In this post we explore how to mix drums and a guide to understanding drum frequencies. One of the most commonly used mix tools is the equaliser (EQ), which allows us to manipulate the volume of different aspects of an audio waveform’s frequency spectrum. Beware, the equaliser is rarely used in mixing for making things “equal”, though! That was its original intended purpose, since some early audio systems (record players, amplifiers, and loudspeakers) were incapable of playing out all frequencies equally, so the audio equaliser allowed some manipulation of the sound to counteract these adverse effects. In mixing, we tend to use an equaliser to make things less equal nowadays and to give different recording tracks specific characteristics that allow them to shine and stand out, and avoid clashing, competing, or masking with respect to other recording tracks. Unlike many instruments, drums occupy the entire frequency range, so it’s no surprise that EQ can be one of the most important tools when mixing drums.
The standard parametric equaliser allows a number of frequency bands to be adjusted and has settings of frequency, bandwidth, and gain. The frequency setting is self-explanatory, which allows us to choose which frequency in the range of human hearing (20–20,000 Hz) is to be manipulated. The bandwidth setting is usually denoted Q, since it is the term of a mathematical equation for widening or tightening the frequency band which is being manipulated. Gain can be set positive or negative to either boost or attenuate the chosen frequency band. For frequency bands that are at the top or bottom end of the range, we usually have a choice of EQ shape – so at the top and bottom of the audible range we can use either a drastic full-cut or a more gentle shelf-shaped EQ.
If you are mixing drums in a track, the EQ can be the tool which allows you to bring an edge of power, clarity, and identify to the drums, so they stand out or blend in, dependant on what you are trying to achieve with the track. EQ can help you remove muddiness and give your low-end the definition it needs to be forceful and direct without compromising the other instruments in the mix. But adding EQ to drums can be hit and miss, especially if you are not fully sure how different frequencies relate to different characteristics of drum sound – so here are a number of tips to consider when mixing drums with EQ, all related to the following example image of EQ applied to a snare drum track.
1. Using EQ for cutting low frequencies
Cutting low frequencies might seem counter-intuitive for an instrument that occupies the low-frequency range, but usually drum recordings that have used a number of different microphones and microphone positions will benefit in clarity and presence if the low frequencies towards the bottom range of human hearing are carefully treated. With all the different microphones, drums which sound great in individual microphones can combine to cause a muddy, dull mess when all played back at the same time. Cutting low frequencies can have a very positive effect on this, predominantly by reducing the amount of phase-related clashing when the microphone channels are all mixed together and reducing the build-up of low-frequency reverberation captured in each mic and compounded when the channels are mixed together. It’s extremely valuable therefore to apply a low-cut filter to most or all drum recordings and choose carefully where to set the low-cut frequency, which should generally be lower than the fundamental frequency of the drum being considered. We know that kick drums have a fundamental frequency of around 50 or 60 Hz, so it makes sense to remove frequencies below about 50 Hz, since this content can only be low-level rumble and low-level reverberation in the room. With the snare, we have the same situation, but also with low-frequency bleed from the kick drum into the snare mic too, so if our snare is tuned to 200 Hz, we know we can safely set a low-cut EQ on the snare channel at, say 100 Hz. This low-cut filter is also removing low-frequency room sound and attenuating the bleed of the kick in the snare mic too, reducing the chance of phase coherency issues when we blend the two microphone sources together in the sub-mix. Using low-cut filters on the cymbal, overhead, and room mics is often beneficial too, either directly on each microphone channel or on the sub-mix channels. If you are looking for a very crisp sound of each instrument in the kit having its own clear definition in the mix, then low-cut filtering the cymbals will work well. However, sometimes the overhead or room mics capture some valuable sonic qualities of (particularly) the snare drum, which are not evident in the snare’s spot mic recording. So you may want to set a low-cut filter on your cymbal sub-mix and gradually increase the frequency, listening careful to the full mix to hear how the snare sound changes as you take the filter higher. If you prefer the sound of the snare’s close mic, then you can take the cymbal cut all the way up towards 500 Hz, but if you want more of the snare’s natural room sound in the mix, then you’ll need to keep this lower at around the snare’s fundamental frequency of 150–200 Hz.
