If you’re new to the world of power tubes and their respective sounds, lets begin with a crash course in two of the most popular power tubes—6L6s and EL34s.
Until a few years ago, my understanding of the technical aspects of tube amplifiers was very basic. But more recently, I’ve delved into the world of valve-driven amps and have learned a great deal about how different components affect tone. In order to control your sound, it helps to have an understanding of how tubes work. If you’re new to the world of power tubes and their respective sounds, lets begin with a crash course in two of the most popular power tubes—6L6s and EL34s.
6L6s and EL34s are of the octal-plug variety, meaning both are 8-pin tubes. Here’s where they differ: 6L6s are loosely described as delivering an “American” sound, primarily because they were the main tubes used in Fender amplifiers. Tonally, their sound is big, fat, warm, and round. They have a nice balance of lows, mids, and highs, with a little bit of a mid scoop and added thickness on the bass side. A 6L6 is great for providing clarity, detail, sparkle, and presence to your sound. In many cases, the 6L6 is the preferred tube for clean tones or bluesy, overdriven colors.
EL34s are often described as having more of a “British” tone. They are tight and punchy in the low mids, tend to have a touch of a mid scoop, and are a bit brighter than 6L6s. The EL34s distort more quickly than 6L6s and tend to clip in the upper-mid range and treble range. EL34s are great for achieving semi-dirty tones for rhythm playing. The sound of vintage Marshalls comes from driving EL34s hard.
Both 6L6s and EL34s can usually be installed in the same socket. So, if you currently have 6L6s in your amp and are looking for a more British sound, you can most likely replace them with EL34s. But wait, there’s a catch—and its called biasing.
Every tube type requires a basic range of voltage and current for the manufacturer’s optimum, recommended operation. Before you go plugging any old octal tube into your amp, you need to understand the specs of the tubes and see if your amp can accommodate the requirements. Every tube varies in its current draw when it comes off of the manufacturer’s finish line, and this is the reason amps and tube devices have to be properly biased. While most amps have an adjustable bias, there are amps where the bias is fixed.
I mainly play Mesa/Boogie amps, which are fixed-bias amplifiers. The benefit of a fixed-bias amp, loaded with properly rated and tested tubes, is that the tubes can be swapped out without having to take your amp to a tech for biasing. The bias will not drift in a fixed-bias amp. The advantage of adjustable-bias amps is that an individual has the option to alter the amp’s tone by running the amp hotter or colder than the manufacturer’s recommended specification for a given tube. The hotter you run an amp, the quicker the tube will reach its clipping threshold, which will result in a more overdriven sound. Personally, I like gear that is easy to tech on the road, so I stick with fixed-bias amplifiers for hassle-free tube changing on tour.
So how can you tell when a tube is starting to go bad and needs to be changed? Well, the most obvious clue is when you hear a change in tone. The most extreme ends of the frequency spectrum tend to be the most obvious tip-offs. Generally, you’ll notice a loss in the amp’s high end—a reduction of clarity and brilliance. You may also experience a mushy or “flubby” response in the low end. Tubes, like guitar strings, wear out over time and will begin to sound dull.
It’s best to use your ears when evaluating tube life because visual diagnostics can be misleading. Just because a tube is glowing does not mean it is working properly. Of course a tube that is not lit has certainly reached the end of its life. And while we’re on the topic of failing tubes, a faulty preamp tube will never cause your fuse to blow. If your fuse is blown and the issue is tube related, the problem will lie in your power tubes or a rectifier tube. Before you go on the road, it’s a good idea to test all of your tubes with a tube tester, including your spares.
If you’re interested in gaining a deeper understanding of tubes, fuses, biasing, and how they all work together, one good resource is Mesa/Boogie’s Amplitudes newsletter, which is available on their website. Tube-amp fanatics also praise Understanding Tube Amps, a DVD by Gerald Weber of Kendrick amps, and Groove Tube founder Aspen Pittman’s The Tube Amp Book—Deluxe Revised Edition.
The more you learn about how your gear works, the better equipped you’ll be to perform repairs and make tonal changes. You’ll be that much closer to capturing that ever-elusive “perfect tone.”
Arpeggios are the musical equivalent of greeting someone by name—it’s the most direct way you can communicate with a chord and it’s going to take your playing up a notch.
Chops: Intermediate
Theory: Advanced Beginner
Lesson Overview:
• Learn how to apply arpeggios
directly to a blues progression.
• Break out of only playing
pentatonic scales.
• Easily combine different
arpeggios in the same position.
Have you ever wanted to break out of the pentatonic scale when playing blues? While there is nothing as universally accepted, used, taught, and beloved as the minor-pentatonic scale for playing over a blues progression, it’s not your only option. The pentatonic scale works well over blues changes because it contains enough of the notes from the underlying I–IV–V progression to match up and work well. Plus, there’s something about the pentatonic scale that just works.
Here’s an analogy that might help: Using the pentatonic scale is akin to walking into a room and saying, “Hey everyone!” It’s more general than greeting someone by name, but it almost always works. Arpeggios are the musical equivalent of greeting someone by name—it’s the most direct way you can communicate with a chord and it’s going to take your playing up a notch. Let’s take a look at a 12-bar blues in A to understand what our chord progression is in Fig. 1.
