Lowering show volume: input gain vs fader vs master

SQ SQ General Discussions
1

We’re mixing a musical with mics and recorded music. At the default gain of 28 for the mics, mic faders at the zero line, and the master at zero we would blow out everyone’s ears. We’ve brought down the mic input gain to 20, keeping the input faders at the zero line, and have the master fader at -25. It still is too loud.

By lowering the gain are we loosing range? Where should we start? The meters for the mics are mostly green with an occasional yellow.

Where should we start if we want to lower the volume of the mics more? Is bringing the master down below -25 (and increasing the music input so it doesn’t decrease as well) have consequences other than the obvious desired volume change (like range)? Is there a better way to solve this problem?

We have 36 scenes, so whatever changes we make involve going through 36 scenes, adjusting and re-saving. I’m also curious workflow-wise, how others handle processing changes to a show with lots of scenes better than what we’re doing. We’re new at this, so any insights would be appreciated.

2

The goal should be to avoid having to make major changes to your entire musical, which you’ve already created and successfully saved in scenes.
There are several ways to reduce the level, and the easiest would probably be to reduce the input of the connected power amps or speaker management.
And someone here in the forum has decided to buy passive attenuators and insert them into the output cables.
Alternatively, if you don’t want to reduce your main fader (further), you can also send the signal through a matrix and reduce it there, or use a DCA (which could then also additional be used for excessively loud monitors.).
The respective fader (MTX or DCA) you could practically “hide”.
To avoid having to change your scenes, you would have to block these additions in the global filters.

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3

Thoughts from me would be that SQuser has answered all the good options, really.

If you’ve got a good gain structure already on the console, personally I would try reducing the output on your amps/powered speakers - it may be that they’re set a bit hot.

Or go for a DCA for the Main LR and then add it to your global filters (depending on whether you’re changing DCAs with scenes already) so that it doesn’t change with your scene recalls. That way you can add whatever attenuation you need but just leave the Main LR at unity.

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4

Every Level adjustment function has its purpose. You should use it for that and not for other things.

The Word you are looking for is called “gain structure”. Just read about it, there are plenty of HowTo’s out there going into details.

In short:

Always keep signal levels as high as possible as long as possible, but never too high. Lowering your signal level means your signal has less distance to the noise floor, which at the End also results in less usable dynamic range. A too high level means overdriving and clipping which sounds terrible. You simply want as low noise as possible and absolutely no clipping (which obviously is kind of a target conflict).

The difficulcy is that you can almost never know exactly how high a signal level will rise (and start to clip). You have to guess that. So all Level Controls need to be checked often and good metering is an important Part of that checks. SQ has mighty tools for that - you should absolutely learn how to use them!

Best Practice is to leave some “headroom” of level range which ideally gets not used (but helps if you guess wrong) - how much depends on your signals and your hardware, on a SQ 12-20 dB Headroom might be a reasonable point to start since it has a really fine dynamic range and 24 Bit samples. With that you are still beyond the quality Level that an Audio CD could even deliver. Beware: the metering might have a “0dB” Mark which already gives some headroom, check your documentation for that!

Additionally it might be a good Idea to use Brickwall Limiters on (or before) Inputs. They at least can stop going into hard clipping too much. Setting them to stop Peaks at 2 to 6 dB below the Hardwares clipping point should be safe. Sp if you work correctly, they never do anything at all. If you make a mistake they can reduce damage dramatically.

The Rest is “source to drain”. Use the Gain Control to keep the Peaks of your Input Signal at the Headroom level. Use Channel Faders to adjust relating levels between Signals and keep the Mixing bus on reasonable signal levels. If there is one, use Master Trim/Master Gain to adjust the Peaks to Headroom level.

To set your overall Show Loudness, it is best to set reasonable Levels on the final Amplifiers or with large PA Systems on the System Controllers the Mixer delivers its output to.

The Master Fader should be used to fine-adjust loudness while the show is running or to lower overall Volume temporarily because the Gig needs that (for example: on a Party, you should use Master to set different Levels for Dancing and Chilling time).

If you use Groups, it is the same, you just have one more gain stage to control it is easier to make groups of Signals more or less Loud in relation to the others.

If you cannot access the frontline levels directly, it is the least bad way to use your Master Fader for that (or route Master through a Matrix which can be used to set a reasonable maximum loudness so you can put Master to around 0dB on normal (loud) Operation.

