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All About Speakers

May 28, 2008
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Any top amp tech, thoughtful manufacturer, or clued-in player will tell you that your speakers are responsible for an enormous chunk of your tone. Despite this fact, the speaker is often the last thing a player considers in any quest to overhaul an unsatisfactory sound. Replacing a stock speaker with a different type can instantly alter your amp’s sound more than any other single change, and it can be the simplest, quickest, and potentially cheapest means of converting a mediocre combo into a raging tone machine.

Swapping to a more desirable speaker—or replacing a faulty one—is not always simply a matter of installing a “better” unit, so knowing a little about the general characteristics of speaker types can prove valuable to any guitarist. Speakers vary in size and power-handling capabilities, but also in resonant character, construction of cone and magnet, efficiency (that is, loudness relative to power input, also referred to as “sensitivity”), and so on. To smoothly achieve your triple flip into the deep end of the knowledge pool, I’ll break up different speaker types into more easily digestible genres. In this post-modern age, it isn’t entirely fair to categorize all components in the field so rigidly—and many manufacturers make speakers that blend a range of characteristics—but this is still the easiest way to get a handle on the subject. So let’s split our speakers into two fairly broad categories, “vintage” and “modern”—each of which is subject to two subdivisions, “American” and “British.”

Vintage

In the 1940s, ’50s, and early ’60s, guitar amps rarely carried speakers rated higher than 15 to 30 watts (although we’ll look at a few exceptions below). Indeed, early guitar amps rarely put out more than the higher figure, until the arrival of the 80-watt Fender Twin of the late 1950s, and a few others. These speakers were fine when used singly in small venues or recording studios, or in multi-driver cabs at dance-hall volumes. Push them hard, however, and they started to break up, adding a degree of speaker distortion to the amp’s own distortion when played near peak operating capacity.

As guitarists found themselves in bigger and bigger venues that required higher clean-volume levels, amp makers sought out more robust speaker designs. Those they found, however, cost more than the lower-rated drivers, so even when available, they weren’t universally employed. And that’s probably a good thing. A lot of players who weren’t seeking absolute “clean clean” tone enjoyed the added grit, bite, edge, and compression that a touch of speaker distortion adds to the sonic brew. Lower-powered speakers, with all their gorgeous “flaws” became a big part of the rock and roll and blues sounds, and they have retained this role for more than 50 years.

In the United States, Jensen was the big name in (lower-powered) speakers in the 1950s and early ’60s, and, in the years after, the company retained a reputation as the hottest vintage American make to own. Jensen’s P10R and P12R (15-watt, 10" and 12" alnico speakers), P10Q and P12Q (20 watts), P12N (30 watts) and a few other models played a big part in the signature sounds of great American ’50s amps from Fender, Gibson, Ampeg, Magnatone, Premier, Silvertone, and others.

The respective ceramic-magnet descendants of these models—marketed in similar designations with a “C” prefix in place of the “P” prefix—were the voice of many ’60s classics. Each of these models has some distinctive characteristics, but they are broadly characterized by bell-like highs; somewhat boxy, but rather open and transparent mids; and juicy, saturated lows (to the point of flapping, farting, and all-out low-frequency freak outs in lower-rated units when they’re pushed hard). Whatever adjectives we apply to them, these performance properties combine to yield sweet, tactile clean sounds when driven a little, and gorgeous, rich, chewy overdrive when driven a lot.

Depending on availability, many of the same amp manufacturers also used speakers from Utah, Oxford, CTS, and others. These models usually shared some vintage Jensen properties, but are generally not as revered by players. The original Jensen company has long been out of business, but Italy’s Recoton manufactures a Vintage range based on the most popular alnico and ceramic models of the ’50s and ’60s. These speakers capture at least some of the tonal characteristics of the originals, although materials are not 100 percent matches between the new and old units. Major American manufacturer Eminence, which evolved out of the CTS company, also makes a number of vintage-American-voiced drivers, including its popular, long-running Legend speakers, and many speakers in the newer Patriot range. The smaller Indiana-based manufacturer, Weber Speakers, likewise offers a range of highly regarded vintage-style units—many of which are based on Chicago-era Jensens.

