Bass drum depth - some facts,

Andy

Honorary Member
OK, I feel compelled to post this up. I know it theoretically should be in the drums section, but I believe it to be of general interest.

Over the last couple of years, amongst many other things, we've really been digging into drum depth, & bass drum depth specifically. Everyone has their preferences, but there are some misconceptions touted as good advice, & through experimentation + testing, I want to put some of those misconceptions to bed. I'll try not to get too far into the science :)

Popular thinking is that a deeper bass drum delivers more bottom end. In some circumstances that can be true, but only to a point. Some think the reverse is true, & that's correct too, but as always, these individual factors need to be taken in context, & really, it's context that this thread is all about.

The basics:
All other elements being equal, the more shallow the drum, the nearer to it's fundamental the resultant sound will be. In a shallow bass drum, harmonics and inharmonic overtones are still produced, but are at a lower amplitude compared to deeper drums. Essentially, there's less space for them to establish, & less shell area available to augment the sound. As the fundamental is the lowest meaningful frequency the instrument can produce, it manifests itself as a clean "bottom end". This uncluttered sound has more of a clean note impression to it, & is therefore usually easier to distinguish in the mix too, but can sometimes be a bit "thin".

A deeper bass drum produces more harmonics & inharmonic overtones. An increase in harmonics can offer a "fattened" sound, rather like adding a chorus to a bass guitar (not an exact analogy). An increase in inharmonic overtones however starts to detract from the bottom end. Eventually, if the drum is deep enough, those inharmonic overtones can dominate and the result is often a nasty metallic sound. Dampening can reduce such inharmonic overtones, but it also diminishes harmonic overtones that are widely regarded as beneficial to a nice fat weighty sound.

Thickness:
Usually adds mass & rigidity, but not in every construction. Similarly, a thicker shell usually resonates less, but again, not always. A thicker shell will deliver the fundamental more effectively, but often stifles harmonics at the cost of increased inharmonic overtones.

Resonance:
A highly resonant shell often delivers the fundamental less effectively, as it promotes development of harmonics but also slightly sharp or flat harmonics, these being perceived as the "character" of the drum. A resonant shell usually produces less inharmonic overtones, but only when correctly aligned to mass. A high mass/rigid shell delivers the fundamental more effectively, but with the negatives mentioned under thickness.

Bearing edges, tuning, head choice, etc, all have a profound affect on the resultant character, but I'm concentrating on the non variables - the foundation of your bass drum sound. I'm also relating the following to the more commonplace ply shells. Solid shells can behave differently, & offer exceptions that can be exploited.

Deeper bass drums generally benefit from having a thicker shell. This allows for more efficient delivery of the fundamental, but usually requires more muffling to control inharmonic overtones. Such a setup is better suited to those wanting punch, presence, & projection. More shallow bass drums usually benefit from a thinner shell. This allows for more harmonics to be generated, & greater resonance usually sharpens/flattens those harmonics to produce a more wholesome sound.

A more shallow thin shell bass drum will generally produce more bottom end than a deeper thicker shell bass drum.

Extremes:
Any bass drum of square dimensions or above will produce excessive inharmonic overtones, almost irrespective of construction. The result is weak delivery of the fundamental and a confused voice that detracts from the lower frequencies. A bass drum who's depth is half or less of it's diameter will deliver the head fundamental with few harmonics or inharmonic overtones, due to reduced shell involvement. The result is a thin sound, but one that will effectively sit separately in the mix.

These are the basics, & assume an industry standard ply shell construction. Solid shells can be used to substantially augment the basics, but only to a point. Similarly, wood species can have some affect too. As with all drum constructions, all elements of the specification must be taken into account, as very little in isolation has meaning, but I thought I'd concentrate on depth & thickness, as they're the two subjects that crop up the most.

I hope some of you find this of interest, especially if you're soon to make drum choices.

Andy.
 
thanks for that. very informative. i've experimented with a few bass drums and combinations. recently bought my thickest bass drum ever and finding it is so different than all the others.
so many factors....one of my interests in drums is how there are so many variables resulting in a given sound.
 
thanks for that. very informative. i've experimented with a few bass drums and combinations. recently bought my thickest bass drum ever and finding it is so different than all the others.
so many factors....one of my interests in drums is how there are so many variables resulting in a given sound.
Exactly! There's a ton of variables. I know how almost all of them work together, but still get surprised from time to time. Our instrument of choice has so much to give :) In this thread, I've just tried to tie down a couple of the most common elements that seem to crop up here weekly, & apply them to the most common construction.

