Debunking the Tap Test - How Drums Work/Drum Shell Vibrational Modes | Drum Nerd Lab 

Finally, it was about time for someone to debunk this marketing aimed lie

I have been saying it for years that tapping a shell before final assembly is only one dimension of sound. Thank you for your engineering prowess to explain it far better than I ever could!!!

I appreciate what you mentioned about mass. I feel like there's a trend in high end, boutique drums to be really high-mass, heavy and dense woods+metals, with bulky hardware. I like drums to be easy to activate, dynamic and warm. Often student-model drums (Acrolite etc) are what I keep around.

When I saw John Good taping the shell with a mallet to read the note.....I laughed so hard!

I appreciate the work you're putting into this. Can't wait to get more of your drums!

This was really, really great! You all have an opportunity with technical videos like this to fill a void on YT. I’ve seen comparable series for other instruments and gear, but not for drums from such a credible source, so well-shot. Part of what first interested me in INDe’s was Josh’s background and the fact that he designed his drums from the ground up, with original designs intended to maximize drums’ potential, rather than filling out a product line of recreations of other makers’ classic drums. I own a Kalamazoo kit in big-boy sizes and 2 INDe snares. They’re all extremely well-made, but most importantly, they sound absolutely fantastic and are very responsive no matter what you do to them.

Brilliant! Love your company and concept. Refreshing to say the least!

Great material, and really appreciate your time and sharing of knowledge. Keep ‘em coming!

Interesting stuff! Definitely identifies a valid approach to drum shell manufacture.

Thanks for explaining. For anyone on the fence about these drums, I've tried them. They are top quality and wonderfully sounding instruments

i loved every second of this

awesome!! this is 1st time i've heard this discussion ANYWHERE! i've always used the 'Inde recipe' on drums i build, though never really knew the explanation of why i like that sound over thicker shelled and sharper edged drums. the drawbacks of massive hardware is of course self explanatory.

Great video, easy to understand, even for a layman like myself. Keep'em coming!

Don’t forget about bearing edge, plastic wraps, solid vs ply, orientation of plys, heads. There are so many variables!

this is a very good job and good information..just by applying concepts of acoustic physics can be understood the functioning of a musical instrument and not with bizarre theories.. all materials resonate under the effect of an acoustic wave and drum shells they are no exception..

Great video! 👌👏

I was at a PASIC convention 15 years ago, working light & sound for the Hyatt Regency, holding the event at the Convention Center here in Columbus OH. Anyways, I was standing behind a Ludwig Drums family member and Johnny Carson’s old drummer, Ed Shaunessey, when Bill Ludwig said “a drum is a drum is a drum” - meaning - we’ve been stretching animal skin over logs and hitting them with tree branches for hundreds of thousands of years. There’s only two drums: good sounding drums and bad sounding drums. All the peripherals? It’s just so much “stuff” - now, were they drinking at the bar when all this was said? Yes. But a drum is a drum is a drum. The good ones sound best. It’s ALL subjective.

I like that you are addressing drum sound using the physics of modal vibration. But I don't think you've identified the shell mode that is most strongly excited when you strike the head, and thus is the greatest modal contributor to sound. The shell is forced by tension variation in the batter head. When the head is struck in the center, it deflects downward and tension is increased. This pulls the bearing edge slightly toward the central axis of the drum. Then the restoring force in the head pulls it close to flat and back up higher than its initial (quiescent) state, which again increases head tension and pulls the bearing edge inward. Like the guitar string example, this oscillation continues as the "note" is sustained. Interestingly, the inward forcing on the bearing edge occurs at twice the frequency of the head vibration, as the edge is pulled inward twice for each oscillation of the batter head. Of course this is a simplified explanation; there are many modes excited when the head is struck, and I've reduced the complexity by stating the head was struck in the center so the vibrations are concentric. This symmetry is broken if the head is struck elsewhere, but most of the energy is still in the symmetric fundamental mode. So the shell mode that is excited is primarily that which responds to forcing at the bearing edge, which is similar to a vibrating beam mode, think glockenspiel. Most industry marketing is bogus but the concept of nodal points where some drum makers mount lugs to minimize energy transfer to the hardware does have some merit. Whether it affects sound quality is debatable but at least it is logically consistent and experimentally verifiable. -amateur drummer, professional physicist

You just got a new sub. Great stuff.