Across the pond, Elac, Goodmans, and Celestion were manufacturing speakers in the 1950s that had broadly similar characteristics to their American cousins. Using pulp-paper cones and alnico ring magnets to achieve power handling conservatively rated in the 12- to 20-watt ballpark, these appeared most famously as the Goodmans Audiom 60, and, more famously, the Vox Blue—a Celestion G12 relabeled by the amp manufacturer. Celestion’s “Blue”—still available today as an excellent reissue, the Alnico Blue—is famous for its sweet, rich, and musical mids, appealing highs, slightly rounded low-end response, and plenty of aggression when pushed. The Blue has always been a highly efficient speaker, too—which means that it translates a relatively high proportion of the wattage pumped into it into volume. The G12 has a sensitivity rating of 100dB (measured by driving the speaker with one watt, and then evaluating the volume level from a distance of one meter), compared to figures of 90dB to 97dB for similarly styled vintage Jensens and other speakers. Such sensitivity means, for example, that a pair of G12s in a 2x12 Vox AC30 can produce a lot of noise from that 30-plus-watts tube amp—even making it sound as loud as a 60-watt or 100-watt amp with less efficient speakers. Higher efficiency might sound like a universally good thing—and, for some players, it is—but louder isn’t always better, and, in some circumstances, you might want to tame a little volume to gain dynamics and easy break up.

In the mid 1960s, Celestion evolved its cornerstone guitar speaker into the ceramic-magnet G12M “Greenback” (rated at 20-25 watts), which were typically found in multiples of four inside closed-back Marshall cabs, setting the early standard for rock’s amp-stack sound. The Greenback is warm, gritty, and edgy, with a bottom that isn’t particularly firm, but which can still pack plenty of oomph when doing its thing in fours or eights in a closed-back cab or two. This speaker, as much as any amplifier, typifies the “British” sound sought by so many classic rock and blues-rock players. In the late ’60s, the slightly higher-rated G12H took on a heavier magnet—and a slightly more efficient design—to offer a bigger low end, and a little more volume and punch. Celestion today produces two variations of the Greenback and G12H—one each in the British-made Heritage Series and Chinese-made Classic range. Eminence covers both sides of the Atlantic by also offering a wide range of Brit-voiced drivers in its Red Coat line, and California maker Tone Tubby pays homage to the original alnico G12 with its hemp-coned speakers. Likewise, Weber Speakers offers many units based on classic Celestion models, while Texas-based Kendrick has its own line of Blackframe, Brownframe, and Greenframe speakers. (Kendrick also distributes Fane speakers in the U.S.)

Modern

As already mentioned, the quest for more volume also sent amp manufacturers seeking speakers that could handle the power. Increasing a driver’s power-handling capabilities usually brings other performance changes along with it, however, so we can broadly characterize “modern” speakers not only as being able to take more of a beating, but also as having a tighter, clearer voice that is usually accompanied by firmer lows than the typical vintage speaker offers.

The first such driver widely used by a major amp manufacturer came into play a lot earlier than our previous discussion might imply. In developing the loud Showman amps of the early ’60s for surf guitar sensation Dick Dale—as well as the unusual ported and closed-backed speaker cabinets that accompanied them—Fender sought a sturdy, efficient driver, and came up with the JBL D120F and D130F (12" and 15" speakers, respectively). Based on the JBL D120 and D130 models used in the hi-fi audio industry—the “F” added to denote Fender OEM units—these speakers had enormous alnico magnets, sturdy cast-metal frames, and large voice coils, and, as a result, they exhibited power-handling capabilities like almost nothing else available in the world of guitar amps. They succeeded in making Showmans hellaciously loud amps, and when added as an option to Twin Reverb combos a few years later, they also helped to make these amps both unfathomably loud and excruciatingly heavy. JBLs classically present firm lows, a round midrange with an edge of bark and a slightly nasal honk, and ringing, occasionally piercing highs. There are speakers suited to loud playing—when you really want to cut through.

