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How And Why Unity Mixing Can Make All The Difference In The World

You can tell the difference just by listening? Yes! Good unity mixes sound open, alive, immediate and unrestrained

By James Cadwallader March 20, 2009

Put yourself through the exercise of "What if I can't move the faders from unity?"

A few years ago, I was given tickets to a concert at the local arena. It was a co-headlining show where one act played, then the other, ending with both acts playing together. 

Being the supreme el cheapo, I eagerly accepted the tickets and acted like Romeo when informing my wife that I was taking her out.

We arrived early and naturally I took stock of the audio setup. Each act had its own reinforcement system complete with separate FOH, monitor mix positions, and line arrays du jour. 

Admittedly, one act had larger arrays, but like my dad once told me, when fishing, it’s the wiggle that gets the fish, not the size of the worm.

For a few moments I entertained the thought of going down and schmoozing with the front-of-house engineers, but that would have entailed a lot of smooth talking and/or somehow muscling my way past Butch and Bubba (one of which I’m sure had two x chromosomes) to get to the floor. I abandoned the thought and contented myself with enjoying the show to come.

Unfortunately, the audio for act one was a disappointment. In fact, it was horrible. 

Act two, on the other hand, sounded fantastic. Why? 

Was it because act two had the larger system and thus could put out greater SPL? Nope – I’m too old to fall for that one. When someone declares an immediate and unequivocal improvement in what they’re listening to, I get out my SPL meter and compare the levels. Don’t even try to get that one past me.

image

Picture A

What I heard was the difference between running a console at unity and running it without headroom. You can tell the difference just by listening? Yes!

.
Good unity mixes sound open, alive, immediate and unrestrained while mixes overdriven in the console sound small, closed, lifeless and harsh.

It has been my observation that when the system is properly set up and aligned, and the sound ain’t so great, the console faders tend to look like Picture A

Conversely, when it sounds good, the faders look like Picture B. Where the faders are positioned has everything to do with the channel preamp gain setting.

image

Picture B

When I first got into sound as a wee lad, one of the earliest questions I had was how to properly set the preamp gain on the console.

.
The answer, of course, was to turn the knob until the little red light flashed and then back it down until the flashing stopped. Not. This produced maximum signal-to-noise ratio, but there was absolutely no headroom at the mix bus summing amplifier at unity.

Today, I so wish I could slap that person like they deserve, but that’s what I knew and that’s what I did. My mixes looked like Picture A, and most importantly, sounded like it. Something felt audibly wrong, but I couldn’t find a way to hear outside of that paradigm.


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Mark Dubosky says

The technical reason that this works is that when the faders are set at unity, then the input trims can be set for the maximum signal to noise ratio, while still allowing for sufficient headroom, usually around 15-20 db.  If the faders are very low, then the input runs the risk of being overloaded, even when the channel output is at the desired level.

This is not to say that the faders always stay at unity during a live mix.  But rather it is a good starting point and allows for good control to make balance adjustments as needed during a performance.

Also, keep in mind that at the bottom of the fader, the db range is very large, making fine adjustments to the mix difficult.

I hop this answers the question.

Mark Dubosky
Natural Sound Audio Services
Bangor, Maine

Eilon says

I was wondering, is there a technical reason for this? Is this true in every case? For example for loud sources or quiet ones? Does it matter if its a live situation or studio recording? I have to admit that I had the opposite experience where by mixing from the gain stage sound was worse, which is the reason for my question. Anyone?

Knows enough to be dangerous says

I do a bunch of live sound for a couple clubs.  Have I been making a mistake by using the PFL to set gain level first?  I guess my faders mostly sit at unity afterward anyway…  After reading this article, I'm questioning my process.

Also, what about "output" on my compressor?  and main LR faders?  All of these clubs have their own systems with the amps wide open.  Some with some pretty serious gear and at one particular club, the LR really can't go above -15 without removing paint from walls.  (I don't really like to let it get above 110db)

Mixing music says

How to mix music?
1/you gain for reasonable signal/noise. To make every source "talk the line levellanguage" No Problem with any system post 1965.
2/Starting at somewhere at or below unity you USE YOUR FADERS to Make the instruments you for musical reasons want to hear less of lower. And The Instruments you want to hear more of higher,
You shoot for a reasonable VU level at the program bus. In a proper system resulting in an appropriate SPL.

This does very rarely result in faders being at unity.
Music has never been a unity gain democracy kind of game.

This article is in my opinion less than brilliant, it is infact nowhere close to exact, either by musical or technical standards.

