Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Steve Babine]

How many of you out there mix a live event from unity and up on your faders? I have a guy in our church who insists that if we pull the faders down below the U then it degrades the signal. By "degrades" he means squashes or distorts it so it sounds bad. I can turn down, say, the electric guitar so it is barely coming out of the house speakers and walk up to them and it is at a low volume but still crystal clear.

[Frank DeWitt]

It sounds like he was given a lesson in gain structure and got it a bit wrong.   Ideally when the mix is right and the volume is right all the faders including the main should be at about unity.  That is where you should start and then bring up the input gain pots to get the sound you want.

clearly as the show goes on, some faders will go down and some up. The signal doesn't degrade, but what does happen is the signal and the noise get closer to the same level. There is some self generated noise coming from your board. You want the signal considerable louder then the noise for good sound.

You asked how many do it,  I don't  I start at about -5.  Why, because It gives me a little more room. 

Bottom line,  It is not a big deal but overall your faders should be up there and your meters should be working.  If the whole board is low, your gain structure is wrong.  Go turn down the main power amp.

Frank

[g'bye, Dick Rees]

It sounds like he was given a lesson in gain structure and got it a bit wrong.   Ideally when the mix is right and the volume is right all the faders including the main should be at about unity.  That is where you should start and then bring up the input gain pots to get the sound you want.

Frank...

I'm going to offer an alternative to your suggestion.

I prefer to set the input gains first to get an optimum level, then proceed to build a mix.  The master faders and the channel faders can be anywhere you need them to be without really bringing up the noise floor.  The input gain setting is more critical in this respect.  Also, I want as much "power in reserve" at the faders rather than changing the input gain......which will affect any monitor mix you may be using.  Think of it as "air in the tires".  You want that to be right before you start driving rather than having to pull over and adjust your tire pressure for the road conditions.

The only time I go back and re-adjust the input gain is if I've had to make some cuts in the channel EQ and want to restore a bit of the gain lost in doing that or if someone sound checks at a much lower level than their performance.  But I'm used to setting singers mic channels a little low during setup as a large percentage of them will only get to their actual level when the curtain goes up.

[Kent Thompson]

Or if someone sound checks at a much lower level than their performance.  But I'm used to setting singers mic channels a little low during setup as a large percentage of them will only get to their actual level when the curtain goes up.

If I had a dime for how many times this has happened...

I start out at unity but, don't stay there. For one reason or another than I end up deviating from it. I really don't sweat it. If I have someone I set at unit who all of the sudden change their sounds or patches and the volume drops what are you gonna do? Gonna slam that fader to the top because if I change gain in the middle of the show I just messed up monitor world. Same goes if they get too loud. Gain knobs are not meant for mixing The faders are.

[Brad Weber]

I think Frank and Dick both have valid points and I tend to apply some mix or blend of the two approaches.  I consider:

• That the trim/gain settings also affect pre-fade sends.
• How much range in level that source may need during the performance or service.
• If setting the trim to a desired level puts the fader where a small movement relates to relatively large change in level or leaves little room to increase the level then that may not be desired.
• That multiple channels will likely sum on the mix buses, resulting in bus levels above any individual channel level.  If I find myself having to apply significant attenuation to a bus then since the higher signal level is still present on that bus for any of the signal path before the fader, it may be desirable to reduce the source levels in order to reduce the resulting bus levels.
• As Dick noted, source levels may change between soundcheck or rehearsal and the actual event, between performances or services or even during an event.  Keyboard patches or guitar effects presets that vary significantly in level are a good example.
• Many sources have noise levels well above that of the console so applying gain to those signals at the preamp only to then attenuate the signal for all mixes may not be desired.
• How the levels may affect, or be affected by, any equalization, filtering and processing between the preamp output and fader or send level control.

Based on such considerations I then subjectively 'best fit' the trim and fader settings to the specific source and application rather than applying a specific approach to all situations.

