Playing out with electronic drums

NOTE: The author is a fast-aging, 'boomer' drummer in a rock/pop group out of Grapevine, Texas, who has done the sound reinforcement for his band and several others for a number of years. The opinions below are his own and do not necessarily represent anything 'official'. You can email him with questions, criticism, or saucy photos of Sigourney Weaver at lmundy@attbi.com.

NOTE: I might add, Larry's experiance in this area is an exceptionally honest and useful read for anyone considering the impact of running Drums or a Bass instrument thru a PA system, with a number of options. Solid Deep Bass requires A LOT OF POWER and most often, BIG speaker cabinets - Jens Moller

If you’re like me, or even if you aren’t, you may have grown up playing conventional, 'acoustic' drums with shells and hoops and heads and all that. Most drummers still do. But off in the corner at your local music store, maybe you’ve played with a set of electronic drums and noticed that one little magic box can give you the sounds of dozens of drumsets with the turn of a knob. And, you can practice with headphones at 3 AM. And you can carry many electronic drumsets, in a 'folded' state, with one hand, whereas with conventional drums you are carrying maybe a hundred cubic feet of trapped air around in big empty containers. There are so many advantages to electronic drums that I bought an inexpensive set, a Hart Dynamics Prodigy DVC, and an Alesis DM-5 module 'for practice' about a year ago. Within a week I was scheming how I could gig with them and leave those five big wooden shells at home. With a little modification to the cheaper aspects of my cheap set, treated elsewhere on the web ( http://www.acousticdrums.com/members/esp-1qtr02.html), I found that gigging with even inexpensive e-drums was entirely possible, and in fact a big improvement in many ways. Soon you will see my 'acoustic' drumset on eBay.

First, though, a few bits of reality therapy:

Keep your kick pedal too, because almost no electronic set comes with one. It is possible to get a very good kick-drum 'feel' with most or all of the electronic sets I’ve tried, and the sound can be awesome. If you’re like me, you’ve spent hours experimenting with different heads, baffles, pillows, holes in the front head, beater materials, low-frequency microphones, and other advanced voodoo to get that just-right, low, few-overtones-but-not-dead sound a good kick drum should have. Guess what? There are probably 12 kick-drum sounds in my electronic module that sound better than anything I’ve tried on a real drum. But you still need a good, sensitive pedal that has the feel you like, and that’s probably the pedal you already have (if it’s not, they still sell the Ludwig Speed King which has great feel and the springs are on the inside where they won’t rust, break or fly off and hit you in the eye).

It’s great to carry your whole drumset (sans cymbals, of course) under one arm into a gig, and to set it up in 3 minutes (unfold, secure, plug in). But a lot of that space you’re no longer taking up in the van needs to be filled up again, because electronic drums are just like electric guitars, and make almost no discernible sound whatsoever without an amp and speakers. And they demand an absolutely killer amp-and-speakers combo; you can’t just use a spare input on someone’s old guitar amp. That’s basically what this article is about.

Your electronic drum pads plug into the sound module with standard ¼ Inch cables, like the guitar cords we’re all familiar with. My set came with ten of these, all thin as angel hair pasta and with unfixable molded plugs. Cheesy electric guitars come with the same things. Buy or make real cords with heavy, repairable plugs.

Those cords plug into a module with a row of jacks on the back. Mine are labeled 1,2,3 and so on, and there is not enough space to grab a label maker and label them 'tom 1', 'snare', etc. That information is in a tiny chart halfway through the manual for the module. Photocopy that chart and cut it out. Buy a sheet of adhesive 'laminating plastic sheet' at an office supply store. 'Laminate' that chart to the top of your module, or an arm of your rack, or something that will always be with you on a gig. Nothing is worse than having your snare make a cowbell sound, and your tom sound like a crash cymbal, and you’re plugging and unplugging wires in the dark when the gig is supposed to have started.

