1. Go With The Flow
This is the basic concept behind all audio engineering processes- that the sound engineer has a solid understanding of the flow of the signal path.
In simple terms, the flow of the signal is best described in the flow chart below.
PreAmp -> Insert Effects -> Equalisation -> Auxillary Sends (pre-fader) -> Fader Level -> Auxillary Sends (post-fader) -> (subgroups if required) -> Master -> Power Amp -> Front of House
Over the years I have seen sound guys running all the faders at the same level and mixing from the gain knobs at the top of the mixing strips. This is not only clumsy, it is not maximising the processing potential of your desk.
Those of you who are guitarists would be familiar of a guitar amp having a pre-amp (or gain) with a master level (or volume) at the end of the tone stack. This developed because guitars, microphones and other audio devices run at varying volume (or voltage) outputs, normally not strong enough to do any sort of processing with.
While high gain in the preamp stage is preferable with guitars, in sound reinforcement you generally want to get the signal as close to "line level" as possible. This is indicated as 0 dB on most desks.
In a live setting (and to a lesser extent the studio) you have the issue of dynamics. The dynamic range of an instrument or vocal is the degree to which the output varies (and in turn changing the gain required on the desk). For this reason (without using other affects like compressors or limiters) you need to be aware of how much fluctuation in the instrument volume there will be and what impact it will have on the gain setting.
Instruments like guitar amps and keyboards tend to only have a small variation in dynamic range (if the musician has set them up correctly) whereas vocals can vary greatly. Depending on the desk I generally like to have all gains set to about -6dB, allowing plenty of range if the volume onstage starts cranking before clipping occurs, yet still allows plenty of signal for manipulation. The other issue here with not having enough gain is when you have a low pre-gain setting, turning it up at post gain adds in a lot of hiss at reasonable volume (this hiss is the background signal of the equipment and is referred to the noise floor- more on this in future blogs).
Once the signal has gone through the pre-gain, you have the option to add in effects at this stage (low and high pass filters, compressors, limiters and gates). On an analogue desk there is usually a TRS jack below for the XLR input for this, for a digital desk it is usually just a software patch.
After this base signal is set (the purpose of the pre-gain and compressors, gates, etc) the sound is manipulated through the eq (more on that later), then there's the option to send through to pre-fader auxilliary sends for stage monitors and other effects, through the fader, back through post-fader auxillary sends (generally for effects you do not want in the monitors) and then sent through either a sub group or direct to the main out.
Having a clear understanding of your signal path and what each section does to the signal clarity ensures a solid basis for building a great live sound as well as making your skills as a sound guy translatable to any desk- whether it be analogue, digital, entry level or high grade professional/ studio.
2. What's The Frequency Kenneth?
This classic song is not referring to human hearing, but I certainly am! The audible range of an adult with healthy hearing should be 20Hz to 20kHz. Modern speaker designs allow accurate, clear and strong responses right across this range- but when dealing with a live band this can add a new dimension.
Now just a final note on frequencies that I have to bring up (but will go into greater detail when discussing eq) and that is based around some fundamentals. Firstly, every structure has its own resonant frequency and associated harmonics. For most buildings I have found them to want to boom anywhere from 60Hz to 180Hz, but do not be surprised to find them outside this range. On that note though- harmonics actually occur to some degree whenever the frequency is doubled. So in a room that booms at 60, you will have another rattle at 120, then another at 240, 480 and so on. They do vary in intensity though so you are unlikely to need to play with the graphic eq- but it is valuable to be aware of it. So what to do about it? Generally, if the room has not been 'tuned', I usually pop a depression in the eq at the 80Hz range until I have a chance to hunt it down, and if time permits I will then get a tone generator and either a spectrum analyser or fresh ears (I prefer the latter) and snipe the offending frequency out of the curve. It is a good practice to get into as a happy bass player is a good thing- especially if they know they are moving a lot of air and people aren't grimacing or complaining its giving them a headache.
The last thing is the high pass filter that even primitive desks have. What is it, and what does it do is a common question I'm asked, even by seasoned desk jockeys. Its the little button (normally) up near the gain control that looks like its asking for the square root of 80. What it is actually indicating is that it will start rolling off frequencies from below 80Hz. This is important and this should be activated for nearly every channel on the desk (in fact, every channel where the instrument doesn't spend alot of time under 80Hz, so leave the bass and kick drum alone but push it on for everything else). Mike leads and microphone use pick-up through 'microphonics' stage rumble and hand noise- and this occurs in the 30-50Hz range. By utilising the high pass filter you are actually rolling these sounds out of the signal chain, and stopping them from muddying up the sound.
