are not set to Unity, if THAT signal is sent to the meter the Fader setting is effecting the reading. Most Mixers Send the signal from the PFL button to the Monitor ONLY but Solo is sent to the Main outputs.
Because Mackie SOLO/PFL is combined, the Left Meter reads the signal, and of course the level in your headphones if you were using them to monitor then may go up significantly if previous to this you were monitoring with the fader set below unity.

Sharyn

Sharyn

 

[SHARYNF]

I am not saying I agree with the zero the faders, just trying to offer some input on why the schools seem to be teaching this method

My error on the Solo comment to main out, still early in morning ;-) in a multi track recording setup sometimes what you are actually listening to is the Monitor output as your "main output"

the other thing the schools are probably thinking about, )again don't agree with it but then schools are schools) is that most of the cheaper mixers use a Latching switch, (reason Mackie added the Rude solo light) and so it is easy for the inexperienced to forget that some of the solo buttons are still pushed/

But back to the original question. I agree getting the gain structure correct is essential BUT I still think the problem Might be that the wireless receivers are set to Line instead of mic level.

Sharyn

 

[museav]

Another thought, you noted two level settings, one on the bodypacks and one on the console. There are probably a lot more than that affecting gain before feedback. Start with that your wireless mic may have a gain level on the transmitter and then another on the receiver as well as different level outputs available on the receiver.

The first thing to do is probably to verify whether the receiver output is mic or line and that it is running into the appropriate input. Then step back from what the numbers are on the gain settings and look at what the levels are. If you PFL a wireless mic, what level do you see? What level do you get at the output with just that one wireless mic routed to it and that channel fader at 0?

I won't get into the console trim setting argument, I'll just say that with modern consoles there are electronic and functional pros and cons to both approaches as well as to variations on them (e.g. reducing trim level to account for expected summing on buses). And if you want to take it to another level, look at what many people are doing for remote preamps when they don't have control of the preamp gain at the console, since they can't grab the level easily if it clips they often set the nominal level an additional 10-20dB down to provide more headroom. So don't be afraid to try any of the approaches and find what works best for you in the application at hand.

 

[MillburyAuditorium]

Well not going to answer everyone individually, so here goes,

Well I was looking at the board today trying to figure out why it is so quit but getting so much feedback, this has never happened in previous years. So I am looking at the back of the board, and again we use a mono output.
And I notice the Output Gain is up to 75 Kicked that down to 40 and I will bring the channel gains up a bit and test the mics tomorrow, It was after everyone left rehearsal today. Hope that works.
Whoever said 10 area mics,
Well they are not all on at the same time. The three rear hangings are only used for full stage performances which the plays are not. So two or three hanging mics on, and four floors. Plus the biggest seen uses 5 wireless at the same time.

And so you guys suggest not using the Mic input? I never really thought of that, I assumed it would be the same, and XLR would be better. Right now the wireless receivers are connected to their channel on the board through the Mic In which is an XLR input.
I will try and get 10 5 feet quarter inches if you guys think it will make a difference?

And for whoever wanted the make and model,
They all all Sennheiser makes, and the two new ones we just bought, and they work really great, are ew122 G3's Sennheiser USA - ew 122 G3, lavalier wireless microphones systems, microphone, transmitter, receiver - Professional Audio
And we have 8 older ones, I do not know the model right now. But I cannot find them on the Sennheiser site. Must be to old. But they are the same family I believe.

Edit:

Also, I noticed, even the most cheap Sennheiser body packs are the smallish roundy body packs. Our 8 old body packs are rectangular with flat edges.

 

[mbenonis]

Also, I noticed, even the most cheap Sennheiser body packs are the smallish roundy body packs. Our 8 old body packs are rectangular with flat edges.

Sounds to me like Evolution G1 (the first evolution wireless).

 

[museav]

And so you guys suggest not using the Mic input? I never really thought of that, I assumed it would be the same, and XLR would be better. Right now the wireless receivers are connected to their channel on the board through the Mic In which is an XLR input.
I will try and get 10 5 feet quarter inches if you guys think it will make a difference?

And for whoever wanted the make and model,
They all all Sennheiser makes, and the two new ones we just bought, and they work really great, are ew122 G3's Sennheiser USA - ew 122 G3, lavalier wireless microphones systems, microphone, transmitter, receiver - Professional Audio
And we have 8 older ones, I do not know the model right now. But I cannot find them on the Sennheiser site. Must be to old. But they are the same family I believe.

Remember that an XLR is simply a connector type, it is not limited to mic level signals. The EM 100 G3 receiver has both XLR and 1/4" TRS output connections but they are simply wired in parallel and both are balanced line level (+18dBu max) outputs, so they should run into a line level input on the mixer.

 

[GreyWyvern]

Remember that an XLR is simply a connector type, it is not limited to mic level signals. The EM 100 G3 receiver has both XLR and 1/4" TRS output connections but they are simply wired in parallel and both are balanced line level (+18dBu max) outputs, so they should run into a line level input on the mixer.

A couple quick questions, to (hopefully) help clarify.

When hooking the receivers up with a 1/4" cable, should it be TS or TRS?

Some consoles have a mic/line input button, but both inputs will work regardless of the button position. What is that button for (does it simply select the input level) and what position should it be in for different setups? (Such as xlr out of receiver to xlr into console and 1/4" out of receiver to 1/4" into console.)

Dave

 

[SHARYNF]

A couple quick questions, to (hopefully) help clarify.

When hooking the receivers up with a 1/4" cable, should it be TS or TRS?

Some consoles have a mic/line input button, but both inputs will work regardless of the button position. What is that button for (does it simply select the input level) and what position should it be in for different setups? (Such as xlr out of receiver to xlr into console and 1/4" out of receiver to 1/4" into console.)

Dave

TS or TRS depends on whether the output and input is TS or TRS, A lot of 1/4 inch devices are unbalanced

The line/mic button typically adds a pad to bring down the line level to mic level for the preamp. Some designs might bypass the mic preamp.

Sharyn