2. Treating the fundamental and overtones of each drum
If you know the fundamental tuned pitch of each drum in your kit, then it is very easy to set a parametric EQ on this frequency and boost the fundamental to give more emphasis and a slight exaggeration to each drum in the mix. It’s valuable therefore to identify what the fundamental frequency of each drum in the recording actually is, either with a spectrum analyser tool, or whilst the recordings are being made with a drum tuner app, such as iDrumTune Pro. This works better than just turning up the whole track sometimes and gives a more focused boost to the drum that you want to stand out. This approach can be applied similarly for the drum’s edge overtone, which we know to be about 1.5–1.7 times greater than the fundamental. Often drummers and studio engineers prefer to reduce the snare drum’s overtones both during recording and in the mix, because they can sometimes ring out longer and distract from the more powerful and lower fundamental pitch of the drum. We can manipulate this with EQ therefore and reduce the overtone frequency a little, for example by applying some attenuation at the snare drum’s edge overtone frequency, which will usually be at around 300-350 Hz.
3. Adding attack and presence
It is possible to boost or cut the more timbral frequencies of the drum too – these are those frequencies associated with the drum shell’s design, construction, and materials. We know that drums vibrate subtly at many different frequencies all the way up the frequency spectrum, with vibration of the drum shell, the metal hardware, snare wires, and the mounts all adding that special magic to the sound of the drum. Whilst it’s hard to know what these exact frequencies are, we can make some broad brush strokes with the EQ to make the drum feel brighter or warmer, or to bring out some character or presence in the sound. The metallic hoops and hardware ring out into and above the 1,000-Hz range, and we also know that high-frequency content relates to the attack and sharpness of a musical sound too, so if we want to make a drum sound brighter and cut through the mix, then we might want to add some EQ boost at a frequency between 2 and 8 kHz. It’s never quite obvious which frequency will give the boost you are looking for, so set a parametric EQ boost on the snare, for example, and sweep it up and down until you hear a point where an impactful characteristic of the snare is being enhanced. It’s very easy to overdo this and boost too much, making the drum sound thinner and unnatural, but with careful adjustment you can add some valuable sonic presence to the sound when considered in the full mix.
4. Controlling high frequencies
As with controlling low frequencies, it is also often valuable to control the high frequencies in multi-microphone recordings of drums. There is usually less issue with phase-related artefacts at the high end of the frequency spectrum, but cymbals themselves cause significant bleed in drum recordings resulting in two challenges. Firstly, it is hard to manipulate the relative balance of sounds in the mix; this is common when there is a lot of hi-hat sound captured in the snare mic, for example, and it becomes impossible to enhance the snare sound without causing the hi-hat to become too loud in the mix. Secondly, if cymbals are captured on all of the microphone tracks, then it becomes much harder to create a wide stereo image of the drums in the mix. Cymbal sounds captured on the kick, snare, and tom channels cause a significant amount of cymbal sound to become evident in the centre of the mix, and this diminishes the stereo effect gained by hard panning overheads and close cymbal mics to wide parts of the stereo field. Subsequently, it can be valuable to reduce the high frequencies in drum tracks that do not need so much high-frequency content. In this instance, a high-frequency shelf can be applied to reduce the impact of the hi-hat on the snare channel, allowing the snare channel itself to be compressed, boosted, and enhanced without causing an increased presence of the hi-hat in the mix. There is clearly a trade-off here, as in many mix tasks, since the snare would undoubtedly sound a little more natural and clear without this EQ shelf applied.