Glad to see conversations about drum sound wave dynamics. Cool video, but this really only scratches the surface and leaves a lot of areas open for some juicy debate…. For all of those hating on DW, the “tamber matching” was not a gimmick. Good’s idea was something never considered before when building a kit. The idea was to tamber match the shells so your kit blended nicely. You wouldn’t want a 13”rack tom that had a fundamentally higher note than your 12” rack tom. So the “tap test” would still be a valid method in making this determination when you have a massive selection of shells and want to piece together a kit.

Do we see this vibration at all? I'm just wondering how much shells can vibrate once assembled and under tension, especially considering all of the different materials out there like metals, woods, plastics, and fibers.

Brilliant.

Have you ever tried the tap test after putting mesh practice heads on a fully-assembled drum? This way, you'd hear just the pitch of the drum but not of any heads. It'd be interesting to compare the pitch of the bare shell with the pitch of a shell with lugs and hoops.

This is great!

Fantastic

Wow. Thanks for posting. I wonder how this applies to a ceramic drum like an udu? They don't have a head and they are generally pretty rigid. Would love to see an explanation!

Thanks for this! I have been wondering about how this works. I am also wondering if, when you cut a shell in half to build a nesting drum kit, does this significantly change the resonance of the shell in a way that you could really hear the difference? I have been contemplating having someone build me a nesting kit for travel in my van. (I'm in Michigan, by the way, and have been meaning to stop into the Inde shop)

Ps… the hole oriented laterally through the marimba bar… does “ create a deal spot”… All vibrating bodies have “ nodes” ( dead spots) that fall between major “ anti node “ regions ( the very vibrating, live spots, where the tone is most produced) You drew the nodes in the string… at the ends of the string and in the center ( are some node spots) The holes in the marimba bar dint define the node / dead spot…. The dead spot is THERE so the hole for the string is drilled through it… also we all ( percussionists) learned where to strike the bar instruments ( marimba, vibes, xylophone etc) and even tympani….( the center of a tympani head and the center of a concert bass drum are all thump with no tone… ( those are nodes) We strike and pull away… where we get the best tone…. Depending on the time we want…. But it is almost ( ALMOST NEVER) at the node…. On a marimba bar there are different tones available in different places / tonal regions between the two string node areas. But… Again the nodes are naturally occurring and we use the dead spot for the strings… I hope that this makes sense as…. There are nodes along the length of a drum shell too… And THAT… is where one might find “ ideally placed lugs… and maybe even the newer Yamaha tom mount screws…. AT THE NODE where tone will be least chocked… Thx

Can you comment on the physics behind floor toms with nonstop sustain? I've noticed some floor toms sustain for a long time with others are fairly short. I know it's not just a heads/tuning thing because I've tried the same heads/tuning on different floor toms and gotten different results. Also, I'm familiar with how straight vs bent legs affect the sustain on floor toms. Thanks for making these videos!!

Thank You.

Thanks!

Great video! I have a question - do the woods used to make the plies other than the interior one actually affect the drum's sound? I've heard some people say the interior ply is the only one that really matters, as the sound waves in the drum can't penetrate the wood and glue, therefore essentially debunking the "mixed drum shell" concept. I've heard other people say the middle ply choices do make a difference if they're in contact with the head (e.g. a couple of middle plies of walnut "drying out" a maple shell through head contact). What are your thoughts on the subject?

The claim/question is does the shells fundamental have an effect on the tuning range? It really does seem to and Im not sure this video actually addresses the claim or reasoning. Drum shells still vibrate w a head on and we agree they do have different fundamentals when tapped. I own an Sonor SQ2, Vintage & Champion, Yamaha oak, 2x DW Collectors, and more. My 1x DW to have a Hvlt shell the 14”, 16” and kick all tune like 16,18 and 24” drums (respectively). It’s a very noticeable difference. Doesn’t seem to be the wood or thickness either. To disprove this, I’d think you need to use same size shells w higher and lower fundamentals and show their tuning ranges are the same.

I love to hear your thoughts on the Peavey Radial Pro 1000 kit. No longer in production but utilised a very racial design over conventional drums. I would assume most of the principles you've discussed here will still apply but golly, those drums exploded when you hit them hard. The most impressive sounding drums I have ever heard. They looked weird which is probably what they didn't take off. Also, the Welch Tuning System Drums have applied some really interesting concepts about tuning, and they sound fantastic too.

As a marimba player, I thought I knew why this video was suggested to me.

How do these principles apply to your aluminum shells?

How is there only 1.27k subscribers is the real mystery! This guy is the equivalent of Adam Ruins Everything…and I love him for it. Thanks for letting science do the talking. I’ve purchased a snare throw off for my acrolyte. The hardware is like a piece of art. I need to sack up and buy one of these kits !!!

