Given that my chosen genre is “Indie” (with particular reference to the standard guitar, drums, bass and vox setup), I thought that a good start to my research would be to look up specific techniques used in recording and mixing bass guitar, before broadening my research to Low frequency control in general (in both mixing and mastering).
My first source was Sound on Sound, as I trust that any information provided there would be accurate:
Their thoughts on compression have given me a few things to think about:
“The attack and release settings in particular are critical. Too short an attack, and you’ll squash the important attack phase of the note. Too long a release time and you’ll ruin the groove. If you let the attack phase of the note through, then it’s also a good idea to place a limiter after the compressor, in order to catch any wild peaks, and leave you more room for make-up gain so you can increase the level without peaking.”
The idea of using a release time to “groove” in sympathy with a song is one that I shall take forward to future mixes. Similarly, the idea of using a limiter to catch the “pre attack” transient spikes is one that interests me quite a lot, as it allows for extra control over the ratio between attack and sustain portion.
I was also interested by the idea of parallel compressing the Kick drum and Bass guitar together:
“A common trick to increase the impact of the bass is to send the kick and bass to the same compressor and bring the compressed signal back in quite low, just to glue things together.”
This again, could help maintain some “stability” in the low end of a mix.
As far as equalisation is concerned, their take on high-passing is a little more aggressive than my own:
“As most consumer systems start to roll off around 80Hz, you can tailor your sound to them by placing a sharp high-pass filter at about 50Hz and applying a gentle boost around 80Hz.”
I usually HP at 30-40Hz, being somewhat scared to push any higher and lose too much energy from the signal, but after taking into consideration the limitations of most consumer systems, it makes sense to push this higher and obtain some extra headroom in the mix. Putting a boost in at around 80Hz is a good idea also, although it’s usually around 80-100Hz that I usually like to make my kick drum punch through, so a boost in the bass in this area should be handled carefully I feel, so as not to cause masking of the Kick. Overall though, these are techniques that I use for equalising bass, although I tend to put these figures slightly lower, and perhaps this is what is causing me to have difficulties with LF control.
I generally use distortion as a way of subtly enhancing low frequencies, but this article suggests tube amps in particular:
“A common trick is to use distortion as a send effect, mixing the distorted sound back in at a low level. Tube amps (or their software equivalents) are perfect for this sort of thing.”
I feel that this is another thing worth trying during future mix sessions, as it may allow me to lower the overall level of LF signals in my mixes somewhat, whilst allowing them to still be perceived.
Teaming a Sub synth, gated by the bass guitar is also recommended in this article. I see this not as a primary option, but a good go-to if it’s becoming difficult to generate a full and most importantly stable and controllable low end.
A common theme running throughout many articles is that you should only attempt to mix LF content in a properly treated room with correctly positioned monitors, which is something that I make sure to do. (It’s nice to know that I’m doing something right!) Evidenced:
Many sources make a point of enforcing the importance of assessing the mid-range frequency content of any bass element such as this article:
I feel that this particular phrase is something to keep in mind to help resist the temptation to simply boost low frequencies; “Boosting mid-range won’t make the low element bassier, but it may give it more presence in the mix and draw attention to the low end.” I feel that this is an important consideration to keep in mind, as although I do make an effort to use distortion to create harmonics, it would be helpful to keep an ear on how the midrange affects the low and, and whether it does in fact draw extra attention (or perception) to it.
I tend to be quite tentative with my use of compressors, as I find that my hearing is not particularly well tuned to picking out very subtle dynamic changes, but this particular article urges the reader to “be aggressive” when working with LF:
“The low end is an open canvas for heavy processing. Even a completely flat, sustaining bass instrument can sound awesome over-driving into a compressor. The overtones activate and you get something just as flat, but a lot buzzier.”
I’m slightly dubious of this advice, as being too aggressive with compression could be detrimental to the mix, and completely flattening LF would in my opinion take much of the energy out of a mix, but it’s still a point worth considering, as my tentative approach to bass compression in the past has not helped my mixes.
To conclude, I would say that my research has given me a lot to think about, and even more to play with during future mixes.
The main points I will walk away with are that I should not be so scared of “flattening” LF with compression, that VERY low frequencies are not of as much importance as I thought they were, and to pay close attention to the effects of the mid-range harmonics of a signal, and the ways in which they could help draw extra attention to LF content (without excessive LF boosting). Parallel distortion, compression and sub synth lines are also some tricks that I will definitely try next time I’m struggling with bass in my mixes.