
Fig. 1
Our columnist breaks down the science behind the dB unit specific to digital systems, and divulges a perennial question about comparative amp loudness.
Hello, and welcome to another Dojo. Last month, I focused on the history and development of the VU meter, and then defined some of the more confusing terms regarding decibels (dB, dBu, dBA, and dBSPL), as well as various ways to measure loudness and amplitude. I also asked: “Is a 100-watt amp twice as loud as a 50-watt amp?”—the answer shall be revealed presently. But first, I’m going to focus on a relative newcomer to the scene: dBFS. Tighten up your belts, the Dojo is now open.
More dB Terms?
What is dBFS? It is relegated to the digital realm, and whenever you hear this term, I want you to remember the following joke: “What sounds better than digital distortion? Everything!”
You see, dBFS (decibels full scale), is the unit of measurement for amplitude within a digital system (such as your DAW), and all digital systems have a maximum peak level before clipping (overload) occurs. A reading of 0 dBFS is the highest signal level achievable for a digital audio. Unlike the analog world, where brief moments of being “in the red” of the VU meter won’t adversely affect the audio, dBFS digital “overs” are squared off (or, mercilessly guillotined), and clipping occurs. It sucks, and is to be avoided at all times. The audio irony is that, when or if you see those two teeny-tiny rectangles above your master fader turn red (Fig.1), you’ve got big problems, and need to turn everything down in order to avoid clipping when you bounce/render your mix.
Is a 100-watt amp twice as loud as a 50-watt amp?
I’m going to answer this by helping you learn some more about how we perceive loudness, and I’ll be using dBA as our mode of measurement. Because, as you’ll recall from last month, using dBFS treats all frequencies equally, and that’s not how the human ear works. In other words, our sensitivity to frequency, sound level, and duration vary across our general range of hearing (20 Hz to 20 kHz). Specifically, our hearing has evolved to be most sensitive between the approximate ranges of 2 kHz and 5 kHz.
Using this range as a yardstick, audiologists agree that 3 dB (up or down) is the minimal detectable change the average person can hear. In my experience, in a critical listening environment, I—and anyone else in the studio—can easily hear 1 dB changes—this especially happens when mixing and mastering.
“The audio irony is that, when or if you see those two teeny-tiny rectangles above your master fader turn red, you’ve got big problems.”
However, to increase the sound, 3 dB requires twice the power (intensity). An increase of 6 dB requires twice the amplitude (voltage), and an increase of 10 dB sounds to the human ear twice as loud. Stated another way: +3 dB is 2x the acoustic power, +6 dB is 4x the acoustic power, and +10 dB is 10x the acoustic power. For those who are mathematically inclined (I am not), here is the decibel formula: dB = 10log10 (S1/S2), where S1 and S2 are the intensity of the two sounds.
Remember when I said last month that decibels are based on a ratio, and they are logarithmic? Now we want to look at the relationship of decibels and power. What is the international unit of measurement for power? It’s the watt (W), named after Scottish inventor James Watt (1736–1819). Check out these relationships:
Number of Decibels | Relative Increase of Power |
0 dB | 1x |
3 dB | 2x |
10 dB | 10x |
20 dB | 100x |
30 dB | 1,000x |
50 dB | 100,000x |
100 dB | 10,000,000,000x |
So, let’s say we have a lovely vintage 4x12 cabinet, and we have two amps that we are going to run through it—a 50-watt head and a 100-watt head (both with matching impedance). Using this relationship, we can answer our previous question! Our 50-watt head is the starting point and baseline for measurement.
Let’s say that, as we play our latest epic jam through our dimed 50-watt head, our drummer comes over and says, “It’s not loud enough! They can’t hear it in the parking lot of the Waffle House across from the stadium!” So, we switch to the 100-watt head thinking it will be twice as loud. Wrong! Go back and look at the chart above. We’ve doubled the power (2x) and that only gained us a paltry increase of 3 dB! That’s right, a 100-watt amp is only 3 dB louder than a 50-watt amp. So, what would be twice as loud? Do the math—we’d need a 10x increase in watts (50 W × 10), so a 500-watt amplifier (or 10 dimed 50-watt amps, simultaneously) would be needed! (Yes, but do they go to 11?)
