As with all things guitar, a little patience can yield big dividends.
Think about the last time you bought a new pair of shoes. When trying them on in the store, you probably thought, “These feel pretty good, but I bet they’ll feel amazing once I get them broken in.” So you bought the shoes and wore them every chance you could. Eventually they folded and creased in all the right spots to conform to the shape of your foot.
Now think about the last time you bought a new speaker. Maybe you tried it out, but didn’t immediately like it. Or perhaps you’ve never bought a new speaker and are hesitant to do so because you’re not sure what to expect. All right, what’s the connection between speakers and shoes? The answer is simple: Just like footwear, new speakers need to be broken in. If you didn’t know that, you’re not alone. Many guitarists don’t realize that new speakers need time to break in before they reach their ultimate tonal potential.
Before we can understand why this is necessary, we must understand what needs to be broken in. There are two main parts to consider: the cone and the spider. You probably know what the cone is, but may not be familiar with the term spider. The cone connects to the front of the voice coil. The spider is the term for the suspension that attaches the rear of the coil to the frame. (To see an exploded diagram of a speaker, check out “Alnico or Ceramic … What Gives?”)
For a speaker to function, the voice coil, cone, and spider must all move in and out as one piece. The electric signal from your amplifier causes the voice coil to move back and forth, creating an electromagnetic motor. The spider holds the voice coil in place, and the cone projects the sound outward.
The cone is traditionally made of paper, while the spider is usually a mesh-like material that has been formed into a specific shape. When brand new, these two components are very stiff, and this affects the speaker’s sound right out of the box. This stiffness can create a bit more high-end fizz and somewhat strangled lows, or very little highs and unfocused lows.
The part of the cone where the most movement takes place is the outer edge, or surround. This is the primary focus of speaker break-in, as this is where the most physical change will occur. It’s not a change you can readily see, but relates to microscopic breaks in the paper fibers. This occurs to a lesser extent in the spider, but the main emphasis is on the surround.
So how do you break in a speaker? Players and techs use many methods, though it all amounts to the same thing—getting the cone to move, which causes those creases and breaks to happen. This process necessarily takes time, our most precious commodity, which explains why some folks run recorded music through a speaker, while others use a Variac to send a 60-cycle hum into it. Some folks chemically “age” their cone with fabric softener (though that seems like cheating to me).
Personally, I don’t care for any of these methods. I like the good old-fashioned approach—simply playing guitar. It makes sense to feed a speaker the same frequencies it will receive in the future, and the variability in your playing won’t cause the same heat buildup as a Variac. The break-in period depends on the speaker and how it’s designed. To get a speaker mostly broken in, I recommend playing through it at a moderate volume for 12 to 20 hours—but it could even take 50. As the creases work into the cone, the unwanted fizz or strangled sound will diminish or disappear, and the speaker gets a little louder.
Sure, a speaker might not sound exactly like you want at first, but it will only get better and better the more you play it—just like those new shoes once you wear them for a while. Best of all, this “play it in” approach gives you a reason to practice—something I always encourage.
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What happens when a Deluxe Reverb meets an Electro-Voice EVM12L?
After seeing a recent video by Paul Rivera on the subject, I’ve become fascinated by the interesting relationship between the Electro-Voice EVM12L and the blackface Fender Deluxe Reverb amp. I’ve known Paul since filling the chief amp-tech position at Valley Arts Guitars that he vacated back in 1979, so I rang him up to find out more. Rivera helped establish Valley Arts as the go-to hub for pro players in Southern California, and it is here that my career in amp design began to take shape.
On the phone, Paul basically reiterated what he’d said in the video and, in typical Rivera fashion, he encouraged—make that challenged—me: “Go get a Deluxe and an EV and do some measurements.” That I did, and with the kind cooperation of jazz/funk king Paul Jackson Jr., for the speaker, and Joe Gamble, a frequent Fryette demo-video producer who provided an excellent early ’60s Deluxe, I was on my way.
Before we take the deep dive, let’s look at the context in which the Deluxe came into being. Intended as a student model, and hitting the market just prior to mass adoption of distortion as a sonic device, the Deluxe Reverb came with a low-powered 12" speaker fitted with a 20-ounce magnet. This cost-conscious production choice no doubt presumed that in those days one simply didn’t turn the volume past 3 or 4. However, as players began to explore the territory beyond 3, they also ran up against the consequences of doing so. Enter the speaker upgrade.
