Mixer and Powered PA Settings

[guitarguy1376]

So here is the question. I am recently getting back into playing out. We have slowly started to accumulate enough gear. This week I made a purchase to finish the package. The problem is I am trying to figure out how to set the levels on various devices.

I have a peavey 10 mixer going to 2 powered QSC K-12’s. Each mixer channel has the normal slider on the bottom and a gain at the top of the channel. The mixer of course has the two main sliders for output. And finally the QSC has a Gain control as well.

In what order should I raise these levels? Should I start with the QSC on half or ¾ and use the sliders to bring me to a suitable volume? Or do I set the slider on the channel to 0 and adjust the gain on the mixer to meet a suitable level and then bring the power PA up until happy with the level? I have heard that if your output from a board is not high than the sound quality could suffer. I have also heard that if you have powered speakers and do not have them up to at least half they will not produce an optimum sound.

Any input is greatly appreciated

[Tomm Williams]

Gain is gain, where you draw it from (generally) is not an issue BUT...........your channel trims also affect volume at the monitors (if you run any) so just be aware that you might be affecting more than what you intend. The general rule of thumb is to run your amps wide open and then achieve a balance using the channel sliders and trim controls. Having said that, these controls are meant to be used for whatever ends you demand. If you find that running the amps wide open leaves your other gains barely usable, then cut back where needed so you can obtain a balance throughout. Certainly one thing to avoid is where you have one stage so hot (speakers?) that you cannot get a smooth adjustment anywhere else as a small movement produces huge gains.

There is actually a proper procedure for gain structuring but it really applies to getting the most from a system at higher volumes. If this is your situation, the topic goes a little beyond a post but can be easily found in numerous sites. Opinions on this also vary (doesn't everything?) but the general idea is there. About the only dead-fast rule is do not drive any gain stage into a clip and you'll be fine.

[lschwart]

How you approach this ultimately depends on your needs, I'm assuming that this is for a small acoustic gig. In any case, there are some fundamentals that hold true no matter what the situation.

It's a good idea to read up a little on gain structure and what each stage in your chain is designed to do, but these are the very basics and a "rough and ready" way to get usable settings in what I assume is your situation:

Each signal coming into the mixer at the inputs needs to have its level set so that you've got a good balance between signal and noise and that you have, as a starting point, all your signals at about the same level coming in. This is achieved by using the gain knobs on each channel.

Set your channel faders a little below the "zero" mark and the main out down all the way (you can have your speakers on or off at this point, and I'd put their input level knobs at "zero" for now--12:00--more on that later).

Just have each musician play or sing as loudly as they are likely to do during the gig, one at a time.

On your mixer, turn up the channel gain for each signal until you see the little "clip" light on the channel start flashing on the loudest bits. Back off a little until it flashes only very occasionally if at all.

Once you have the levels set for each channel, turn on your speakers and/or turn up the main output with the musicians playing to see how the level is in the room. The input level control on the speakers is a sensitivity control, not a "volume" control. It sets the input level at which the amp in the speaker is driven to its highest output by the signal that comes into it. With that control at 12:00 (or "0 dBs"), you should have enough play on your mixer's main fader to drive the amps and speakers to more than enough volume for a small acoustic gig, and you should be able to make adjustments on the main fader that are comfortable in the sense that you don't have to push the fader very far to produce a reasonable difference in the output level, nor do very small adjustments make a huge difference. If you find one or the other of these to be the case, just turn the sensitivity controls on the speakers up or down until the adjustments are comfortable and the upper limit of the level is somewhere around "more than enough." Set it at a comfortable level for the room as a starting point (you may need to turn up later, when more people fill the room). You should now be able to adjust the EQ for each channel and the channel faders and FX--if you use them--to get a good, balanced mix (although that, of course, is a whole art unto itself....). If you're experiencing feedback before you get to the maximum level you need for the gig, you'll need to do some troubleshooting with the placement of your mics, pickups, and speakers--and there are devices that can help, too--but again that's a whole other matter. And monitors can add more complexity as well as some ways to fix this problem.

If you need to be able to access the maximum volume of which your system is capable--as you might for a larger gig, or if your were a rock band--there are more complex ways of doing this that will really tune your system to its optimum and maximum, but the above should work for a small acoustic gig in most local situations where you're responsible for running your own sound. If you don't have enough volume in the end, and everything is correctly and optimally set and working properly, you need a more powerful system, although I doubt that will be the case in your case.

I hope that's helpful.

Louis

[ljguitar]

Originally Posted by guitarguy1376

So here is the question. I am recently getting back into playing out. We have slowly started to accumulate enough gear. This week I made a purchase to finish the package. The problem is I am trying to figure out how to set the levels on various devices.

