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!
Onstage, Tommy Emmanuel executes a move that is not from the playbook of his hero, Chet Atkins.
“My biggest decision every day on tour is, ‘What do I want to start with? How do I want to come out of the gate?’” Emmanuel explains to me over a video call. “A good opener has to have everything. It has to be full of surprise, it has to have lots of good ideas, lots of light and shade, and then, hit it again,” he says, illustrating each phrase with his hands and ending with a punch.“You lift off straightaway with the first song, you get airborne, you start reaching, and then it’s time to level out and take people on a journey.”
In May 2023, Emmanuel played two shows at the Sydney Opera House, the best performances from which have been combined on his new release, Live at the Sydney Opera House. The venue’s Concert Hall, which has a capacity of 2,679, is a familiar room for Emmanuel, but I think at this point in his career he wouldn’t bring a setlist if he was playing Wembley Stadium. On the recording, Emmanuel’s mind-blowingly dexterous chops, distinctive attack and flair, and knack for culturally resonant compositions are on full display. His opening song for the shows? An original, “Countrywide,” with a segue into Chet Atkins’ “El Vaquero.”
“When I was going to high school in the ’60s, I heard ‘El Vaquero’ on Chet Atkins’ record, [1964’s My Favorite Guitars],” Emmanuel shares. “And when I wrote ‘Countrywide’ in around ’76 or ’77, I suddenly realized, ‘Ah! It’s a bit like “El Vaquero!”’ So I then worked out ‘El Vaquero’ as a solo piece, because it wasn’t recorded like that [by Atkins originally].
“The co-writer of ‘El Vaquero’ is Wayne Moss, who’s a famous Nashville session guy who played ‘da da da’ [sings the guitar riff from Roy Orbison’s ‘Pretty Woman’]. And he played on a lot of Chet’s records as a rhythm guy. So once when I played ‘El Vaquero’ live, Wayne Moss came up to me and said, ‘You know, you did my part and Chet’s at the same time. That’s not fair!’” Emmanuel says, laughing.
Atkins is the reason Emmanuel got into performing. His mother had been teaching him rhythm guitar for a couple years when he heard Atkins on the radio and, at 6, was able to immediately mimic his fingerpicking technique. His father recognized Emmanuel’s prodigious talent and got him on the road that year, which kicked off his professional career. He says, “By the time I was 6, I was already sleep-deprived, working too hard, and being forced to be educated. Because all I was interested in was playing music.”
Emmanuel talks about Atkins as if the way he viewed him as a boy hasn’t changed. The title Atkins bestowed upon him, C.G.P. (Certified Guitar Player), appears on Emmanuel’s album covers, in his record label (C.G.P. Sounds), and is inlaid at the 12th fret on his Maton Custom Shop TE Personal signature acoustic. (Atkins named only five guitarists C.G.P.s. The others are John Knowles, Steve Wariner, Jerry Reed, and Atkins himself.) For Emmanuel, even today most roads lead to Atkins.
When I ask Emmanuel about his approach to arranging for solo acoustic guitar, he says, “It was really hit home for me by my hero, Chet Atkins, when I read an interview with him a long time ago and he said, ‘Make your arrangement interesting.’ And I thought, ‘Wow!’ Because I was so keen to be true to the composer and play the song as everyone knows it. But then again, I’m recreating it like everyone else has, and I might as well get in line with the rest of them and jump off the cliff into nowhere. So it struck me: ‘How can I make my arrangements interesting?’ Well, make them full of surprises.”
When Emmanuel was invited to contribute to 2015’s Burt Bacharach: This Guitar’s in Love with You, featuring acoustic-guitar tributes to Bacharach’s classic compositions by various artists, Emmanuel expresses that nobody wanted to take “(They Long to Be) Close to You,” due to its “syrupy” nature. But for Emmanuel, this presented an entertaining challenge.
He explains, “I thought, ‘Okay, how can I reboot “Close to You?’ So even the most jaded listener will say, ‘Holy fuck—I didn’t expect that! Wow, I really like that; that is a good melody!’ So I found a good key to play the song in, which allowed me to get some open notes that sustain while I move the chords. Then what I did is, in every phrase, I made the chord unresolve, then resolve.
Tommy Emmanuel's Gear
“I’m writing music for the film that’s in my head,” Emmanuel says. “So, I don’t think, ‘I’m just the guitar,’ ever.”
Photo by Simone Cecchetti
Guitars
- Three Maton Custom Shop TE Personals, each with an AP5 PRO pickup system
Amps
- Udo Roesner Da Capo 75
Effects
- AER Pocket Tools preamp
Strings & Picks
- Martin TE Signature Phosphor Bronze (.012–.054)
- Martin SP strings
- Ernie Ball Paradigm strings
- D’Andrea Pro Plec 1.5 mm
- Dunlop medium thumbpicks
“And then to really put the nail in the coffin, at the end, ‘Close to you’ [sings melody]. I finished on a major 9 chord which had that note in it, but it wasn’t the key the song was in, which is a typical Stevie Wonder trick. All the tricks I know, the wonderful ideas that I’ve stolen, are from Michael Jackson, Stevie Wonder, Lionel Richie, James Taylor, Carole King, Neil Diamond. All of the people who wrote really incredibly great pop songs and R&B music—I stole every idea I could, and I tried to make my little two-and-a -half minutes as interesting and entertaining as possible. Because entertainment equals: Surprise me.”