Deep research results you'll find in Fletcher, Rossing, Bork et al. I'v seen the resaerch results in the Physical Institute in Brunswick in their laboratory. Bork clearly explained that a handful of Germanys leading drummers couldn't say of which wood toms of the same size were made of. >Just one guess was right. The sound radiation of any shell makes between 1.5 and 2.5% of the overall sound.

So that explains why, to me, your drums have a vintage vibe to them without re-rings.

Great video! I didn't hear you say this specifically in the video, but it sounds like you are saying that when you strike a drum head, the shell vibrates and emits a tone that you are able to hear, is that correct? If so, is this tone louder or softer than the tone that comes from the head? Does the vibration of the shell have any effect on how the drum head vibrates?

Turns out I liked the walnut the best in all three rounds an the tulip the least. Didn't dislike any of them and the difference wasn't huge, so all in all the type of wood doesn't matter that much, but at least it tells me there is a difference.

You’re adding 2 nodes when putting heads on. I tune both a minor third less than the overall pitch I want

This phenomenom is also called the overtone series, and is how brass instruments work.

I already have the drums that I want and let me tell you the drums I have sound awsome !!!

It does kind of take some of the fun out of it when we start talking about drums like pieces of furniture, but at the end of the day it's about sitting...err...the drum sounding like a drum. Double irony here because for many years, shells were manufactured for drum builders by furniture makers.

Good video. If the person at DW in charge of checking the tuning of the shells sees this, they can realize the time wasted, for marketing it can help, but in practice... Besides, we all know great instruments made many years before and have recorded albums and in many cases with better sound than today. I can't imagine Bernard Purdie, Steve Gaad, Bonham or Max Roach saying "this 12" should have a semitone less." None of them needed this. For years they have filled our heads with worthless nonsense and they make us believe that we need them. It is time for brands to make good, practical, durable and honest products.

That's a theory. However, the sound really comes from the heads: top and bottom. The shell acts as a sound chamber. Period! You play the heads, not the shell. What's more, hardware is attached to a drum. If a shell really contributed that much to a drum's overall sound, the hardware (i.e. lugs, screws, washers, hoops, etc.) would hinder anything the shell might contribute. The smaller the drum, the more mass that's affecting the shell. Which is why, if you listen to recorded music, you can likely tell the sizes of the drums being played (e.g. a bebop kit) rather than what the shell is comprised of. Permission to believe I suppose. Drum companies have relied upon this strategy for years.

Great video. But, how do you explain getting a "dud" drum? You know... It just doesn't sit well with the rest of the kit, or it doesn't belong in terms of tonality. Anyway, regardless of how DW markets their drums, if I tune my bottom heads to the note stamped on the inside of the shell, and the top a whole step above the bottom head (as DW recommends), they sound great. I certainly don't think that's the only way to tune, but it does produce a nice sound that's repeatable, if that's a sound you like. I also think DW experiments with grain orientation so the pitch of the shell ends up where a bottom head would sound good tuned to.

Am I wrong in assuming that Inde shells are somewhat like Gretsch shells (thin, rounded edges)?

Tap the shell without lugs and get one note. Tap the shell with lugs and get another. Mass changes tone.

John Goode : “I’ll get my coat“ 😁

Don't take away my fantasy! I like to think that John Good himself knocked on the shells of my DW and matched them based on that and that it matters!

So what about those long lugs that span almost the whole depth of a drum shell, that must kill all the shell vibration ?

1 / 2pi x square root of (L x C) Resonant frequency of a tube with two closed ends.

I built a bass drum using 0.8 mm Finnish ply. The hyper thin plywood is suspended between two 5 inch wide 24 inch diameter shell hoops for lack of a better description. The thin plywood shell is bendable to the touch. Much like a toilet roll cardboard tube there is an intrinsic strength when material like hyper thin plywood is bent into a circumference. The bass drum has a very low pitch which I believe comes from the reduced mass of the shell. I was hoping for a lower volume bass drum but I have found that the type of shell doesn’t seem to have an effect on the actual volume of the drum. in my attempt to build a lower volume drum I am beginning to believe that the air inside the drum has to be manipulated somehow to reduce the volume of the drum. If anyone has any ideas how to make a great sounding low volume drum I’m all ears!

OMG... 🤯

Getting John Good unemplayed?😉

9:18 John Good's head exploding

6:48

Ooops BIG TYPO…. CORRECT TO… “ the hole in the marimba bar does …NOT … create the node”… the laterally drilled hole is located WHERE THE NODE ALREADY IS.. this minimizes dampening of the resonance of the bar.