If you are not doing these last two tricks now, give them a go as soon as you can and see for yourself how much more clarity in the mix overall you will get, but especially down in the bottom end (and we all love lots of bass).
3. Epic ('You Want It All But You Can't Have It")
This last song is actually a little bit tongue in cheek and is actually more relevant to the tour manager than the sound guy. Every venue, each piece of equipment, set list, musician and audience member comes with its own set of limitations- and conversely advantages. As you become more experienced as a sound engineer you will become more accustomed to being asked the impossible, and infrequently acheiving it. It is not about being a proud underachiever, it is more about being realistic in your expectations and making sure you communicate it to those around you. Often in many settings performing artists are happy to accomodate limitations in equipment or expertise in order to give the best performance possible- and you'll be thanked for your honesty too! Who knows, they may even be able to solve the problem for you. There will be other times when you will not be able to get skin thick enough to deal with the ego, so enjoy the easy going artists when you can and hopefully you won't be getting many beer bottles thrown at you in between times (anyway in my experience its usually the band who cops the beer bottles, not the sound guy!)
Be committed to doing your best and do not let yourself get hung up on success or failure- some gigs will go exceptionally well and others won't and on both occassions it will probably be due to factors outside your control. Above all, be prepared to meet some truly interesting people, have fun and enjoy the experience!
2. What's The Frequency Kenneth?
This classic song is not referring to human hearing, but I certainly am! The audible range of an adult with healthy hearing should be 20Hz to 20kHz. Modern speaker designs allow accurate, clear and strong responses right across this range- but when dealing with a live band this can add a new dimension.
Now you can see from this chart that most instruments (from piano, guitar, vocals to drums and the brass section) all sit in the 200- 600Hz range. The piano has the enviable position of being able to cover the broad range of frequencies, and you'll also note that not many instruments get beyond 1,000 Hz (or one kHz) without the harmonic overtones (these are for another blog...)
The issue this creates is you have many instruments competing for the same part of your listening ear- and when you have many instruments playing the same melody they can be lost in the mix quite quickly. A common issue with piano and keyboards when pianists play around the middle of the board in a larger band setting they are quite often unheard completely although the fader is sitting fairly high. Then, once they venture out past those middle octaves, they are incredibly loud and cut through fantastically.
Now this isn't there isn't enough room in this blog for a breakdown on eq setting, but that does have a very small part to play. The main thing for your sound guy to recognise is he (or she) more than likely has a stage full of instruments competing for the same frequencies (even the drums)- so what can they do about it?
If you are mixing for a particular band, have a good listen to their music beforehand or if they have a tour manager have a long chat with them about their set list. They should be able to tell you (if you can't hear for yourself) which instruments are the leading instruments in each song. By this I mean the most prominent one in the mix which will become your reference point. Note it done on your setlist and adjust the mix accordingly. It is a given though that the majority of bands have the vocals as the lead instrument, but this isn't always the case. Many rock bands (aka guitar bands) prefer to have the vocals sitting just under the music, particularly if their genre involves a lot of screaming. Which leads me to the next application, church!
No I am not recommend we take up scream therapy next time we visit the local church, I am referring to the vocals sitting just under the music. The big two factors that affect sound in church is firstly they tend not to be as loud as Wembley Arena (or even hopefully the pub down the road), and secondly (and again hopefully), every member of the congregation is a contributing vocalist. Those of you who studied Physics in High School would have heard of the inverse square law when it comes to sound interpretation- it basically means that the closer a sound source is, the more impact (or louder) it is as well. So, you may have mixed an empty church with a fantastic mix with perfect harmonies and balance of instruments, then the congregation file in and the entire band's family and friends complain that they we only heard on the intros to the songs. This balance and allowance is a skill that is mastered a lot faster if your desk has subgroups, but you need to be mindful that the vocalists are not too below the music or else no one will be able to follow the leader or appreciate the harmonies.