Steve, your cohort may believe that the faders being below unity indicates that there is excessive gain being applied at the preamp or in the EQ and that could have some validity.  However, not only is that not necessarily true but there are also times it may be desired to have the faders below unity.  For example, you may have a vocalist who normally sings backup but has a solo or sings lead on a song, so in order to have the ability to raise the level for their solo and still have some added range if needed you may want to normally have their channel with the fader below unity.

[John Roberts {JR}]

Consoles designers invest effort so users will generally get a good result despite despite various fader baseline preferences.

Twenty or thirty years ago when solid state noise floors were much higher, there were strategies to optimize and maintain S/N between different signals blocks of a console, but nowadays as long as you aren't clipping, and it sounds OK, it is OK...

While there have been long and tortured debates here arguing for only one correct way.  IMO there isn't one. Argue among yourselves, or do a search and revisit the old arguments.

JR

 

[brian maddox]

Twenty or thirty years ago when solid state noise floors were much higher, there were strategies to optimize and maintain S/N between different signals blocks of a console, but nowadays as long as you aren't clipping, and it sounds OK, it is OK...

JR

i was gonna say this exact thing, although my version had a lot more words and a lot less clarity...

[g'bye, Dick Rees]

   

• That multiple channels will likely sum on the mix buses, resulting in bus levels above any individual channel level.  If I find myself having to apply significant attenuation to a bus then since the higher signal level is still present on that bus for any of the signal path before the fader, it may be desirable to reduce the source levels in order to reduce the resulting bus levels.

   

Yeah, I forgot to mention the summing.  In less expensive (read "cheap") mixers, this is often where distortion can occur if the individual channel inputs are set nice and hot.

As usual, it's a balancing act.  Any change anywhere in the signal path will have some effect down the line, desirable or otherwise........

[Bob L. Wilson]

I think Frank and Dick both have valid points and I tend to apply some mix or blend of the two approaches.  I consider:

• That the trim/gain settings also affect pre-fade sends.
• How much range in level that source may need during the performance or service.
• If setting the trim to a desired level puts the fader where a small movement relates to relatively large change in level or leaves little room to increase the level then that may not be desired.
• That multiple channels will likely sum on the mix buses, resulting in bus levels above any individual channel level.  If I find myself having to apply significant attenuation to a bus then since the higher signal level is still present on that bus for any of the signal path before the fader, it may be desirable to reduce the source levels in order to reduce the resulting bus levels.
• As Dick noted, source levels may change between soundcheck or rehearsal and the actual event, between performances or services or even during an event.  Keyboard patches or guitar effects presets that vary significantly in level are a good example.
• Many sources have noise levels well above that of the console so applying gain to those signals at the preamp only to then attenuate the signal for all mixes may not be desired.
• How the levels may affect, or be affected by, any equalization, filtering and processing between the preamp output and fader or send level control.

Based on such considerations I then subjectively 'best fit' the trim and fader settings to the specific source and application rather than applying a specific approach to all situations.

Steve, your cohort may believe that the faders being below unity indicates that there is excessive gain being applied at the preamp or in the EQ and that could have some validity.  However, not only is that not necessarily true but there are also times it may be desired to have the faders below unity.  For example, you may have a vocalist who normally sings backup but has a solo or sings lead on a song, so in order to have the ability to raise the level for their solo and still have some added range if needed you may want to normally have their channel with the fader below unity.

I was trained many years ago on portable and sketchy saloon systems to use lots of input gain to maximize signal to noise ratio ratio. It worked for that specific purpose but often left faders and aux sends in marginally adjustable or visually confusing positions. Now I adjust everything so the faders reflect how I want the mix to sound. My mix strategy started trending this way as it became apparent the noise floor in the church system was so low there was no audible advantage to having the faders end up all crazy. After my favorite go with what works FOH engineer went on record advocating the same philosophy http://www.youtube.com/watch?v=1hwT15SSwgU the vocal criticism I would occasionally get for setting the gains entirely to give desired fader positions kind of went away. If we have soloists as part of a larger choral piece I always set the console up so the faders on the solo mics run higher visually reminding me I need to be intentional about putting them on top of the Choir and instruments. I then set the compressor on the vocal solo subgroup up with a higher threshold than I have set for the choir the two will tend to remain in whatever balance I have set up for them no matter what happens. I have also embraced Dave's two VCA method detailed towards the end of http://www.youtube.com/watch?v=MMMmR1u0CFk to control the overall amount of compression in my mixes very simply. I will also admit to now purposefully clipping the inputs on the console whenever we have congas or timpani based on his suggestion. Midas pres have a very distinct clipping behavior that just works with drum sounds.