Until next time, namaste.
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An ode, and historical snapshot, to the tone-bar played, many-stringed thing in the room, and its place in the national musical firmament.
Blues, jazz, rock, country, bluegrass, rap.… When it comes to inventing musical genres, the U.S. totally nailed it. But how about inventing instruments?
Googling “American musical instruments” yields three.
• Banjo, which is erroneously listed since Africa is its continent of origin.
• Benjamin Franklin’s Glass Armonica, which was 37 glass bowls mounted horizontally on an iron spindle that was turned by means of a foot pedal. Sound was produced by touching the rims of the bowls with water-moistened fingers. The instrument’s popularity did not last due to the inability to amplify the volume combined with rumors that using the instrument caused both musicians and their listeners to go mad.
• Calliope, which was patented in 1855 by Joshua Stoddard. Often the size of a truck, it produces sound by sending steam through large locomotive-style whistles. Calliopes have no volume or tone control and can be heard for miles.
But Google left out the pedal steel. While there may not be a historical consensus, I was talking to fellow pedal-steel player Dave Maniscalco, and we share the theory that pedal steel is the most American instrument.
Think about it. The United States started as a DIY, let’s-try-anything country. Our culture encourages the endless pursuit of improvement on what’s come before. Curious, whimsical, impractical, explorative—that’s our DNA. And just as our music is always evolving, so are our instruments. Guitar was not invented in the U.S., but one could argue it’s being perfected here, as players from Les Paul to Van Halen kept tweaking the earlier designs, helping this one-time parlor instrument evolve into the awesome rock machine it is today.
Pedal steel evolved from lap steel, which began in Hawaii when a teenage Joseph Kekuku was walking down a road with his guitar in hand and bent over to pick up a railroad spike. When the spike inadvertently brushed the guitar’s neck and his instrument sang, Kekuku knew he had something. He worked out a tuning and technique, and then took his act to the mainland, where it exploded in popularity. Since the 1930s, artists as diverse as Jimmie Rodgers and Louis Armstrong and Pink Floyd have been using steel on their records.“The pedal steel guitar was born out of the curiosity and persistence of problem solvers, on the bandstand and on the workbench.”
Immigrants drove new innovations and opportunities for the steel guitar by amplifying the instrument to help it compete for listeners’ ears as part of louder ensembles. Swiss-American Adolph Rickenbacker, along with George Beauchamp, developed the first electric guitar—the Rickenbacker Electro A-22 lap steel, nicknamed the Frying Pan—and a pair of Slovak-American brothers, John and Rudy Dopyera, added aluminum cones in the body of a more traditional acoustic guitar design and created resophonic axes. The pedal steel guitar was born out of the curiosity and persistence of problem solvers, on the bandstand and on the workbench.
As the 20th century progressed and popular music reflected the more advanced harmonies of big-band jazz, the steel guitar’s tuning evolved from open A to a myriad of others, including E7, C6, and B11. Steel guitarists began playing double-, triple-, and even quadruple-necked guitars so they could incorporate different tunings.
In Indianapolis, the Harlan Brothers came up with an elegant solution to multiple tunings when they developed their Multi-Kord steel guitar, which used pedals to change the tuning of the instrument’s open strings to create chords that were previously not possible, earning a U.S. patent on August 21, 1947. In California, equipped with knowledge from building motorcycles, Paul Bigsby revolutionized the instrument with his Bigsby steel guitars. It was on one of these guitars that, in early 1954, Bud Isaacs sustained a chord and then pushed a pedal down to bend his strings up in pitch for the intro of Webb Pierce’s “Slowly.” This I–IV movement became synonymous with the pedal-steel guitar and provided a template for the role of the pedal steel in country music. Across town, church musicians in the congregation of the House of God Keith Dominion were already using the pedal steel guitar in Pentecostal services that transcended the homogeneity of Nashville’s country and Western clichés.
