Your tone control can be a potent sound-sculpting tool, but to be effective, its simple components must be chosen carefully. Photo courtesy of singlecoil.com
Do you always leave your tone pot wide open? Here’s how to squeeze more utility from this oft-neglected knob.
I often hear guitarists say they leave their tone control on 10 all the time—or even disconnect it—because they find it useless. A small turn from wide open takes the tone from “lively" to “clinically dead," and that's all you get. Why is this a common problem with passive guitars? Typically, it's because of two reasons: 1) The tone pot has an ineffective taper and/or resistance, and 2) the tone cap has too much capacitance. Both issues are easy to fix, so let's explore the remedies.
In a passive guitar, the typical tone control is a capacitor connected to a potentiometer—that's it. Because the system is so simple, both components must be chosen carefully to make it work well. Players often complain that the tone pot functions as an “on-off" knob, rather than a control that provides a gradual and even effect over its entire rotation. Fortunately, we can deal with this.
The tone pot. Because of how our ears work, the tone pot inside a passive guitar must be an audio (aka logarithmic) type, not a linear type. (This also applies to a volume pot in a passive system.) The “on-off" problem is typical of audio pots with a ratio of 90:10, which is more or less the standard today. Human hearing simply doesn't work like this and needs a different ratio, preferably 60:40, or at least 65:35, which was the standard in the '50s and '60s. [Editor's note: These ratios indicate the percentage of total resistance measured at the middle of the shaft rotation, i.e., at 5 on a typical knob.]
Using a linear pot as a tone control creates a different problem: There's no apparent change in tone over almost the whole rotation until the “on-off" effect suddenly appears at the very end—exactly the opposite of an audio pot with an ineffective taper.
Besides the pot's type and taper, its resistance can make things worse in a passive system. A simplified rule of thumb: The higher a pot's resistance, the less effective it will be as a volume or tone control. This means 250k and 500k pots work well in these applications, while a 1M pot is pretty useless.
So what's the perfect tone pot for a passive guitar? It's a 250k or 500k audio type with a 60:40 or 65:35 taper. I use a 250k audio type with a 60:40 taper along with a no-load mod, which makes the pot disappear from the circuit when it's fully opened. This recipe preserves a good portion of the high end. Compared to a 500k pot, a 250k pot offers a bit more controllability, but it adds more load to the circuit—that's the nature of the passive beast. The no-load mod compensates for this problem.
The tone cap. The second element in the tone control system is dominated by two factors: type (construction) and capacitance. The type—ceramic, polyester, paper-in-oil, etc.—dictates the overall tone, while the capacitance determines how dark the tone will get when closing the tone pot. Some people claim that when wired into a guitar, all cap types sound the same, but if you experiment with this, I'm pretty sure you'll reach a different conclusion. In previous Mod Garage columns, I've discussed various types of tone caps and how they perform, so we don't need to rehash this here.
Capacitance is often described as “value," and the typical range for guitars is from 0.022 µF up to 0.1 µF. Over the years, cap values have steadily decreased from the original 0.1 µF that Leo Fender chose, so “a guitarist can also play bass lines," to 0.05 µF, which was the standard in the late '60s and '70s, to 0.022 µF, which is the quasi-standard for single-coil pickups today.
But let's face it: Even in the '50s, guitarists never wanted to play bass lines on their Telecasters, and even 0.022 µF is overkill for most players. In other words, 0.022 µF makes the tone incredibly dark and lifeless when the tone pot is closed, which is exactly why so many guitarists don't use their tone control at all. So it's time to fix that! The easy and effective solution is to replace the tone cap with one that has way less capacitance. This will morph the pot into a “warmth control." Capacitors in the picofarad range (pF) are perfect for this, and a useful range to experiment with is from 1000 pF up to 6800 pF.
And that's where we'll pick things up next time. I'll discuss some of the most popular values and what you can expect sonically from them. Until then, keep on modding!
Day 6 of Stompboxtober is here! Today’s prize? A pedal from Revv Amplification! Enter now and check back tomorrow for the next one!
Revv G3 Purple Channel Preamp/Overdrive/Distortion Pedal - Anniversary Edition
The Revv G3 revolutionized high gain pedals in 2018 with its tube-like response & tight, clear high gain tones. Suddenly the same boutique tones used by metal artists & producers worldwide were available to anyone in a compact pedal. Now the G3 returns with a new V2 circuit revision that raises the bar again.