I've still yet to find a way to clarify the biggest misunderstanding amongst drummers though, & that's resonance.
 
Great information. But I take issue with the statement "Any bass drum of square dimensions or above will produce excessive inharmonic overtones, almost irrespective of construction. The result is weak delivery of the fundamental and a confused voice that detracts from the lower frequencies."

I play entirely square drums (except my snare) and most people have at least one square shell in their kit. Square and deeper shells, when correctly tuned, give rich sound, and people have been building deeper drums for thousands of years for this reason. Yes, the fundamental is less emphasized. So? Play roto-toms if you want a clear, simple tone!
 
I'm with you there Caddy...with the "golden ratio" discussion.

Has anyone fooled with a 24 by 14.83, a 22 by 13.59 or a 20 by 12.36? Something for the Guru guys to suss out I imagine! They'd probably be most interested in the 18 by 11.125 size though.
 
Great information. But I take issue with the statement "Any bass drum of square dimensions or above will produce excessive inharmonic overtones, almost irrespective of construction. The result is weak delivery of the fundamental and a confused voice that detracts from the lower frequencies."

I play entirely square drums (except my snare) and most people have at least one square shell in their kit. Square and deeper shells, when correctly tuned, give rich sound, and people have been building deeper drums for thousands of years for this reason. Yes, the fundamental is less emphasized. So? Play roto-toms if you want a clear, simple tone!
I agree, hence my statement in my original post "I'm also relating the following to the more commonplace ply shells. Solid shells can behave differently, & offer exceptions that can be exploited". This applies to your bass drum. Also, usually due to length of note, toms behave somewhat differently. I focused this information on ply bass drum constructions only, simply because it applies to the vast majority of players out there.

Square ply bass drums are on the cusp of falling off the tone cliff, requiring advanced tuning skills to get them sounding good. Anything over square is further stacking up unnecessary challenges to overcome. One thing's for sure, a square or above ply bass drum, irrespective of head choice or tuning skills, becomes a one trick pony. If you're lucky, it has one sweet spot, & sounds like crap outside of it. In putting this information together, I also considered flexibility of tuning, especially loss of fundamental & "overtone choking", as part of the equation.


You forgot to mention how the vintage 3 ply Ludwigs offer the best bass drum sound. Period. :)
Hmmm, not period IMHO, but certainly superior to many. Less plies = behaves more like wood. Age = crystalised lignum. Result - more resonance :)

I'm with you there Caddy...with the "golden ratio" discussion.

Has anyone fooled with a 24 by 14.83, a 22 by 13.59 or a 20 by 12.36? Something for the Guru guys to suss out I imagine! They'd probably be most interested in the 18 by 11.125 size though.
Yes. We did so in our trials, but only a few examples. We found that applying the ratio offers the balance of characteristics you would expect, but nothing more than that. There was nothing "extra sweet" about those precise dimensions. That said, you certainly can't go wrong by applying the ratio - depending on construction & timber species.
 
Cool stuff Andy. How about this? Assuming industry standard ply construction.... it would be cool to have a chart listing drum diameter and shell thickness, and then state the optimal depth for a given diameter at a given thickness. To make it easy for the morons of the world, like me.

Like Gordon Moore's "Moore's Law" that states computer processing power doubles roughly every 18 months, you should have "an Andy's Law" that states the optimal depth for a bass drum at a given diameter at a given thickness. Or at least a Guru recommendation chart.

OK real life scenario, on my 1 ply steambent bass drum you are building, at a 22" diameter...what is the optimal depth for that particular shell thickness? I ordered a 16" depth. Should I be reconsidering?
 
Andy, I find your article really good. Do these apply for other drums as well?

I'm with you there Caddy...with the "golden ratio" discussion.

Has anyone fooled with a 24 by 14.83, a 22 by 13.59 or a 20 by 12.36? Something for the Guru guys to suss out I imagine! They'd probably be most interested in the 18 by 11.125 size though.