The iconic blackface Deluxe certainly has its own thing going, and although the current ’65 reissue comes stock with a 100-watt Jensen C12K, much of the original Deluxe mojo was defined by its strikingly underpowered speaker. Naturally, the minute you replace that with even a moderately more robust unit, the sonic signature that the stock, small-motor speaker is hiding comes roaring to the fore. I should note that for this experiment, I started by installing a custom, Fryette-spec Eminence P75 speaker. With its reasonable weight and typical power-handling capacity, this speaker turns the stock Deluxe into a much more versatile and giggable combo than before. It also provided a nice point of reference, being a well-known and fully documented entity, for this exercise. If you’re inclined to experiment, having a solid baseline is extremely important.
During the Valley Arts heyday of the ’70s and early ’80s, replacement speaker options were rather limited and mostly aimed at increasing clarity and reliability. The JBL D120 and Altec 417B were two of the most popular options of the era. The D120 was notable for its bold midrange and penetrating top end—a prominent feature of the Allman Brothers’ guitar sound, as fitted into a Marshall 4x12 cab. D120s had a distinctive—and to some ears, annoying—nasal chirp due in part to the signature aluminum dustcap. You may be surprised to know that those D-series speakers were alnico types, and for all their robust engineering, were fairly easy to blow in an open-back cab.
Rumor has it that the Allmans took the backs off their JBL-loaded 4x12 cabs in those days, not only because, as many believed, that made it easy to replace speakers, but because the D120s projected so much better than the stock Celestions that the band needed to dissipate some of that sound pressure out the back. This, by the way, also made for a much more ambient playing experience onstage. I should know. I once tried running a 100-watt amp into a 4x12 Greenback cab with its back off. While the reflected sound was a boon to my live gigging setup, I promptly blew 3 of the 4 speakers. Since these high-performance replacement options were out of my price range at the time, the originals got re-coned and I reinstalled the back on my 4x12 cab.
Also featuring alnico magnets and metal dustcaps, the 417B was made famous by Carlos Santana. Mick Taylor used 417Bs with the Stones in the early ’70s, and later Randy Rhoads used them with Ozzy. Both the D120 and 417B had strong personalities, and they were as sought after by some as they were shunned by others for being somewhat overbearing on top.
Electro-Voice was already in the game with their SRO series, but with the advent of the EVM12L, there at last was an alternative that was supremely reliable and sonically appealing to a wide variety of players. As such, the 12L became widely adopted as the dominant workhorse speaker—so much so that it soon found its way into just about every amp available at the time, including the very portable Deluxe Reverb, due in no small part to Rivera’s tenure at Valley Arts.
With its very large magnet, relatively low inductance, and aluminum-wound voice coil, along with the stiff cone, large dustcap, and compliant suspension, the EVM12L seemed to be just the right recipe to counter the flubby low end, scooped mids, and brittle top end one finds in the stock Deluxe with a typical speaker “upgrade.” That assessment still holds surprisingly true, though installing a 20-pound speaker in a 40-pound amp seems counterintuitive today. Contrary to what one might expect, the 12L brings out the pleasing sparkle and warmth of the Deluxe without sounding too piercing on top or too muddy on the low end.
After a fair bit of research and testing, and having spent considerable time delving into speaker inductance and reactive loads, I ran some of my observations by Eminence speaker designer Anthony Lucas. Here’s what he had to say:
“Inductance is certainly a part of what you’re hearing with the EVM12L in the blackface Deluxe, but not everything … maybe not even the most significant part. With its 20-ounce magnet and lightweight paper cone, the stock speaker is both coloring and limiting what the amp can do. It’s much more a part of the tone-creating process, like it or not, because this speaker has more limitations and likely a lot more peaks and dips in response. With its pro-audio cone, the EVM12L offers flatter response, minimal-to-no speaker breakup, and a much broader frequency-response range (down to 55 Hz). The 12L can handle the amp’s low-frequency range without getting muddy and breaking up, and it retains the amp’s clarity. You basically get out what you put in because with its 2.5" voice coil and 80-ounce magnet, the speaker is essentially overkill for the application and it delivers as full a range as physically possible.”
That last tidbit—“as full a range as physically possible”—offers a clue to the nicely tailored top-end response of the 12L-equipped Deluxe. In short, the substantial moving mass embodied in the 12L’s cone/voice coil/suspension assembly is certainly going to inhibit extended top-end response, and this is borne out in the speaker’s graph. You see an unusually smooth curve from 100 Hz to 2 kHz, a nice presence peak at 5 kHz, followed by a steep drop-off with little of the top-end nasties normally present in a guitar speaker.
The reason I find this combination so intriguing is that paired with an amp where much more attention is paid to the balance and synergy of the individual components and speaker, the EVM12L can be surprisingly disappointing. Yet in the Deluxe, the 6V6 power tubes driving an otherwise modest output transformer are allowed pretty much free rein to do their magic, while being massaged and refined by a speaker whose engineers probably never considered this a likely application for their considerable design effort.
