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Gain Staging...what am I doing wrong?

Discussion in 'Recording' started by HippieDave, Dec 7, 2013.

  1. HippieDave

    HippieDave Active Member

    I've read a good bit about gain staging, and thought I had finally gotten a basic understanding, but when I experimented with how a now thought it should be done....disaster.
    I should add that I am approaching this as a live performance set up, but since I also record our live performances, as well as in the studio, I'm hoping I can ask the question here/--System is an Allen & Heath ZED 14 into active EV ZXA1 speakers ...stage monitors I leave for later....right now, they're not hooked up. For this experiment I have our usual stage set up mics...which are two AKG Condenser mics (C4000 and C3000B) for vocals and one Shure 57 to pic up the acoustic guitar.

    So, I start with my Allen & Heath ZED 14 mixer with everything at unity gain (except the channels I'm not using which I mute and take the faders all the way down). I start w/ the gain knob at zero, the channel faders at unity, the main faders at unity and the master control knob on my EV active speakers at zero (it is calibrated to go dB down or up from zero) My understanding is that next I should set the gain control using the meter to push the green lights up to the yellow/orange 'starting to clip' level and that is where the gain should be set. My problem is that I can't get hardly any reading on the meter without getting feedback. If the ideal is to have all settings on the mixer at or as close to unity as possible, how can I get there if I can't get any meter activity at all.?

    Sorry for such a newbie Q, but despite everything I read, this continues to frustrate and confuse.
  2. Boswell

    Boswell Moderator Distinguished Member

    Each channel has a gain trim and a fader. Put simply: The gain trim is used to normalise the inputs so the signals going into the faders are at a standard level. The channel faders then are set to give the required amount of that channel's signal in the mix. The master faders determine how much of the mix is sent to the output. There is no "ideal is to have all settings on the mixer at or as close to unity as possible".

    You should start with all the faders at minimum, all the gain trims fully anti-clockwise (labelled -6 on the Zed14), and all the EQ controls central. Go round the band with one sound source at a time playing into its microphone. For that sound source's channel, turn the gain trim clockwise until the peak LED flashes, then turn the trim back (anti-clockwise) by about 12dB. Once you have done that with all the mic channels and others such as keyboards, you are at a starting point to adjust the faders. You could begin by bringing up the output faders to about -10dB, then each track's fader until that track has a moderate volume in the speakers. Once you have all the sound sources established in the speakers, you can start to balance the mix by adjusting the channel faders and then add EQ as necessary.
  3. HippieDave

    HippieDave Active Member

    Thank you...that is the first simple, clear step by step instructional I've found. Everybody else seems to speak in tongues! I owe ya one (y) Is the process pretty much the same in studio and on stage, or are there differences?
  4. Boswell

    Boswell Moderator Distinguished Member

    Studio is different, because you are usually recording tracks and not mixing a PA. However, setting up the recording pre-amps is much the same as I described in the first step above.
  5. HippieDave

    HippieDave Active Member

    "...turn the gain trim clockwise until the peak LED flashes, then turn the trim back (anti-clockwise) by about 12dB."
    One point of clarification....my decibel meter is green up to zero, and yellow from zero up to +9 dB. I have one red light for anything above +9 (up to +16). When you say "turn the gain trim until the peak LED flashes..." (before you back down about 12 dB) are you meaning 'until your yellow starts to illuminate' or until the top yellow (+9) starts to register, or until you trigger the red?
  6. Boswell

    Boswell Moderator Distinguished Member

    Well, you want to end up with the peaks about 12dB below full scale (-12dBFS). If FS is +16 on the scale, get it peaking in the low yellows, around +3 or +4. If you use this method, you don't need to adjust by 12dB because the metering LEDs have done the work for you. However, I would check at least one channel with the peak LED and then back off 12 to see if you end up in the same ballpark.