Andrea Melega says

I'm not agree.
Why mixing consolle producer put the faders in to the consolle if it's not necessary to use?

Justin Lizama says

Is this the case for Digital consoles as well… where AD/DA conversion is the first that occurs?  Could it be that the difference between a good mix and a poor mix is the engineers ears and what they perceive? I see a lot of engineers these days mixing visually (more so on digital consoles) and feel that is the first mistake.  Thoughts?  To me this article scrapes the tip of an iceberg and that's about it (not to mention live and studio engineering are truly 2 different monsters).

Justin Lizama
Highline Ballroom, NYC
Solidman Inc.

James Cadwallader says

Knows enough to be dangerous:
The question to answer is: Do your mixes sound as good as the best you've heard?  If so, don't sweat it.  Having the main faders at -15 though is a little disconcerting.  This could indicate that your mix may well be clipping the mix bus summing amplifier.  I would work the main fader back toward unity by reducing the channel gains appropriately.

Justin Lizama:
Yes, good process and technique is just as important.  I first mixed digital live 10 years ago and I found that even though the math may be floating point or have some insane amount of fixed point headroom, the resulting sound quality of non-unity mixing was eerily similar.
Does perception influence mixes?  Of course, but perception is a learned ability, not a fixed trait.
I would also caution not to automatically conclude that studio and live are so different.  While the environment may be dissimilar, the goal of both is identical.

Eilon says

James I was wondering, what is your opinion on PFL metering and how to use it?

Usually what I do is use the PFL to see where my level actually is while I adjust it. This way I can make sure that I have enough headroom. Also I monitor the input using a pair of earphones or if I have time during balance I solo it on the main PA. Thoughts?

James Cadwallader says

Eilon:
The only time I use the meter anymore is watching my overall mix so I know what the system processor is doing without having to look at it.  I will solo and verify that I have action in the channel by looking at the meter, but I do not solo when adjusting the gain.

Miguel Castro says

I find it hard to agree.

John says

This article confuses me totally.  It doesn't make sense electronically and it goes completely against the specific instructions of my desk.  I run an Allen and Heath Mixwiz 16 (and am still learning to drive it!)  The manual specifically says NOT to do what is suggested in the article.  I do monitor individual channels and I always check levels with PFL (even when live I will keep an eye on things at this end in case the musicians have kicked their backline amps or fiddled with something.)

Someone tell me that I am doing something right…

mike says

Can you kindly advise me the best gear I should invest in pleeeease!
We play 2 peice to 6 pc band, bass, lead/rhythm, 2 keyboards & drums, all using mics for vocals.
Need a good powered mixer, bass bins & midtops.
Thought of Dynacord powermate 1000 , EV bass bins & EV SX300/ 200. Also heard of a new Yamaha P'mixer that has got everything including compression on every chnl. Got to be light, as small as possible & practical to transport. NO MORE HEAVY LUGGING! Many thanx

James Cadwallader says

John:
I'm old enough to know now that just because someone builds a tool doesn't mean that they know how to use it to its full potential.  I've known mechanical and electrical engineers who could build large mechanized systems and not have the slightest idea how to operate them effectively or efficiently.  Those directions make sense to the technical writer who wrote them, but will get you into trouble because you'll likely be overdriving the mix bus at unity.  You can clip the mix bus without the meter even going into the red.

mike:
Visit your local retailer, or post in the LAB Lounge and see if anyone bites.
http://srforums.prosoundweb.com/index.php/f/5/0/

Mixing music says

This comedy has to end.
There is no substance or truth to this article. Technically or musically.

Tom S says

With all due respect this article is misleading and will only confuse people as they endeavor to learn their craft. In my thirty years of live sound mixing I’ve more often found the opposite of your observation to be true. There are plenty of books and online resources that cover correct console gain structure.

Additionally, with two different PA systems, two different monitor rigs, two different bands, two different sets of mics, two different monitor mixers, two different FOH sound mixers (on and on) there is just no way you can attribute one mix sounding better than the other based on a visual of each consoles fader settings.

John says

Its what I thought as well.  The emperor has no clothes and someone is brave enought to admit it in public.  The article is fundementally flawed and it doesn't make sense electronically.  Just because some desks/systems have a very large dynamic range, and allow you to get away with using them in such a way doesn't make it right.

I do know something about signal to noise ratios and gain structures and I guess that I will continue to use my desk as the designer's intended.