Spend some time setting up your module, particularly the sensitivity and crosstalk settings, so that one pad doesn’t trigger another. Have your bass player put that giganto cabinet facing your set close-up and play scales from open E to the highest thing he’s got, and see if anything he does triggers a drum sound. What works perfectly at a quiet practice can suddenly sound like mutant machine guns when everyone is cranked up onstage. Your pads should trigger a sound when you hit them, and ONLY when you hit them.

Some Thoughts About Amplifiers

Okay, now the next step is that your module has an output, and another cord has to go to an amp and speakers somewhere. This is the critical juncture if you want to gig with your electronic drums. On certain kick-drum settings, your module puts out lower tones than any bass guitar regardless of how many low strings it has. The sampled overtones of your snare (and your electronic cymbals, if you use them) extend to and beyond the range of human hearing. You need a very powerful, full-range amp/speaker combination to do your sound justice.

Through a conventional guitar amp, you will sound like someone is playing drums in the garage next door, no matter how powerful the amp is. Guitars have a limited tonal range and guitar amps are designed for that, with response falling off on the low and high ends because it isn’t necessary. Most guitar amps lack the power to reproduce low notes, which is probably OK because most guitar speakers won’t handle low notes anyway. Really expensive, coveted guitar amps are also made with tube circuits and 'vintage-type' speakers whose job it is to distort in a way that can be really pleasing on that blues guitar solo. But trust me, bluesy fuzz just makes electronic drums sound cheesy. Use a guitar amp for practice in the garage if you have to, but don’t even think about gigging with a guitar amp.

Bass amps are a little better, because at least they are designed for more low-frequency punishment, with heavier speakers and more powerful (usually solid-state) amps. But because basses also have a limited tonal range, little or no design attention is paid to reproducing high frequencies. Bass-amp speakers are built to reproduce low notes. Some bass speaker setups come with high-frequency horns to better reproduce high-register notes and percussive 'slaps', but even the best of these run out of steam well before 10,000 Hz, which for our purpose is essentially 'midrange'.

Another note about weird stuff like impedance and sensitivity. Electric guitars and basses, unless they are the fancy kind with an onboard preamp and batteries, put out a very low-level signal because it’s basically electromagnetic pulses from the coils of little bitty wire in the pickups. Long story short, guitar and bass amps are usually looking for that little feeble signal. Your drum module puts out a much stronger signal known as line-level, which can overload a guitar amp input and cause all sorts of weird distortion and maybe even damage. If you use a guitar amp and it has multiple inputs, use the one that makes the sound softest and cleanest at a given volume setting.

Better still is a keyboard amp, which is designed for the full range of a piano or organ and has both low-and high-frequency speakers (not all do, though. Many 'keyboard' amps are merely guitar amps with a different label on them, and keyboards played through these tend to sound muffled and midrange-y as you might expect). Few of these have the high wattage output necessary to reproduce really low notes cleanly, but of the three types (guitar, bass, keyboard), the keyboard amp is the best for e-drums. It is looking for line-level output, too, because your drum module and the tone-generation circuitry in an electronic keyboard are kissin’ cousins.

Equally good, and maybe better, is a good PA amp and full-range PA speakers. The better PA setups tend to have a good bottom end, crisp highs, and powerful amps. The amps aren’t loaded with distortion effects you don’t need, and there are usually 2 or more cabinets which spreads the power requirements around. The drawback is, these things are usually huge and worse than carrying a regular drumset and a couple anvils and some Zulu tribesmen in the back of your Toyota.