[g'bye, Dick Rees]

I was trained many years ago on portable and sketchy saloon systems to use lots of input gain to maximize signal to noise ratio ratio. It worked for that specific purpose but often left faders and aux sends in marginally adjustable or visually confusing positions. Now I adjust everything so the faders reflect how I want the mix to sound. My mix strategy started trending this way as it became apparent the noise floor in the church system was so low there was no audible advantage to having the faders end up all crazy. After my favorite go with what works FOH engineer went on record advocating the same philosophy http://www.youtube.com/watch?v=1hwT15SSwgU the vocal criticism I would occasionally get for setting the gains entirely to give desired fader positions kind of went away. If we have soloists as part of a larger choral piece I always set the console up so the faders on the solo mics run higher visually reminding me I need to be intentional about putting them on top of the Choir and instruments. I then set the compressor on the vocal solo subgroup up with a higher threshold than I have set for the choir the two will tend to remain in whatever balance i have set up for them no matter what happens. I have also embraced Dave's two VCA method detailed towards the end of http://www.youtube.com/watch?v=MMMmR1u0CFk to control the overall amount of compression in my mixes very simply. I will also admit to now purposefully clipping the inputs on the console whenever we have congas or timpani based on his suggestion. Midas pres have a very distinct clipping behavior that just works with drum sounds.

The funny thing is that we end up in the same place by looking at the glass as "half full" or "half empty".  When I set my gain structure the way I do it, I end up with the faders "looking like I want the mix" as you describe.......unless the players are of drastically different levels of ability and experience and offer wildly varying input levels during performance.

Still, the number 1 consideration for me is whether or not the monitors are being mixed from FOH.  No matter which direction you go....mains > gains or gains > mains.....if you're mixing  both monitors and house from the same console, I prefer not to mix with gains. I don't think you're doing this.  I just want to keep it clear for the OP that both ways will work and that focusing on input gain levels does not necessarily preclude having the faders visually represent the mix levels once you've gotten your method down.

As an aside: Having a meter bridge is the coolest way to get visual representations.  That's why I like the "output" selection for the FAT channel LED's on the Presonus StudioLive desks.

[Frank DeWitt]

Frank...

I'm going to offer an alternative to your suggestion.

I prefer to set the input gains first to get an optimum level, then proceed to build a mix. 

I don't understand.  where do you set your faders before setting the input gain?  They need to be somewhere other then infinity. 

To clear up what I was saying, I set the faders at -5 then set the input gain, then never touch the input gain again for that practice and service.  We have 11 other mixers running off the preamps so adjusting the input gain causes trouble for lot's of people.

[g'bye, Dick Rees]

I don't understand.  where do you set your faders before setting the input gain?  They need to be somewhere other then infinity. 

To clear up what I was saying, I set the faders at -5 then set the input gain, then never touch the input gain again for that practice and service.  We have 11 other mixers running off the preamps so adjusting the input gain causes trouble for lot's of people.

Frank....

That's what the PFL or "cue" buttons are for.  Solo the channel to get it hooked to the metering, then set the input gain according to the meter.  Different folks prefer different input levels according to their experience and the dynamics of the performance.

If your board is a lower level one without the capability of "soloing" the channels, then yes, you'd set your faders how you want them to be for the mix and dial in the input gain using the meters in this mode.  It's another case of "6 of one.......".  Either way, you're using the meters.  I prefer using the PFL/solo/cue method as I don't then subject everyone else to blasts of sound as I dial in the inputs.