Beauty and sweet sonority elevate a simple-to-use, streamlined acoustic and vocal amplifier.
An EQ curve that trades accuracy for warmth. Easy-to-learn, simple-to-use controls. It’s pretty!
Still exhibits some classic acoustic-amplification problems, like brash, unforgiving midrange if you’re not careful.
$1,199
Taylor Circa 74
taylorguitars.com
Save for a few notable (usually expensive) exceptions, acoustic amplifiers are rarely beautiful in a way that matches the intrinsic loveliness of an acoustic flattop. I’ve certainly seen companies try—usually by using brown-colored vinyl to convey … earthiness? Don’t get me wrong, a lot of these amps sound great and even look okay. But the bar for aesthetics, in my admittedly snotty opinion, remains rather low. So, my hat’s off to Taylor for clearing that bar so decisively and with such style. The Circa 74 is, indeed, a pretty piece of work that’s forgiving to work with, ease to use, streamlined, and sharp.
Boxing Beyond Utility
Any discussion of trees or wood with Bob Taylor is a gas, and highly instructive. He loves the stuff and has dabbled before in amplifier designs that made wood an integral feature, rather than just trim. But the Circa 74 is more than just an aesthetic exercise. Because the Taylor gang started to think in a relatively unorthodox way about acoustic sound amplification—eschewing the notion that flat frequency response is the only path to attractive acoustic tone.
I completely get this. I kind of hate flat-response speakers. I hate nice monitors. We used to have a joke at a studio I frequented about a pair of monitors that often made us feel angry and agitated. Except that they really did. Flat sound can be flat-out exhausting and lame. What brings me happiness is listening to Lee “Scratch” Perry—loud—on a lazy Sunday on my secondhand ’70s Klipsch speakers. One kind of listening is like staring at a sun-dappled summer garden gone to riot with flowers. The other sometimes feels like a stale cheese sandwich delivered by robot.
The idea that live acoustic music—and all its best, earthy nuances—can be successfully communicated via a system that imparts its own color is naturally at odds with acoustic culture’s ethos of organic-ness, authenticity, and directness. But where does purity end and begin in an amplified acoustic signal? An undersaddle pickup isn’t made of wood. A PA with flat-response speakers didn’t grow in a forest. So why not build an amp with color—the kind of color that makes listening to music a pleasure and not a chore?
To some extent, that question became the design brief that drove the evolution of the Circa 74. Not coincidentally, the Circa 74 feels as effortless to use as a familiar old hi-fi. It has none of the little buttons for phase correction that make me anxious every time I see one. There’s two channels: one with an XLR/1/4" combo input, which serves as the vocal channel if you are a singer; another with a 1/4" input for your instrument. Each channel consists of just five controls—level, bass, middle, and treble EQ, and a reverb. An 11th chickenhead knob just beneath the jewel lamp governs the master output. That’s it, if you don’t include the Bluetooth pairing button and 1/8" jacks for auxiliary sound sources and headphones. Power, by the way, is rated at 150 watts. That pours forth through a 10" speaker.Pretty in Practice
I don’t want to get carried away with the experiential and aesthetic aspects of the Circa 74. It’s an amplifier with a job to do, after all. But I had fun setting it up—finding a visually harmonious place among a few old black-panel Fender amps and tweed cabinets, where it looked very much at home, and in many respects equally timeless.
Plugging in a vocal mic and getting a balance with my guitar happened in what felt like 60 seconds. Better still, the sound that came from the Circa 74, including an exceedingly croaky, flu-addled human voice, sounded natural and un-abrasive. The Circa 74 isn’t beyond needing an assist. Getting the most accurate picture of a J-45 with a dual-source pickup meant using both the treble and midrange in the lower third of their range. Anything brighter sounded brash. A darker, all-mahogany 00, however, preferred a scooped EQ profile with the treble well into the middle of its range. You still have to do the work of overcoming classic amplification problems like extra-present high mids and boxiness. But the fixes come fast, easily, and intuitively. The sound may not suggest listening to an audiophile copy of Abbey Road, as some discussions of the amp would lead you to expect. But there is a cohesiveness, particularly in the low midrange, that does give it the feel of something mixed, even produced, but still quite organic.