    This is about more than simply not overloading the amplifiers on each channel. Most mixer pre-amps have a "sweet spot" or at least a "sweet range" where they sound best. It may take more familiarity with the mixer to hit that range without having to think too hard about it, but my advice is to begin at -12dBFS on each channel and get the whole system sounding right before starting on fancy footwork.
  7. Boswell

    Boswell Moderator Distinguished Member

    I know this is an old-ish thread, but gain-staging is a perennial topic. There's a new article by Chuck McGregor in Pro Sound Web that's worth a look. Although I don't agree 100% with him about some of the practical aspects of the topic, his analysis of gain bands, clipping levels and noise floor is technically correct.
  8. RemyRAD

    RemyRAD Well-Known Member

    When using any kind of a mixer, with multiple sources, the combined energy of the multiple sources has the propensity to cause feedback. So in setting all the levels, it's something of a juggling act. The problem arises when you don't quite understand how many separate gain stages there are, from where you plug a microphone in. To where everything is combined and summed together, before it's again boosted for the output. And when you don't have all of your little decibel ducks in a row? You're going to have feedback issues, overload and distortion issues. And if it really was that easy? Everybody would be a recording engineer. But they're not. So while it's easy for me and easy for Boswell, you're still on a learning curve and a listening curve.

    A lot of folks really don't know where to put their PA speakers so as to better avoid feedback. You don't put them up there on stage parallel with your microphones. No. Your microphones are behind the front of house speakers. This small placement difference and timing differential can make all the difference in the world. So just knowing where to put your speakers and how to angle your microphones for best feedback rejection, isn't necessarily something that comes naturally to one's self. You have to know what sound does. What the room goes to the sound. How to deal with the sound in the room. And what are the best microphones for the application?

    Too often folks are using condenser microphones in a tight close environment with the front of house speakers and/or floor monitor speakers that is a perfect recipe for raucous annoying feedback. So ya use the condenser microphones for your recordings. Ya don't use them for the PA system. No. They are overly sensitive. They pick up gunk at frequencies you don't need, offer no help and frequently cause feedback both high and low in pitch. Lesser sensitive, slightly bandwidth reduced dynamic microphones like the SHURE, SM-57 & 58's along with the 7's is what ya need for PA vocals. Let's be clear about that. Because if ya don't? We can't help ya. It's like, you rarely wear snowshoes to the beaches in the summertime. Or at least I hope you don't? What would be the purpose for that? You can keep the sand off your feet with other items that won't over encumber your transit. Right? Right.

    So my suggestion is, you work it, the other way, around. You sing, into the 57 (with a foam pop filter) or a 58 (with a foam pop filter) and you put your lousy condenser microphones on your guitar.

    You make sure your front speakers are in front of you and not even or parallel with you. As far in front of you as practically possible. This always improves gain before feedback.

    As you may have already realized? (Likely not yet?) There are devices known as feedback controllers. These feedback controllers can be effective simple cheap things from China or they can be of a higher end type. They all essentially do the same thing. They replace the need for you to have multiple 1/3 octave equalizers and calibration microphone based spectrum analyzers to tell you what the frequency is that is feeding back. At which point you would lower that particular 1/3 octave frequency. Which will then give you quite a few more DB gain before feedback. The feedback controller simply automatically analyzes what the feedback frequency is. Then it automatically dials that frequency in and provides a very tight notch cut. The better units have multiple stages of those to handle multiple frequencies that might be feeding back. But to use the thing, one does so, without the need for the band playing anything. You would, say, grab the lead vocal microphone. You would turn it up. You would turn it up until it starts to feedback. But you don't lower the volume controls anywhere. You just wait for the feedback controller to do its thing. And like magic... the feedback is gone.

