Basic Mixing Techniques Intro – Kick, Bass Guitar and Vox
Remember, from earlier Posts, it always a good idea to have a Limiter set at 0dB on the Master output, for both real mixing desks and DAW software, especially in a live band environment where leads and plugs may get pulled out, or people drop mics etc. This stops any accidental spikes/surges going through the PA or whatever and deafening people or damaging equipment.
Always turning volume controls down on all amps before turning them off is also a good habit to get into. (Home stereos too!)
When packing away, always turn off any condenser mic Phantom power (48V dc) FIRST, before unplugging their leads.
Like anything, it’s always best to have a plan to work to, and take a methodical, structured approach. This is especially so when mixing sound. Our college lecturer gets the kick drum and bass guitar to sit nicely together first, which sets the foundation for all other parts of the mix to sit on and around, so I’ll go through his process.
We have a spectrum of sound from about 20Hz-20kHz for the “average” human ear response, in which to try fit all the instruments in without getting in the way of each other, and leave each in its own “space” as best as possible for clarity.
We are most sensitive to about 1-4kHz and less sensitive to bass frequencies in general. The spectrum can be broken down into 3 areas at its most basic – low, medium and high, with the mid section being the first to go as most instruments fit this section – guitars, keys, vox, most wind instruments for example. Generally, the kick drum and bass instruments fit in the low, but with a kick drum “click” to be allowed for, to help it cut through the mid band, and is the usually place to start in getting the kick and bass to sit nicely at the heart of the mix, usually panned in the centre of the stereo “sounds-scape”.
In two dimensions, we have stereo full left to right, and can add false impression of 3D depth via the use of FX such as reverb and delay, that fools the brain into thinking it is in a 3D space.
Starting with the kick drum, you can look at its spectrum in FLS ParametricEQ2 (or maybe other packages and utilities), and it’s the best I’ve seen so far. Not seen this in Apple Logic Pro yet, but it may have similar.
I raised the gain a little too high here – usually 12-16dB is enough to get the signal to peak at its loudest part of the track for an analogue signal, at about 0dB in the right side level meter. The peak dots are a little higher above the red line, so 16dB is about right for this particular kick mic signal. We always want as high a signal to work with as possible without clipping, for any signal. Analogue line level is about 16dB lower than digital (0dB) line level – that is why I had to raise the gain here in the first place. Another thing to note about mixing desks is that fader 0 line is a 1:1 gain – i.e NO amplification of the signal. This means should get the loudest sound in a mix at that point, so the others can then be mixed down from it, so no distortion takes place.
Ok, the kick drum can be swept from high to low using the ParaEQ slider 7, using your ears to tell you when you are cutting off sound you DO want from the kick drum, so that unwanted high frequencies can be identified and removed from the kick drum channel, to start leaving that frequency range clear for other instruments later.
Each of the 7 sliders are defaulted at particular frequencies which is shown when you hover them with the mouse – start learning these so you build a picture of where in the spectrum different instruments sit in general.
These are: 63, 136, 294, 632, 1363, 2936, and 6324Hz
Sweeping to where you decide you still want to keep the higher frequencies of the kick tone may look like:
Do the same at the low end also:
Let your ears, not your eyes dictate where to cut each end.
Now for the “trick” of kick and bass mixing; find the frequency range that defines the “click” of the kick drum, by boosting one of the EQ faders, and squeeze it thin (BandWidth dial bottom right), then sweep the sound until you hear the “click” you want.
This may be around 1200Hz like:
This will then be the frequency we will make a corresponding “cut” or “hole” in the bass guitar track(s), to allow that click to come through, so it’s not swamped by the richer frequencies that will normally be present on a bass guitar. This is easy to see in a DAW but you would have to do this by ear alone on a mixing desk, using the mid/upper mid parametric pots.
Always check back to the original sound of the instrument you had, by turning the EQ on and off in the FX slot (or the right button on a desk) to check that the changes you have made actually improve the sound against the original – it may have made it worse!
Once that is done, you just make the one you want the loudest –at its loudest point in the track – sitting at 0 on the mixer fader, and mix the other volume level down from it. That is then the foundation for all the other tracks to fit around.