I have a peavey 10 mixer going to 2 powered QSC K-12’s. Each mixer channel has the normal slider on the bottom and a gain at the top of the channel. The mixer of course has the two main sliders for output. And finally the QSC has a Gain control as well.

In what order should I raise these levels? Should I start with the QSC on half or ¾ and use the sliders to bring me to a suitable volume? Or do I set the slider on the channel to 0 and adjust the gain on the mixer to meet a suitable level and then bring the power PA up until happy with the level? I have heard that if your output from a board is not high than the sound quality could suffer. I have also heard that if you have powered speakers and do not have them up to at least half they will not produce an optimum sound.

Any input is greatly appreciated

Hi gg…

You have heard a lot of stuff.

I work from instrument/mic in the chain.

• Individual input channel gain (top knob in each channel strip on the Peavey 10) - and make sure it's not being overdriven by the mic/instrument. It probably has a clip light. I set it so a mic or instrument played full-out loud is barely flickering the clip light. The master doesn't even have to be on to set this since you are only adjusting the signal coming into the board - not what's going out of it.
• Channel volume slider on each channel so they not overdriving the mixer. The channel volumes are how you mix/balance all the inputs into a pleasing sound.
• Then the master on the board so it's not overdriving the speakers.

A high quality amp/speaker combination will give you good performance at low or high volumes. If they cannot adjust at both ends, they are not very useful. QSC are fine throughout their volume/dynamic range.

Most mixers have a suggested line (often 0.0) where the expected level to operate exists, but it's a suggestion not a demand. I tend to want more Master Volume signal from the mixer because the speakers will exhibit less self-noise from the electronics.

Most mixer gear these days don't exhibit a lot of self-noise (electronic noise which is still present even when the mixer is turned down to zero). But keeping the master up to a healthy level minimizes our ability to hear it in the output. Guitar pedals, and other processing gear tend to have/add noise to the chain.

If I need to adjust the master volume in the room, I set the mixer where it normally operated, and turn the powered speakers up/down. On a system where the amp is separate from the speakers, then I control output to the room from the mixer's main output slider(s).

The one thing I always look for is a hi-pass filter & if it does, I engage it. It lets the high frequencies pass through, and shelves/cuts off the frequencies which are so low they muddy the bass instead of contribute to decent sound.

Hope this helps at least give you a place to start experimenting…

[Tomm Williams]

Nice reply Louis, I really did not have the time or patience to get into that detailed of an answer. Nice that you did.

[lschwart]

Originally Posted by Tomm Williams

Nice reply Louis, I really did not have the time or patience to get into that detailed of an answer. Nice that you did.

Just trying to pay forward the kindness of some experienced folk who helped me a few years ago when I was trying to figure this stuff out myself! Among them posts by Larry and yourself (and many others) on this and other forums.

Louis

[midwinter]

Many forum members here were very helpful when I asked this same question.

I tend to approach my rig in the way Larry suggested. Get gain levels clean at each stage in the chain (channel sliders at unity, adjust gain using meters), then set mix levels using the channel volumes, then out to the speaker. I tend to turn up my speakers a little hotter than necessary and turn down the master so I have a little headroom if I need to bump up the volume.

[jseth]

Try Googling "Gain Staging" before you start turning a bunch of knobs... this will set you on the right track (which is pretty much what many here are saying); it's always good to have a general understanding of what you are doing...

[guitarguy1376]

Wow!! I was hoping for "some" input but what you all have provided this quick is amazing. lschwart, I really appreciate the time you spent with your reply. I was viewing gain as volume instead of input sensitivity. The light bulb clicked with that sentence. I also am using a mackie thump for a monitor so I appreciate the post from Tomm advising that I might be affecting the monitors as well. Good Advice! I'm gonna print these posts out and start messing around with the new toys. Wish me luck Thanks for all of your knowledge. You cant find this stuff in a book. At least not a short one!

[lschwart]

Originally Posted by guitarguy1376

Wow!! I was hoping for "some" input but what you all have provided this quick is amazing. lschwart, I really appreciate the time you spent with your reply. I was viewing gain as volume instead of input sensitivity. The light bulb clicked with that sentence. I also am using a mackie thump for a monitor so I appreciate the post from Tomm advising that I might be affecting the monitors as well. Good Advice! I'm gonna print these posts out and start messing around with the new toys. Wish me luck Thanks for all of your knowledge. You cant find this stuff in a book. At least not a short one!

No problem! Glad the post was helpful. You're right about the books. They can be useful, but they tend to be very general. It's difficult to ferret out what you need for a particular situation--especially if you haven't yet absorbed the underlying technical principles in at least a basic way--and especially if you're not running sound for a rock band in a club, which is more less what 90% of the general information out there assumes. Of course the real teacher is time spend doing it and working things out in the way that works best for your situation. Trial and error and trying again. Eventually things click and you don't have to think about it all quite as much.

Enjoy the process!

Louis