Another gain staging question

[Cliff]

I think I understand basic mixer gain staging.
1. Set channel faders, sub group faders, and main faders to zero, or unity
2. Set the gain (at the top of the board) so that you get the level of sound you want.
3. Set the amps/powered speakers so you get the level of sound you want in the sanctuary.


What I am wondering is what you do with inputs/instruments with there own volume controls.
I have read that you set these onboard volume controls to the highest possible level, and lower the gain at the top of the mixer.

With the acoustic guitar with pick-up that we have he can't even get 1/2 way up and I have my gain on the mixer all the way down. Is this the correct way to go?

When using a computer or Ipod or the like, Do i turn them all the way up? Even if I have to put the gain all the way down? In order to keep the faders at 0.

When using a submixer(line mixer), in my case for converting stereo inputs (computer, Ipod, CD) to mono and only using 1 channel on the board instead of 6. What level should it be at? There are 2 volumes that effect each one, the dial for it's volume and a master volume.


Thanks for all your help. My mixes are getting better because of yo guys

[tropicalfish]

1. Set channel faders, sub group faders, and main faders to zero, or unity
2. Set the gain (at the top of the board) so that you get the level of sound you want.
3. Set the amps/powered speakers so you get the level of sound you want in the sanctuary.

No.
1. Set gains so that signal for each individual channel averages around 0dB on the LED meters. If you don't have LED meters that you can PFL to, then set it to below clipping.
2. Set the channel faders to AROUND 0dB/unity. (the faders should represent a visual of the levels).
3. Raise main fader to loud enough. Ideally (in a permanent setup), your amp gains get set and then never touched again.

I generally like having the main fader up to like -10 for a loud service.


What submixer do you have?

[tdangelo]

Cliff,

Regarding your acoustic guitar pick-up, Ipod, computer, etc. the output level on the device “depends.”

As a general rule setting the output gain on the device higher rather than lower is better as the higher output level on the device will give generally you a better signal to noise ratio. There are exceptions to this rule however. If setting the output gain on the device higher causes you to overdrive the input stage on the mixer, beyond that which can be adjusted by an input pad or trim control, then it would be wise to lower the output setting on the device to a point which it does not overdrive the console input.

In the case of your guitar example it sounds like the input on the console is set to “mic.” Have you tried the console input set to “line” and then adjust the trim accordingly?

[Cliff]

It is a cheap no name line mixer.
Our gain staging has never been set proper and I am now trying to. The powered speakers were way up and I had to run the gains & faders way low or it was way to loud.

The guitar goes through a Di on the stage then comes via the snake to the board.

[Cliff]

Originally Posted by tropicalfish

No.
1. Set gains so that signal for each individual channel averages around 0dB on the LED meters. If you don't have LED meters that you can PFL to, then set it to below clipping.
2. Set the channel faders to AROUND 0dB/unity. (the faders should represent a visual of the levels).
3. Raise main fader to loud enough. Ideally (in a permanent setup), your amp gains get set and then never touched again.

I generally like having the main fader up to like -10 for a loud service.


What submixer do you have?

Thanks for the clarification.

[audiomatic]

Cliff,

Thanks for the thread! We were all "taught" to keep all inputs at similar levels (0 dB gain) and try to ride the channel faders around unity. This is known as "0 dB mixing" and presumably works great in studios with near-field speakers and very little room ambiance. What if you're in a typical church sanctuary mixing flute and synthesizer? The flute has a comparatively narrow frequency range, and the synthesizer can have many frequencies, including low frequencies which travel more easily through air and tend to build up at the back of the room. If they're both at 0 dB gain coming into the mixer, you'll find yourself turning down the synthesizer fader so that the flute can be heard in the room. Maybe it would be better to leave both faders at unity, and turn down the gain of the synthsizer. This is known as "unity mixing."

Most people who participate in this forum use "0 dB mixing," because that's what we were taught. Tropicalfish seems to be in this category. Check out this poll.

http://www.churchmedia.net/forums/li...ol-volume.html

Eighty-six percent of us use 0 dB mixing because that's what works best in a studio. I'm inclined toward unity mixing because of the better signal quality when faders are near unity. (This is not to say that a live performance should be mixed with the gain knobs; during practice, set the channel gains as needed with the faders at unity, then adjust the faders as needed during the performance)

While 0 dB mixing seems to be more popular among us, there are detractors who should probably be heeded. Check this one:

http://www.cordernotes.com/blog/mixi...-mixing-part-1

http://www.cordernotes.com/blog/mixi...-mixing-part-2

http://www.cordernotes.com/blog/mixi...ixing-followup

http://www.cordernotes.com/blog/mixi...ixing-followup

Bottom line is, in my opinion, why would you want the same energy coming into the mixer from a flute and synthesizer if you're going to turn one of them down so that the other can be heard in the room?