IIRC the Origin Classic series have a 20 by 12 inch bass drum...close enough to that ratio.
 
I agree, hence my statement in my original post "I'm also relating the following to the more commonplace ply shells. Solid shells can behave differently, & offer exceptions that can be exploited". This applies to your bass drum. Also, usually due to length of note, toms behave somewhat differently. I focused this information on ply bass drum constructions only, simply because it applies to the vast majority of players out there.

Square ply bass drums are on the cusp of falling off the tone cliff, requiring advanced tuning skills to get them sounding good. Anything over square is further stacking up unnecessary challenges to overcome. One thing's for sure, a square or above ply bass drum, irrespective of head choice or tuning skills, becomes a one trick pony. If you're lucky, it has one sweet spot, & sounds like crap outside of it. In putting this information together, I also considered flexibility of tuning, especially loss of fundamental & "overtone choking", as part of the equation.


Hmmm, not period IMHO, but certainly superior to many. Less plies = behaves more like wood. Age = crystalised lignum. Result - more resonance :)

Yes. We did so in our trials, but only a few examples. We found that applying the ratio offers the balance of characteristics you would expect, but nothing more than that. There was nothing "extra sweet" about those precise dimensions. That said, you certainly can't go wrong by applying the ratio - depending on construction & timber species.

Thanks for posting all of this........very informative. What's crystalised lignum?
 
Thanks for posting all of this........very informative. What's crystalised lignum?

Lignums are woody tissue in the wood. That's from an online definition I got. Crystallized lignums are a result of wood aging and becoming more resonant as the lignums harden. I'm pretty sure I'm right about this. Andy would know. He knows everything.

Better to have your lignums harden than your arteries. I'll be here all week folks, and do be sure you tip your servers.
 
This is very useful information--thanks for putting this together!

And, I "second" Larry's chart idea.
 
I can imagine that the problem with doing a chart is that there are several different factors that go into the 'perfect' depth - aside from personal preference.

You have (on ply shells) the number and thickness of plies, the bearing edge profile, the shell material, the heads (some will produce more fundamental, some will produce more harmonic content) as well as the hardware attached to the shell.

Considering any one of these factors in isolation with the size will work but to add them all together would require some very complicated mathematics that I doubt has been developed in this specific instance. Theoretically it's possible to determine the fundamental note of a membranophone based on a theoretical head of thickness n (which is probably infinitesimally thin) but then adding in the rest, e.g. the mass of the hardware m and the plies, wood, etc. would be an horrendously complicated and unnecessary exercise in number crunching.
 
OK real life scenario, on my 1 ply steambent bass drum you are building, at a 22" diameter...what is the optimal depth for that particular shell thickness? I ordered a 16" depth. Should I be reconsidering?
Not in my personal opinion. Working from my knowledge of the soundscape you like, I think 16" is perfect. As I pointed out, solid shell forms offer the possibility of exceptions to the rules, especially in the areas of resonance, thickness, presence of fundamental & overtones of all kinds. My personal bass drum is 20" x 18"!

Andy, I find your article really good. Do these apply for other drums as well?
IIRC the Origin Classic series have a 20 by 12 inch bass drum...close enough to that ratio.
Some of my observations apply to other drums, some do not. As for the little 12" Origin bass drum, it's closeness to the golden ratio is purely coincidental, but we did produce it partially to prove a point ;)

Thanks for posting all of this........very informative. What's crystalised lignum?

Lignums are woody tissue in the wood. That's from an online definition I got. Crystallized lignums are a result of wood aging and becoming more resonant as the lignums harden. I'm pretty sure I'm right about this. Andy would know. He knows everything. He most certainly does not!
Spot on Larry. When the lignum hardens, it produces a more defined series of conduits along the grain, & the hardening in itself promotes enhanced resonance. This is why shells tend to improve with age, & also why the less plies used, the more the shell behaves like wood. Clearly, solid wood benefits from this process the most. Larry, your kit will sound better in a few years time than it will when you first set it up.

Cool stuff Andy. How about this? Assuming industry standard ply construction.... it would be cool to have a chart listing drum diameter and shell thickness, and then state the optimal depth for a given diameter at a given thickness.
This is very useful information--thanks for putting this together!

And, I "second" Larry's chart idea.

I can imagine that the problem with doing a chart is that there are several different factors that go into the 'perfect' depth - aside from personal preference.

unnecessary exercise in number crunching.
Yes, such a chart is entirely practical, but it's application is so subjective & contextual, that it's almost a pointless exercise. It might however be useful to describe the change in bias across the depth spectrum, all other elements being equal. In the real world however, I don't see why I should provide a handy reference for drum companies. Frankly, they can go & pay for their own research ;)

As for Guru, our recommendations are already on our website. If we offer a depth in our standard ranges, we think we're offering the optimum depth for that specific construction. If someone wants to go custom, we advise the implications accordingly. If someone insists that we build something we believe won't sound good, we politely advise them to go to another drum company.
 
thanks for this post!

I purchased a pretty deep bass drum awhile back and haven't found an effective way to get a satisfactory sound. this gives me something to go on.



scott
 
Really great stuff Andy. This helped me work out some of the details in my own mind. Thanks.

I have also thought and hoped for a chart of bass drum sizes with sound files. A matrix of honest capture sound files would be a great base line reference for anyone at any level. Sure, its not going to be all inclusive and everyone is going to have their own opinions and criticisms, but 30 sound files for all even sizes 16"-26" x 12"-20" would be a freaking awesome thing have imo.
 
Wonderful and helpful information, explanation and advice Andy, as usual :)

My personal bass drum is 20" x 18"!

That's quite a deep shell, however, if my memory is correct, it still very responsive and articulate, with more "oommph" than the little brother 20x12 cappuccino shell...

As for the little 12" Origin bass drum, it's closeness to the golden ratio is purely coincidental, but we did produce it partially to prove a point ;)

Have you tried different depth for the 20" diameter classic serie bass drum yet? Somehow in my mind, I would love to try a 20x14, being a more conventional ratio of diameter vs depth, it could give a little deeper sound, making it more like a funk/rock perfect bass drum.

This is why shells tend to improve with age, & also why the less plies used, the more the shell behaves like wood. Clearly, solid wood benefits from this process the most. Larry, your kit will sound better in a few years time than it will when you first set it up.

My faithfull little Tama is 24 years old last January, but I can't remember how it sounded when I bought it, lol, so the A-B comparison is somewhat lost, but when I take my time at tuning these days, it does sounds good to my ears :)

If someone insists that we build something we believe won't sound good, we politely advise them to go to another drum company.

Very wise Andy, in a funny way, it's better to be safe than sorry, I mean at least you won't have to say "I told you so"

..................

Slightly off topic here (sorry Andy), but many drummers chose their bass drums solely on looks, they don't really care about optimum depth, harmonics, response and such like, they'll go for the image, what looks good within the kit.

Furthermore, many drummers do not chose the (ideal) depth of their bass drum as they're buying "standard" set-up offered by all the major brands, and often, the depth is chosen by the manufacturer, not the drummer. It's also more expensive to buy a kit shell by shell than a standard config, and by a large margin.
 
I'm a double bass drum player, I currently play Yamaha stage custom (phillipine mahogany, not the good stuff) 24"x17"s. They sound pretty good, but of course I'm always thinking of my "Dream-kit." (Which I would like to build myself one day)

First my "Dream-kit" contained 24"x24" square Keller vintage mahogany kicks. I want the absolute lowest fundamental I can get, that's also very punchy and attack driven. I'm a metal head, but I hate the "clicky" kicks found so often in metal nowadays. I want the same level of definition that the clicky sound provides, but with a note that's actually in the extreme bottom of the bass range.

So as I read more threads and articles and learn more, I get to thinking that that huge 24" depth will turn the sound into mud, no definition between notes, and difficult to move that whole column of air within the drum. So I think, instead of going up in depth, go up in diameter, so now I'm thinking 28"x14". Huge diameter, but shorten that depth up so I can move all the air, and get some good attack. Also switched up the material to Swamp Ash Stave for the look of it.

So now both depths are at opposite ends of your extremes, square, and half. I want the Diameter to Depth ratio to have some sort of correlation, I'm quite a numbers geek, so I really liked the idea of square, or half, I also considered golden ratio either way, but 24"x14.8" seems too short for 24, and 28"x17.3" seems too deep for 28. Considered 26 briefly, but figured, if 26, why not 28, I like to be unique, and on the edge of extremes.

So where do I go from here?
 
thanks for this post!

I purchased a pretty deep bass drum awhile back and haven't found an effective way to get a satisfactory sound. this gives me something to go on.
scott
Try a higher tension on the reso head. That will shorten it's voice slightly, & raise it's pitch. It may not sound that much better to you from the driver's seat, but it will certainly sit better in a band mix. To advise you further, I'd need a lot more info.

Good luck :)

Really great stuff Andy. This helped me work out some of the details in my own mind. Thanks.

I have also thought and hoped for a chart of bass drum sizes with sound files. A matrix of honest capture sound files would be a great base line reference for anyone at any level. Sure, its not going to be all inclusive and everyone is going to have their own opinions and criticisms, but 30 sound files for all even sizes 16"-26" x 12"-20" would be a freaking awesome thing have imo.
The honest capture stuff we could do no problem, but to make it meaningful to a wide range of players, would be close to impossible. The number of variables is so vast, it's overwhelming.

Have you tried different depth for the 20" diameter classic serie bass drum yet? Somehow in my mind, I would love to try a 20x14, being a more conventional ratio of diameter vs depth, it could give a little deeper sound, making it more like a funk/rock perfect bass drum.
Yes Henri, we have tried it, & a certain member will be trying it herself soon too :)

I'm a double bass drum player, I currently play Yamaha stage custom (phillipine mahogany, not the good stuff) 24"x17"s. They sound pretty good, but of course I'm always thinking of my "Dream-kit." (Which I would like to build myself one day)

First my "Dream-kit" contained 24"x24" square Keller vintage mahogany kicks. I want the absolute lowest fundamental I can get, that's also very punchy and attack driven. I'm a metal head, but I hate the "clicky" kicks found so often in metal nowadays. I want the same level of definition that the clicky sound provides, but with a note that's actually in the extreme bottom of the bass range.

So as I read more threads and articles and learn more, I get to thinking that that huge 24" depth will turn the sound into mud, no definition between notes, and difficult to move that whole column of air within the drum. So I think, instead of going up in depth, go up in diameter, so now I'm thinking 28"x14". Huge diameter, but shorten that depth up so I can move all the air, and get some good attack. Also switched up the material to Swamp Ash Stave for the look of it.

So now both depths are at opposite ends of your extremes, square, and half. I want the Diameter to Depth ratio to have some sort of correlation, I'm quite a numbers geek, so I really liked the idea of square, or half, I also considered golden ratio either way, but 24"x14.8" seems too short for 24, and 28"x17.3" seems too deep for 28. Considered 26 briefly, but figured, if 26, why not 28, I like to be unique, and on the edge of extremes.

So where do I go from here?
For a metal player, a short but distinct/powerful voice is desired. Actually, swamp ash is a good choice, as it's naturally short. Equally, stave is an excellent construction choice too. Again, slightly towards the dry side, but with much more resonance than a ply equivalent. The crafting of those drums is critical to the result. Thickness, bearing edges, & especially depth are key. You're builder will really need to know his stuff. Standard thinking on depths, bearing edges, & other considerations do not apply, or at least, not in the same way. If you're hung up on 28", good luck finding a builder who can turn them correctly. Most, if they're brave enough to take it on, will hand form the shell, & that's usually not a good solution. FWIW, I'd probably go for 18" depth with that construction in 28" diameter. Good luck with a reasonable head selection too. My gut feeling is you'd be better off with a smaller diameter, but you probably don't want to hear that. Keep me posted. I'm interested to see which way you jump on this.
 
OK, I feel compelled to post this up. I know it theoretically should be in the drums section, but I believe it to be of general interest.

Over the last couple of years, amongst many other things, we've really been digging into drum depth, & bass drum depth specifically. Everyone has their preferences, but there are some misconceptions touted as good advice, & through experimentation + testing, I want to put some of those misconceptions to bed. I'll try not to get too far into the science :)

Popular thinking is that a deeper bass drum delivers more bottom end. In some circumstances that can be true, but only to a point. Some think the reverse is true, & that's correct too, but as always, these individual factors need to be taken in context, & really, it's context that this thread is all about.

The basics:
All other elements being equal, the more shallow the drum, the nearer to it's fundamental the resultant sound will be. In a shallow bass drum, harmonics and inharmonic overtones are still produced, but are at a lower amplitude compared to deeper drums. Essentially, there's less space for them to establish, & less shell area available to augment the sound. As the fundamental is the lowest meaningful frequency the instrument can produce, it manifests itself as a clean "bottom end". This uncluttered sound has more of a clean note impression to it, & is therefore usually easier to distinguish in the mix too, but can sometimes be a bit "thin".

A deeper bass drum produces more harmonics & inharmonic overtones. An increase in harmonics can offer a "fattened" sound, rather like adding a chorus to a bass guitar (not an exact analogy). An increase in inharmonic overtones however starts to detract from the bottom end. Eventually, if the drum is deep enough, those inharmonic overtones can dominate and the result is often a nasty metallic sound. Dampening can reduce such inharmonic overtones, but it also diminishes harmonic overtones that are widely regarded as beneficial to a nice fat weighty sound.

Thickness:
Usually adds mass & rigidity, but not in every construction. Similarly, a thicker shell usually resonates less, but again, not always. A thicker shell will deliver the fundamental more effectively, but often stifles harmonics at the cost of increased inharmonic overtones.

Resonance:
A highly resonant shell often delivers the fundamental less effectively, as it promotes development of harmonics but also slightly sharp or flat harmonics, these being perceived as the "character" of the drum. A resonant shell usually produces less inharmonic overtones, but only when correctly aligned to mass. A high mass/rigid shell delivers the fundamental more effectively, but with the negatives mentioned under thickness.

Bearing edges, tuning, head choice, etc, all have a profound affect on the resultant character, but I'm concentrating on the non variables - the foundation of your bass drum sound. I'm also relating the following to the more commonplace ply shells. Solid shells can behave differently, & offer exceptions that can be exploited.

Deeper bass drums generally benefit from having a thicker shell. This allows for more efficient delivery of the fundamental, but usually requires more muffling to control inharmonic overtones. Such a setup is better suited to those wanting punch, presence, & projection. More shallow bass drums usually benefit from a thinner shell. This allows for more harmonics to be generated, & greater resonance usually sharpens/flattens those harmonics to produce a more wholesome sound.

A more shallow thin shell bass drum will generally produce more bottom end than a deeper thicker shell bass drum.

Extremes:
Any bass drum of square dimensions or above will produce excessive inharmonic overtones, almost irrespective of construction. The result is weak delivery of the fundamental and a confused voice that detracts from the lower frequencies. A bass drum who's depth is half or less of it's diameter will deliver the head fundamental with few harmonics or inharmonic overtones, due to reduced shell involvement. The result is a thin sound, but one that will effectively sit separately in the mix.

These are the basics, & assume an industry standard ply shell construction. Solid shells can be used to substantially augment the basics, but only to a point. Similarly, wood species can have some affect too. As with all drum constructions, all elements of the specification must be taken into account, as very little in isolation has meaning, but I thought I'd concentrate on depth & thickness, as they're the two subjects that crop up the most.

I hope some of you find this of interest, especially if you're soon to make drum choices.

Andy.
This information is excellent. Something I have wondered is the effect of a heavier shell will have. Now, not necessarily thicker, but heavier. Being that the shell may move "less" when the drum head is struck, would this result in a louder volume, or punch. Here is a scenario. When I was younger, my buddies and I would install our car stereos. At one point, I installed 6x9 speakers in the back of a car with a hatch back. The board we installed the speakers in was thin and flimsy. When music was played, there was very little punch and bass. Basically, the board with the speakers in them would vibrate and this cancelled the air movement. We next replaced this thin board with a thick wooden board. Once we did this, all the bass came in powerfully and we got the full 6x9 bass offered from the speakers.
So, if a drum barely moved when you hit the drum head would this push more air? On the other hand, if you have drum that moves excessively when you hit it, would this sort of cancel out or greatly reduce air movement or reduce volume? Thoughts? Now you don't really need a heavier drums shell, you could have a shell mount that keeps the drum very stable. Just throwing this concept out there. Thank you - Tom
 
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