So why not just plug into your band’s PA system? I can think of two reasons not to do this. One is that you may not be able to hear your drums through the monitors, if you’re not also a vocalist with your own monitor. The big reason, though, is that most bands’ PA systems are completely inadequate for this. They are built and sized for vocals, and many of them just have little 'speakers on sticks' that don’t handle low frequencies all that well. Start feeding electronic kick-drum sounds and sharp percussive transients from your other drums and/or cymbals through these, and they will (1) distort like crazy; and (2) distort the vocals along with it. I know, you have all the other guitar-amp sounds feeding through your microphones all the time, but as noted above, those sounds are not as demanding on amps and speakers as e-drums are, and most microphones have a response fall-off well above the low register of a bass guitar, so those sounds don’t bleed through anyway. That’s a far different picture than plugging your module directly into your PA amp and delivering thundering low frequencies and sharp 'attack' transients through your poor little PA speakers. So, if AND ONLY IF you have the sort of PA where all the stringed instruments including the bass, play through teeny amps and are miked through the PA, and if your PA has more raw amp power (RMS wattage) by a factor of 'several' than everything else in the group put together, and you have huge bass bins and maybe a biamped setup, and your PA takes up a whole cargo van to move, then by all means plug your e-drums into it (and insist on your own personal monitor speaker). If you don’t have that sort of setup, rig up a standalone amp-and-speakers combo for your e-drums or you will turn those little PA speakers inside out and there will be no drums, no vocals, no gig.

One of those integrated PA heads (mixer, preamp, amp all in one, sometimes called a 'powered mixer') can work great for electronic drums, though, for a couple of reasons. One is that it’s used to outputting to at least two speakers, maybe more, and usually has a stereo mode where the power output to each speaker is individually adjustable. Some are set up so one channel can feed the mains, and another channel can feed monitor speakers, and this is just as useful for e-drums as it is for vocals. If you’re blasting drum sounds into the audience from speakers in front of you, you still may not be able to hear what you’re doing. If you have a small monitor sending the sound of your own drums back to you at a reasonable level, you will know what you’re doing AND you won’t destroy your hearing. Another good thing about integrated PA heads is that most accept both line-level signals with ¼ inch inputs, and microphone-level inputs through Canon-type 'XLR' connectors. If you use 'analog' cymbals (or any sort of acoustic percussion doodad) as part of your set, you will need to mike them for large venues, and a PA head allows you to input both your drum module and microphones, and mix them as you like.

The downside of an integrated PA head is that most small ones with 4 or 6 channels (all you probably ever need in terms of inputs, since your drum pads can be separately adjusted by your module) aren’t built to output low bass at high levels. The preamp/mixer stage will handle anything, but it may be inseparably paired to a 100- or 150-watt amp that just won’t reproduce that electronic bass drum cleanly at high volumes. For larger venues, I’d recommend a separate power amp, the standard rack-mounted kind used for PA’s and such, with a power rating of several hundred watts. That doesn’t mean that you will be playing so loud you will vaporize small mammals; it just means that you will have what sound engineers call 'overhead' (or 'headroom') with enough reserve power to reproduce just about anything cleanly without the 'clipping' distortion that is the sign of an amp working too hard. Clipping fries speakers, probably more often than simply driving them past their design limits, because it introduces a sound that is very difficult for them to reproduce and builds up tremendous heat in their voice coils - its also very hard on Tweeters. It’s amazing how many bass guitarists think their speakers are crappy, when the problem is that they’re driving them with an inadequate amp that distorts at the volume levels they’re trying to achieve. More than once I’ve seen a high-power amp bring those 'crappy' speakers back to life. Look for a power amp that can be 'bridged' to deliver a higher-wattage mono signal, and it’s a plus if the one you find has some sort of protection circuits against overload. The best is some sort of 'compression/limiter' circuit that tells the amp when it’s in danger of clipping, and backs off the level. Peavey makes good power amps. So do Crown, Crest, QSC, and about a bazillion other companies. Generally these are designed for rack-mounting, and weigh about as much as a car. For large venues or outdoor gigs, avoid amps that are not fan-cooled; this is a sure sign of either low power output no matter what the claimed power is, or a thermal breakdown waiting to happen.

