Shell thickness as related to drum size

drumhedd

Senior Member
Hey gang!

I'd like to discuss shell thickness- specifically the notion that as sizes of drums increase, shells should become progressively thinner. This is something that Danny Carey of Tool spoke about briefly in an interview in Modern Drummer a few years back.

One would think the opposite should be true, in order to keep the shell thickness proportional to the amount of air inside the drum. However, when you consider the fact that drumheads and hoops do not get proportionally more massive, and the charactaristics of sound waves, this theory makes a little more sense (to me anyways).

As smaller drums vibrate at higher frequencies, the nature of the soundwaves is not hindered by a thicker shell, but rather would become more focused.

In addition, because larger drums are moving a lot more air at much lower frequencies, one would want the shell to do more of the work in order to even the playing field.

Carey's Sonor designer kit has extremely thick shells on the 8x8 and 10x10 rack toms (probably close to 15 plies) and thinner shells for the 14x16 and 16x18 floors, as well as the 24x18 kicks (dia.xdepth). In planning for a future kit, I've been considering doing something similar (albeit with less extreme variation).

Thoughts?! Any sort of more accurate scientific knowledge would be appreciated :)
 

Andy

Administrator
Staff member
If you want to accentuate the organic differences in shell diameters, then smaller = thicker, bigger = thinner is a good thing to do. However, if you wish to balance the characteristics more, then the reverse is the way to go.

Without getting too deep into the science, you need to take a step back & quantify an important differentiation between head resonance, & shell resonance. Although they are different elements in the resolved sound, they react together to define the instrument's character.

Shells resonate as a response to input from the batter head, both by direct & sympathetic mechanisms, the ratio being dictated by the bearing edge profile. Typically, a thinner shell is easier to excite than a thicker shell (depending on construction & timber species). The shell responds to some frequencies more than others, thus shaping the sound by "absorbing" certain frequencies, & introducing typically lower overtones. The result is often termed as being "warm". As the shell becomes progressively thicker, it's more difficult to excite, & therefore absorbs less frequencies from the head tone. This is often termed as "focussed", as the fundamental tone is transferred to the listener in a more intact manner, but usually with the addition of higher overtones due to greater reflection. bigger drums generate a bigger input to the shell, thus the usual principal's applied that the bigger the drum, the thicker the shell.

The whole subject is much more complicated than this. Above a certain thickness, a shell will have little impact on the resolved sound. A thicker shell will always be louder, so dynamic balance should be considered.
 

dmacc_2

Well-known member
I have a set of Gretsch New Classics that are designed on the philosophy Andy lists and is much more qualified to converse with than I on the topic

According to the Gretsch site".... Featuring proportionate Gretsch-formula maple shells, this drum-set produces a vintage Gretsch tonality while giving these drums their own distinctive sound. Proportionate shells increase in thickness as shell diameters increase to give a full, balanced tonality across the entire drum set....."

This being said, I only play a 4 piece set with one - in this case the snare - not being a New Classic drum so it may be a little less noticeable in either direction one way or the other as far as balance of sound goes.
 

drumhedd

Senior Member
If you want to accentuate the organic differences in shell diameters, then smaller = thicker, bigger = thinner is a good thing to do. However, if you wish to balance the characteristics more, then the reverse is the way to go.
Shells resonate as a response to input from the batter head, both by direct & sympathetic mechanisms, the ratio being dictated by the bearing edge profile. Typically, a thinner shell is easier to excite than a thicker shell (depending on construction & timber species). The shell responds to some frequencies more than others, thus shaping the sound by "absorbing" certain frequencies, & introducing typically lower overtones. The result is often termed as being "warm". As the shell becomes progressively thicker, it's more difficult to excite, & therefore absorbs less frequencies from the head tone. This is often termed as "focussed", as the fundamental tone is transferred to the listener in a more intact manner, but usually with the addition of higher overtones due to greater reflection. bigger drums generate a bigger input to the shell, thus the usual principal's applied that the bigger the drum, the thicker the shell.
Perhaps that is what I'm after... focused, punchy, loud rack toms paired with warmer floor toms with lower overtones.Thank you for the quick layman's explanation, putting it in terms I can understand is very helpful! What I'm considering are various Keller Maple VSS thicknesses:

racks: 8x8, 10x9 - 10 ply, 12x11 - 8 ply

floors: 15x14, 18x17 - 6 ply

kicks: (2x) 22x18 - 5 (or 6?) ply with reinforcing rings

As someone who has more knowledge in this area, what are your thoughts/opinions?
 

