
All 9V blocks are not created equal. Here's what to look for to avoid hiss, hum, and crackle.
(Originally published April 22, 2020)
At the dawn of the guitar-effects age, powering pedals was relatively simple. If an effects pedal didn't take a standard 9V battery like your AM transistor radio, it plugged into the wall like your avocado-green toaster. Forever dissatisfied, guitar players eventually grew weary of changing batteries, and plugging stuff into the wall was kind of a drag, too.
As the industry was looking to eliminate its batteries and Edison plugs, the effects purveyor Boss went a long way to standardizing pedal power by putting a 2.1 mm coaxial power jack on all their pedals, and while their market dominance made the 1/8" jack on certain Ibanez and Pro Co pedals outliers, even they couldn't stick to one standard for long as they transitioned from 12V ACA spec pedals to 9V PSA spec pedals.
Once that growing pain subsided, it was relatively peaceful on the pedal-powering front for many years, and the standardization allowed companies to produce power supplies that let players power all their pedals simultaneously and without harming a single battery. Some supplies had a single output with daisy chains to fan out power to multiple pedals. Some were isolated, offering an individual power port for each pedal and eliminating daisy-chaining all pedals in a parallel fashion. Isolated supplies were a huge development in pedal-powering history, so let's dig in there before wading further into the power morass of today.
In this context, isolated power supplies are those supplies that are essentially a series of separate power sources in one enclosure. Each supply stands on its own with no direct connection to any of the other supplies, and, as such, the effects they power have no direct connection to one another through their respective power ports.
There are several reasons power supply isolation can be anything from favorable to crucial. First, some pedals have a positive-ground scheme, where the audio ground of the effect is connected to the positive terminal of the battery, usually due to the type of transistors used in the pedal's circuit.
Isolated power supplies are those supplies that are essentially a series of separate power sources in one enclosure.
While fuzz pedals are often set up this way, most pedals have a more conventional negative-ground scheme. If you parallel connect the power of a positive-ground pedal to a negative-ground pedal, and then connect their audio grounds together with a patch cable, you'll cause a power supply short, and neither pedal will get power. The power source will complain, too! Isolated supplies mimic a battery as each device gets its very own power source to use independently of any other device.
Crosstalk is another reason for isolation. Some pedals don't play well with others when powered in parallel. Like so many playground bullies, tremolos and vibratos can tick and pop while overdrives and DSP effects with switch-mode supplies and high-speed processors can whine, and they can torment their boardmates with their glitches. These deficiencies might not bother the offending pedal, but the trash they put on their power supply ports gets leaked to other connected devices that may not be able to reject the noise quite as well. Isolation breaks the link and prevents such crosstalk.
The last reason for isolation we'll list here is ground loops. In general, for guitar rigs, it's best practice to have just one ground path. Typically, that one path should be the ground connections of all of your patch cables extending in a line from guitar's output to amp's input. Daisy-chaining power creates other ground paths that make closed loops from one section of your signal flow to another. These ground loops can make your rig more susceptible to hum pickup in the presence of electro-magnetic fields. If you have daisy-chained pedals both in front of an amp and in its FX loop, and dozens of feet of cable between them, the associated ground loops can become very large and produce a great deal of noise. Using an isolated supply disconnects the links that make the loop, and the induced hum can no longer be sustained.
With isolation addressed, power supplies remained relatively unchanged for many years. Then, digital-signal processing became cost-feasible for common use in guitar-pedal effects. We'll dig further into their high-current demands and how they've complicated the power supply marketplace in my next column.
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Do you overuse vibrato? Could you survive without it?
Vibrato is a powerful tool, but it should be used intentionally. Different players have different styles—B.B. King’s shake, Clapton’s subtle touch—but the key is control. Tom Butwin suggests a few exercises to build awareness, tone, and touch.
The goal? Find a balance—don’t overdo it, but don’t avoid it completely. Try it out and see how it changes your playing!
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
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Tobias bass guitars, beloved by bass players for nearly half a century, are back with the all-new Tobias Original Collection.
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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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