Of course, a power amp just takes a signal and amplifies it. You can plug your module right into a power amp if you want, I’ve done that, and it sounds OK because all of the reverb, echo, etc. you’ll ever need is already built into the sampled sounds in your drum module. As noted above, however, it’s useful to be able to hook up microphones, and you may want some eq or tone control over your drum sounds. There are two ways to do this; one is to take that integrated PA head that lacks power and just use the preamp stage, if it has a 'line out' or equivalent that will bypass its internal power amp (or use its little power amp for your monitor, and send the line-level signal to the monster amp). If you don’t have a spare PA amp around, though, all you really need with your monster amp is a simple mixer. If you’re not miking cymbals, etc., a 'line-level mixer' will work fine (but then, so will a direct hookup to your power amp). I’d recommend a mike-and-line mixer, though, for its flexibility (and resale value when you’re too old to rock and roll). There are units out there that take up a single rack space, so that your mixer and your power amp can both fit into a 4-space rack, or even less. If it works, cheap is good; you don’t really have to care that much about signal-to-noise ratios and all that. I’d recommend eBay as a source for amps and mixers; since they are used by bands, DJ’s, churches, bus stations, whatever, there are always a lot of them for sale.

Microphones - Special needs

If you use microphones, you probably already know this because you miked your regular drums, but regular 'dynamic' mikes, even 'drum mikes', won’t reproduce cymbals very well. Those vocal or 'dynamic' drum mikes you might have lying around don’t have the high frequency response to pick up cymbal overtones; only 'condenser' microphones do that well. And, of course, you don’t need to mike your snare, toms or bass anymore, so you can sell those drum mikes on eBay. There are inexpensive (sub-$100) condenser mikes all over the place. If you mike cymbals, get some little clip-on mike holders rather than big, bulky stands. Cymbals are miked from above (a pain, outside a studio) or below (where your cymbal stands are conveniently waiting for clip-on mic holders like 'Mic-Eze'), but not from the side if you can avoid it. Weird sound things are happening at the edge of your cymbals. Experiment.

Speaker Systems

Okay, now speakers. I have designed, built, fiddled with, refurbished, destroyed and generally messed with a vast variety of instrument and PA speaker cabs over the years, so while some of this may not fit with your prejudices about speakers, this is the voice of long experience. And remember, speakers for electronic drums are a whole different animal than speakers for guitars, home stereos, football stadiums or what have you. I’ve mentioned above how terrible conventional 'guitar speakers' are for e-drums, and how you need a very broad frequency range. I’d recommend you learn something about actual speaker drivers rather than simply shop for a giant cabinet, because there aren’t many appropriate ones out there and they’re expensive, and if you’re handy with plywood and screws and have a couple power tools, you might consider making your own cabinet anyway. Hopefully I will do a later article about making your own cabinets, but for now there is very good advice available on the Shavano Music site. Or, you can go with an existing or factory cabinet, and if you don’t like the sound or blow the drivers, upgrade the drivers to heavier-duty units within that same cabinet.

To reproduce a kick drum, you need a very strong speaker or speakers with large magnets, giant voice coils to dissipate heat (speakers are notoriously inefficient - higher SPL = better efficency), and lots of Xmax (basically, maximum cone excursion - do your comparison shopping in the specifications). They must be rated to handle the wattage you will be feeding them, and able to reproduce sounds down below the 30hz range. This means that the speaker you need to reproduce your e-kick-drum will be a bass guitar or 'Pro-Audio' speaker. The bass guys seem to be of two camps: one likes lots of smaller speakers (like those 4-10 cabs) because you get a lot of voice coils dissipating the heat of high-powered bass notes, as well as better ability to reproduce slap/overtones on the Bass. The other likes monster speakers, 15’s or 18’s, because they reproduce the low end better. If they have a van or trailer, they may have one or two of each so they can look like John Entwhistle used to, with a wall of speakers behind them.

For e-drums, my personal prejudice is for fewer, larger bass speakers so you can better reproduce the very low kick-drum tones from your module. These sorts of drivers are expensive; I’d recommend the heavy-duty models from a broad-range manufacturer like Eminence over a manufacturer like JBL or Electro-voice, whose bass drivers are very rugged and clean but can cost more than you probably paid for your amp. Eminence Kappas or Omegas work great. Parts Express has a Dayton line of pro audio speakers with 4 inch voice coils that will take amazing abuse. Overall, just whatever you would use for high-power bass guitar will probably give you a good sound. But remember, big speakers that will reproduce bass at high levels won’t extend very far into the midrange, where a lot of your snare and tom sounds are lurking. You will need a 2 or 3-way speaker setup to extend the frequency response into this area. If you use a lot of smaller speakers, those will have a better high end, but still not as much as you will need.