Boom

Silver Member
You sound like you know what you are after, I'd just like to point out that Gavin Harrison, whose drums sound amazing everywhere..youtube..recordings..whatever... I believe he goes the opposite way of what you say Carey does. I believe he goes from thin to thick as he goes from smaller drums to larger ones.

Both Carey and Harrison's drum sound great (both Sonor guys right?) and yet they go about it completely differently. That's why it is great to have Andy (KIS) here to help us understand this stuff.
 

Stixnergard2

Senior Member
Everyone has their own concept regarding shell thckness. Here is a quote from the Spaun Drum Company on their views regarding shell thickness:

"First, it's important to note that thinner shells produce lower fundamental notes than thicker shells of the same diameter. To this day, many drum companies increase the thickness of their shells as the drum diameters increase. Back in the old days when shell forming technology was limited, this was necessary to help keep the drum shells in-round. Reinforcement rings were also added as a way to keep shells round.

The problem with using shell designs that are thinner on small toms and thicker on larger toms, is the tuning range of the drum kit is diminished. Imagine a setup beginning with a thin shell 10" tom and ending with a thicker shell 16" tom. The overall tuning range is less than if you maintained a thin shell 16" tom with the thin shell 10" tom. Spaun drums maintain a consistent shell thickness to insure both maximum tuning range and consistent voicing from drum to drum."
 

drumhedd

Senior Member
Everyone has their own concept regarding shell thckness. Here is a quote from the Spaun Drum Company on their views regarding shell thickness:

"First, it's important to note that thinner shells produce lower fundamental notes than thicker shells of the same diameter. To this day, many drum companies increase the thickness of their shells as the drum diameters increase. Back in the old days when shell forming technology was limited, this was necessary to help keep the drum shells in-round. Reinforcement rings were also added as a way to keep shells round.

The problem with using shell designs that are thinner on small toms and thicker on larger toms, is the tuning range of the drum kit is diminished. Imagine a setup beginning with a thin shell 10" tom and ending with a thicker shell 16" tom. The overall tuning range is less than if you maintained a thin shell 16" tom with the thin shell 10" tom. Spaun drums maintain a consistent shell thickness to insure both maximum tuning range and consistent voicing from drum to drum."
Innnnteresting... so subscribing to this theory leads one to believe that thicker shelled rack toms would have additional low-end added to their range and thinner-shelled floor toms would have additional high-end....

It's funny how many different philosophies there are out there in regards to this stuff. I wish there was some way I could just try out every possible combination hahaha... dream on...
 

drumsagogo

Junior Member
yep,interesting topic; I've been DIYing drums for a few years, mostly Keller and RCI shells thru Precision; after a bit of research I decided to put together some Keller Maple 3.3mm shells (toms) and 5 mm (BD); to me thin shells represent a very vintage sound: max tone and resonance. I've put the toms in suspension systems/cages, initially a lot of resonance but I added a series of small holes at the base of each shell (can't be seen behind the head rim) and this has decreased (to my ear) the amount of resonance. I'm yet to finish the kit so haven't had a chance to test them out properly yet. There is a drum company in Sydney Aust, Pansini Percussion (http://www.pansinipercussion.com/), he only makes acrylic drums, totally custom, a wide range of widths, which is in contrast to the RCI shells which are only 1/4" or 6.35mm, apart from some snares which are 1/2". So one could apply the thin/thick principal in designing an acrylic kit. I have one of his snare drums (the clear one towards the top of the pics on his site), crisp, pure tone, loud etc etc, very happy with it. The following quote guided me in my decision to make up the thin shells: 'The thinner the shell the more easier the transfer of energy from the head to the shell thus causing the shell to vibrate more easily, giving a rich wood tone, but less volume and projection than thicker plies though. This shells provide greater resonance, pitch and sensitivity, most appreciated in near field applications and especially in recording (http://mikedrums.com/tuning/shell.html).
 

grunta57

Junior Member
Interesting post ...there are drums that simply baffle us (pardon the pun) ..I have a 1956 Ajax 14 x 5 snare that has a way lower fundamental tone than anything of that size I've ever heard and resonant and loud too. The 3 ply birch/mahog shell is very thin and the internal and external plies are both vertically oriented. The shell must only be 3 mm and was very weak when I got the drum. As a result the lugs kept ripping out and couldn't hold the tensions or tune properly. I've actually added special internal glass fibre curved plates to support the lugs and the strains and it sounds absolutely fantastic now. The snare bed is deep and narrow which I may change slightly, and the bearing edges about 20 deg with round over but I've got more of an edge on them now. Bit naughty to experiment like this but as I say this is the lowest beautiful tone I've ever heard from a wooden drum this size. Go to Grants Drum Emporium on facebook I will try to set up a gallery specific to this subject..Thanks
 
Top