The Verdict
Taylor got one thing right: The aesthetic appeal of the Circa 74 has a way of compelling you to play and sing. Well, actually, they got a bunch of things right. The EQ is responsive and makes it easy to achieve a warm representation of your acoustic, no matter what its tone signature. It’s also genuinely attractive. It’s not perfectly accurate. Instead, it’s rich in low-mid resonance and responsive to treble-frequency tweaks—lending a glow not a million miles away from a soothing home stereo. I think that approach to acoustic amplification is as valid as the quest for transparency. I’m excited to see how that thinking evolves, and how Taylor responds to their discoveries.
The evolution of Electro-Harmonix’s very first effect yields a powerful boost and equalization machine at a rock-bottom price.
A handy and versatile preamp/booster that goes well beyond the average basic booster’s range. Powerful EQ section.
Can sound a little harsh at more extreme EQ ranges.
$129
Electro-Harmonix LPB-3
ehx.com
Descended from the first Electro-Harmonix pedal ever released, the LPB-1 Linear Power Booster, the new LPB-3 has come a long way from the simple, one-knob unit in a folded-metal enclosure that plugged straight into your amplifier. Now living in Electro-Harmonix’s compact Nano chassis, the LPB-3 Linear Power Booster and EQ boasts six control knobs, two switches, and more gain than ever before.
If 3 Were 6
With six times the controls found on the 1 and 2 versions (if you discount the original’s on/off slider switch,) the LPB-3’s control complement offers pre-gain, boost, mid freq, bass, treble, and mid knobs, with a center detent on the latter three so you can find the midpoint easily. A mini-toggle labeled “max” selects between 20 dB and 33 dB of maximum gain, and another labeled “Q” flips the resonance of the mid EQ between high and low. Obviously, this represents a significant expansion of the LPB’s capabilities.
More than just a booster with a passive tone, the LPB-3 boasts a genuine active EQ stage plus parametric midrange section, comprising the two knobs with shaded legends, mid freq and mid level. The gain stages have also been reimagined to include a pre-gain stage before the EQ, which enables up to 20 dB of input gain. The boost stage that follows the EQ is essentially a level control with gain to allow for up to 33 dB of gain through the LPB-3 when the “max” mini toggle is set to 33dB
A slider switch accessible inside the pedal selects between buffered or true bypass for the hard-latch footswitch. An AC adapter is included, which supplies 200mA of DC at 9.6 volts to the center-negative power input, and EHX specifies that nothing supplying less than 120mA or more than 12 volts should be used. There’s no space for an internal battery.
Power-Boosted
The LPB-3 reveals boatloads of range that betters many linear boosts on the market. There’s lots of tone-shaping power here. Uncolored boost is available when you want it, and the preamp gain knob colors and fattens your signal as you crank it up—even before you tap into the massive flexibility in the EQ stage.
“The preamp gain knob colors and fattens your signal as you crank it up—even before you tap into the massive flexibility in the EQ stage.”
I found the two mid controls work best when used judiciously, and my guitars and amps preferred subtle changes pretty close to the midpoint on each. However, there are still tremendous variations in your mid boost (or scoop, for that matter) within just 15 or 20 percent range in either direction from the center detent. Pushing the boost and pre-gain too far, particularly with the 33 dB setting engaged, can lead to some harsh sounds, but they are easy to avoid and might even be desirable for some users that like to work at more creative extremes.
The Verdict
The new LPB-3 has much, much more range than its predecessors, providing flexible preamp, boost, and overdrive sounds that can be reshaped in significant ways via the powerful EQ. It gives precise tone-tuning flexibility to sticklers that like to match a guitar and amp to a song in a very precise way, but also opens up more radical paths for experimentalists. That it does all this at a $129 price is beyond reasonable.
Electro-Harmonix Lpb-3 Linear Power Booster & Eq Effect Pedal Silver And Blue
Intermediate
Intermediate
• Learn classic turnarounds.
• Add depth and interest to common progressions.
• Stretch out harmonically with hip substitutions.
Get back to center in musical and ear-catching ways.
A turnaround chord progression has one mission: It allows the music to continue seamlessly back to the beginning of the form while reinforcing the key center in a musically interesting way. Consider the last four measures of a 12-bar blues in F, where the bare-bones harmony would be C7-Bb7-F7-F7 (one chord per measure). With no turn around in the last two measures, you would go back to the top of the form, landing on another F7. That’s a lot of F7, both at the end of the form, and then again in the first four bars of the blues. Without a turnaround, you run the risk of obscuring the form of the song. It would be like writing a novel without using paragraphs or punctuation.