Bass guitar cabinets sometimes have little horns to extend high frequency response. These reproduce mostly overtones and are not sized to take a lot of high frequency sound. What you need is something closer to a PA application where the midrange and high frequencies are handled by drivers, usually horns of some sort, capable of handling lots of power. An array of small speakers will work to extend the frequency range too, but for size and cost considerations, it’s hard to beat a horn design.

All the details and vagaries of multi-way speaker design are way, way beyond the scope of this article. You can look on the web or check a five-foot stack of books out of your library if you really want to get into this; you can use software programs to automate cabinet design parameters. For purposes of this article, all I can tell you is some basics. Your mid and or high-range speakers will be handling lots of power with what are called sharp attack transients (roughly, 'pop' noises rather than 'hum' noises). So even though high-frequency speakers are fed less power in watts during 'ordinary musical program material', for electronic drums you still need something pretty heavy-duty. The horn in that borrowed PA cab may not be up to the task.

Horns

Most good horn drivers come in two pieces, the horn and the driver, so that the driver is removable and replaceable. Parts of the driver itself (the voice coil and diaphragm) may also be replaceable. This is because a lot of undersized drivers overheat and blow up with depressing regularity. What I am about to recommend about horn driver types doesn’t fit with what most people will tell you, because 'most people' are talking about PA systems reproducing vocals or DJ systems playing recorded music.

Most horn drivers work just like 'regular' speakers - they have a voice coil that moves around in a magnetic field, and a diaphragm or dome on one end of the voice coil pushes or compresses air through the horn that comes out as sound (these are generally called 'compression' drivers). To have decent high-frequency response, these parts and pieces are much lighter and more delicate than their giant counterparts in bass speakers. To keep them from self-destructing instantly, we have to keep those high-power bass sounds out of them with a network of capacitors and inductors (or a capacitor, at least) called a 'crossover'. There are whole books on crossover designs and if you read them all you can probably test out of introductory electrical engineering classes in college. Let me just say this: the components in crossover networks must be just as heavy-duty as the speakers and amps you are using, and heavy crossover components get expensive. They add complexity to a design and since they are passive doodads inserted into the output from the amp, they introduce power inefficiencies. Even though the bass speakers take the brunt of the beating in a PA cabinet, I’ll bet there are just as many crossover burnouts as catastrophic woofer failures, and more burned-out compression drivers than both of those put together. Compression drivers (good ones) can have a smooth, natural sound which is great for wide-range musical program material and the subtle nuances of Barbara Streisand’s voice. But for e-drum purposes, we don’t care about that; we want to project a loud snare shot to the guy in the 93rd row. Let me tell you about piezo drivers; they are a better invention than sliced bread.

Very High Frequencies

Piezos, or 'piezoelectric drivers', don’t have a magnet or voice coil. A piece of ceramic crystal stuff is 'excited' by the current from your amp, and it flexes and moves producing sound waves, which then go out of the horn and into the ears of that 93rd row guy. Piezos are cheap; you can get a really bad one pre-attached to a little plastic horn for a couple of bucks. Because of their design, they have high-frequency response that compression drivers can never match, and which extends way beyond human (and maybe even canine) hearing ranges. And since you can only 'blow' them by applying so much current that you crack a (very heat-resistant) ceramic disk, they are tough as nails. You will find cheap piezo tweeters in cheap PA cabs for all these reasons. And because of the way they work, piezos don’t need a crossover at all. Technically, they present an increasing capacitive load to the amplifier as frequency drops, but all you have to remember is hey, no crossover needed! And one more interesting thing - piezo drivers are simply electronic drum pads in reverse. When you hit an e-drum pad, a piezo pickup or 'trigger' is slightly deformed and puts out a small electrical signal, which goes through the cable to your module and says 'hey, someone just hit me', and the module then translates that into the appropriate sound. There are instructions on the web for making your own electronic drums out of the guts of cheap piezo tweeters or buzzers, some old coffee cans, PVC pipe, glue, and so on. Personally I’d rather buy a factory-made drumset, but you can do some amazing things on a tight budget!