I wonder if the direction of the grain isn’t even a big factor and also the modes in the shell may not be so important. Because heads. A drum is a hollow space. A string is a line A marimba key is a 3D solid body so: different rules But. A drum is not a solid body. So that’s why I’m thinking: there must be completely different rules for drums as well.

The sound of a drum is the heads

lo sapevo gia' :)

DW has all kinds of voodoo marketing going on.

I hit like and subscribe from just seeing the title of the video. I have always felt that John Good's presentation of pitch is pure BS, now I know it is.

but DWs still sound great.

I hope John Goode has watched this! 🤣

I would appreciate it if you contact me… You certainly understand the concepts… But … I taught teachers… to find the cleanest path…. To teach a topic. I would love to talk with you about what you’re saying , how you’re saying… in what order … etc Ps .. My Marimba Teacher… Gordon Stout And… I am a percussionist, drummer ( retired piano tuner ) … and a training program manager. I think that I could help you sort out this discussion.. for clarity Thx

The folks at DW would disagree...

shhh, dont tell DW your workings out, they love the tap test on their drums!!! XD

I couldn’t care less. All I want is a high quality shell with precision bearing edges and I can do the rest with a drum key and my ears.

9:14 Dem Wacky myths have been BUSTED!

John Goode was very convincing with his marketing of DW but it was all BS stamping a note on a drumshell and timbre matching ..

No ruffled feathers here, just confusion. To me that actually proved the thump test to be valid. So I checked with a virtual piano online, and the initial thump test you did on the shell was a F#2. When you went to the edge test, it was a F#4. But still an F#. I double checked and googled a sticker from a DW shell, and it only has the note, not the pitch. So in this situation, they would have slapped just a "F#" on it, and it would have aligned with your testing as well. But I could very well be jumping the gun here. I just don't see where the lie is.

Oh, ya gonna go there huh?!!! 😂 Throw down the gauntlet! I guess something irritated him.

100% agree, i always knew it was BS

John Good at DW must be racking his brain and fumbling right about now.😂

how dare u go against DW and John Goode

In other words, Juliet Golf, over at Delta Whisky drums, is full of shit? lol

The tap-test as it relates to drum tuning was always a bullshit, made-up theory pushed by John Goode and Drum Workshop. Tapping a raw shell will produce one fundamental tone, but as soon as you attach lugs to that shell and tap it again, the perceived pitch will change radically. And if you wrap the shell in a covering, the pitch will change again. So, long before heads and rims are ever assembled on the drum, the very concept of tuning to the raw-shell tone is absurd. Plus, DW would actually print the note inside the shell that was supposed to represent the ideal tuning point based on the raw-shell tap-test at the factory. But in reality, that note was never close to the ideal pitch of the toms when fully assembled and tuned up. It was pure fantasy.

Im very pleased to not see any man buns or feminine whatever's with soft hands.

Good is talking trash. The note of a raw shell means nothing anyway. Add lugs, strainer, muffler screws, holders not to talk abt. adding strength and stress by rims.

Sorry DW !! Haha debunked. Sick of everyone going to DW for this idea. If shell timbre note is true that would mean every pro company not doing what DW is doing would be poor craftsmanship and false drums. Meanwhile Ludwig Pearl and any other company still work just fine.

stop exposing gimmicks! I suppose next you're gonna hate on gluedrums (dead sounding drums with too many too thin plies)

Sad you feel it necessary to attack DW. What they say about a drum having a fundamental pitch is an actual fact, and your assertion that the shell is vibrating like you depict is a huge exaggeration and is in and of itself bad science. Fact is when you install a reinforcing hoop, a couple of pounds of lugs, and restrain the shell by stretching a piece of Mylar across both ends and clamping it in place with a heavy steel hoop you are really just creating a resonant chamber for the head which is creating a vast majority of the sound. Sure, all drum manufacturers want to differentiate themselves but the area you are focusing on has a minuscule effect on the sound compared to the head choice and tension. You might change the sustain or resonance of the drum but not a whole lot else. It’s like the audiophile industry where people obsess over $1000 speaker cables and what it does to the midrange of their system and if you swap out to a different set of speakers the sound changes COMPLETELY. Shells are speaker wires. Heads are speakers. DW makes great drums, and they innovate regularly. That is a great thing for the drum industry. You should just try to differentiate your products on their inherent value and performance and not trash other companies. Drumming is a brotherhood, and we all want to support companies that inspire us in our playing and bring innovative products to market. Best to focus on that. I think, please.