These usually sit in stereo centre of the track, because the human ear is not so good at detecting distance separation of objects at lower frequencies anyway, so placing them full left or right has little image meaning compared to other instruments, but the other good reason is that these have a lot of electrical energy in terms of driving speakers at volume, so you want to drive both sides of your stereo amp more or less equally, so as not to burn one side out compared to the other.
The same upper and lower sweeps apply to all tracks so they sit in their own spectrum as best as possible, leaving as much spare overlap between instruments natural range as possible, without losing much performance or sonic nuance.
It is worth spending as long as possible to get this kick and bass EQ right, before moving on, as if you are not happy now, you will definitely be unhappy later as your mix will probably just deteriorate into a swampy mess like the AarronRap mix I did yesterday. The kick just sounded like a big woolly mess through the whole of the process, and it just made doing the rest of the mix progressively harder work.
The other main thing to remember is what genre of music you are mixing – things like Dance and Rock may need a constant kick level driving it all the way through, in which case compression at 6:1 or more is your friend, to compensate for real drummer kick level inconsistency and make the kick, snare and hi hats cut through the others to drive the rhythm.
Genres like soft jazz may have quiet and louder sections to them, where you want to hear the two parts of the very different dynamic ranges, so compression on very low settings like 2:1 may do – IF you even need it at all.
Bass guitar is usually compressed for the same reasons, as is vocals, if the singer is moving back and forth from the mic as they dance about, shriek or mumble etc.
Compression – in the simplest nutshell – makes the louder parts quieter and the quieter parts louder – by raising the gain of the quiet bits and placing a maximum ceiling above which the loud parts can’t go.
For example, a 6:1 compression ratio means for every 6dB the larger signals would go over the Threshold level you set, it get squashed down to 1dB. This allows you to say, raise the gain of the quieter parts by that 6dB closer to the Threshold without them being compressed, to hear them better.
So, back to that Aarron Rap mix I had so much trouble with, which is made more difficult with so much overspill from all other instruments coming through all the other mics – the snare coming in on the kick track being an obvious one. This then requires you cut the snare out with a cut in its frequency band, which is why the visual spectrum view is so cool.
You can just squeeze out that small band:
The kick channel EQ now looks like this, with spike 4 being the “click” even though it doesn’t show as a spectrum line:
The negative spike next to the kick spectrum is to remove the snare from this channel – before:
The Limiter (in Compressor mode) was added to even out the levels of the “Click” spike and inconsistencies in drumming.
There were 2 bass guitar tracks – DI and a PG52 mic – and the levels were all over the place, I think from a dodgy bass jack connector on the DI box so again, compression added to help even all that out:
Also, the info gained from the kick track snare overspill at about 190Hz was used to try to cut snare from the bass amp mic also:
We can make up lost bass guitar mic frequencies from the bass DI track (which is why bass guitar is usually recorded on 3 tracks where possible – amp mic, DI, and ambient amp mic – this gives the whole range of frequencies from amp and bass to choose from when mixing):
This retains the nice fretless stick bass slides.
Here’s the Kick, and 2 bass, with Vox track before treatment:
See how much of the rest of the band and drum kit has spilled into the kick, vox and bass mics?
Aaron was isolated in a room outside of the studio, but spill was still an issue through my SV200 mic. This can helped by dropping the fader between verses via an Automation track in FLS, as it would be done manually with a real desk.
And the post EQ and Compression treatment:
In summary, even though I have spent longer doing this and writing this Post than I did on the whole duff mix yesterday, I am happy to have achieved pretty good isolation of each track from the overspill problem, I have a more solid foundation because of having these 4 important tracks EQ’d and compressed to be able to fill in the pieces of the rest of the picture later, which if taken in isolation in the same manner, each track can be treated, added to the others by mixing levels, then panned and/or Effected as I like.
The snare drum and the rest of kit follows, then either guitar or keys, then ambient room mics last – they are a big help in adding high frequency definition to the snare and hi hats, and of course, natural room reverb.
The rest is atmospheric window dressing – stereo panning, FX and 3D imaging at my pleasure.