So why doesn’t everybody use piezos for everything? Because most of the cheap ones sound like crap, very tinny with overemphasized high frequencies. And because most of them won’t handle frequencies below 3 or 4,000 hz, whereas your giant bass woofer has given up long before that, leaving a midrange hole or necessitating a separate midrange speaker, crossover, etc. For that reason, you see piezos doing the high-end work in 8 inch or 10 inch PA cabs where the smaller woofer has more high end. But excellent piezos which will handle some lower frequencies at high power levels are out there and still phenomenally cheap. If you have a cabinet with a horn that takes screw-in (threaded) drivers, or are building your own, here is my only specific product recommendation: get a Motorola/CTS model KSN 1188 Powerline Piezo Driver, and screw it into your horn (or buy a cheap plastic horn for your homebrew job, about $10; I found a round horn at MCM electronics which is only 6 inches in diameter and works great). The 1188 is the big-daddy piezo driver from the best piezo manufacturer; it has useful response down to 800 hz and it will take 400-watt transients. It has its own self-protect circuit inside, weighs just a few ounces, and get this: it’s less than $30 from Parts Express or MCM or any number of other sources. This puppy will pick up where your woofer left off and will go from there to the highest shimmery sound of an electronic cymbal, and I have only blown one of them (out of a whole bunch) in my whole life - and that was due to an amplifier breakdown that sent pure DC current down the speaker wire, had smoke coming out of the low-frequency speaker, and basically melted down everything inside the whole cabinet.

Another problem with piezos, indeed with any high-frequency speaker device, is that high frequencies are far more directional than low frequencies. That’s what your horn is supposed to help with, dispersing the sound over a wider area. But since peizos are cheap, another alternative is to get an array of smaller ones wired together in a cabinet that points them in all directions, enhancing the power-handling capability of the small piezos and spreading out the sound. You can find these premade, or you can do it yourself, but remember that the smaller piezos don’t have as low a midrange response as a big separate driver and will leave a 'response hole' in the midrange. But if you use several smaller drivers for the bass, like a 4-10 inch cabinet, this may be another good, inexpensive option. With any piezo, it’s a good idea to wire a resistor in line to present a little more load to the amp, for reasons you can read about in a technical paper at http://www.ctscorp.com/pzt/speakerappnote.htm. A 20-ohm, 20-watt resistor for this purpose, which will outlive all of us, currently costs 55 cents; I just solder them into the wiring somewhere ahead of the piezo and attach them to the inside of the cabinet somewhere with a wad of 'Goop' or similar silicone adhesive. Actually, this is not a bad idea even if you have a compression-driver setup, because most high-frequency drivers are more efficient than the bass drivers they share a cabinet with and need a little resistance to lower their relative volume (that’s what those tweeter volume controls or 'L-pads' do, but they have little tiny windings of wire and can burn out too; unless you need the adjustability I’d just figure out an appropriate amount of resistance and hard-wire things for reliability).

Summary

So there you are, with an amp and speakers just like the other guys in the band. All the other concerns that apply to them, now apply to you - carry along a good-sized power cord and/or multi-outlet power strip, extra cords and so forth. Do not, ever, put your speaker cabinet where it aims right at you, especially if you are using piezo drivers for the high end, or you will end up as deaf as I am - point it at the audience and destroy their hearing instead (see above about monitors). Go through your set list and make notes about module settings for each song - echoey heavy-metal drumset for this song, muffled country drumset for that one - and you will have improved the variety of sounds your band produces by one more notch. If you have songs that require changes in loudness or dynamics and your e-drums are not as velocity-sensitive as you might like, do what the guitar guys do - get a cheap foot-pedal volume control and plug it in the output line from your module. I know your module has a volume control, but can you really adjust that little knob while you’re playing with both hands? Set a volume pedal by your hi-hat and you’re totally in control. And have fun!

Questions or Comments about this article? Larry Mundy wants to hear them

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