So what do I mean by how they are sitting in the mix? I'm sure you've all heard a mix and thought, "Gee, that guys a bit loud!"- this is the way it is done! Rather than bring everyone up if someone is too loud, bring the loud one down so you can't quite make him out, then bring them up a fraction more. By referencing the music off a particular instrument as well makes the mix a lot easier- you actually go (for example, drums as your reference), is the bass louder than the drums? Is the guitar louder than the drums? Is the keyboards.... (you get the idea)
The other thing with competing frequencies is making use of the fact that most of the audience have two ears, and most venues have a left and right speaker stack. What am I getting at? 95% of venues I have come in to help have up until I arrived run mono front of house. There used to be a philosophy (based around the inverse square law) that if someone was sitting on the far left of a building, they would only get half the stereo image as they were too close to the left speaker. If your venue is massively wide this may be the case, but most facilities have modern speakers with wide dispersion which tends to alleviate this issue (although they are probably running mono as well!)
If you utilise your pan controls on the desk, you should be able to create a well defined stereo image that supplies sufficient room to each ear of the listener to allow them to distinguish the various instruments. Me personally, I like to run a guitar hard left and hard right, kick and snare mid centre with toms spread from left 30% to right 30%. Bass is always mid centre, and keys I will generally pan them left/right 50% if there are two of them (or a piano and keys), or if there are other instruments such as violins or flutes then I will match them against the keys at 50% left/right. Vocals I always have the leader dead centre with the back-ups blended based on where they are standing on stage. This is my personal preference as I find it gives the best clarity to each ear, but it is only my personal preference and you get to put in your own creativity into it. A word of warning though- ignore the soloist at your peril! Always be sure to bump them over mid centre for their solo (especially if they are a guitarist!) and reset them back to their original position.
Now just a final note on frequencies that I have to bring up (but will go into greater detail when discussing eq) and that is based around some fundamentals. Firstly, every structure has its own resonant frequency and associated harmonics. For most buildings I have found them to want to boom anywhere from 60Hz to 180Hz, but do not be surprised to find them outside this range. On that note though- harmonics actually occur to some degree whenever the frequency is doubled. So in a room that booms at 60, you will have another rattle at 120, then another at 240, 480 and so on. They do vary in intensity though so you are unlikely to need to play with the graphic eq- but it is valuable to be aware of it. So what to do about it? Generally, if the room has not been 'tuned', I usually pop a depression in the eq at the 80Hz range until I have a chance to hunt it down, and if time permits I will then get a tone generator and either a spectrum analyser or fresh ears (I prefer the latter) and snipe the offending frequency out of the curve. It is a good practice to get into as a happy bass player is a good thing- especially if they know they are moving a lot of air and people aren't grimacing or complaining its giving them a headache.
The last thing is the high pass filter that even primitive desks have. What is it, and what does it do is a common question I'm asked, even by seasoned desk jockeys. Its the little button (normally) up near the gain control that looks like its asking for the square root of 80. What it is actually indicating is that it will start rolling off frequencies from below 80Hz. This is important and this should be activated for nearly every channel on the desk (in fact, every channel where the instrument doesn't spend alot of time under 80Hz, so leave the bass and kick drum alone but push it on for everything else). Mike leads and microphone use pick-up through 'microphonics' stage rumble and hand noise- and this occurs in the 30-50Hz range. By utilising the high pass filter you are actually rolling these sounds out of the signal chain, and stopping them from muddying up the sound.
If you are not doing these last two tricks now, give them a go as soon as you can and see for yourself how much more clarity in the mix overall you will get, but especially down in the bottom end (and we all love lots of bass).
3. Epic ('You Want It All But You Can't Have It")
This last song is actually a little bit tongue in cheek and is actually more relevant to the tour manager than the sound guy. Every venue, each piece of equipment, set list, musician and audience member comes with its own set of limitations- and conversely advantages. As you become more experienced as a sound engineer you will become more accustomed to being asked the impossible, and infrequently acheiving it. It is not about being a proud underachiever, it is more about being realistic in your expectations and making sure you communicate it to those around you. Often in many settings performing artists are happy to accomodate limitations in equipment or expertise in order to give the best performance possible- and you'll be thanked for your honesty too! Who knows, they may even be able to solve the problem for you. There will be other times when you will not be able to get skin thick enough to deal with the ego, so enjoy the easy going artists when you can and hopefully you won't be getting many beer bottles thrown at you in between times (anyway in my experience its usually the band who cops the beer bottles, not the sound guy!)
Be committed to doing your best and do not let yourself get hung up on success or failure- some gigs will go exceptionally well and others won't and on both occassions it will probably be due to factors outside your control. Above all, be prepared to meet some truly interesting people, have fun and enjoy the experience!