    Now like anything else... one can try to overdo it. Still culminating in less than satisfactory results. Because the size of the room and its internal natural resonance along with the speakers and microphones can literally make for a nightmare. This is not as simple as one might think? Because it's not. Do you know that sound travels at 1100 ft./s? And if so? How does that fit into your equipment selection, microphone placement, reduction of feedback, a quality sound that fat and punchy. With great presence and great clarity. Whoa... that's a big order to fill. And guess what? If you can't get satisfactory results with your equipment? I'm sorry to tell you... it's not the fault of your equipment. Though it certainly gives you an easy way out to blame it on your equipment being less than satisfactory or less than professional. But it's rarely the equipment's fault. It's only the equipment's fault when it blows up and completely fails. Otherwise, if you're doing. And you can't always get what you want when not in the right location. Cubic footage of volume and space for sound to properly propagate in its environment. Given an area too small? You'll have to blame the room. And then it gets no more ice cream. It's already made you nuts. So you got that part covered. All that's left is the whipped cream and the cherry. Just remember... please use a condom... on your microphones.

    I can get those sounds. So you can get those sounds with what you've already got. Dealing with feedback? That's a whole different animal from making recordings. Sometimes it works out great.. Other times not. Frequently, not. Because the cubic footage isn't large enough. Ain't much you can do about that. Because sticking foam thingies on your walls can just make the matter all that worse. That sucks out frequencies you don't want to suck out. It leaves behind the frequencies you want to get rid of. Because that takes mass and not lightweight foam to do. How are ya going to deal with that? It is up to you. In a rental apartment you are generally screwed. In a single-family home, you'll likely be waking up baby all too often?

    These are decisions you should have made before you figured out how to masturbate a hook on a fishing pole. I'm just saying LOL. I think you understand where this is going? Right... down the toilet. That's a different kind of bass trap. You need the other ones.

    I've had problems with my bass trap. So I ate some yogurt.
    Mx. Remy Ann David
  9. pcrecord

    pcrecord Don't you want the best recording like I do ? Well-Known Member

    ??? I'm kind of disturb by that image ! :sick:
  10. paulears

    paulears Well-Known Member

    I don't get this at all? You are saying you don't use condensers for live events only for recordings because they are the main cause of feedback? If so, then I'm amazed. I use condensers for PA all the time - SM86/7s for vocals, drum overheads, acoustic guitars, saxes, flutes - all sorts. The only issue with feedback being worse is if you are trying to squeeze extra gain at the top end, and the extra top end response over a dynamic is too high for me to hear anyway. Sure - a condenser has more gain, so this control is set lower. Sure - it's brighter so your eq settings may well tame this a bit - but I don't get any significant feedback problems from using condensers. If I am trying to run a mic at too far a distance from the source, then feedback happens, and I agree - it happens at a higher frequency than a dynamic in most cases - but that's just how it is.

    As for feedback suppressors, great tools, but to make them work, you need to let the system feedback, so the notches activate - but when people move about the stage, the feedback frequencies change, so unless you let the system honk, they don't work - and as a result, they're in my view the devil's spawn. They also are a really blunt tool - perhaps for a conference, with no op, or a poor one - there is some ear protection function, but generally they're pointless in my view.

    If you get feedback too soon - then the speaker v mic placement is poor, the system eq has nasty spikes in it, or the room has a nasty resonance at the same place as the mics/speakers. The cure for feedback is not "don't use a condenser mic" That's plain silly, and far too many people have a mic box full of condensers for it to be good advice. No volume before feedback is a problem somewhere else. Sure - condensers may reveal the problem sooner than a dynamic, but it's not their fault!
  11. dvdhawk

    dvdhawk Well-Known Member

    Since this thread has been resurrected…

    I also loathe feedback suppressors - blunt tool indeed.

    Personally, I have no qualms about using condenser mics live, in the right application. And I absolutely agree with Paul, mic and speaker placement are the key to getting what you want from any mic versus the feedback threshold. I will say though, that I think most novices would be better served by something other than an LDC. In this case, the OP is long gone, but the E-V ZXA1 (being an active 8" 2-way) implies very small venues and I would contend that a mic less sensitive to the room around it would be the second thing I'd change - IF I were having feedback problems. The first being, speaker position.