Two other makers of advanced, modern-styled American speakers, Electro-Voice and Altec, started popping up in guitar amps in the 1960s. Early examples employed big alnico magnets—although EV’s most famous guitar driver, the EVM-12L, was a ceramic-magnet speaker that came to fame in many Mesa/Boogies and other big rock amps of the ’80s. Rated at 200 watts, and still available today, it is famed for its ability to stand up to incredible punishment, and keep pumping out pristine clean tones and rich, detailed overdrive. (The current Zakk Wylde signature Black Label EVM-12L is rated at an awesome 300 watts.) Altec’s most popular rock speaker was the 417-8H, which is no longer available. These were also optional equipment in Mesa/Boogie amps, and were a key ingredient in the mid-period Santana tone, as well as being favored by the likes of Randy Rhoads and other big stadium-rock wailers. These 100-watt drivers are known for powerful, full-throated clean tones, while translating cranked-amp overdrive tones with a minimum of speaker distortion.

Many big names in vintage speakers survived to produce designs that fit more easily into the modern category. Celestion, for example, also offers the much-loved G12T-75, G12H-100, Classic Lead 80, and others—all powerful rock drivers with big voices and serious power-handling capabilities. Meanwhile, many blur the lines between vintage and modern. Eminence carries robust speakers in its Legend, Patriot, and Red Coat ranges that have impressive power-handling specs, but achieve tones that fall more into the vintage-voicing camp. Look to the Legend V128 (120 watts), Swamp Thang (150 watts), and Man O War (120 watts) for examples from their respective camps. Even one of Celestion’s most popular speakers of the past couple of decades, the Vintage 30, was developed in an effort to capture the vintage-styled British tones of an AC30 in a more contemporary package that can handle 60 watts. Similarly, the recently introduced Celestion Alnico Gold seeks to capture the tone of the 15-watt Alnico Blue in a sturdier 50-watt package. Another British manufacturer, the oft-overlooked Fane (whose speakers powered many a Hiwatt in the late 1960s and ’70s), still manufactures an alnico speaker, the AXA12, that looks for all the world like a vintage driver, but handles a whopping 100 watts.

The Speaker for You

Selecting the driver to best meet your tonal requirements, as an upgrade or replacement, involves a soul searching of sorts, where you navigate between all the characteristics described above, and consider them in light of power-handling requirements and desired sensitivity/efficiency. Great players throughout tone history have stumbled upon some distinctive and utterly outstanding sounds by employing unlikely speaker choices in unexpected places, so don’t let the American/British categories discussed here imply any rigid rules. I’ve heard great results with a Brit-voiced Eminence Red Fang in a vintage tweed-styled American amp, and an American-voiced Weber 12A125 in a British class A-type amp. Experiment as much as time, budget, and your local guitar store will allow, take tips from friends’ rigs and those of name players whose tone you admire, and discover what works for you.

Speaker Distortion

When we talk of speaker distortion, we mean a form of distortion—distinct from amplifier distortion—that is generated when a driver is pushed near its operating limits. The voice coil and paper cone begin to fail to translate the electrical signal cleanly, and, as a result, produce a somewhat (or, sometimes, severely) distorted performance. Put simply, the voice coil begins to saturate, the paper cone begins to flap and vibrate beyond its capacity, the magnet’s performance compresses, and the entire electro-mechanical network that makes up a speaker cooperates to bring its own degree of fuzz to the brew. The concept of such distortion is sometimes confusing, because it often occurs on top of any distortion the amplifier itself is producing. The distortion produced by a high-gain preamp stage—or a floored output stage—can occasionally be heard on its own when an amp is played through high-powered speakers that refuse to distort (or distort very little), even under high-output conditions. In most cases, when an amp is raging, you’re hearing a little of both.

Alnico vs. Ceramic Magnets

Alnico magnets possess a certain buzz in the speaker world (and also in the world of guitar pickups), and are considered to be a more “musical magnet” that’s revered for sweetness and dynamics. Alnico is an alloy of aluminum, nickel, and cobalt (blended with a quantity of iron). Thanks to the relative scarcity and expense of cobalt, it’s an expensive alternative to the ceramic magnets that are also employed in speaker manufacturing, and alnico was all but dropped from use in the 1970s and ’80s. While this description of alnico implies a certain superiority, be aware that several classic speakers—even many vintage models, and those that remain the driver of choice for countless major players and tonehounds—were (and continue to be) made with ceramic magnets. Celestion’s G12M Greenback and G12H-30 are both ceramic speakers, as are plenty of great units from Eminence and revered early to mid-’60s Jensens.

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