The most common turnaround is the I-VI-ii-V chord progression, which can be applied to the end of the blues and is frequently used when playing jazz standards. Our first four turnarounds are based on this chord progression. Furthermore, by using substitutions and chord quality changes, you get more mileage out of the I-VI-ii-V without changing the basic functionality of the turnaround itself. The second group of four turnarounds features unique progressions that have been borrowed from songs or were created from a theoretical idea.
In each example, I added extensions and alterations to each chord and stayed away from the pure R-3-5-7 voicings. This will give each chord sequence more color and interesting voice leading. Each turnaround has a companion solo line that reflects the sound of the changes. Shell voicings (root, 3rd, 7th) are played underneath so that the line carries the sound of the written chord changes, making it easier to hear the sound of the extensions and alterations. All examples are in the key of C. Let’s hit it.
The first turnaround is the tried and true I-VI-ii-V progression, played as Cmaj7-A7-Dm7-G7. Ex. 1 begins with C6/9, to A7(#5), to Dm9, to G7(#5), and resolves to Cmaj7(#11). By using these extensions and alterations, I get a smoother, mostly chromatic melodic line at the top of the chord progression.
Ex. 2 shows one possible line that you can create. As for scale choices, I used C major pentatonic over C6/9, A whole tone for A7(#5), D Dorian for Dm9, G whole tone for G7(#5), and C Lydian for Cmaj7(#11) to get a more modern sound.
The next turnaround is the iii-VI-ii-V progression, played as Em7-A7-Dm7-G7 where the Em7 is substituted for Cmaj7. The more elaborate version in Ex. 3 shows Em9 to A7(#9)/C#, to Dm6/9, to G9/B, resolving to Cmaj7(add6). A common way to substitute chords is to use the diatonic chord that is a 3rd above the written chord. So, to sub out the I chord (Cmaj7) you would use the iii chord (Em7). By spelling Cmaj7 = C-E-G-B and Em7 = E-G-B-D, you can see that these two chords have three notes in common, and will sound similar over the fundamental bass note, C. The dominant 7ths are in first inversion, but serve the same function while having a more interesting bass line.
The line in Ex. 4 uses E Dorian over Em9, A half-whole diminished over A7(#9)/C#, D Dorian over Dm6/9, G Mixolydian over G9/B, and C major pentatonic over Cmaj7(add6). The chord qualities we deal with most are major 7, dominant 7, and minor 7. A quality change is just that… changing the quality of the written chord to another one. You could take a major 7 and change it to a dominant 7, or even a minor 7. Hence the III-VI-II-V turnaround, where the III and the VI have both been changed to a dominant 7, and the basic changes would be E7-A7-D7-G7.
See Ex. 5, where E7(b9) moves to A7(#11), to D7(#9) to G7(#5) to Cmaj9. My scale choices for the line in Ex. 6 are E half-whole diminished over E7(#9), A Lydian Dominant for A7(#11), D half-whole diminished for D7(#9), G whole tone for G7(#5), and C Ionian for Cmaj9.
Ex. 7 is last example in the I-VI-ii-V category. Here, the VI and V are replaced with their tritone substitutes. Specifically, A7 is replaced with Eb7, and G7 is replaced with Db7, and the basic progression becomes Cmaj7-Eb7-Dm7-Db7. Instead of altering the tritone subs, I used a suspended 4th sound that helped to achieve a diatonic, step-wise melody in the top voice of the chord progression.
The usual scales can be found an Ex. 8, where are use a C major pentatonic over C6/9, Eb Mixolydian over Eb7sus4, D Dorian over Dm11, Db Mixolydian over Db7sus4, and once again, C Lydian over Cmaj7(#11). You might notice that the shapes created by the two Mixolydian modes look eerily similar to minor pentatonic shapes. That is by design, since a Bb minor pentatonic contains the notes of an Eb7sus4 chord. Similarly, you would use an Ab minor pentatonic for Db7sus4.
