What is resonance, & why does it matter.

keep it simple

Platinum Member
This response from Les encouraged me to start this thread:

Subjectivity? MOONGELS are selling very well thank you.

Shell resonance/head vibration two different factors/things??? You're talking hocus pocus to average Joe Drummer.
I'll try to keep this brief, maybe dig into more detail by answering questions if asked, but let me start by saying a highly resonant drum is not necessarily a "better" instrument, it's just another choice in terms of your instrument's character. A non resonant drum is an equally valid choice, indeed, it can be better under some circumstances. I'll continue.

Most drummers perceive a resonant drum as one that offers long sustain. This can be true, but a long sustain can be achieved by just sharp bearing edges & tuning on a drum with very little resonance. Most of what you're hearing in those circumstances is head sustain/decay. Notice how you hear it most from the driver's seat. Close mic's pick it up too, but step out front, even a short distance, & notice how that "sustain" disappears. It disappears because it has no shell tone to back it up. It's a localised low volume thing that only the drummer or mic's hear to any degree.

A highly resonant drum produces a much more dominant fundamental note. This is the note that lasts about one second or so after you strike the drum. It's the very voice of the instrument, & it's a tone you can hear from the other side of the room. It's this affect that really shows the real world benefit of resonance. For example, a very resonant bass drum with a ported reso & muffled heads will still produce a stronger fundamental tone & a longer note, compared to a less resonant drum with the same setup, yet they both have little - no head sustain. It's all about the length & dominance of that initial note.

Of course, a non resonant bass drum will produce a higher pitch, will cut more (often termed as projection) because it offers a brighter sound & is slightly louder. Again, a most valid choice, but very different to a highly resonant drum. In a non resonant drum, that initial note is much shorter. This is because the shell is more difficult to excite.

Let's choose Les's specific example - Moon gel. Many drummers ask, why do I need a resonant drum when I want little sustain & I use Moon gel to keep my drums focussed? The answer is simple, you may want a focussed sound, but you still want tone - right? It's shell resonance that fills out the tone with both a more defined fundamental as well as a range of lower overtones, rather like a chorus. It's what contributes to the drum tone being satisfying & "phat". Moon gel puts the brakes on the head, it doesn't affect the drum's tone.

Ever noticed how a drum's tone carries better to the audience when it's tuned higher? Of course, there's an optimum point, but this affect happens because the drum's shell is more readily excited at medium - high frequencies than it is at very low frequencies.

So, shell resonance is much more about how the drum sounds than it is about how long the head sustain lasts for. Of course, the interplay between different elements & the results obtained are much more complexed than my little explanation, especially with respect to overtones (both the ones you want, & the ones you don't want), but I'll leave it at that unless there's specific questions.
 

opentune

Platinum Member
Thanks for that. To me its all about the fundamental, that 'voice' in a drum.
I can only relate one humble puzzling experience. On one kit I have a Tama birch bass drum...it has great 'cut', 'projection' , easy to control, and records well..... but to be honest I cannot stand its 'voice'!
 

larryace

"Uncle Larry"
Prior to Andy's coming here I always mistook head sustain for shell resonance. Good factual info as always Andy.
 

Les Ismore

Platinum Member
A highly resonant drum produces a much more dominant fundamental note. This is the note that lasts about one second or so after you strike the drum. It's the very voice of the instrument

And it produces that note/voice through the drumhead, most definitely a synergetic relationship.



So what came first, the log, or the drum stick implement?
 

Duck Tape

Platinum Member
So it doesn't sound like there's any way to differentiate the head sustain from the shell tone, other than the presence of a note from a distance away from the drum.

Is that right?
 

keep it simple

Platinum Member
Thanks for the responses guys - just hope you find some use for the information, & in some way, it helps you make sense of the marketing info.


And it produces that note/voice through the drumhead, most definitely a synergetic relationship.
Absolutely! The shell has very little audible sound of it's own. It makes it's presence heard through the heads. I often use a hifi speaker as an example of the mechanisms at play. Not an exact comparison, but pretty close. The speaker cone represents the heads, & the speaker cabinet represents the drum shell. As we all know, the speaker cabinet materials & design make a big difference in shaping the resulting sound from the speaker. The speaker coil/cone produce the sound source, the cabinet/enclosure shapes the sound, yet produces little - no sound of it's own.

So it doesn't sound like there's any way to differentiate the head sustain from the shell tone, other than the presence of a note from a distance away from the drum.

Is that right?
That's easy. The fundamental is part of the tone you hear in the first second. The head sustain is the sound you hear decaying after that first second burst. The richness/individuality/complexity of the sound in the first second or so is partially dictated by the fundamental, & that's dictated by the shell's resonance profile.

A classic example is the snare drum. This is an application where head sustain is rarely a feature or desired. The note is short. The individuality of the drum's sound is dictated, to a large extent, by it's fundamental. A low resonance shell will typically deliver a higher pitch, usually with a greater portion of high overtones, & a somewhat generic voice. A highly resonant shell with usually deliver a lower pitch, & a greater mix of lower overtones, & a more distinctive voice. The more resonant the shell, the more dominant the fundamental is, & the more distinctive/representative of it's material it's resulting voice becomes. Of course, there are multiple caveats. I'm just trying to keep this simple.
 

