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Push the levels - desk or PA?

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Re: Push the levels - desk or PA?

Postby AlecSp » Mon Feb 11, 2019 11:24 pm

Blimey, the OP does seem to have complicated things with all the crunching of (unreliable?) numbers.

My approach is much more hands on. Ensure no clipping in the channel strips/mixer signal path. Run your typical noise at 0dB on the desk i.e., fader positions - I don't care about what the numbers on the meters say, as long as they're allowing for plenty of headroom (digital mixer here). Then adjust the speakers for the required level for the show. That way, you can mix at 0 as standard, but have another 10dB of master gain if you need it.

Whatever happens, you shouldn't be damaging the speakers by asking too much from them - that's the benefit of the system protection. Doesn't mean they won't sound ropey as you push them past the limiter. But carry on hands on - look and see if the limiter light on the speaker is on more than occaisionally at both "standard" and "more pokey" levels. Do this a few times and you should soon be familiar with what your kit can do.

In the end, gain is gain, whether it's in the channel pre, the channel fader, the DCA, the master fader, or the speaker input (although the latter is more about attenuation, but that's no more than negative gain).

Using your ears can be way more effective than using a calculator... :thumbup:
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Re: Push the levels - desk or PA?

Postby Folderol » Mon Feb 11, 2019 11:28 pm

Late to the party here.
I've always considered this to be conflicting requirements.
In the most extreme cases, for the best noise performance you want the last control in the line to be doing most of the attenuation, but for the best distortion performance it should be the first (bear with me I'm an old valve jockey).
However, over time input stages have become quieter and with better linearity. These days, even on my modest setup I tend to start out with everything in their mid ranges and adjust final volume at the amplifier for convenience more than anything else.

As for what peak power means to the listener. It is meaningless without the centre frequency, bandwidth and duration. The surprising one is duration. Try playing with various simple waveforms at different frequencies and an envelope shaper and you will find the fewer the cycles the quieter it sounds. What's even more strange is that (especially at higher frequencies) if you increase the drive you find a point where it becomes very uncomfortable without sounding loud - and I'm not talking about when you're going out of your normal hearing range.

P.S. I forgot the magic words.
"In my opinion/experience"
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Re: Push the levels - desk or PA?

Postby witzendoz » Tue Feb 12, 2019 12:40 am

I have a touchmix 16 and the touchmix does seem to have less output than some other mixers.

What I have found is that even if you push each channel quite hard with the manual knob the main left / right outs still seem a little low output at fader unity. However if you go into the individual channel settings there is a digital gain control. This gain is after the channel manual knob so that a gain increase here does not overdrive the channel (as long as you don't go mad I suppose). So gain each channel up a few dB and then when setting the manual gains on each channel to a sensible level the master left / right will increase without clipping the channel gain.

Hope that made sense.
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Re: Push the levels - desk or PA?

Postby Hugh Robjohns » Tue Feb 12, 2019 10:43 am

manleyelop wrote:...would it be best to have my desk fader levels more around unity & back off the power amp level? i usually find my faders are below unity but still get good sound results but would rather do things different if what im doing is bad practice

It depends how much below unity they are!

You want to keep your channel faders around unity to maximise the precision and ease of your balancing adjustments. If you end up running the main output fader at -10dB to achieve a sensible level in the room, that's no big deal but if they're at -30 the gain structure is going a bit awry.

It's all about optimising the signal-to-noise ratio while also maintaining a sensible headroom margin.

In your case, you also have the option of optimising levels between the mixer and amps with the DBX crossover, of course...
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Re: Push the levels - desk or PA?

Postby manleyelop » Tue Feb 12, 2019 11:34 am

Hugh Robjohns wrote:You want to keep your channel faders around unity to maximise the precision and ease of your balancing adjustments. If you end up running the main output fader at -10dB to achieve a sensible level in the room, that's no big deal but if they're at -30 the gain structure is going a bit awry.

It's all about optimising the signal-to-noise ratio while also maintaining a sensible headroom margin.

In your case, you also have the option of optimising levels between the mixer and amps with the DBX crossover, of course...

Yes i must admit some of my channel faders where floating around fairly low but not -30 should i adjust those faders to around -10 check gain levels & lower the power amp volume ?
Although my desk master fader was in good health floating around unity

Thing is i do pfl each channel when setting up im using an old allen & heath mix wizard
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Re: Push the levels - desk or PA?