The next four turnarounds are not based on the I-VI-ii-V chord progression, but have been adapted from other songs or theoretical ideas. Ex. 9 is called the “Backdoor” turnaround, and uses a iv-bVII-I chord progression, played as Fm7-Bb7-Cmaj7. In order to keep the two-bar phrase intact, a full measure of C precedes the actual turnaround. I was able to compose a descending whole-step melodic line in the top voice by using Cmaj13 and Cadd9/E in the first bar, Fm6 and Ab/Bb in the second bar, and then resolving to G/C. The slash chords have a more open sound, and are being used as substitutes for the original changes. They have the same function, and they share notes with their full 7th chord counterparts.
Creating the line in Ex. 10 is no more complicated than the other examples since the function of the chords determines which mode or scale to use. The first measure employs the C Ionian mode over the two Cmaj chord sounds. F Dorian is used over Fm6 in bar two. Since Ab/Bb is a substitute for Bb7, I used Bb Mixolydian. In the last measure, C Ionian is used over the top of G/C.
The progression in Ex. 11 is the called the “Lady Bird” turnaround because it is lifted verbatim from the Tadd Dameron song of the same name. It is a I-bIII-bVI-bII chord progression usually played as Cmaj7-Eb7-Abmaj7-Db7. Depending on the recording or the book that you check out, there are slight variations in the last chord but Db7 seems to be the most used. Dressing up this progression, I started with a different G/C voicing, to Eb9(#11), to Eb/Ab (subbing for Abmaj7), to Db9(#11), resolving to C(add#11). In this example, the slash chords are functioning as major seventh chords.
As a result, my scale choices for the line in Ex. 12 are C Ionian over G/C, Eb Lydian Dominant over Eb9(#11), Ab Ionian over Eb/Ab, Db Lydian Dominant over Db9(#11), and C Lydian over C(add#11).
The progression in Ex. 13 is called an “equal interval” turnaround, where the interval between the chords is the same in each measure. Here, the interval is a descending major 3rd that creates a I-bVI-IV-bII sequence, played as Cmaj7-Abmaj7-Fmaj7-Dbmaj7, and will resolve a half-step down to Cmaj7 at the top of the form. Since the interval structure and chord type is the same in both measures, it’s easy to plane sets of voicings up or down the neck. I chose to plane up the neck by using G/C to Abmaj13, then C/F to Dbmaj13, resolving on Cmaj7/E.
The line in Ex. 14 was composed by using the notes of the triad for the slash chord and the Lydian mode for the maj13 chords. For G/C, the notes of the G triad (G-B-D) were used to get an angular line that moves to Ab Lydian over Abmaj13. In the next measure, C/F is represented by the notes of the C triad (C-E-G) along with the root note, F. Db Lydian was used over Dbmaj13, finally resolving to C Ionian over Cmaj7/E. Since this chord progression is not considered “functional” and all the chord sounds are essentially the same, you could use Lydian over each chord as a way to tie the sound of the line together. So, use C Lydian, Ab Lydian, F Lydian, Db Lydian, resolving back to C Lydian.
The last example is the “Radiohead” turnaround since it is based off the chord progression from their song “Creep.” This would be a I-III-IV-iv progression, and played Cmaj7-E7-Fmaj7-Fm7. Dressing this one up, I use a couple of voicings that had an hourglass shape, where close intervals were in the middle of the stack.
In Ex. 15 C6/9 moves to E7(#5), then to Fmaj13, to Fm6 and resolving to G/C. Another potential name for the Fmaj13 would be Fmaj7(add6) since the note D is within the first octave. This chord would function the same way, regardless of which name you used.
Soloing over this progression in Ex. 16, I used the C major pentatonic over C6/9, E whole tone over E7(#5), F Lydian over Fmaj13, and F Dorian over Fm6. Again, for G/C, the notes of the G triad were used with the note E, the 3rd of a Cmaj7 chord.
The main thing to remember about the I-VI-ii-V turnaround is that it is very adaptable. If you learn how to use extensions and alterations, chord substitutions, and quality changes, you can create some fairly unique chord progressions. It may seem like there are many different turnarounds, but they’re really just an adaptation of the basic I-VI-ii-V progression.
Regarding other types of turnarounds, see if you can steal a short chord progression from a pop tune and make it work. Or, experiment with other types of intervals that would move the chord changes further apart, or even closer together. Could you create a turnaround that uses all minor seventh chords? There are plenty of crazy ideas out there to work with, and if it sounds good to you, use it!