I share with Emmanuel that the performances on Live at the Sydney Opera House, which include his popular “Beatles Medley,” reminded me of another possible arrangement trick. In Harpo Marx’s autobiography, Harpo Speaks, I preface, Marx writes of a lesson he learned as a performer—to “answer the audience’s questions.” (Emmanuel says he’s a big fan of the book and read it in the early ’70s.) That happened for me while listening to the medley, when, after sampling melodies from “She’s a Woman” and “Please Please Me,” Emmanuel suddenly lands on “While My Guitar Gently Weeps.”
I say, “I’m waiting for something that hits more recognizably to me, and when ‘While My Guitar’ comes in, that’s like answering my question.”
“It’s also Paul and John, Paul and John, George,” Emmanuel replies. “You think, ‘That’s great, that’s great pop music,’ then, ‘Wow! Look at the depth of this.’”
Often Emmanuel’s flights on his acoustic guitar are seemingly superhuman—as well as supremely entertaining.
Photo by Ekaterina Gorbacheva
A trick I like to employ as a writer, I say to Emmanuel, is that when I’m describing something, I’ll provide the reader with just enough context so that they can complete the thought on their own.
“You can do that musically as well,” says Emmanuel. He explains how, in his arrangement of “What a Wonderful World,” he’ll play only the vocal melody. “When people are asking me at a workshop, ‘How come you don’t put chords behind that part?’ I say, ‘I’m drawing the melody and you’re putting in all the background in your head. I don’t need to tell you what the chords are. You already know what the chords are.’”
“Wayne Moss came up to me and said, ‘You know, you did my part and Chet’s at the same time. That’s not fair!’”
Another track featured on Live at the Sydney Opera House is a cover of Paul Simon’s “American Tune” (which Emmanuel then jumps into an adaptation of the Australian bush ballad, “Waltzing Matilda”). It’s been a while since I really spent time with There GoesRhymin’ Simon (on which “American Tune” was first released), and yet it sounded so familiar to me. A little digging revealed that its melody is based on the 17th-century Christian hymn, “O Sacred Head, Now Wounded,” which was arranged and repurposed by Bach in a few of the composer’s works. The cross-chronological and genre-lackadaisical intersections that come up in popular music sometimes is fascinating.
“I think the principle right there,” Emmanuel muses, “is people like Bach and Beethoven and Mozart found the right language to touch the heart of a human being through their ears and through their senses ... that really did something to them deep in their soul. They found a way with the right chords and the right notes, somehow. It could be as primitive as that.
Tommy Emmanuel has been on the road as a performing guitarist for 64 years. Eat your heart out, Bob Dylan.
Photo by Jan Anderson
“It’s like when you’re a young composer and someone tells you, ‘Have a listen to Elton John’s “Candle in the Wind,”’ he continues. “‘Listen to how those notes work with those chords.’ And every time you hear it, you go, ‘Why does it touch me like that? Why do I feel this way when I hear those chords—those notes against those chords?’ I say, it’s just human nature. Then you wanna go, ‘How can I do that!’” he concludes with a grin.
“You draw from such a variety of genres in your arrangements,” I posit. “Do you try to lean into the side of converting those songs to solo acoustic guitar, or the side of bridging the genre’s culture to that of your audience?”
“I stole every idea I could, and I tried to make my little two-and-a-half minutes as interesting and entertaining as possible. Because entertainment equals: Surprise me.”
“If I was a method actor,” Emmanuel explains, “what I’m doing is—I’m writing music for the film that’s in my head. So, I don’t think, ‘I’m just the guitar,’ ever. I always think it has to have that kind of orchestral, not grandeur, but … palette to it. Because of the influence of Stevie Wonder, Billy Joel, and Elton John, especially—the piano guys—I try to use piano ideas, like putting the third in the low bass a lot, because guitar players don’t necessarily do that. And I try to always do something that makes what I do different.
“I want to be different and recognizable,” he continues. “I remember when people talked about how some players—you just hear one note and you go, ‘Oh, that’s Chet Atkins.’ And it hit me like a train, the reason why a guy like Hank Marvin, the lead guitar player from the Shadows.... I can tell you: He had a tone that I hear in other players now. Everyone copied him—they just don’t know it—including Mark Knopfler, Eric Clapton, Jimmy Page, all those people. I got him up to play with me a few times when he moved to Australia, and even playing acoustic, he still had that sound. I don’t know how he did it, but it was him. He invented himself.”
YouTube It
Emmanuel performs his arrangement of “What a Wonderful World,” illustrating how omitting a harmonic backdrop can have a more powerful effect, especially when playing such a well-known melody.