Postby Hugh Robjohns » Tue Feb 12, 2019 11:53 am

I wouldn't worry too much if the masters are -20dB or so, especially at the start of the gig (it's not unusual for the master to creep up a bit as the gig progresses). A decent desk should still be quiet enough that your signal-noise ratio isn't too badly compromised running in that way -- at least in a live sound situation.

But if it's a regular thing and concerning you, then dial the power amp input attenuators back by 10 or 20dB and run the console masters closer to unity.

H
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Re: Push the levels - desk or PA?

Postby manleyelop » Tue Feb 12, 2019 1:25 pm

Hugh Robjohns wrote:I wouldn't worry too much if the masters are -20dB or so, especially at the start of the gig (it's not unusual for the master to creep up a bit as the gig progresses). A decent desk should still be quiet enough that your signal-noise ratio isn't too badly compromised running in that way -- at least in a live sound situation.

But if it's a regular thing and concerning you, then dial the power amp input attenuators back by 10 or 20dB and run the console masters closer to unity.

H
Thanks Hugh My desk master fader usually sits around unity during live gigs from memory,ive read about folk liking to see there ch faders sit around unity also but some of mine are way down from that but that is where the mix sounded good to me perhaps im just worrying about a problem that doesn't exist :headbang:
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Re: Push the levels - desk or PA?

Postby Hugh Robjohns » Tue Feb 12, 2019 2:14 pm

manleyelop wrote:ive read about folk liking to see there ch faders sit around unity also but some of mine are way down from that but that is where the mix sounded good to me perhaps im just worrying about a problem that doesn't exist :headbang:

The faders have a non-linear scale, so the finest resolution (level change per mm of travel) is around the unity mark. That's why it's a good idea to arrange channel input levels so that you can keep the faders near unity during the mix/show.

If you find you're having to work with a channel fader well below that, it's simply because you don't need much of that source's contribution in your mix (perhaps you're hearing a lot of it acoustically from the backline, or it's a banjo that you don't want audible in the mix... ;-) ).

You could simply turn down the channel's input gain control to allow you to raise the fader closer to unity while still contributing very little to the mix -- but bear in mind that will also reduce the level being fed out to any pre/post fade aux send and any direct output recording feeds.

H
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Re: Push the levels - desk or PA?

Postby manleyelop » Tue Feb 12, 2019 3:35 pm

Hugh Robjohns wrote:The faders have a non-linear scale, so the finest resolution (level change per mm of travel) is around the unity mark. That's why it's a good idea to arrange channel input levels so that you can keep the faders near unity during the mix/show.

You could simply turn down the channel's input gain control to allow you to raise the fader closer to unity while still contributing very little to the mix -- but bear in mind that will also reduce the level being fed out to any pre/post fade aux send and any direct output recording feeds.

H

yes that's what i was wondering about some of my ch faders have been hovering around -20 mainly drums & bass & im wondering if that's a bad way of doing things.the trim gain pot on the kick drum was pretty low so perhaps i should have padded it down & raised the trim level so i could raise the ch fader more
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Re: Push the levels - desk or PA?

Postby AlecSp » Tue Feb 12, 2019 3:51 pm

manleyelop wrote:ive read about folk liking to see there ch faders sit around unity also but some of mine are way down from that but that is where the mix sounded good to me perhaps im just worrying about a problem that doesn't exist :headbang:
If it sounds good to you (and others) then don't sweat over it. Better working practices can make you life easier, but your ears shouldn't be lying!
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Re: Push the levels - desk or PA?

Postby manleyelop » Tue Feb 12, 2019 4:02 pm

AlecSp wrote:
manleyelop wrote:ive read about folk liking to see there ch faders sit around unity also but some of mine are way down from that but that is where the mix sounded good to me perhaps im just worrying about a problem that doesn't exist :headbang:
If it sounds good to you (and others) then don't sweat over it. Better working practices can make you life easier, but your ears shouldn't be lying!

yes my ears told me it was a good balance & everyone was happy im always willing to learn to do things better by habit plus i have lots to learn but really appreciate this forum :mrgreen:
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Re: Push the levels - desk or PA?

Postby Hugh Robjohns » Tue Feb 12, 2019 4:09 pm

manleyelop wrote:...some of my ch faders have been hovering around -20 mainly drums & bass & im wondering if that's a bad way of doing things.