    The gain-staging is a separate issue, assuming he's using the correct Line-In rather than the Mic-In. His problem seems to come from making all of his adjustments based on his eyes rather than his ears. The ZXA is an exceptional little speaker, designed for use in cozy venues. If I were at a point where I had to slam all the meters to squeeze every last decibel out of the ZED and powered speakers, I seriously doubt anyone will hear the subtle vocal nuances the LDCs bring to the table. If the venues are more intimate, to a large extent you can forget those optimum meter settings - the resulting output will be much too loud for the room. Ears…. they're not just for holding up your glasses.
  12. paulears

    paulears Well-Known Member

    I've done some odd things over the years, and have a fairly large number of condensers, small and large elements, and budget to expensive. I had a big band event to do, and the rider specified that EVERY band member needed to be miked (which afterwards, made me smile because for some, I'd have liked a negative gain mic to make them quieter!) So in the end I had everything miked with almost my entire stock - so the trombones and saxes got the LDCs, the clarinets and flutes the small ones, and everything else a rather random selection. Feedback in this case wasn't an issue, apart from the double bass, that I found troublesome with the SDC wrapped in foam, under the bridge legs - something I'd done before with some success. I swapped this for an AKG D112, on a short stand, and this oddly worked better - so maybe there's something in it?
  13. DonnyThompson

    DonnyThompson Distinguished Member

    I've used 414's, KM184's - and even the much despised CS1000's - LOL - while doing live reinforcement; for applications like drum overheads, percussion rigs, saxes, horn sections, acoustic guitars that didn't have built in Line Outs, etc., using both SDC's and LCD's - more times than I can count...

    ...and I've never had any trouble. As far as FB Suppression, I've never used it, or at least I haven't used it to my knowledge -( because many of those shows were using house PA's so perhaps they had one in place using settings they got on a previous ring-out) - so I can't consciously comment, other than I believe I would have heard it kick in if it was in use... but I don't ever recall FB even starting. If you pay attention to mic placement vs speaker placement, you shouldn't have any problems.

    The only real problems I've ever had almost always involve stage volume. Some of these cats play so damned loud, that I've had their channels OFF and they are still crushing the audience with sound. I understand the whole "Power God" with a Marshall stack thing, but at some point you have to come to the realization that you're gonna sound a whole lot better if you realize you are in a band - an ensemble - and that you aren't the only person on that stage.

    By keeping your stage volume reigned in, you give your FOH guy far more control to make you sound as good as you can to the audience.

    Which brings me to another thing I see happening more than I prefer , and that's sound "engineers" who feel the need to constantly twiddle - pushing and pulling faders, turning knobs. etc.

    With very few exceptions, you can pretty much lock down the mix at sound check, and as the room fills, make subtle adjustments here and there... but as a musician playing on a stage, the first thing that makes me nervous is to see the sound guy continually changing settings on the console after the sound check has been done and things sounded good to begin with. You just KNOW that they're out there ****ing it all up. ;)

    IMHO of course. ;)

  14. audiosphinx

    audiosphinx Active Member

    DonnyThompson, I disagree about fiddling with the levels. There is no way that a sound check (especially without the hype and a full body count), can be left alone all night long. It's a great starting point, but as the players dynamics change throughout, the FOH engineer needs to also make the adjustments...Especially when the live performance isn't as dynamic as you'd like...sometimes they need a little help, so riding faders, adjusting levels a little, really is not so bad...of course, you gotta trust the sound guy...so I understand if the FOH is inexperienced, but with seasoned pros, that's a good sign they're paying attention.
  15. RemyRAD

    RemyRAD Well-Known Member

    When I indicated that the use of condenser microphones for PA applications can be somewhat impractical. That's basically based upon what this particular person has for a system. When you can't get those FOH speakers in front of the microphones and your stuffed into a tight place? That's when those condenser microphones small or large can be impractical to less sensitive dynamic microphones. Sure, I've used all those great sounding condenser microphones with PA systems as well. But they're on PA systems that are real PA systems, and a proper sized venue with proper placements of speakers and microphones. Which isn't a miniature system crunched into a 100 square-foot stage in a bar. And where so many will use the FOH speakers slung around also as their monitors because there are stages to small along with their system for any monitors. I'm not talking about a professional venue I'm talking about Bob's bar and Grill on the corner.