Pedal steels are most commonly tuned in an E9 (low to high: B–D–E–F#–G#–B–E–G#–D#–F#), which can be disorienting, with its own idiosyncratic logic containing both a b7 and major 7. It’s difficult to learn compared to other string instruments tuned to regular intervals, such as fourths and fifths, or an open chord.
Dave Maniscalco puts it like this: “The more time one sits behind it and assimilates its quirks and peculiarities, the more obvious it becomes that much like the country that birthed it, the pedal steel is better because of its contradictions. An amalgamation of wood and metal, doubling as both a musical instrument and mechanical device, the pedal steel is often complicated, confusing, and messy. Despite these contradictions, the pedal-steel guitar is a far more interesting and affecting because of its disparate influences and its complex journey to becoming America’s quintessential musical instrument.”The author dials in one of his 20-watt Sonzera amps, with an extension cabinet.
Knowing how guitar amplifiers were developed and have evolved is important to understanding why they sound the way they do when you’re plugged in.
Let’s talk about guitar amp history. I think it’s important for guitar players to have a general overview of amplifiers, so the sound makes more sense when they plug in. As far as I can figure out, guitar amps originally came from radios—although I’ve never had the opportunity to interview the inventors of the original amps. Early tube amps looked like radio boxes, and once there was an AM signal, it needed to be amplified through a speaker so you could hear it. I’m reasonably certain that other people know more about this than I do.
For me, the story of guitar amps picks up with early Fenders and Marshalls. If you look at the schematics, amplifier input, and tone control layout of an early tweed Fender Bassman, it’s clear that’s where the original Marshall JTM45 amps came from. Also, I’ve heard secondhand that the early Marshall cabinets were 8x12s, and the roadies requested that Marshall cut them in half so they became 4x12s. Similarly, 8x10 SVT cabinets were cut in half to make the now-industry-standard 4x10 bass cabinets. Our amp designer Doug Sewell and I understand that, for the early Fender amps we love, the design directed the guitar signal into half a tube, into a tone stack, into another half a tube, and the reverb would join it with another half a tube, and then there would be a phase splitter and output tubes and a transformer. (All 12AX7 tubes are really two tubes in one, so when I say a half-tube, I’m saying we’re using only the first half.) The tone stack and layout of these amps is an industry standard and have a beautiful, clean way of removing low midrange to clear up the sound of the guitar. I believe all but the first Marshalls came from a high-powered tweed Twin preamp (which was a 80-watt combo amp) and a Bassman power amp. The schematic was a little different. It was one half-tube into a full-tube cathode follower, into a more midrange-y tone stack, into the phase splitter and power tubes and output transformer. Both of these circuits have different kinds of sounds. What’s interesting is Marshall kept modifying their amps for less bass, more high midrange and treble, and more gain. In addition, master volume controls started being added by Fender and Marshall around 1976. The goal was to give more gain at less volume. Understanding these circuits has been a lifelong event for Doug and me.
Then, another designer came along by the name of Alexander Dumble. He modified the tone stack in Fender amps so you could get more bass and a different kind of midrange. Then, after the preamp, he put in a distortion circuit in a switchable in and out “loop.” In this arrangement, the distortion was like putting a distortion pedal in a loop after the tone controls. In a Fender amp, most of the distortion comes from the output section, so turning the tone controls changes the sound of the guitar, not the distortion. In a Marshall, the distortion comes before the tone controls, so when you turn the tone controls, the distortion changes. The way these amps compress and add harmonics as you turn up the gain is the game. All of these designs have real merit and are the basis of our modern tube–and then modeling—amplifiers.
Everything in these amps makes a difference. The circuits, the capacitor values and types, the resistor values and types, the power and output transformers, and the power supplies—including all those capacitor values and capacitor manufacturers.