DR

[Don Sullivan]

Mixing from unity is a wonderful concept full of lousy assumptions. While it is a good idea to operate your input gains in a manner that lets you keep your faders around "unity", there are plenty of times you need to raise or drop a fader significantly above or below unity, such as when a singer moves away from a mic and you want more of them, or instruments suddenly play louder (or badly) and the fader is the first thing you use to drop them into noise. The balance between multiple singers and instruments is your responsibility and often needs riding to keep a reasonable mix. I do not regard a mixer as a "set it and forget it" rotisserie appliance. YMMV.

[Brad Weber]

Mixing from unity is a wonderful concept full of lousy assumptions. While it is a good idea to operate your input gains in a manner that lets you keep your faders around "unity", there are plenty of times you need to raise or drop a fader significantly above or below unity, such as when a singer moves away from a mic and you want more of them, or instruments suddenly play louder (or badly) and the fader is the first thing you use to drop them into noise. The balance between multiple singers and instruments is your responsibility and often needs riding to keep a reasonable mix. I do not regard a mixer as a "set it and forget it" rotisserie appliance. YMMV.

There may be some different aspects being addressed as I think what was being discussed in many of the responses was not 'set and forget' mixing or always keeping the faders at the same level but rather how to set the nominal starting point for the faders.

[g'bye, Dick Rees]

There may be some different aspects being addressed as I think what was being discussed in many of the responses was not 'set and forget' mixing or always keeping the faders at the same level but rather how to set the nominal starting point for the faders.

I think that a person learns how to set their input gains according to their dynamic needs.  I do a lot of catch-all audio, so I like to have as much head-room on the faders as possible.  If you're in the same situation with essentially the same musicians all the time, you learn the way that works for you in that scenario.  If you're never in the same situation in anything other than the general sense.....trench audio.....then you need a bit different approach.

Frank mentioned establishing an input gain with the faders set around -5.  I do pretty much the same thing, but I set my input gains by meter and to the "hottest" practical level.  I'll let the channel faders and mains levels develop as needed, but often find that I start our mixing the channels at around -5.......in the beginning.  As "more" becomes needed, I'll get the channel faders up around unity or above.

So I think it depends on the dynamics of the situation.  And that is a fairly large variable.

DR 

[Jay Barracato]

I think that if someone thinks that not having the fader at unity causes some noise problem, then the designer of the mixer need not of included that part at all.

[Karl Stringer]

Interesting discussion.
This is a very good article by rane:
http://www.rane.com/note135.html

I took their advice and set the input preamps/trim, whatever you want to call it to give as much signal as poss without clipping. This means all our chanel faders are at -20 to -5 at the most.
I could change that by just bringing the main down, but what would be the point? I set the main up by sending pink noise through at unity, with the master at unity and slowly turned the power amp down until it just stopped clipping (so, in theory at least, setting the maximum level that the amp can handle). Then set the main at -5 to give it a bit of breathing space.

Is it just aesthetics or am I missing something important in my understanding of how a board works (well, a digital one).

Thanks
Karl

[g'bye, Dick Rees]

Interesting discussion.
This is a very good article by rane:
http://www.rane.com/note135.html

I took their advice and set the input preamps/trim, whatever you want to call it to give as much signal as poss without clipping. This means all our chanel faders are at -20 to -5 at the most.
I could change that by just bringing the main down, but what would be the point? I set the main up by sending pink noise through at unity, with the master at unity and slowly turned the power amp down until it just stopped clipping (so, in theory at least, setting the maximum level that the amp can handle). Then set the main at -5 to give it a bit of breathing space.

Is it just aesthetics or am I missing something important in my understanding of how a board works (well, a digital one).

Thanks
Karl

I think the main consideration is not overloading any summing amps.   

[John Roberts {JR}]

Yawn, are you guys still flogging this?

When was the last time you had to back off faders because your summing amps were clipping....  anybody?

For Karl... One problem with pushing your preamp trims up to the edge of clipping at sound check, is what happens if the talent was holding back, and the inevitable volume creep as the night goes on, means that just before clipping, turns into  actual clipping.

I would leave a few dB of front end headroom JIC.

As I already mentioned once, modern consoles don't require walking the old school tightrope of hitting the bus hard to maximize dynamic range.