It would only be 'bad' if, with the faders for those channels at unity, the signals would be so loud that they overload the output of the desk -- because in that situation you're clearly driving way too much signal through the channel strip and risk major distortion.

But if you've set the channel input gains (using PFL, perhaps) so that the signal averages around or a little below the 0VU mark on the meters, then you have the ideal headroom margin, and you're simply pulling the fader back because you don't want much of that particular signal in the mix, for whatever reason.

If that's the case, then yes, it is an acceptable way to work... and a lot of people often find themselves doing exactly the same thing...

... but there are some practical implications that may or may not be important.

I've already mentioned the poor fader resolution when working far away from the unity mark, so if you want to tweak the source level very slightly that would be more difficult and less precise with the fader at -20dB instead of around 0dB.

It's also less convenient when switching between sound check and gig if there's a warm-up band in between, since it's much easier to push all the faders to unity and know you have a reasonable starting point for the mix, rather than try to remember Ch3 has to be at-20, Ch5 at -35 and so on...

And then there's the disparity between the levels being sent to pre-fade and post-fade Aux outputs, meaning you'd have to have wildly different aux send control positions for the same actual output level... which could become confusing -- or extremely unpleasant if you decide to swap a send from post to pre for some reason!
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Re: Push the levels - desk or PA?

Postby blinddrew » Tue Feb 12, 2019 4:45 pm

Hugh Robjohns wrote:or it's a banjo that you don't want audible in the mix... ;-) ).

Again with the banjos!

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Re: Push the levels - desk or PA?

Postby manleyelop » Tue Feb 12, 2019 5:05 pm

Hugh Robjohns wrote:
And then there's the disparity between the levels being sent to pre-fade and post-fade Aux outputs, meaning you'd have to have wildly different aux send control positions for the same actual output level... which could become confusing -- or extremely unpleasant if you decide to swap a send from post to pre for some reason!

yes i see i didn't consider that STILL no banjos in this equation though :bouncy:

Do you know the allen & Heath mix wizard desk Hugh?

The stereo channels St1 to St6 confuse me regarding there usage i.e which ones i can use for ext fx & which ones i shouldn't the manual just makes me scratch my head again.I never use the console built in fx they sound horrible to me.i would like to have 3 pre fade aux for monitors & 2 aux's for ext fx
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Re: Push the levels - desk or PA?

Postby Hugh Robjohns » Tue Feb 12, 2019 5:25 pm

manleyelop wrote:Do you know the allen & Heath mix wizard desk Hugh?

See other thread: https://www.soundonsound.com/forum/viewtopic.php?f=26&t=64970&view=unread#unread
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Re: Push the levels - desk or PA?

Postby AlecSp » Tue Feb 12, 2019 6:44 pm

Hugh Robjohns wrote:If that's the case, then yes, it is an acceptable way to work... and a lot of people often find themselves doing exactly the same thing...

I've already mentioned the poor fader resolution [...]

It's also less convenient when switching between sound check and gig if there's a warm-up band in between, since it's much easier to push all the faders to unity and know you have a reasonable starting point for the mix, rather than try to remember Ch3 has to be at-20, Ch5 at -35 and so on...

And then there's the disparity between the levels being sent to pre-fade and post-fade Aux outputs, meaning you'd have to have wildly different aux send control positions for the same actual output level... which could become confusing -- or extremely unpleasant if you decide to swap a send from post to pre for some reason!
Quite - "mixing at 0" needn't be an absolute religion, but it does make life easier.

I used to be an anal "set every channel gain individually by PFL" person until Mark Payne (from SFL) mentioned that he simply takes each channel, sets the fader to 0 and turns up the gain until it sounds right. (All assuming ample headroom in the system) It sounded to primitive, but really is that easy. And makes for super quick sound checks when that's critical. (Band with a 24 channel mix arrive 30 mins before doors, anyone?)

Your ears will (or should) let you know what's not right...
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Re: Push the levels - desk or PA?

Postby Hugh Robjohns » Tue Feb 12, 2019 6:54 pm

AlecSp wrote:...he simply takes each channel, sets the fader to 0 and turns up the gain until it sounds right.

Yep, that's the way I usually approach it too. Gets you in the right ball park very quickly.

H
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