I give you this truncated, general history to let you know that the amp business is just as complicated as the guitar business. I didn’t even mention the speakers or speaker cabinets and the artform behind those. But what’s most important is: When you plug into the amp, do you like it? And how much do you like it? Most guitar players have not played through a real Dumble or even a real blackface Deluxe Reverb or a 1966 Marshall plexi head. In a way, you’re trusting the amp designers to understand all the highly complex variations from this history, and then make a product that you love playing through. It’s daunting, but I love it. There is a complicated, deep, and rich history that has influenced and shaped how amps are made today.
Lenny Kravitz’s lead-guitar maestro shares how his scorching hit solo came together.
Hold onto your hats—Shred With Shifty is back! This time, Chris Shiflett sits down with fellow west coaster Craig Ross, who calls in from Madrid equipped with a lawsuit-era Ibanez 2393. The two buddies kick things off commiserating over an increasingly common tragedy for guitarists: losing precious gear in natural disasters. The takeaway? Don’t leave your gear in storage! Take it on the road!
Ross started out in the Los Angeles band Broken Homes, influenced by Chuck Berry, Buddy Holly, and the Beatles, but his big break came when he auditioned for Lenny Kravitz. Kravitz phoned him up the next day to tell him to be at rehearsal that evening. In 1993, they cut one of their biggest hits ever, “Are You Gonna Go My Way?” Ross explains that it came together from a loose, improvisatory jam in the studio—testament to the magic that can be found off-leash during studio time.
Ross recalls his rig for recording the solo, which consisted of just two items: Kravitz’s goldtop Les Paul and a tiny Gibson combo. (No fuzz or drive pedals, sorry Chris.) As Ross remembers, he was going for a Cream-era Clapton sound with the solo, which jumps between pentatonic and pentatonic major scales.
Tune in to learn how he frets and plays the song’s blistering lead bits, plus learn about what amps Ross is leaning on these days.
If you’re able to help, here are some charities aimed at assisting musicians affected by the fires in L.A:
https://guitarcenterfoundation.org
https://www.cciarts.org/relief.html
https://www.musiciansfoundation.org
https://fireaidla.org
https://www.musicares.org
https://www.sweetrelief.org
Credits
Producer: Jason Shadrick
Executive Producers: Brady Sadler and Jake Brennan for Double Elvis
Engineering Support by Matt Tahaney and Matt Beaudion
Video Editor: Addison Sauvan
Graphic Design: Megan Pralle
Special thanks to Chris Peterson, Greg Nacron, and the entire Volume.com crew.
Tobias bass guitars, beloved by bass players for nearly half a century, are back with the all-new Tobias Original Collection.
Built for unrivaled articulation, low-end punch, and exceptional ergonomics, the all-new Tobias Original Collection comprises an array of six four and five-string bass models all offered in both right and left-handed orientations. The Tobias range features Classic, Killer B, and Growler models, and each is equipped with high-quality hardware from Babicz and Gotoh, active electronics from Bartolini, and the iconic Tobias asymmetrical neck design. Crafted from the finest tonewoods, Tobias Original Collection bass guitars are now available worldwide on Gibson.com, at the Gibson Garage locations, and at authorized Gibson dealers.
The bass world has been clamoring for the return of the authentic, high-end Tobias basses, and now, Tobias has returned. Combining the look and tone of the finest exotic tonewoods, such as quilted maple, royal paulownia, purpleheart, sapele, walnut, ebony, and wenge, with the feel of the famous Tobias Asym asymmetrical neck and the eye-catching shapes of the perfectly balanced contoured bodies, Tobias basses are attractive in look and exceptional in playing feel. However, their sonic versatility is what makes them so well suited to the needs of modern bassists. The superior tone from the exotic hardwoods, premium hardware, and active Bartolini® pickups and preamps results in basses with the tonal flexibility that today’s players require. Don’t settle for less than a bass that delivers everything you want and need –the look, the feel, and the sound, Tobias.
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“It’s amazing to see this icon of the bass world return,” adds Andrew Ladner, Brand Manager for Epiphone and Kramer. “These models are truly a bass player’s bass, and true to the DNA that makes Tobias world-class—the ace up the sleeve of bass players around the globe since 1978. Today’s players can find that unique voice and feel that only Tobias can offer.”
For more information, please visit gibson.com.