Perhaps the only real truth is that gain structure through a whole system needs to be monitored to ensure there is sufficient headroom at all stages from pre-amp through to PA and speakers.

CSJ says

This article can be a bit misleading, because it really all depends on what you are trying to achieve.

The key point here, is if you slam all your inputs to 2dB below clip and multiply that by 48, in most analog boards, or digital boards with limited dynamic range, you will clip the summing amp, which sounds nasty.

The overlooked point though is this - often how hard you drive the preamps at FOH has more to do with the sound you are trying to produce from them, than what your output level at the summing amp looks like. some preamps perform better in the top 10% percent of their dynamic range, some dont. the important thing is to be aware of whats happening in summing stages for which you have no meter.
Good pre's dont respond linearly so we need to be aware of their behavior to achieve the sound we want.

The converse point though, is that if you are too abstemious with preamp gain, your noise floor will increase fairly significantly, and you may end up adding gain in stages which are less than ideal.

The reality is, if you use group and VCA bussing well, you can have the best of both worlds, great preamp levels that achieve the sound you desire and a sensible amount of headroom at the mix buss.

Miguel Castro Rios says

It will clip the summing amp?

Well you have sub groups wich will help, and the main bus doesn't have to be turned up to the point where it will clip, nor the individual faders.

I just don't agree with the article, what if you are ussing multiple consoles? One for TV station FOH and Monitor console, or what if you have a multitrack recorder.

And even if you use ONE single console for the musical event, most of the time you have to use your aux sends for monitors and effects, wich some of them will be set to "pre" making it hard to achieve clean and balanced aux mixes, I believe this technique can really mess up the balance between other electronic devices and your console.

"'T" says

This article is misleading. Actually it's just wrong.

30 years ago, having the fader position homed at unity mattered (a bit). Boards were noisier.

Today? - It does not.

You can easily measure this with a clean sine wave input to a channel, Then measure the channels output with the fader then set at various points from unity on down, leaving the preamps at the same position.

There is no difference.

The faders do not matter! I would venture to say that more often than not - the CONVERSE of what you say is true as respect to sound-quality. Especially when too many, too hot, signals sum and overdrive the bus output summing amp.

Dave Dermont says

With all due respect to the author…

Ya gotta be freakin' kiddin' me.

First of all, this article is about as far away from the spirit of Study Hall as it gets. There is very little technical information here, and what little there is, is wrong.

Secondly, I really doubt the "small, closed, lifeless and harsh" sound the author hears is caused by a fader being pulled down. In fact, I'm sure of it. I'd be willing to bet that the bad sound was what is commonly referred to as "The Band Sucking Out Loud".

This might be a good article for the editorial section, but this has no place in Study Hall.

Dave "biting the hand that feeds me" Dermont
ProSoundWeb Sound Reinforcement Forum Moderator

Andy Peters says

James,

So you referenced a LAB thread. Why not come on over and discuss your techniques?

-a

James Cadwallader says

Andy,
If there's a thread you'd like me to visit please provide the link.  I'd be happy to have a look and join in if appropriate.
James

Dave Dermont says

Mr. Cadwallader,

You are invited to join the discussion of this article in The LAB Lounge. Please follow the link below.

Careful, some of those guys have been sharpening their pitchforks and are waitin' on you.

http://srforums.prosoundweb.com/index.php/t/44118/81/

James Cadwallader says

Yes Mr. Dermont, the pitchforks have been sharpened haven't they.  Thank you for the graciousness of your forewarning.  Once the blood has cooled, if anyone there has a sincere question they can post it here and I'd be happy to respond.

Andy Peters says

James-in your comment from 3/25, you linked to the Lab Lounge.

Seriously-you should come over to the forum and defend your article. It's easier to have a real back-and-forth discussion in the forum rather than in the comments section of a blog.

Also, as a professional electronics engineer, I take exception to the following generalization: "I’ve known mechanical and electrical engineers who could build large mechanized systems and not have the slightest idea how to operate them effectively or efficiently."

Those of us who actually design stuff know how it works. (Of course our customers might surprise us with, um, interesting applications.)

You made that comment in response to poster John, who mentions the procedure in the manual for his Allen and Heath mixer. If you bothered to come over to the LAB, you'd see a bunch of posts by Carey Davies, the guy who's the head designer at A+H, and he still goes out and mixes bands when he has the chance. So your comment is completely off the mark.

James Cadwallader says

Andy,

I also saw your comment to my previous article.  Congratulations, I bow to your obviously superior technical intellect.  I'm no match for your prowess.  You are the master.