5

Back when analog consoles/gear were used, the “best practice” was to run the amps at max power and then adjust the output of the console to ensure the volume in the room is at the desired level. This was done because the amplifiers were the “quietest” device in the signal chain. In other words, any “amplification” of the signal had the least amount of noise if it was done at the amplifiers and not in the console/preamps. This often meant that consoles were outputting signals at a level well below unity levels. It wouldn’t be uncommon to run a console’s output at -25db as in your situation.

However that line of thinking changed when the use of digital consoles became popular. Now the console is just as quiet (if not quieter) than the amplifiers. Therefore the current “best practice” is to run audio through the console at “line level” (ie at unity levels). This means the output of your console should be at unity (+/- 0 db). Now you want to adjust the level of your amplifiers to ensure the volume in the room is at the desired level.

My suspicion is that your amplifiers (or active speakers) are turned all the way up (ie to 10) which is actually too loud for your room/situation. As others have suggested, search for “live sound gain structure” for more details on how to set this up using today’s “best practices”.

6

Sure this wasn’t simply an urban Legend? An Amp cannot distinct between Noise and Signal, it simply always amplifies both. A Fader on a Mixing Bus will always reduce the self-produced Noise of the Bus much less than the level of the processed Signal because the self-produced Noise has substantial constant Components (for example thermal noise from resistors or badly filtered voltage artifacts from the power supply).

So at least in Theory, if you put Amp Gain high and Desk Levels low, you may generate less noise in the Amp but you definitely amplify much more noise coming from the Desk since the Amp has a much bigger Amplification factor. The Audience will not be able to distinct between Noise (from the Amp) and Noise (from the Desk and amplified by the Amp).

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Well, from a more comfortable Perspective of Work:

  1. adjust your Amplifiers to the maximum Loudness you need at all (including some reserve for situations when the audience is loud, too). You won’t want to touch them during the Show at all.

  2. if possible, Adjust your Mic Gains to a Maximum that won’t clip and that won’t feedback when faders set to unity.

  3. use the Master Fader to adjust main Loudness down to the really needed Level in the live Situation. This is the Knob you want to touch during Show if needed. Use Channel Faders to adjust single Signals.

  4. If it is too loud near the front line but you need the Loudness a bit away, you have to adjust the Frontline setup, e.g. flying Speakers, using Line Arrays (and Near Fills if necessary) or use one or more Delay Line Speakers to have a more constant loudness in the whole Area.

  5. don’t forget your monitor speakers, even when it comes about feedback!

  6. you always want to mute all momentary unneeded signal sources if possible, especially microphones. While you don’t need them, all they can generate is trouble. Don’t let them. There are helpful tools to get there, from Scene setup to Opto Gates.

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I’m old enough to have mixed on analog gear. This isn’t just “hearsay”…

First, your theory is actually fundamentally flawed. There WASN’T more noise coming from the desk at low levels. It was actually the opposite. The more your turned you desk up, the louder the noise got and it accounted for more and more of the total output signal.

Now you are correct in saying that an amplifier will increase both desired signal as well as any noise that has already been introduced into the signal by the desk. However the analog amplifiers were very good at amplifying the audio (source signal and any noise already present on the source signal) without actually add any ADDITIONAL noise to the source signal.

So if you low level output from the console had 60db difference between the source signal and the noise floor, you could amplify that cleaner signal much more and still not hear any audible noise. Compare that with a noise floor that was already audible at a line level output of the console (maybe a 20db difference) and even though the amplifier didn’t have to amplify the signal as much as the low level output example, it still resulted in a MUCH noisier overall signal.

These numbers are made up for this next example as I don’t recall any actual specs of the analog equipment I have used and I simply don’t care enough to look it up. The point is more to show the “math” we are talking. Think of it this way… If my output signal of the low level console output was .25v total, but the noise level only accounted to .00025 of that number, I could amplify that 100 times over and still have a noise floor of just .025. If the output signal of my console was at line level that would be 1v (of this example), but the noise level might be a .05 in this example. Now I only have to amplify that signal 1/4th as much as the low output example, but multiplying .05 times 4 is already at .2 which is 8 times the amount of noise that the low level console system created.

Of course we are speaking in general terms here. I’m sure someone will chime in that amplifier XYZ was very noisy or something like that, but generally speaking, you tried to run your console with as low an output as realistically possible, and you used your amplifiers to increase the volume of that relatively clean signal which just made a louder clean signal.

It’s why with an analog system you start gain structure at the amplifiers by turning them up all the way and then working backwards until you ended up at the console last. With a digital system, you handle gain structure the opposite way. You start setting gain structure at the console and work your way through the system until you end up a the amplifiers last.