5. Avoiding excess!
There are certainly many scenarios and possibilities for using equalisation when mixing drums and other instruments. In many respects, the equaliser is used to boost characteristics of different instruments to make them stand out in the mix, whilst also being used to reduce some of the unavoidable compromises made through recording with multiple microphone set-ups, which generate bleed and phase-related issues when summed together. A good approach is to avoid using excessive EQ where possible, firstly to avoid significantly noticeable and unwanted artefacts generated from extreme gains, cuts, and Q values, and secondly as a challenge to improve your recording skills and better achieve the sound you are looking for before the mixing session starts. Additionally, it is quite easy to add EQ to a single audio track and improve the sound, but the benefit of EQ is predominantly on the effect you can make to a sound when heard within the complete mix; so, whilst it is valuable to solo tracks and evaluate them in isolation, it is usually most valuable to apply EQ while listing to a full mix or a sub-mix of instruments all at once. Equalisation is hence an extremely powerful tool for shaping and crafting the mix, but with such great power comes great responsibility!
Some common questions related to drum frequencies
What frequencies are drums?
Drums give off many different frequencies, but the most prominent frequencies that we hear are the fundamental and first overtone vibration frequencies of the drumhead itself. The most prominent frequency is the fundamental, which is the drumhead simply vibrating up and down at a number of times per second, this defines the pitch of the drum and is heard most powerfully when the drum is hit in the centre. Most drums in the popular drum kit have a fundamental frequency between 50-250 Hz, depending on their size, what drumheads are used, and how they are tuned.
What should I tune my drums to?
Every drum can be tuned to a number of different frequencies and sound good, depending on what style of music you are playing and what your personal preference for drum sound is. For example, a 16 inch floor tom can feasibly be tuned to have a fundamental frequency at 80 Hz or at 120 Hz. Usually the lower frequencies suit rock drum sounds and higher frequencies better suit jazz setups. A standard 14 inch snare drum can usually be tuned sound great at a fundamental frequency of 170 Hz and also tiger up at 200 Hz too.Thinner and lighter drumheads can be tuned to vibrate at higher frequencies, which is an acoustics principle that applies to guitar strings too. So if you want to tune low and powerful, use thicker, coated or heavier drumheads, and for tuning to higher pitches, use thinner and lighter drumheads.
Do drums need to be in key?
No, drums do not need to be in key, though there can be some advantages to tuning to musical pitches in certain circumstances. Drums do not create strong musical harmonics, owing to the acoustic principles of drumhead vibration, so we do not hear them in the same way as we do with string or wind instruments. As a result, it’s possible to tune drums to any frequencies (i..e not in any musical key) and they will usually sound good when being played in a band or on a recording. However, with good tuning and particularly if the drums are tuned to ring out with a song resonance, drums do start to have a sense of musicality and they can sound even better if tuned to be in key with the song or at pitch intervals that give exciting fills and grooves. It’s well worth learning how to tune drums in key, because there will often be a situation where the song or setup deserves a more musical tuning, particularly slower songs which allow the drum sound to ring out for longer.
What frequency should a kick drum be?
Kick drums can be tuned to have a fundamental frequency as low as 50 Hz and as high at 80 or 90 Hz depending on the drum size, the type of drumheads used and the style of music that is being played. Sometimes the kick drum will be the lowest frequency sound in a performance or recording, and this is common for rock and pop music. Alternatively, often a higher frequency kick drum will be used in jazz or classical genres, allowing the double bass to be the lowest frequency instrument in the band. It’s interesting that metal music often uses a relatively high frequency, but heavily damped, kick drum tuning in order to achieve a sharp and identifiable kick sound which can be performed at high speed and stand out in a mix that might be densely made up of many instrument sounds.
If you want to know more about the underlying science of drumheads and drum sound, and learn more creative approaches to drum sound and drum tuning, check out the free iDrumTune ‘Drum Sound and Drum Tuning’ course at www.idrumtune.com/learn
Author Professor Rob Toulson is an established musician, sound engineer and music producer who works across a number of different music genres. He is also an expert in musical acoustics and inventor of the iDrumTune Pro mobile app, which can be downloaded from the App Store links below: