8. The Wonderful World of Drumheads!
Updated: Oct 14, 2020
Being a drummer is both a blessing and a curse! The great thing about drums is that there are far more ways to personalise a drum kit than there are for any other musical instrument – the number of permutations of drum types, sizes, depths, materials, configurations is endless. But the counter-side to this is that it takes a huge journey of learning, testing and experiencing different setups in order to find your personalised ‘perfect’ sound. No single aspect of the drum sound can be personalised more-so than the drummer’s choice of drumheads used on the kit. Great drumheads and knowledgeable tuning can turn a cheap battered drumkit into a badass rock-n-roll machine. Equally, with a well-crafted drum kit, you can create impactful and musical sounds by choosing the best drumheads for your style and tuning them effectively. It’s very clear that, of course, the type and size of drums you choose to use have a big influence on the sound of your kit, but nothing comes close to influencing the sound as much as the drumheads you choose and the way you tune them. We’ve got so many choices, clear, coated, single-ply, double-ply, built-in overtone vibration control systems, centre dots and combinations of all the above, not to mention different materials, designs and manufacturing approaches preferred by different drumhead companies.
The drummer’s drumheads can be thought of as ‘guitar strings on steroids’! The basic principles for guitar strings apply very similar to drumheads, though with far more options and possibilities for personalisation. In fact, many of the acoustics principles that relate to guitar strings apply very similarly to drumheads, except with a few deviations. For starters, there’s a very famous acoustics equation that defines the frequency or fundamental pitch of a guitar string, called Mersenne’s Law – we won’t go into it here, but do look it up if you’re interested in this sort of thing. And, no surprise, there is a very similar law that relates frequency and pitch to the physical properties of drumheads too (or ‘circular membranes’ as we call them in the world of acoustics!). The drumhead relationship is described really well, though in quite deep physics theory, by Fletcher and Rossing in their book ‘The Physics of Musical Instruments’, but we can break it down here and see how it becomes useful for drummers and sound engineers to know about.
So, the ‘drumhead equation’, as we might call it, looks like this:
Where f is the drumhead’s fundamental vibration frequency, T is tension applied to the drumhead, the Greek letter ρ is the density of the drumhead material, t is drumhead thickness and d is the drumhead diameter. The value k is just a number, 0.7655 to be precise!
So how is this useful to drummers and sound engineers? Well, it explains a number of things we already know about drumhead design which relate to the sound of drumheads – it’s kind of the science that explains what we already know from listening and experimenting with drumheads.
Looking at the drumhead equation, firstly, we see that if the value of T increases, then the value of f will increase too. So increasing the tension, i.e. tightening the drumhead with a drum key, the frequency goes up. Well that was obvious, all drummers know that!
Secondly, we see that all the other variable terms are on the bottom, underside, or denominator of the fractions in the equation, so if any of those values increase, then the result of the equation (f, frequency) will decrease. So, a bigger diameter d means the drumhead frequency is lower – we knew that already, since bigger diameter drums give lower pitch drum sounds.
Now, specifically relating to drumhead design, we see that if the drumhead is thicker, the frequency of the drumhead is lower. So thicker drumheads give a lower frequency, and hence sound, as some might be aware, a bit ‘warmer’ or ‘deeper’, whereas thinner drumheads have a bit more ‘brightness’ and can be tuned to higher frequencies. In fact, rather than have thicker drumheads, often the thickness is provided by having two thin drumheads sandwiched together, known as 2-ply drumheads. These allow the benefits of thicker drumheads without actually having to make the drumhead material so thick that it becomes harder to vibrate properly. So you can kind of think of 1-ply drumheads as being ‘thin’ and 2-ply drumheads as being ‘thick’ – because the scientific principles apply very similarly.
We also see that the density of the drumhead makes a difference, and a higher density material (i.e. with a higher ρ value) also gives a lower frequency. So it’s no surprise that coated drumheads, which essentially are made heavier and more dense by the coating, also sound a bit ‘warmer’ or ‘deeper’, whereas uncoated (less dense) drumheads have a bit more ‘brightness’ and can be tuned to higher frequencies.
So that’s the core science relating to drumheads, and it explains a number of things we intrinsically know from experimenting with drumheads, listening for ourselves, and of course matches what a number of drumhead manufacturers will say about their different drumhead types when helping you to choose the most appropriate kind for your preference. But there are a number of other factors with drumheads too, including the relationship of overtones to fundamental frequency, which is something we always come back to discussing.
We know the fundamental frequency relates to the overall pitch of the drum and it’s excited most when we hit the drum in the middle. And we know that the overtones are excited more when we hit the drum at the edge. But really, all the frequencies are vibrating all together at the same time, and each drum has a slightly different balance of energy between the fundamental and the overtones. This explains why some drums give a deep thud sound with not much brightness whereas others seem to ring on forever with a high frequency shimmer, lasting long after the main drum sound has decayed away. Well, different types of drumheads give very different balance between the fundamental and overtones that we hear, often owning to the thickness or coating, but also drumhead manufacturers have learnt how to manipulate this relationship and create drumhead designs that allow all ranges of overtone control. In particular, many drumhead designs have overtone dampers built in around the edge of the drumhead to stop the overtones from vibrating too long. So if you prefer your drums to be low, bloomy and powerful, you should perhaps go for a coated drumhead with overtone control built in. If on the other hand you like a bright, rich sound that is more ‘toneful’ and with a longer decay time, then go for a thin clear drumhead without overtone control built in.
So it’s clear there are loads of different options and many innovative approaches by drumhead manufacturers. Let’s break these down into categories with a little information summary on each:
1-Ply or 2-Ply:
As mentioned above, 1-ply or thinner drumheads tend to have a bright character and can be tuned to higher frequencies, whereas 2-ply or thicker drumheads give a lower frequency, and hence sound ‘warmer’ or ‘deeper’.
Coated or Uncoated:
As with thin and thick drumheads, clear drumheads tend to have a bright character, stronger overtones and can be tuned to higher frequencies, whereas coated drumheads give a lower frequency, and hence sound ‘warmer’ or ‘deeper’. Coated drumheads give another sonic characteristic which is to do with the stick contact; because the coating is a harder material than the standard mylar drumhead material, the stick contact is much more like a contact between two hard objects. As a result, the contact time is reduced and this gives the result of what we call a fast ‘attack’ - it’s a more crisp sound of stick contact which some people like, particularly for heavier music genres where the drums are intended to cut through the mix more significantly. A faster attack can be compared to the difference between a hard contact of a beater on a metal glockenspiel in comparison to a softer impact on a wooden xylophone. So clear drumheads have a slightly softer attack sound to coated drumheads, which have a more ‘crisp’ sound when the stick makes contact. This is reason why snare drums are usually set up with a coated drumhead, to give a sharp crisp sound, as well as the fact that the coating brings a bit more durability and enhances the drumhead’s lifespan too. Note that there are many different types of coatings by different manufacturers, some drumhead coatings are thicker and heavier, some are more lightweight transparent and described as ‘frosted’, some even use synthetic felt or fibre coatings to give a retro nod to the days when stretched animal hide was used for drumheads.
Edge control is essentially the addition of some form of mass, extra thickness, or other design which is intended to reduce the overtones that are excited at the edge of the drum. While we use the first overtone frequency to tune the drumhead and ensure the head vibrates evenly, many drummers do not like the sound of the overtone ringing on longer than the main fundamental frequency of the drum. Drumhead manufacturers use different techniques to achieve the same result - some manufacturers use a built in damper ring, some have an extra ply of material around the edge of the drum, some even sandwich a little bit of fluid or glue in between each of the drumhead plys at the edge. Whatever the approach, the point is that these drumheads have a reduced overtone sound in comparison to the volume of the fundamental pitch of the drum. It has to be said though, that overtones are not a bad thing, moreover they suit some styles of music more than others. Generally you’ll find that jazz drummers quite like to hear the drumhead’s overtones whereas rock and metal drummers prefer the overtone to decay quite quickly and let the fundamental frequency stand out alone. But there are no rules and there are plenty of examples of great drummers who had completely opposite approaches.