Diet Kirk

Silver Member
So it doesn't sound like there's any way to differentiate the head sustain from the shell tone, other than the presence of a note from a distance away from the drum.

Is that right?
Also if you really want to know what the tone of the shell sounds like, you can take all the hardware and heads of it, hold it lightly with one finger and tap with your other hand. This way you can hear that fundamental tone of each shell.

Bit time consuming, but once you know, you know!
 

jornthedrummer

Silver Member
It could be interesting to follow up the theory with measurements. I think I have the required equipment at work, but I dont have time. Maybe someone else have.

I think a calibrated microphone(or perhaps a contact microphone like a C-Ducer), an audio interface and a computer can do a long way.
Meaurement software can probably be found free on the internet. We need to see frequency spectrum and a so called 'waterfall' to see the decay.

And aneneonic chamber would be nice, but not absolutely necessary for comparison measurements.

I am thinking to first strip snares of different construction from all hardware, suspend it somehow and hit the shell with a drum mallet.
Trick is to suspend them the same way, hit the same spot and with the same force.
Somebody can probably wotk out a method for that.

Could be repeated with the hardware installed to see the difference.

thx

jorn
 

keep it simple

Platinum Member
Also if you really want to know what the tone of the shell sounds like, you can take all the hardware and heads of it, hold it lightly with one finger and tap with your other hand. This way you can hear that fundamental tone of each shell.
I am thinking to first strip snares of different construction from all hardware, suspend it somehow and hit the shell with a drum mallet.
Trick is to suspend them the same way, hit the same spot and with the same force.
Somebody can probably wotk out a method for that.

Could be repeated with the hardware installed to see the difference.

thx

jorn
All good stuff guys, but to some extent, carrying out such a comparison tells us very little of use with all the hardware & heads off. Measuring resonance frequency, amplitude, decay, etc tells us something about the shell, but not how those differences translate in the real world. It's how those shells, c/w all attachments, influence the sound emitted by the heads. After all, it's only the sound from the heads that you'll hear.

The only thing that has real world affect is the complete instrument. A highly resonant shell ceases to be a highly resonant shell if you bolt heavy lugs or other high mass assemblies onto it. You have to associate a shell with a hardware system somehow, even on free floating designs. The shell's resonant qualities are just one part of the picture, but of course, the very foundation you have to get right. It's a starting point, but everything else needs to work in a defined way to produce the required result.
 
T

The Old Hyde

Guest
so Andy I have a question. When I play my bass drum. is it resonance or sustain I hear. Its big and boomy. 24 inch no muffling ( just the ring on the inside of the Superkick 2 head. and an AMAZING kickport ( you really need one). I bury the beater but it doesn't choke the drum.
 

keep it simple

Platinum Member
so Andy I have a question. When I play my bass drum. is it resonance or sustain I hear. Its big and boomy. 24 inch no muffling ( just the ring on the inside of the Superkick 2 head. and an AMAZING kickport ( you really need one). I bury the beater but it doesn't choke the drum.
Good question :) Without hearing your drum, I couldn't tell you what the bias is, but the short answer is, you're hearing everything (or at least, you are from the driver's seat).

But let's examine resonance for a moment. Even with a non resonant shell, resonance still plays a huge part. What I'm talking about is the resonant behaviour of the heads. Of course, drum heads are the very definition of highly resonant. They respond to the smallest of influences. When you strike your bass drum, the first thing you hear is the fundamental. That's made up of the tone produced inherently by the shell chamber containing a moving column of air that interacts with the heads & bounces around off the shell walls. In a highly resonant drum, that fundamental is further augmented by the excited shell. All this is in the first 1 second or so after the initial strike. The "boom" is all head sustain in a non resonant drum, but assisted by influence from an excited shell in a very resonant drum. The reason I'm differentiating between bass drum & other drums in terms of shell resonance contributing to the decay, is that it only really happens noticeably on bigger drums.

Essentially, you can get a great "boom" out of a non resonant drum nearly as well as you can from a highly resonant drum. The difference is that the highly resonant drum's decay will typically be longer, & have more substance to it in terms of a chorus of lower overtones. The non resonant drum will be somewhat one dimensional by comparison, & the boom or sustain that you're hearing will dissipate rapidly the further out front from the drum you are. The flip side is that the non resonant drum will throw it's sound a little better because of slight increase in volume, pitch, & brightness.

BTW, I don't need a kickport. On a highly resonant drum they seem to make little difference, except to add dampening to the reso head.
 

wsabol

Gold Member
The fundamental is part of the tone you hear in the first second.
Ok, by that do you mean a literal second, or just the proverbial "second"? Obviously the exact time is very dependent on the drum and near impossible to put in general terms, but that not what I'm asking. A literal second seems like a long time on drum note terms. Even on toms it could a 50%+ of the entire note. I imagine even in a highly resonant shell we are only really talking about half a second or less. But of course, I could be wrong.
 