What I will never cede is that people like you and me are most often the greatest hindrance to truly great sound.  Perhaps you walk in higher engineering circles than I do.  Good for you.  I'm glad someone does.  As for me, I can distinctly see that the reason why we frequently suffer from less than the best audio quality is not because of a lack of technical ability, but because of a lack of proper perspective and a much too complicated process.  Personally, it was time for me to re-examine every bit of technical knowledge I believed as concrete when confronted by someone who had zero technical ability yet could mix circles around me, and who refused to accept compromises forced upon him for "technical" reasons.  You guys on the LAB can snicker and call into question a guy's mix or hearing all you like, but I frequently don't see you offering anything other than more technical slavery.

I dare you to abandon your belief structure and see what you can really do.

Oh, and thank you for driving up my page views.  I'm negotiating for a view bonus.

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Greg says

First off, I totally disagree with the ‘faders at unity' concept.

Almost every ‘pro' sound tech (guys who do sound on ‘known' bands tours) that I've worked along side do this whole ‘fader at unity' technique. I ask them all why they do it and the only answer I've heard is, "it's how I was taught". Then every single one of them who have to run monitors from FOH never have enough gain to drive their aux's for monitors. . . THEN the performers get upset when their monitor mixes change constantly as the mixing engineer is tweaking his gains.

After taking Electronics Engineering and having to build A to D converters at school I understand how they work. As a preliminary statement, let me say that I also am a recording engineer and would like to point out that there is a reason people record at high bit depths - it's to achieve a more ‘analog' (smooth) waveform. See photo of analog (or high bit depth and sample rate) vs low bit depth/low sample rate/low gained digital waveform here:

http://media.soundonsound.com/sos/sep05/images/forgotten1aquantisation.l.jpg

Quoting the webpage from where I got that picture… "With a higher bit rate, there are more possible amplitude values". Well technically speaking, the larger the waveform going into a A to D converter, the truer the representation of the waveform. If the preamp is turned way down (because you want that channel on your mixing console quiet in the mix), then you may end up with a block like digital square wave (sounding like junk) vs a truer to analog type waveform with a properly gained input to your converter.

To touch back onto my earlier statement about recording at higher bit depths, it's mostly heard in things like reverb tails where near the end of the tail are very small signals… which in the digital realm end up being square waves.

Having said all of that, your theory is flawed… big time. . . at least on digital consoles.

For analog consoles, it's all about signal to noise ratio. EVERY single electronic component introduces noise. So technically you SHOULD keep your signal to noise ratio as awesome as possible… in other words keep your signal as large as possible.

Lastly, if your having troubles with clipping summing stages (like you say in your article), fix yourself. haha Keep an eye on everything, that's your job. If you clip after a compressor, turn your makeup gain down! If you're clipping the stereo buss input, slide all your faders (or group faders) down! Making sure you're not clipping is the first step to mixing!

Sadly, the people who mix with their faders at unity probably will always mix that way. . . and I'll continue to laugh inside at them haha

Snarky Atheist says

Greg,
Some comments. You've "designed" ADCs, so you should have some familiarity with sampling theory. As such, you'd know full well that the picture to which you linked, which shows a stair-step approximation of the digitized waveform, is completely _WRONG_. Hint: a sample represents the amplitude of the signal at the sampling instant. There is no amplitude value between the samples. It could like like this: http://cnx.org/content/m0009/latest/cosine.png
To get back to a continuous-time signal, you need to apply a reconstruction filter, which is what fills in the time between discrete samples. And this is _independent_ of sampling frequency or sample word length ("bit depth" is the wrong term).

Second, the reason for using longer word lengths is to increase resolution at the bottom end. A 24-bit word pushes the quantization noise down below the noise floor of the analog electronics. So turning down the preamp and digitizing a cold signal won't give you that "block like" signal you describe. Reverb tails are _NOT_ square waves. As noted, that's NOT how sampling works.

For BOTH analog and digital consoles, you make a trade-off, which is summing headroom vs signal-to-noise ratio. In both cases, if you trim the inputs hot, in order to mix without overloading a mix bus, you have to pull down the input faders.  You can get away with hot input trims when doing a solo-acoustic act on a big console, because of how the console's summing attenuates each input, but when you run all of the inputs hot, you're in trouble.

Please, go back and study your textbooks about sampling theory and come back to the conversation when you actually know what you're talking about. It's clear that Cadwallader has no idea what he's talking about-don't be like him.

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