    Of course you guys are all correct. I'm with ya. Right down to dynamic mixing of PA because the band has a sound guy. And not a Mackie 1604 sitting next to the guitarist. That then, sets the faders and doesn't touch them the rest of the night. Perhaps entertaining? Certainly not exciting. That's why good bands have good sound guys. And so every once in a while a good band that knows me and has a special gig, will sometimes contract me to come out and mix the PA for them. Not something I generally do. Because I don't like doing PA it's too loud.

    I wouldn't have the hearing I have today if I had played in rock bands like most of you have. I know what the long-term damage can do. I made a good chunk of my earlier living of troubleshooting by listening not by test equipment. And as I have aged I can hear, what I can't hear anymore. Which is something of a non sequitur I know. But when you start to get " chicken neck ", you know your eardrums can't be far behind LOL?

    I don't need my diaphragms tightened as I can't get pregnant anymore anyhow. Never could LOL.
    Mx. Remy Ann Pregnant
  16. paulears

    paulears Well-Known Member

    I did a swap a few years ago and stopped wearing black and started playing in a band - what struck me was how stupidly loud it can be on stage - especially when the band get squeezed into being closer together. The keys player at soundcheck would always say "Paul have you got enough of me in your wedges?" when I had none of him at all because I could hear him from his monitors on the other side. After a few gigs I started to get the tints back, I'd worked hard at stopping when I first noticed it. It just hurt. So I went to IEMs, and the old lags in the band just couldn't see how I could do this - despite the singing drummer having done the same thing the year before. Getting the keys and guitar turned down was impossible - both guys would have identical settings each night, on the principle that the room sound was for the PA guy, their stage sound, would be identical. The trouble is that it wasn't - for everyone else. For them - their distance to the monitor, and their amps was always the same - even on a smaller stage. Me - I don't care about amps because I don't use bass effects, and we often play 'PA supplied' gigs where for logistical reasons, we just fly in with guitars, and leave the amps to the local promoters. I do a DI, and that's what I hear, and rarely hear what comes out of my amp - I don't need to. Sometimes when the amp is close, I can feel it! Auto feedback controllers are such a blunt instrument that I'll leave it to the engineer.

    On the subject of fiddling - we did a soundcheck for a large corporate function - sounded good to me, we went off to find food. While eating we started hearing "one - cheeeew - tessssssst - checkkkkkkkkkk" and other odd things, but didn't really pay much attention. We didn't see the rack of compressors they then patched into everything, and our first number starts with with 2 bars of light picked guitar, then I play a long sustained bass note - and when I did the world shook! Over the years, because we sing complicated multi-part harmony (we're a Beach Boys tribute band) we often get strangers mixing, who don't know how the original songs sounded - plus we throw the lead lines around like mad - we can't rely on an engineer working out which three are harmony and which one is melody, and by the time they find it, we change. So we move into the mics for our lines, moving back just a touch to do the harmonies - so on a four faders in a line mix, it works. Not with cranked up compressors it doesn't. Equally, the keys go up and down in volume continually - but with a compressor, the volume pedal doesn't do anything. The keyboard player looks at the monitor guy and I see him angrily miming compressors - cut throat and lots of pointing. They pulled the compressors and normality returned. Why they thought adding compressors after the sound check was sensible, I'll never know. So I am firmly in the 'no knob twiddlers' camp!

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