GruntersDad

Administrator - Mayor
A highly resonant drum produces a much more dominant fundamental note. This is the note that lasts about one second or so after you strike the drum. It's the very voice of the instrument

And it produces that note/voice through the drumhead, most definitely a synergetic relationship.



So what came first, the log, or the drum stick implement?
the Log. The stick came from a smaller branch, cut to size, or made from the log itself. If a drum falls in the forrest and no one is there to hear it does it resonate.?
 

8Mile

Platinum Member
Prior to Andy's coming here I always mistook head sustain for shell resonance.
Me, too. One of the most important things I've learned here.

I'm glad you posted this. It distills a single, really important thing to simple parts. Good info for drummers to know, from choosing drums and heads to tuning.
 

keep it simple

Platinum Member
Ok, by that do you mean a literal second, or just the proverbial "second"? Obviously the exact time is very dependent on the drum and near impossible to put in general terms, but that not what I'm asking. A literal second seems like a long time on drum note terms. Even on toms it could a 50%+ of the entire note. I imagine even in a highly resonant shell we are only really talking about half a second or less. But of course, I could be wrong.
Yes, the exact time depends on many factors, including drum size, so it's a figurative reference rather than a literal one. That said, on a highly resonant shell, a noticeable fundamental tone lasting 1 second is very much achievable, even on drums as small as 10" (although that's really pushing it). On an 18" floor tom with sufficient input & tuned for maximum resonant response, you could even get to 1.5 seconds of audible fundamental (again, that's right at the extremes). The length of audible fundamental that's substantially shaped by shell resonance is directly proportional to drum size & how readily the shell is excited. Dynamic of initial input obviously affects that too, but on most drums, tops out quite quickly (headroom)

You're correct, on a thin shell ply 12" drum with relatively low mass hardware, you're looking at around half a second on average.

Me, too. One of the most important things I've learned here.

I'm glad you posted this. It distills a single, really important thing to simple parts. Good info for drummers to know, from choosing drums and heads to tuning.
Thanks Larry. If you get just one snippet of useful info that helps you with your choices, I'm a happy guy :)
 
T

The Old Hyde

Guest
I have a feeling something here is thinly veiled, I just cant figure out what it is.
 

keep it simple

Platinum Member
I have a feeling something here is thinly veiled, I just cant figure out what it is.
No veils, just sharing what we've found out in the hope someone finds it of use. This info isn't brand or construction favoured, it just is. Although I've concentrated on more resonant forms & constructions, I've stated clearly that a highly resonant drum is just a choice that's available. It's no more valid than a non resonant drum, because sometimes, a lack of resonance in the instrument construction offers characteristics that are beneficial in some situations, or according to personal taste. The only reason for discussing the more resonant forms, or more accurately, the mechanisms at work, is because the more resonant forms act as a vehicle for the discussion points.

This information came to light because of a decision to strip the components of drum sound down into design choice elements, then find out what combinations produced what results. In short, mainly through A-B testing, we discovered which elements/feature were based on historical trend/fashion, and which had a basis in fact. Sometimes, stripping everything back & starting with a clean sheet of paper is very revealing.
 
T

The Old Hyde

Guest
have you come across anything that doesn't always apply? like say for example your Guru 14 inch padauk is very resonant. are they always so when you make each one or do they actually very drum to drum?

and just to clear up something, not each one sold, i know your standards are extremely high, but is there a difference in process that says this drum will or will not have good sustain or resonance?
 
Last edited:

keep it simple

Platinum Member
have you come across anything that doesn't always apply? like say for example your Guru 14 inch padauk is very resonant. are they always so when you make each one or do they actually very drum to drum?

and just to clear up something, not each one sold, i know your standards are extremely high, but is there a difference in process that says this drum will or will not have good sustain or resonance?
In a nutshell, because wood is a natural material, sometimes there are pieces that fail to perform well. We filter almost all examples out at the wood selection stage. Dean's keen eye knows exactly what to look for, sometimes even looking for evidence that might suggest an unwelcome feature without actually identifying it. We typically go through about 20 boards to select one, so if we need 20 boards, that's 400 boards we trawl through. Finally, we tap test each board before agreeing to take it. We do all of this on the supplier's premises. The reason for telling you this is, it's super rare for a less than ideal board to slip through the net. If it does happen, it's picked up fairly early in production.

Solid shells are more susceptible to wide sonic variation than their ply counterparts, simply because the natural structure is intact. Ply shells effectively "spread the risk" across a number of sheets, & because much of the original structure is lost anyhow, any deficiencies tend to be structural & therefore easy to identify or hide/avoid.

Especially in solid shells, there will always be variations in tonal response from board to board, irrespective of how carefully selected they may be, but those variations are within fairly tight limits with us. Selection is key. I've said it before but it's worth repeating, I've seen/heard more poor examples of solid shell drums (as a percentage) than I have poor examples of ply drums (outside of the really cheap/nasty stuff). Just because a drum has a solid shell doesn't automatically mean it will sound good. If it's cheap, there's a reason for it, & a prime candidate is timber selection.
 
Top