T4.2 BETTER MIXES

Joe Pearce

Static MixesA static mix is a mix in which there is no automation necessary to adjust the defined decibel to the producer’s requirements. A static mix is obtained by correctly giving the instruments you are recording the necessary head room and adjusting recording faders so that the take you have recorded needs no automation. There are other things you can alter using automation in a mix other than volume, such as being able to pan, solo & mute.

Here is an image showing an example of a Static Mix and what it will look like on Logic Pro X

Here’s a picture of a mix using Automation to attenuate the dB level of the drums whilst there is quite a somber melody being played by the keys and performed by the vocalist. Also in this picture you can see there is a slight boost in dB using automation to the electric guitar as there is a guitar solo being played in this part of the song.

Signal to Noise Ratio (SNR)

Signal to Noise Ratio is a microphone placement technique used in music recording situations in which you decide whether you desire the natural acoustics of the space in which you are recording such as recording in a church or cathedral to obtain a natural reverb or if you are recording in a sound proofed studio you would most likely only want to record the sound of the instrument and get as little noise from the space itself as possible.

An example of how I used SNR in my recordings/finished mixes is how I miked the saxophone for the football chant song. The reason I am choosing to talk about this is due to the amount of bleed I received from the drum kit also being played in the same room at the same time. If I had miked up the saxophone differently, then I would have been able to mix these individual instruments more professionally which in turn would create a much more enjoyable mix for the target audience.

DBFSDBFS or decibels relative to full scale is a term used when talking about analog or digital audio signals to avoid digital distortion. “The term 'distortion' describes any change made to a waveform: even a simple change to the amplitude is technically a form of distortion” – http://www.soundonsound.com/sos/apr10/articles/distortion.htm

when using digital equipment you will notice how decibels are shown in the negatives to further show how you need to avoid raising the level of any singular track or output volume to above 0 DBFS and in-turn receiving digital distortion which is rarely desirable. “'FS' stands for 'full scale'. 0 dBFS is the level of a signal that is at the maximum level your system can cope with without clipping the tips of the waveform. So -10 dBFS means a level that is 10 decibels lower than the maximum level your system can handle.” – http://www.audiomasterclass.com/auralize/what-is-the-difference-between-0-db-and-0-dbfs

On the left here is an example of where you would most likely want your signal level to be reaching between -12 & -6dB to allow for head room in a mix.On the right is an example of peaking signal levels which are passing over 0DBFS & creating digital distortion.

Dynamic RangeDynamic Range is the difference in ratio between the highest peak and the lowest drop of decibel in a mix. It will be the reason that if your output is so far above 0 DBFS (in digital monitoring) that the waveform is cut off and everything will sound distorted, yet flat and undesirable. In genres such as classical music there is a huge dynamic range as there is no compression being applied to live orchestras, they use the acoustics of the venue to perfectly create a dynamic range which works best for the human ear.

Here is a picture showing two bounced mixes and how the Dynamic Range between them both is different but not clipping above 0 DBFS thus receiving no digital distortion.

Head RoomHead Room is effectively the freedom of space in the recording mixer you allow the musician to play with, using different velocity and different techniques to match and play fluently alongside partnered musicians and set pieces of music which need to raise to a higher decibel in certain parts of a composition. If you do not allow for head room, your recording will most likely peak over 0 DBFS and start to obtain digital distortion which you do not want for the most part.

Here’s a picture showing how we set the recording faders to allow head room for the musicians to play their instruments without clipping into digital distortion. As the different signal levels came in, we adjusted the faders accordingly.

EQ/Frequency SpectrumEqualizers are a way of affecting the desired frequencies in a DAW. There are Parametric EQ’s which can affect the Hz, DB and width of a selected frequency or Semi-Parametric EQ’s which can only effect the Hz & DB of frequencies. There are many different reasons for using an EQ, such as attenuating an undesirable frequency out of the mix; for example if there was resonance coming from the floor tom then you could use EQ to isolate that frequency and remove it from the track. Another good use of EQ is to boost a certain frequency or to give it precedence and cut through in the mix which will make it more audible for the audience & their enjoyment.

In this picture you can clearly see how we used EQ to cut a resonant frequency from the snare drum in post production. You can also see how we boosted the low end frequencies of the snare drum to help make this signal less tinny and create a fuller sound in the mix.

Digital DistortionWhen talking about analog distortion you may like the sonic effect which is taking place as you play your instrument plugged into an amplifier, but when talking about digital distortion this is something that is rarely (if ever) desired. Digital distortion occurs when the output of any singular track is higher than 0 DBFS which causes the top of the waveform to be cut off which is in turn significantly reducing the dynamic range and leaving you with a finished product that is loud, flat and generally highly unpleasant for the listener.

Here’s a screenshot of a bounced mix opened up in logic which will have extreme levels of digital distortion due to the output being excessively above 0 DBFS.