If it sounds good and you don't see clip lights, it is good... don't over think this..

JR

[g'bye, Dick Rees]

Yawn, are you guys still flogging this?

When was the last time you had to back off faders because your summing amps were clipping....  anybody?

The last time I had to use a cheap, crappy mixer supplied by an AV company.  And it wasn't me backing off my stuff.  It was me correcting the signal flow for the owner of the company.........

It can be done, but it requires a cheap mixer and significant OE.

[Kent Thompson]

The board we had before we went digital but, yeah your point is well taken.

[Ivan Beaver]

When was the last time you had to back off faders because your summing amps were clipping....  anybody?

It was just a couple of years ago.  We were providing stacks and racks-the band provided everything else.  A LARGE outdoor event (the audience area was around 1000' deep and probably at least 2000' wide.  Loud was not the requirement here-but coverage was needed (at least to be able to hear the band)

I setup my system and then just took a line out of their console.

The problem was on the vocals.  With 1 2 or 3 vocals everything was fine.  But when the 4th vocal came in-the vocals would distort.  Almost every time.

So I went up to to the mixer (they were doing the mix on stage-typical for them).  I dropped the vocal channel levels a bit and increased the vocal subgroup level (by the same amount) and everything was fine.

While I agree it is rare-it does happen.  However I can only think of this one particular case in which it did happen---------------So take it for what it is worth-no much.  But it did bother me for a little while anyway.

[John Roberts {JR}]

Only two examples? You guys can do better then that.

My point is that bus saturation is "generally" over-estimated as a problem. Of course it "can" happen. I designed one recording console with over 100 stems feeding the L/R bus. it can happen.

Looking at your 4 vocals singing at the same time... ASSuming the worst case summation (if they were making exactly the same signal, they don't) it would sum to 4x or +12dB. So if the bus was capable of cleanly passing +20dBu that means every vocal was peaking above +8dBu at the same exact instant. If the signals were not coherent they would only increase 2x or +6 dB meaning every vocal would have to be peaking to +14 dBu simultaneously... lets split the difference and say they were probably hitting +11 dBu each,, so pretty hot for a single stem, let alone a 4 part vocal harmony.

This is why we put meters on buses, and when no meter is budgeted, at least a bus clip light..(while some value products may not even indicate there).

Like I said if it sounds OK and no clip lights are flashing, it is OK. If you hear audible clipping like Ivan did, find it and fix it. It's not like the old days when we wanted to hit the mix bus hot to get decent S/N. While some may not have gotten that memo yet.

JR 

[brian maddox]

Like I said if it sounds OK and no clip lights are flashing, it is OK. If you hear audible clipping like Ivan did, find it and fix it. It's not like the old days when we wanted to hit the mix bus hot to get decent S/N. While some may not have gotten that memo yet.

JR

i'm with JR on this.  early in my career it was pretty critical that i pay scrupulous attention to gain structure throughout the console and the whole signal chain just to get something decent coming out of the speakers.  but times have changed.  i now have a very pragmatic approach to fader level made possible by the advent of electronics with a very wide area between the noise floor and clipping.  i'm certainly aware of where the limits are, but i'm not afraid to use the real estate given to make my final product as consistent and seamless as possible.

so now i tend to mix with the faders as close to the -5 to unity range as possible.  i long ago realized that using the on/off buttons on the channels was very abrupt and distracting during a show so i always use the faders to turn on and off microphones.  if i've set my gain structure such that the correct level for that mic is somewhere close to unity, than i don't need to 'remember' where the fader was, i just bring it to that level and then if it needs a bit more or less i just gently nudge it in that direction. 

i've also been known to use unity as my 'maximum safe level before possible feedback' when doing lavs and lectern mics.  especially with lectern mics this is very handy.  as different people get up to speak i can vary the level always knowing that i'm safe until i get to unity at which point i know i may be pushing it and i need to turn my 'critical ears' on so that if there's a hint of anything i hear it before anyone else does.

as usual, this is a long way to say what JR already said.  if it sounds OK, it is OK... 

[ProSoundWeb Community]