The centre dot is almost the same principle as the edge control, but focused on the centre of the drum rather than the edge, and predominantly designed specifically for snare drums. The centre dot is an extra thickness or mass at the center of the drumhead, which changes the vibration of the fundamental frequency. The extra weight of the centre dot causes the drumhead to stop vibrating after a shorter time, so the sustain of all frequencies (fundamental and overtones) is reduced by a similar amount. The dot also gives an increased attack to the sound, similar to an extra thick coating might, and hence gives a crisp sonic ‘focus’ and increased lifespan and durability. Centre dot drumheads tend to be used more often on snare drums, to reduce the sustain of the sound and to enable hard hitting drummers to avoid replacing their snare heads too often!
Of course, you can have combinations of the above too, so the possibilities are almost endless, and make choosing drumheads a virtually impossible task! Here’s a table of some different combinations for tom drums, and some examples of each type by three of the main drumhead manufacturers Aquarian, Evans and Remo.
The drumhead theory relates similarly for snare drums too. Usually a coated drumhead is used on the snare, to improve the attack or focus of stick hits and also because they are more durable and last longer. But many drummers choose to use a centre dot type or one with edge control to dampen the fundamental and/or the overtone frequencies of the drum too. Here’s a table of drumhead examples for snare drums (all coated drumheads):
OK, so let’s see some of this in action! Below are what we call spectrogram or waterfall plots of two identically tuned drums that are using different drumheads. Each drum is a 13” Tama Superstar tom and both are tuned to a fundamental frequency of 135 Hz with an RTF value of 1.5 Hz. The only difference between the two drums is the batter drumhead. The waterfall plot shows the same information as iDrumTune’s Spectrum Analyzer feature, except with an additional time axis, so we can not only see what frequencies are present in the sound, but we can also see how those frequencies change over time. We’ve taken the two extremes of the tom drum table for comparison, so the first chart (left) is that of a single ply clear drumhead (Aquarian Classic Clear) and the second chart (right) is that of a double ply coated head with edge control (Evans EC2S). Both drums are fitted with a standard thin and clear resonant drumhead. From the waterfall plot we can see that the clear drumhead has a very strong overtone that decays along with the fundamental, whereas the coated drumhead with edge control has a much less powerful overtone that remains at a relatively low level throughout the sound – so that’s evidence of the edge control performing its magic!
This theory all relates equally for the resonant drumhead as well. With the resonant drumhead, you can experiment just the same, though the influence on the overall sound is reduced a little. Most drummers start off with thin clear drumheads on the resonant drumhead, and we think that works great with most drums, but if you find that your drums still ring out too much for your taste, a 2-ply, coated or edge control drumhead on the underside might be what you are looking for.
There is so much information out there and lots of different explanations, terms and theories, and not enough time to try them all out! We suggest you consider the options above to decide what kind of sound you are aiming for, and then experiment from a best first estimate of what you need. Don’t be afraid to invest in good drumheads and try a few different types until you find your perfect type - they really do have the most influence on your drum sound than even the drums themselves. It’s not uncommon for a cheap old drum kit with well-chosen and tuned drumheads to sound really great, whereas it's very possible to make an incredible expensive drum kit sound horribly wrong with low quality drumheads that are poorly tuned.
Most drumhead manufacturers have videos and tutorials online showcasing their range of drumheads and demonstrating how they sound different, and what styles of music they suit best. We’re currently in the process of recording our own sample library of all the drumheads listed above - so very soon you’ll be able to listen and compare the differences for yourself!
By Professor Rob Toulson - Professor of Musical Acoustics and Inventor of iDrumTune Pro.
iDrumTune Pro is available in the Apple and Google Play App Stores for iOS and Android.