Compression Threshold

The threshold inside of a compressor affects and reduces the decibel level of any audio signal when it’s volume is greater than a specified threshold. A compressor’s threshold is often set to use decibels which means a lower threshold such as -40 dB affects a higher majority of the signal; whereas a higher threshold like -10 will not effect nearly as much of the audio signal.

This is a screen shot showing the compression threshold but due to the overhead microphones picking up a lot of the hi-hats & cymbals I didn’t want to compress it too harsh as I felt that the high end of this track fit well.

Compression Output /Make Up Gain

After setting the compression threshold and noticing a difference in peak or RMS (Root Mean Square) signal output you will want to apply some make up gain. Make up gain is used to boost the compressed signal level back up to an optimum level in the mix without a harsh dynamic range ruining your listening experience.

This screenshot is showing the make up gain I applied to the tambourine after setting the compressor threshold to how I wanted it. As the tambourine signal was already quite soft it didn’t need a lot of compressing or make up gain to bring the overall level back up to sit well in the mix.

Compression RatioThe compression ratio simply put is the ratio in which your compressor allows dB through the threshold. “At low ratio settings (something like 1.5:1) the overshoots are nudged politely back towards the threshold, whereas at higher settings (12:1, for instance), overshoots are beaten back by club‑wielding thugs. At the highest settings — and some compressors offer infinity (or ∞):1 — overshoots are effectively stopped in their tracks, unable to cross the threshold at all.” – https://www.soundonsound.com/sos/sep09/articles/compressionmadeeasy.htm

This screenshot shows the level of ratio I used when compressing the left overhead microphone and shows how I selected 3.5:1 to allow a certain amount of dB through the compressor and not be cut.

Compression AXack & Release

Attack & Release are another crucial part of the how a compressor works, for example you may solo and compress a snare drum only to quickly find that this is not the sound you want from this particular high attack drum. While mostly you will only be altering the attack & release of the compressor by milliseconds you will quickly notice the difference in your ears. Raising and lowering the attack time of the compressor quickly tells you everything you need to know about what it does to an individual track by altering the speed of which the compressor kicks in and attenuates the RMS or peak signals. A fast attack compressor on a snare drum will significantly soften the instant impact of the drumstick to the skin of the drum making so the snare isn’t unbearable in a more chilled song but you can also do the opposite for different hard hitting songs where you will want the snare to cut through in the mix.

Raising and lowering the speed of the release in a compressor does just that, a high release speed will make it so that the reset speed of the compressor is more delayed (& Vice Versa); again usually only by milliseconds but these millisecond’s can make the difference in your mix.

Here’s a screenshot showing the Attack & Release times I chose to use on the compressor set on the kick drum. I chose to slightly lower the attack time as I thought the kick cut through the mix too much and adjusting the attack time made it so the compressor kicks in quicker and shuts off peaking signals. I also raised the release time to 72ms so that the compressor resets slower due to the amount of kick being played in this song. The drummer used a double bass pedal so to raise the release time seemed necessary to not throw the signal around too much.

Final ThoughtsI will now make clear which tracks I have chosen to talk/write about in this write up each with what I enjoyed about the track and what the I would re-record/what I could have done better as a sound engineer. Track One: We Can Work It Out – Andy & Rich What I enjoyed was being given a static mix to play around with and just gain experience in mixing. What I could have done better to really make this a whole new sonic piece of work would have been to spend more time and attention on adding input effects and EQ’ing instruments differently to make a greater dynamic range of instrumentation.

Track Two: Football Chant Song – Various Musicians I really enjoyed the whole experience of helping to create this recording, mix & syncing of the video to the song. What I enjoyed sonically about this finished product was getting in a group of musicians to overdub a football chant and adding space designer to the track to really get that feeling of being inside a passionate footballing environment. I also really enjoyed miking up a real saxophone and being able to experiment with the Logic Pro input effects to see what sounds I could get from it in post production.

Track Two: Football Chant Song – Various Musicians What I could have done better in this recording would have been to record the drums separately as every single microphone in the room picked up bleed from the drum kit being played simultaneously. Even adjusting microphone positions and taking SNR into account couldn’t save certain tracks from being overwhelmed and eventually cut from the final bounce & video sync of this song.

Song Three: War Song – Various Musicians What I enjoyed about this mix was the contrast from the first song me & my group recorded. It made us have to do things differently in the recording and mixing process due to the different musician’s techniques and playing styles. I enjoyed gaining the experience of syncing the recorded mix to the video as well as having to automate the film clip’s in and out to get war sound effects from the film itself. Lastly I enjoyed doubling and panning the overdubbed haunting vocals towards the end of this song which I think created a nice effect and synchronized well with the film clip.

What I think I could have done better as a sound engineer would have again been to record the drums separately as we received the same problem with bleed like the earlier recording of the football song. Also I would like to go back and be a bit more attentive to the compression of the drums which I think cut through in the mix a bit too much. (Subjectively speaking) ~Fin