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.
Weber Speakers guru C.J. Sutton demystifies magnet lore in the second installment of our new column series.
I’m going to tell you something you already know: People like different things. Shocker, right? Apples or oranges, cake or pie, Strat or Les Paul … the list goes on. And it seems the more polar opposite things are, the more likely a person may gravitate toward one choice and show disdain for the other. Like the English and Scottish in Braveheart, guitarists can end up on opposing sides ready to do battle over such life-or-death issues as whether to use tube or solid-state amps. That said, I urge us all to agree on one thing: Amplifiers don’t make sound without speakers. Even the simplest amplifier can be an extremely complex piece of electronics, but a speaker is a very basic electromagnetic motor (Fig. 1).
When you apply signal to a speaker, the voice coil begins to move in and out in response to that signal. As a result, the voice coil creates a magnetic field of its own, which works against the magnet and tries to demagnetize it. However, the magnet generates energy in the opposite direction, and it becomes a back-and-forth struggle. Gluing a cone to a moving voice coil harnesses this motion and makes it audible. That’s the basic idea behind a speaker.
A voice coil is like an electric motor. The bigger the voice coil and the more wire used, the more torque or pulling power you have to move the cone. With the proper match of components, you can get more sensitivity, wider frequency response, and more power-handling ability. The size and type of magnet also affects a speaker’s sound. There are two major types of magnets used in loudspeakers: alnico and ceramic. These magnet types differ and this difference affects a speaker’s overall tone. Let’s take a closer look.
The first crop of speakers in the early 1950s used alnico magnets, which is why some people say they sound more “vintage” than speakers built with ceramic magnets. An alloy comprising aluminum, nickel, and cobalt, alnico demagnetizes relatively easily, which gives a smooth response with compression at higher average volumes.
As the voice coil’s effect lowers the available magnetic field of the alnico magnet, the speaker becomes less efficient, and the voice coil moves less. The physics of it is that the small magnets near the surface of the magnet poles (called “domains”) begin to change state, or flip directions. The result is smooth compression, which is the same kind of operating-curve compression that occurs in a tube amplifier.
During the 1960s, the popularity of speakers with ceramic magnets increased. The most common type of ceramic magnet is strontium ferrite, which demagnetizes much less easily than alnico. The domains change state much faster, so there is little to no compression as the voice coil moves to its mechanical limit. Because the ceramic magnet isn’t introducing compression, the result is a cleaner sound in comparison to alnico.
Some folks might liken the difference between alnico and ceramic speakers to the difference between tube and solid-state amplifiers, where one compresses smoothly and the other gives all it has and then clips hard. I don’t know that it’s a fair comparison because the differences between the speaker types aren’t as starkly contrasted as the differences between the two amp types. Furthermore, by varying the size of the magnet, it’s possible to build very efficient alnico speakers, as well as very inefficient ceramic speakers.
Now that you know the reasons why the two magnet types do what they do, you can decide which side of the battlefield you want to be on. Or you can decide that it doesn’t have to come to war at all. That maybe it’s best to have each type of speaker, so you can be ready for whatever tone might be necessary at any given time. Some players even mix alnico and ceramic speakers in the same cabinet. Though different in the way they operate, their purpose is the same: to supply energy to the motor, so the cone will move and thus everyone will hear whether you’ve been practicing or not.
In this new column debut, amp guru Steven Fryette discusses how to make sense of the speaker data manufacturers spend so much time and money on.
Guitar speakers are like car tires. They all function basically the same way, but small differences in materials and design can produce noticeably large differences in performance. Given the wide range of currently available speaker choices and consumers’ insatiable appetite for information, most speaker manufacturers offer graphical models of their products to help us navigate the options. So what do these graphs tell us and how useful are they in helping plan our next speaker purchase? To answer these questions, let’s look at how those graphs are created and what they really say.
Here’s how my good friend, Eminence’s Anthony Lucas, explains the graphing process: “To plot speaker response, the speaker is mounted on a baffle that is open on the back and facing an anechoic chamber in front. This ‘infinite baffle’ configuration ensures minimum environmental coloration of the speaker under test. The speaker is driven by a solid-state power amp fed by a frequency sweep generator with a microphone placed one meter away from the center of the cone. The microphone is specially designed for this test and is connected to a software-based measurement system. To eliminate distortion artifacts from the test results, the solid-state power amp is chosen for extremely low distortion and high linearity. The speaker is driven at 1 watt to minimize external reflections and mechanical distortion. A final step in this process involves a ‘correction file.’ This is a compensation filter that prevents any remaining room artifacts, known as room signature, from impacting the results.”
This test simply measures frequency response (and sometimes a speaker’s corresponding impedance curve, a subject we’ll explore later) in an idealized environment, so the test power amp is important. When comparing two different manufacturers’ speaker graphs, we assume that different speakers are tested under similar conditions to assure a realistic comparison. Makes sense, right? Sure, as long as all manufacturers use the same procedure. Which begs the question: Do they? Theoretically yes, assuming they use similar equipment and test environments. In reality, there are procedural and technical variations from manufacturer to manufacturer. Absent a rock-solid baseline, that makes the comparison somewhat subjective. This sounds discouraging until you consider that what happens to a guitar speaker in a tube amplifier makes much of this testing precision seem rather moot.
A solid-state power amp is going to depart in performance from a tube power amp in a couple of important ways that turn out to be crucial in choosing a speaker for a particular tube amplifier. First, as explained above, a solid-state amp is relatively distortion free, and secondly, its low effective output impedance reduces its interaction with the behavior of the speaker.
Most players assume that power tubes have a unique “sound” that’s largely responsible for the sound of their amplifier. This is one of two common myths about tube amps. If that were true, how then do you explain all the “linear” hi-fi tube amps of the ’50s and ’60s? The simple fact is, tubes are generally neutral regardless of type, with the most obvious differences in behavior being attributable to their operating environment—meaning the circuit design, operating voltages, and transformer designs associated with them.
Eminence’s Anthony Lucas generating a SPL (sound pressure level) versus frequency graph. Image courtesy of Eminence
The second myth is that tube amp sound is due to special added distortion. The fact is that any amplifier can be induced to add distortion of one kind or another. The question is, what kind and how much? I’ll cover this in more detail in an upcoming column, but here’s what we need to know right now: How you operate a power amp determines how much distortion it produces, and in this respect distortion can be set aside for the purposes of our discussion.
When discussing speaker behavior, the most important difference between solid-state and tube power amps is source (output) impedance. Our solid-state amp, having a very low effective output impedance, will force a speaker to behave in a more linear fashion. Conversely, a tube power amp exhibits a much higher output impedance, and this allows the speaker to influence the behavior of the power amp. In other words, the solid-state power amp will restrain speaker behavior, producing a flatter graphical profile, while a tube power amp and speaker form a system in which each is an integral part of the sonic result we all know and love.
In addition, the special reactive relationship between the speaker and tube power amp is influenced by the size, shape, and resonance of the speaker cabinet itself. At this point it should be apparent that the test environment described above seeks to eliminate that resonant reactive behavior. So now is a good time to ask: How helpful is a graph of speaker performance stripped entirely of its normal operating environment in making an informed speaker choice? The answer: It depends.
This graph shows the frequency response of Eminence’s EJ-1240, the company’s 40-watt Eric Johnson signature alnico 12". The red line represents frequency response and the tan line indicates the speaker’s corresponding impedance curve. Image courtesy of Eminence
It may surprise you to learn that many amplifier manufacturers don’t put a lot of initial stock in these graphs when deciding which speaker to use for a given amp design. While they’re very useful in making a final decision between two candidates with very similar signatures, the real work takes place long before we ever get to the nitpicking graph comparison stage. That means we, the amp manufacturers, have made the most critical decisions about sound, application, and overall performance much earlier than that. Once we get close to final production design, we may pay a little more attention to the graphs to fine-tune the amp/speaker/cab relationship in ways that the player would be wise to think about before replacing the stock speaker with another unit.
What a speaker graph shows is that most guitar speakers perform similarly on paper, and all bets are off when you install them in your amplifier. With that in mind, the first step in making a speaker purchase should be to establish your desired outcome. Then look at the manufacturer’s recommendations about the models you feel line up with your goals and fit your budget. Forums can be a valuable resource, but try to avoid getting into the weeds when soliciting opinions online by carefully vetting responses that address your specific application.
After you’ve narrowed your search, it’s time to have a look at those graphs. Pay particular attention to the more prominent peaks they reveal. Those are the areas that are most subject to operational variables like output impedance and cabinet resonance. The higher the impedance, the greater the impact those peaks will have on your amplifier’s performance and, consequently, the more they will drive cab resonance. And since internal feedback (more on this in a future column), as found in most power amp designs, plays a role in output impedance. A power amp designed with low or no feedback—such as in AC30-style amps—will exhibit higher effective output impedance and further exaggerate those curvalicious peaks!