All About Amp Wattage

August 1, 2009

OH, HOW WE GEAR WRITERS LOVE TO THROWAROUND the saucy old cliché that declares “size does matter.” But when it comes to amplifier wattage, we’ll discover that the smaller weapon is often more suitable for the job at hand. The myriad sizes of guitar amplifiers all have their applications, but advances in sound reproduction—partnered with increasing awareness of the detrimental effects of exposure to excessive volume—have meant that it’s a very different environment up on the stages of 2009 than it was on the stages of 1969. As such, All About Amp Wattage seeks to initiate a reality shift of sorts, to offer a clear-eyed assessment of how much power different playing situations require.

We all enjoy standing in front of a raging 100-watt full stack now and then, right? There’s nothing else quite like the windin- the-hair, thump-in-the-gut feeling of unleashing an evil riff with all that firepower— the hovering, edge-of-feedback immediacy and totally alive playing feel of it. It’s fun to consider the occasions when we might be able to justify such wattage, but let’s apply a gigging scenario that’s more like something you might encounter most nights. The average venue is a compact 80 to 120-seater club, in which your 15-watt 1x12 tube combo works so well that you may even be asked to turn it down. Every once in a while, a slightly larger booking in a 250-seat room turns up, and you briefly consider bringing a 45-watt amp but wisely decide, “No, let’s just take the opportunity to crank the little fella’.” Does it suffice? Yeah, in spades—and as if on cue, the sound guy even asks you mid-sound check to turn it down a little. The fact is, given the capabilities of modern sound-reinforcement systems— with good mixes running both in the mains and the monitors—you really don’t need any more volume than you could comfortably tolerate in a room the size of the stage you’re on, and when the aforementioned monitors are done right, you can get away with even less. In reality, the oversized amp often just leads to the heartbreak of unsatisfactory tone. It’s not just that everyone else in the room will be your friend if you use a smaller amp, but you’ll enjoy your own playing experience a lot more, too, because you’ll be able to hit that sweet spot where shimmering clean segues over into succulent distorted at the thwack of a pick. Err on the side of too large, on the other hand, and the powers that be— which usually means the sound guy or your lead vocalist—will just force you to turn down, stranding you short of the golden tone zone. If they don’t, chances are you’ll obliterate the room with excessive volume anyway, and that’s another sure-fire show spoiler. (Note that all of these considerations go double in the studio.)

But that 100-watt double stack is out there, calling to you, begging you to uncork its glowing tubes with your hot riffs… right? Sure, and for good reason. Way back in the early ’60s when rock was on the way to becoming the monster it is today, bands found themselves moving from basement clubs, to dance halls, to theaters, to stadiums, and because the P.A. systems of the day weren’t up to the task, they needed progressively bigger guitar amps to get themselves heard. Fender designed the Showman for Dick Dale, Vox came up with the AC50 and AC100 for the Beatles, and Marshall created the JTM100 for Pete Townshend. All of this was relevant 40 years ago, sure, but if you grew up with the sound of Eric Clapton, Jimmy Page, Jimi Hendrix, or Paul Kossoff through a Marshall stack, it’s hard to get that tone—and that image—out of your head. You want the rig of doom, even if the world won’t let you play it. Of course, certain scenarios that allow, or even encourage, the use of big amps do still exist. As a rule of thumb, if you’re touring with a signed act that plays stages larger than the footprint of your house or apartment, and have got someone to carry the road cases for you, you can probably still get away with the stack. However, even many large, professional acts—Nashville artists in particular—are moving away from massive stage volume levels, running amps behind plexiglass shields or even under the stage, and monitoring everything with in-ear units. Or, if you’re a country or jazz player who needs 100 watts in order to obtain the clean headroom that 40 percent of its potential provides you, or a 7-string metal thumper who wants to project pure punch and crunch with a lot of low-end rumble, you might very well need the power. Also, the player who uses a lot of pedals to achieve overdrive and distortion, or who uses a channel-switching amp’s high-gain lead channel coupled with appropriate master volume levels to rein in output, might find a 50-watter is appropriate, and even necessary. By and large, though, the rest of us bar and club giggers can put the old dream of macho-looking amplification behind us, and embrace the new dream of muy grande tone.

In order to work toward weaning ourselves off excessive amplification, let’s take a look at how power ratings actually equate to volume. The peculiarities of the human ear and the logarithmic nature of our perceptions of volume mean that output ratings don’t correspond directly to volume levels. While a 100-watt amp packs five times the power of a 20-watter, its perceived volume is really only around twice that of the smaller amp (this is an imprecise science, since it involves many variables, including considerations of frequency perception). What does increase more dramatically with the higher-wattage amp is its headroom and the ceiling for the onset of breakup, meaning you have to push it hard to get the distortion juice.

Before moving on, let’s examine another scenario. Ever wondered why your bass player with the 200-watt head and 4x10 cab is always grumbling that your 15-watt 1x12 combo is too loud? For one thing, it takes a lot of wattage—that is, more tubes and a bigger output transformer—to adequately reproduce the low frequencies that bass guitar requires. For another, human hearing is more sensitive to midrange and high frequency sounds than it is to lows, and the nature of these changes as an amp transitions into distortion. Therefore, the frequency range and distortion content of any given amp will also skew our perception of apparent volume. Stand your 15-watter and your bass player’s 200-watter side-by-side, set his volume at noon and yours at 10 o’clock, and chances are you’re still cutting through just fine. All of which, of course, brings us to the issues of speaker type and efficiency, and cab design and speaker complement, all addressed thoroughly in All About Speakers (GP, May 2008). In brief, be aware that a more efficient speaker will make any amp louder, so let’s consider all of the above as if rendered on an equal playing field, speaker-wise. And, while a big 4x12 has a lot more surface area, and will therefore pump more air than a little 1x12, I have run the same amp head through both types of cabs side by side and on some occasions found the efficient open-backed 1x12 to have a higher perceived volume level than a closed-back 4x12 (remember: a 40-watt amp doesn’t pump 40 watts through each speaker in a 4x12, but divides the total into 10 watts each, while it does pump all 40 watts through the single driver in a 1x12 cab).

If you’re mostly playing smaller bar and club gigs but are attached to your bigger 50- or 100-watt amp, there are ways to tame its output level somewhat, and to therefore get it to sing and break up a little bit shorter of ear-splitting volume. Note that none of these solutions will yield exactly the same tone as running the same amp flat out as designed, but they might make acceptable compromises in some instances. A range of highquality output attenuators is now available from THD, TAD, Weber, Dr. Z and others, and can be connected between amp output and speaker to decrease the level in increments. Be aware, however, that cranking an amp through one of these devices will still burn through tubes just as fast as running it flat out without an attenuator. A few makers offer isolation cabs that carry small, high-powered speakers and internal mics, so you can muffle that stage or studio level down to nil, but still capture the tone of a cranked amp into a real speaker. There are also tube converters from companies such as THD and TAD that make it possible to use less powerful EL84s in amps designed for 6L6s, EL34s, 6550s, and other common power tubes. Lastly, many tube amps these days come equipped with “halfpower” switches or other power-reducing functions that can be very helpful in situations where volume is an issue. The fact that such features can even be found on some 20-watt amps underscores just how far things have come in the quest to give guitarists the ability to enjoy “cranked amp” sound at seriously reduced volumes.

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