ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: 1 2 3 [4] 5 6 7   Go Down

Author Topic: Couldn't Stop Mic Peaking  (Read 9727 times)

Isaac South

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 341
  • Central Kentucky
Re: Couldn't Stop Mic Peaking
« Reply #30 on: December 12, 2017, 04:15:10 pm »

OK Isaac, It is quite simple: A MIC channel is for, ahum, MICS. That is: A mic connected with an XLR cable. LINE channels are for everything else like CD players etc. The major difference is the input level. A LINE source gives a lot more signal (hotter) than a Microphone.

Almost all mono channels with an XLR input are MIC channels. Almost all channels with a TRS (Jack) input are LINE channels. You can't use a line channel for a MIC, and usually not a mic channel for a line source, as you have experienced.

You should connect your sources to the correct input, and it should be possible to adjust the level with the gain knob that the level meter (VU meter) is comfortably near the green-yellow level. Red is always bad.

For all others: yes i know there are exceptions, but please keep it simple for once.

It makes perfect sense now.  I will never forget that.  Thank you for being clear and easy to follow!
Logged

Stephen Kirby

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3006
Re: Couldn't Stop Mic Peaking
« Reply #31 on: December 12, 2017, 05:46:52 pm »

Since a wireless receiver basically has a preamp in it, I've tended to look at their outputs as line level.  I've turned down the output level on mine so it's easier to stuff into any channel.  But if someone comes up to me with one, I'll usually start 10-15dB down from where I usually set mic inputs.  And if it's pegging things, find it's output level.

I also seem to need to toggle back and forth on the mic gain settings depending on how strong singers are.  If I know they're strong, or I hear distortion (typically the receiver is up on the stage but I'll go up and look at the metering if I hear something) then I'll turn the mic down at the next break.  Usually, folks get louder as the show goes on so what might be an occasional clip  in the first set can turn into full Decapitator mode by the last if I don't reset the mic.

I'm also thinking that the OP might want to use his compressor as more of a peak limiter, high ratio, fast attack and fairly fast release, than as a general compressor.  This would allow the speaker to have more dynamics in their delivery but keep the egregious shouts from pegging things.  Once they've set everything upstream to handle those peaks.
Logged

Brian Adams

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 403
    • Adams Production Services
Re: Couldn't Stop Mic Peaking
« Reply #32 on: December 12, 2017, 06:58:11 pm »

Mic and line are differences in level, and not dependent on the connector. As a very basic introduction, line level is typically +4dB, while mic level is around -50dB. That's more than a 50dB difference, which is a lot. A mic level input is expecting a mic level signal, which is low, so the preamp adds additional gain. A line level input is expecting a line level signal, which is much hotter than mic level, and doesn't have a preamp and doesn't inherently add gain. The gain pot adjusts the level further, but there is always additional gain on a mic level input. When you plug a line level source into a mic level input you can easily overload the input with the hotter signal. When you plug a mic into a line level input you'll struggle to get enough level from it, although you'll get some.

Mic level signals tend to be XLR, but are occasionally other connectors. An example would be a high-Z mic with a 1/4" connector. Probably not something you'll run into these days, except maybe on a harmonica mic, and you probably won't be running that directly into a mixer anyway. But it can happen that you'll see mic level on a 1/4" connector.

Line level signals can be on nearly any connector. On the input side of a mixer they're often 1/4" TRS, but line level outputs can be XLR or 1/4". Line level in the professional world typically uses XLR connectors, since TRS connectors kinda suck. RCA connectors are also line level, but typically not as hot at around -10dB. Some consoles have a pad switch to attenuate line level signals, which typically reduces them by 20dB and is often enough to avoid clipping. Some consoles have a wide enough range on their preamp that they can handle a line level signal on a mic input.

A mic level input on a mixer is typically XLR and line level inputs are often 1/4" TRS and sometimes RCA. Some mixer's outputs are switchable to mic level, but most are line level XLR, occasionally some 1/4", and sometimes RCA. Most professional consoles only have XLR line level outputs.

But again, it's not the connector that determines the level, but the signal. The connector can be an indicator, but there are always exceptions. In any case, you probably want your receivers set to mic level if you're connecting them to the mic inputs of a mixer.
Logged
Brian Adams
Adams Production Services
Vermillion, SD
adamsproductionservices.com

Jeremy Young

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 443
  • DSL SM80, JTR OS-Pro/C212Pro, A&H iLive T112/R72
    • Brown Bear Sound
Re: Couldn't Stop Mic Peaking
« Reply #33 on: December 12, 2017, 08:43:04 pm »

I had the gain all the way off.  Actually, -5.  With no gain, shouldn't his level have completely been off?  What am I not understanding.  For example, on an analog mixer, if you turn the gain knob all the way off, there is nothing coming through the speakers for that channel.  Right?