Now, to the original question. Input signals have different levels. From lowest to highest:

Phonograph (record player)
Mic
Guitar pickup
Line level (CD player, keyboard, and acoustic guitar pickups with a preamplifier!)

Your acoustic guitar player uses a preamp. As tdangelo has said, make sure your channel input is set for "line level" rather than mic level, or it will be overdriven. Same with all other line level devices. Also some mixers have a "pad" button that damps the level. Useful for input signals with too much energy.

My rule of thumb is: guitars and electric bass should be turned all the way up giving the sound tech control throughout the service; raise/lower the gain as needed during practice to account for the level in the mix and in the room. Keyboards and other line level inputs might need to be at 75% to avoid overdriving the mixer inputs; pad them if you can.

I wish there were a formula for input levels and gain staging through the mixer, amps and speakers. Unfortunately, the only thing that really matters is how everything sounds in the room. I try not to pay too much attention to polls. It's more important for it to sound good than to have "proper" gain staging.

[tropicalfish]

Well, ideally, mixing with the faders and not the gain controls is best because it provides the best signal to noise ratio, and because console/board manufacturers recommend against gain mixing.
Here's a few selections from an Allen & Heath GL manual.

Important note on setting channel levels: Use PFL to set the GAIN
controls for correct signal level through each channel. The main LR
meters provide a high resolution display of the channel signal level.
Use the faders to balance each signal in the mix. To ensure optimum
gain structure we do not recommend the practice of setting the faders
to ‘0’ and mixing using the GAIN controls.

...


Use the equipment meters to set each item within the system path to
operate at its nominal level. We advise that the speaker processor or
amplifier trims are set so that the console outputs can drive up to their
nominal ‘0’ level. It is a common mistake to set amplifier trims to
maximum sensitivity when this results in the console master faders
being operated at very low positions, with low meter readings, and
reduced dynamic range and therefore audible residual system hiss.


...


There is a technique
used by some operators where they set all the faders to ‘0’ position
and balance the mix using the channel gain controls. We do not
advise this method as the signal to noise ratio and control resolution
can be severely degraded. In addition, it is impossible to mix monitors
from FOH in this way as changes to the gain settings affect the
monitors too.
The correct method is to use GAIN to match the source to the
operating level of the channel for optimum dynamic range, and then
use the FADERS to balance each source into the mix. With correct
system gain structure, prime sources such as vocals would have their
faders operated around ‘0’ while sources low in the mix such as
backing vocals and acoustically loud brass and drums would display
their true contribution with their lower fader positions. This is a much
more visual and accurate way of mixing.

[Tim Padrick]

I use a combination. Weak signals (vocals, mainly) get the PFL 0 treatment. Loud stuff gets set so I have the volume level I think I'll need with the faders at -10. This allows the faders to be in a usable area as opposed to -20 to -30 (where they'd be if I used PFL 0 on those sources).

[waynehoskins]

Another variable to throw in the mix is compression. Since it reduces each channel's peak level to be closer (by whatever amount you desire) to its average level, the 10 or so dB you might have to ride a dynamic singer or instrument is largely taken care of, faster than you could react to it as well. You can overdo compression, squishing the life out of everything, but done tastefully it can sure help.

My general technique is peaks around 0 dB on the PFL meter, compression bypassed; then compression as desired, and generally this lets the faders live in the -10 to 0 range for mixing.

[Tim Padrick]

I find compression to be a necessity on vocals if you want to be able to hear all the lyrics (I find that many if not most folks mix as though they know the words - and as such I cannot discern what they are). On instruments, I often find that compression does not help much, except as a limiter when someone dials up a patch that's way out there volume wise. But I still experiment.

But remember: On most all analog consoles, the inserted compressor also compresses the signal to the monitors. So one really needs two channels per source - one for the monitors, and one for the house. Many digital consoles give you a choice as to whether the auxes are pre or post dynamics. Some also give you a choice as to whether the dynamics are pre or post EQ. If you are cutting the low mids to compensate for mic proximity effect, choose post EQ for a much smoother result.

[Cliff]

Getting a little off topic but that is OK.
Why not compress the vocal sub mix? say put all vocals in sub mix 1 and compress that before it goes to the main?
I do not have a compressor --- yet!

[Tim Padrick]

Originally Posted by Cliff

Getting a little off topic but that is OK.
Why not compress the vocal sub mix? say put all vocals in sub mix 1 and compress that before it goes to the main?
I do not have a compressor --- yet!

That can work. The caveat is that if you have say a soft singer and a loud singer, the compressor will push them both down, so the soft one will pretty much disappear.