In the ’70s and ’80s, when LA’s studio A-listers were schlepping their gear to several sessions a day, and probably a club gig at night, this versatile, high-performance little package—beefed up with a few of the must-have Rivera mods of the time—was considered practically indispensable, and helped launch the portable powerhouse-amp revolution.
So, should you consider installing such a massive appendage into an otherwise reasonably portable combo amp today? Only your chiropractor knows for sure, but if you can fairly well establish that any sonic roadblocks in your amp are likely caused by the stock speaker, it’s certainly a worthwhile and potentially enlightening experiment.
Discover which three elements of a guitar speaker have the biggest impact on tone.
When building a guitar speaker, one can make 101 micro-adjustments, whether it’s an extra turn of coil wire here or a thicker bead of glue there. However, these things are secondary to the three key elements that control most of a speaker’s tone, and it’s the speaker designer’s prime directive to get these three elements working together in harmony.
The membrane. Chief among these things is the sound-producing membrane—the cone. Guitar speaker cones are (still!) made from pulped and chemically treated paper pressed into the conical shape we’re all familiar with. After all these years, we still use paper because it provides the attributes we need: It’s lightweight, relatively (but not too) rigid, easy to shape, and cost-effective to produce.
Despite being made of humble materials, the cone is by no means a simple thing, and we can introduce variation into its production to control tonality. Thickness of the membrane is important. I’ve already touched on this in a previous column, but it bears highlighting again: A thinner cone deforms more easily under the pressure caused by coil movement. If you make the cone thicker, it becomes more resistant to those forces. However, these “deformations” are part of what contributes to the speaker’s tone. The skill of the speaker designer is to make a cone that’s thin enough to produce a musical tonality, while still being strong enough to withstand the application of a satisfyingly powerful kerrang.
The shape of the cone itself is also interesting. Way back in the days of radio, when a 1-watt amp was as powerful as you could get, straight-sided cones were used to tease as much output from the system as possible. The geometry of a straight-sided cone made it stiffer, so it could be constructed lighter, which enabled greater sensitivity and thus higher output.
It turns out that if you put enough signal into a speaker with a straight-sided cone, it eventually reaches a point where it suddenly and very quickly breaks up and resonates. Any audiophiles worth their salt would likely cover their ears in disgust, but that’s what we guitar players know as tone. And this explains why the modern guitar speaker evolved from the old-fashioned, straight-sided radiogram speaker.
Poles apart. When Celestion first started making moving-coil speakers for guitar amps in the late ’50s, we used an alnico magnet. This was the most commonly available technology at the time and what was used for all loudspeakers, regardless of application.
Forward to the 1960s and alnico became increasingly difficult to source, so guitar speakers were made instead with an iron-based ceramic magnet. While it was relatively simple to replicate the amount of magnetic force of an alnico magnet with the ceramic material, the two magnet types produced a noticeably different tone.
With its more aggressive, in-your-face sound, coupled with a high-end “graininess,” the ceramic magnet assembly was perfect for the music that rock ’n’ roll was evolving into during the ’60s. Compare this to alnico, which was relatively laid-back in its attack and delivered an overall smoother feel and a distinct chime at the top end.
After further experimentation, engineers and designers discovered just how much the size of the magnet affected tonality. By the end of the ’60s, Celestion offered their original ceramic guitar speaker in three different magnet sizes: the 50-ounce H (heavy), 35-ounce M (medium), and 20-ounce L (light). As magnet weight increases, so does the control of voice coil and cone movement. This has the effect of tightening the bass end and adding extra aggression in the vocal range.
In recent years, neodymium has become another magnet material used for guitar speakers. It’s very powerful for its size, and if properly controlled, neodymium can be used to provide a tonality that’s somewhere between that of ceramic and alnico, but with an additional level of note separation and fidelity that many consider desirable.
Wind me up. The voice coil is a length of copper wire wound around a “former.” It’s the moving part of the speaker’s motor whose configuration and performance is very much wrapped up in the amount of power a designer can make a speaker capable of withstanding. This, too, affects tone.
Consider the coil-former material: A paper former, as used in the 1950s, is less heat resistant than, say, fiberglass. The difference in material properties will impact the speaker’s tolerance of heat, which contributes to overall power rating (heat resistance directly correlates to power handling). And because various former materials sound different, this too contributes to the speaker’s tonal character.
Just as important is the diameter of the voice coil. A smaller coil flexes less than a larger one, but results in a larger cone length (the distance between cone neck to surround), meaning the cone is more likely to bend. A bigger coil will flex more, but the cone length is shorter, which means the cone is geometrically stiffer. A smaller coil will also have less mass and less inductance. All these physical attributes impact the sonic signature. Smaller coil speakers tend to feel brighter and break up more aggressively. Their fans consider them to be “sparkly,” whereas detractors would say they were “lightweight.”
More than anything, speaker tone is a direct result of a bunch of physical processes doing different things all at the same time. The better we can get these individual elements to work together in concert, the more desirable the resulting tone.
An aluminum dome looks pretty under stage lights, but it has an important job: protect the voice coil (left) and dissipate heat.
Does the humble dustcap affect your sound? Here’s what you need to know.
“Hey man, I really like your guitar box thing."
“Oh, my amp? It's a '72 Fender Twin Reverb. I put new tubes in it, re-capped it, and modded the circuit for more—"
“Yeah, yeah, yeah, but I just really like the way you can see the metal dome or whatever through the grille. That looks so cool."
“Oh yeah, those are the original JBL speakers that came with—"
“Well, see ya later."
I'm sure a similar conversation has occurred many times between thousands of guitarists and bar-goers. Between gear geeks and non-musicians. And probably between thousands of other people who may not realize that the “metal dome or whatever" has a significant effect on the tone of the speaker (self-professed gear geeks included).
As we've learned previously in Speaker Geeks, the cone is responsible for the lion's share of a speaker's tone. In the center of the cone is an opening where the voice coil is attached, and the voice coil sits inside a gap created by the speaker's front plate and magnet pole. It is vital that the voice coil doesn't rub against either part. It's also very important that no foreign particles can get inside and wreak havoc. Enter the dustcap, so named because it prevents dust from getting in this gap.
Call it a dustcap, dustcover, dome, or any other word that begins with D, the primary function is to keep dust and debris out of the inner workings of the speaker. But as early speaker designers quickly learned, the shape, size, and material of the dustcap play a huge role in a speaker's sound, specifically the high end.
It's important to note that most of the treble comes from the center of the speaker, beaming out from the top of the magnet pole. As the sound waves travel from the center and up the cone and radiate out, any ribs or ridges in the cone also send treble forward and into your ears. Some of the earliest designs, like the '50s Jensen P10R, used a piece of felt as the dustcap. Standing guard against those pesky particles, it got the job done, but it wasn't terribly sophisticated. This type of material absorbs a lot of the high end and results in a warmer sound without a whole lot of detail.
In the late '50s and into the '60s, speakers saw a lot of development and experimentation. Some speakers were built with hard fiber dustcaps like you might see on a vintage C12Q or C12N. This harder material deflects some treble, but allows the majority to pass through and provide plenty of detail.
Another type of dome is a large screen, which diffuses much of the high end and provides a warmer sound. Its dome shape spreads out the highs more evenly. The larger size also means a greater distance from the magnet pole, so the treble hits the material a little farther out, which also helps with the diffusion. Many harmonica players like this kind of dome, because highs cause feedback, and a screen dome helps reduce or eliminate that.
The other big dustcap is the aforementioned metal dome, which is typically made of aluminum because of its heat-dispersing attributes. When you play guitar, the amp's output signal travels to the speaker where it is converted to electromagnetic energy to make the voice coil move … and heat. The latter builds up in the voice coil gap, which is usually no problem when you have a speaker with a higher power rating than the amp puts out. However, with larger amps that put out more power, the heat resistance of the voice coil material alone may not be enough. Different techniques are used to combat that heat buildup, including venting the heat out the back through a screen, through holes in the voice coil, or sometimes through vents in the dustcap itself. Aluminum domes have sufficient heat-resistance properties to stave off heat without a vent—at least the amount of heat we're talking about.
So you'll typically see aluminum domes on amps with high output ratings, like the Fender Twin Reverb, at 85 to 100 watts, and the Roland Jazz Chorus at 120 watts. And those domes sure look cool—especially on a stage with lights reflecting off them. Dazzling. But as anyone who has ever played a speaker with an aluminum dome knows, the high end can be pretty crispy. The hard aluminum material extends the high frequency range, too. Where a typical guitar speaker falls off around 5 kHz, an aluminum-domed speaker can go as high as 7 kHz. This extended high end can sound very pleasing for certain music, such as some jazz and surf, where the tone is uncompromisingly clean. But when you start adding overdrive, watch out. It can very quickly sound like a swarm of bees.
Maybe you want that kind of tone. Who am I to judge? But now at least you know there's more to a metal dome than its pretty looks, so you can make an informed decision on your next speaker acquisition.