Hi Joe,  you've gotten some great advice here.  Since I didn't see a direct answer to this question above I thought I'd try to elaborate for you.  Bear with me, this got long-winded.


Here goes: No.  Try not to think of it as on or off.  It's not a "master volume".  -5 would just mean 5dB less than what's entering that connector on the mixer.  If it were a wired dynamic microphone, it may seem as though you have "muted" the input, but with the gain set as far counter-clockwise as possible, there is still the opportunity for signal to be contributed to the channel and therefore the mix.  Different manufacturers of mixers use different terminology, or different methods of working with "line" and "mic" level inputs.  Some use the same XLR connector but insert something called a "PAD" to reduce the level by a fixed dB value (which is also different brand to brand sometimes), others use two sets of connectors, one for each level of signal with different sensitivities at each input.  Pads are usually enabled with a button.  You may have a "hot" signal, where once you enable the PAD, you find your signal is too low and you need to add gain once again. 

Hopefully the explanations already given on the different relative output levels of "mic" or "line" level devices will help in picturing this, but let's say you feed a signal of -20dB into that channel.  That's the output of the source (let's say it's a microphone). 


When it enters this channel strip on the mixer, the job of the preamp/headamp/gain/trim(/whatever other name seems to be used by manufacturers) is to adjust that level to one that brings the electrical signal into a usable range.  It's the first "signal amplifier" in the mixer signal chain, but there are PLENTY of places in a live sound mixer to increase or reduce signal level. 


In this case we would take that tiny little (analog) electrical signal created by sound pressure waves at the microphone diaphragm, and add gain in the preamp before the signal is converted into a digital representation of itself.  From there, that signal is modified through EQ, compression, etc, or changed in level again by your fader, combined with other sources, converted back to an analog electrical voltage swing, and then the mixer spits it out as a (line level typically) electrical signal to your speaker system.  The amplifiers are just taking this small (still larger than mic level) voltage swing, and increasing it once again to the point it can move speaker cones in and out.  We'd call that "speaker level".  The day I started thinking of signal levels as voltage swing it became easier for me to picture this process.


If your entering signal were +6dB, then with the "first amp in the chain" knob (preamp gain) turned fully counterclockwise (until that standard gets changed on us) you would be reducing that by 5dB.  As you can see, the same gain setting on the board, with two different input levels can lead to two different signal levels in the channel strips.


Your mic is wireless, the receiver is what is wired to the mixer, and it can put out different levels ("mic" or "line") to make it compatible with a range of equipment.  It needs to be optimized for your setup.  "Gain staging" - that is, the process of establishing the best places to increase level in your system, takes practice and experimentation to do right, or even understand.  Done right, you can have a system that has the potential to get very loud, but when no sound is "heard" at any of the inputs, is still very quiet (low "noise floor").


To put it as simply as I can think of, you generally want the signals entering your mixer to be as high/loud/large/hot as possible without "clipping" or "peaking" so that you have a high resolution representation of the source signal with which to mix.  If the source is too quiet, we have to add level at other places in the signal chain to get it loud enough, and that will increase the noise floor of your system, among other issues.  When you clip, you have essentially run out of "headroom", or you have a signal that's  bigger than the equipment is designed to work with at that stage.  Where this clipping happens in the signal chain will have different affects, but it's never considered a good situation for any length of time.


Try an experiment.  Turn on some playback music or something with a fairly consistent level (not someone saying "test" into a mic over and over, although that would work if you're consistent enough).  Bring it up in the system and listen to it.  Listen for hiss or noise in the background.  Reduce the preamp gain of that channel, and turn up the master fader until you find yourself at the same level you started with from the speakers.  Now listen for noise, hiss, hum, etc.  I'll bet there will be more noise present in the second listening.  By taking a quiet source and adding a lot of gain to it, you increase the volume of the source, plus any noise inherent in the system.  If you start with a loud source, you don't have to add much gain, and therefore the system noises aren't amplified as much.  Microphone preamps are a great place for the massive gain increase needed at this stage, as they are built with low-noise in mind.


I hope that makes sense.  I've tried to be as entry-level as my mind will let me be with my lingo.  If I've missed something or mis-stated terminology the wise folks on this forum can step in and correct me and we can all learn along the way.
Logged
Brown Bear Sound
Victoria BC Canada

Isaac South

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 341
  • Central Kentucky
Re: Couldn't Stop Mic Peaking
« Reply #34 on: December 13, 2017, 08:41:01 am »

Since a wireless receiver basically has a preamp in it, I've tended to look at their outputs as line level.  I've turned down the output level on mine so it's easier to stuff into any channel.  But if someone comes up to me with one, I'll usually start 10-15dB down from where I usually set mic inputs.  And if it's pegging things, find it's output level.

I also seem to need to toggle back and forth on the mic gain settings depending on how strong singers are.  If I know they're strong, or I hear distortion (typically the receiver is up on the stage but I'll go up and look at the metering if I hear something) then I'll turn the mic down at the next break.  Usually, folks get louder as the show goes on so what might be an occasional clip  in the first set can turn into full Decapitator mode by the last if I don't reset the mic.

I'm also thinking that the OP might want to use his compressor as more of a peak limiter, high ratio, fast attack and fairly fast release, than as a general compressor.  This would allow the speaker to have more dynamics in their delivery but keep the egregious shouts from pegging things.  Once they've set everything upstream to handle those peaks.

You are exactly right, Stephen.  I'm wanting to still allow the preacher to have dynamics in his voice.  One, just for the simple fact of dynamics.  It's normal for a preacher to speak softly at times and then with more intensity at times.  I want the crowd to be able to distinguish some of that.  And two, if I don't allow some dynamics, the crowd will drown him out when they clap and yell amen. 

So I will be using the compressor as a peak limiter for now.  Not saying that's the best decision.  Just saying that's how I'm thinking of it right now.
Logged

Isaac South

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 341
  • Central Kentucky
Re: Couldn't Stop Mic Peaking
« Reply #35 on: December 13, 2017, 09:09:45 am »



I hope that makes sense.  I've tried to be as entry-level as my mind will let me be with my lingo.  If I've missed something or mis-stated terminology the wise folks on this forum can step in and correct me and we can all learn along the way.

Jeremy, this makes sense.  Thank you for that explanation.  Now I understand that you can't determine mic or line merely by looking at it.  And the way the signal comes into the mixer plays a big role in the gain staging that I am able to do.  Which is why I still had plenty of level with the gain at (-5) the other night.

Thanks for clearing that up.
Logged

David Morison

  • SR Forums
  • Hero Member
  • *
  • Offline Offline
  • Posts: 631
  • Aberdeen, Scotland
Re: Couldn't Stop Mic Peaking
« Reply #36 on: December 13, 2017, 09:30:01 am »

Jeremy, this makes sense.  Thank you for that explanation.  Now I understand that you can't determine mic or line merely by looking at it.  And the way the signal comes into the mixer plays a big role in the gain staging that I am able to do.  Which is why I still had plenty of level with the gain at (-5) the other night.

Thanks for clearing that up.

Just had a quick look at the user guide for the Qu series (admittedly not the full manual) and it looks like you don't have the option of a mic/line switch (often called a pad) on the XLR input of that desk. Therefore to get lower gain at the desk itself (if you are unable to turn down the output of the radio mic receiver) you would need to unplug from the XLR and use the TRS line input instead.

FWIW,
David.
Logged

Jonathan Betts

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 540
    • http://www.facebook.com/pages/JLB-Sound-and-Production/156817657745906
Re: Couldn't Stop Mic Peaking
« Reply #37 on: December 13, 2017, 09:47:14 am »

Pads are available for QU when using the Allen Heath GLD series stage boxes.
Logged

Isaac South

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 341
  • Central Kentucky
Re: Couldn't Stop Mic Peaking
« Reply #38 on: December 13, 2017, 09:49:08 am »

Just had a quick look at the user guide for the Qu series (admittedly not the full manual) and it looks like you don't have the option of a mic/line switch (often called a pad) on the XLR input of that desk. Therefore to get lower gain at the desk itself (if you are unable to turn down the output of the radio mic receiver) you would need to unplug from the XLR and use the TRS line input instead.

FWIW,
David.

David - I am able to turn down the gain on the wireless mic receiver.  I remember reading about it when I purchased them.  I will be at the church tonight and I am going to look into that.  Thanks for digging into that info for me.
Logged

Jordan Wolf

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1357
  • Location: Collingswood, NJ
Re: Couldn't Stop Mic Peaking
« Reply #39 on: December 13, 2017, 11:42:25 am »

Therefore to get lower gain at the desk itself (if you are unable to turn down the output of the radio mic receiver) you would need to unplug from the XLR and use the TRS line input instead.
According to the block diagram, this is not the case.



There is no pad shown between the TRS jack and the preamp; it is simply the users choice of connection.

That being said, there should be no issue if the OP sets the receiver output to Mic level and adjusts the preamp gain as needed.

I find that “normal” speech has my QLXD receiver gain set at +10, which has my levels on the unit in the green and tickling yellow. I’d set it lower for very dynamic speakers, maybe at “0” and compensate at the console.

The noise floor with stable RF should be low enough to not cause any issues.
Logged
Jordan Wolf
<><

"We want our sound to go into the soul of the audience, and see if it can awaken some little thing in their minds... Cause there are so many sleeping people." - Jimi Hendrix

ProSoundWeb Community

Re: Couldn't Stop Mic Peaking
« Reply #39 on: December 13, 2017, 11:42:25 am »


Pages: 1 2 3 [4] 5 6 7   Go Up
 



Page created in 0.052 seconds with 22 queries.