As you can see, there are only three
chords, A7, D7, and E7—the I7, IV7,
and V7, respectively. The pentatonic scale
works just fine for all three chords because
it contains just enough notes to talk to each
chord and sound inside. Take a look at the
notes in the chords as they relate to the
notes in the scales:
A minor pentatonic = A–C–D–E–G
A7 = A–C#–E–G
D7 = D–F#–A–C
E7 = E–G#–B–D
The notes in the chords that also appear in the pentatonic are shown in bold. As you can see, the scale talks to each chord in some way, but it does leave out a bunch of nice tones. For example, the A minor-pentatonic scale doesn’t give you the 3rd of any of the chords, and the 3rd is the tone that defines whether a chord is major or minor. It’s amazing that we’ve gotten away without proper 3rds in our pentatonic-based blues playing this long. Arpeggios are going to help us fill in the missing gaps, and when combined with pentatonic scales, they’re going to elevate your playing.
Let’s start mapping out these arpeggios in and around the 5th position. Check out the A7, D7, and E7 arpeggios in Fig. 2. By themselves, they sound like exercises, but when you break them up and combine them with some notes from the A minorpentatonic scale, you can end up with Fig. 3, a phrase that outlines the A7 and D7 in the first four measures of our progression. In this example, I’m leaning on C# and F#—the 3rds of A7 and D7, respectively— because the pentatonic scale omits them and I love the way they sound. Combine that with some simple phrasing, and you have a nice lick that breaks you out of the pentatonic rut, while still sounding bluesy.
To take the idea further, check out Fig. 4 and Fig. 5, which are two examples of playing over E7 and D7 in measures 9 and 10 of the progression.
In both examples, I’m keeping it as simple and melodic as I can, while still picking notes directly from the arpeggios. To stop them from sounding like exercises, I’m focusing on the top two or three strings of the arpeggios and throwing in notes from the pentatonic scale whenever possible to help ground me in the blues language. Just because you have arpeggios spanning multiple octaves at your disposal doesn’t mean you need to play more than a note or two from each in order to connect with your chord progression. As you learn to incorporate these arpeggios into your playing, I’m sure you’ll discover that a few of the notes you were already playing outside of the pentatonic box are actually from the arpeggios—you just didn’t know it yet! There’s clearly a lot more you can do with arpeggios, and hopefully this gets your creative juices flowing to create some licks of your own.
Ampeg’s new GVT series, which offers a power range more suited to clubs than Yasgur’s Farm, honors this oft-forgotten part of the company’s legacy with authentic vintage rock tone and styling.
When rock venues began to include bigger arenas and festival grounds in the late ’60s, the clamor for more potent guitar and bass amplification became as deafening as the amps themselves. Few companies skipped a chance to cash in on the big amp movement, and Ampeg, a company that had built well-regarded amps for years, stepped up with its own line of high-decibel bass and guitar amplifiers. The monstrous SVT bass amp packed a then-unprecedented 300 watts of all-tube power, and their 100-watt V series heads (also available in combo form with more modest output under the VT moniker) were adopted by many high-profile performers—most notably the Rolling Stones, who used V series prototypes on their historic (and infamous) 1969 world tour.
Ampeg’s new GVT series, which offers a power range more suited to clubs than Yasgur’s Farm, honors this oft-forgotten part of the company’s legacy with authentic vintage rock tone and styling. And like the V and VT amps of old, they are an interesting option for players looking for something outside of the typical Fender and Marshall spheres. The GVT52-112 reviewed here is a 50-watt (switchable to 25 watts) 1x12 combo that covers a lot of tone territory.
An Honest Homage
This GVT52-112 weighs in at a hefty 52.2
pounds and sports a pair of 6L6 power
tubes and three 12AX7s in the preamp
section. The birch plywood cabinet of
our review specimen comes packed with
an 80-watt Celestion Seventy 80 speaker,
which can aptly handle the higher wattage
output of the GVT52-112. The amp
looks sharp with its vintage-correct black
vinyl covering, a black sparkle grille cloth,
and a silver faceplate. The control array
is especially user-friendly, with everything
well spaced and logically arranged. The
GVT52-112 offers 2 channels, each with
its own discreet Baxandall EQ section,
Gain, and Volume controls. The footswitchable
spring reverb and effects loop
can be bypassed. And a multi-color LED
that’s too bright to miss indicates the status
of the Full Power/Standby/Half Power
switch. Around back, effects loop and footswitch
jacks can be found aside a variety of
speaker outs for extension cabinets.
Running the Range
I plugged in a Custom Shop Stratocaster
to get a feeling for the amp’s clean and
mild breakup flavors on Channel 1. As I
strummed open chords with the EQ knobs
at noon, the GVT52-112 delivered an elusive
combination of warmth at the low end
of the spectrum and sweet musical clarity in
the upper midrange and highs.
With its ability to independently boost and cut frequencies, the Baxandall EQ made it easy to tweak what’s a very balanced tone to begin with. I could easily adjust the EQ to conjure a variety of crystalline and round Fender-inspired jazz tones that still packed a punch for solos. But the amp’s wide range of bright clean tones and impressive, snappy responsiveness would suit country styles as well. Tonal complexity was quite good across all these cleaner highheadroom settings and excellent for an amp in this price range, but lacked some of the indefinable singing harmonics you’ll hear in the best point-to-point circuits. And though our review unit exhibited a bit of cabinet vibration at certain settings, the amplifier is extremely noise free, which is great given how well it works with stompboxes.
A Voice All Its Own
The Ampeg really started to shine when I
pushed Channel 1 to the point of breakup.
And working through various EQ settings
and gain levels revealed a uniquely fierce
personality. With the EQ knobs dimed and
the Gain at 75 percent, I got an awesome
live Stones sound with a touch of bright,
near-fuzz flavor that would cut through
almost any band mix with ease. Breakup
sounds organic, and distortion is easy to
control with the guitar’s volume knob.
My Les Paul helped deliver classic ’70s crunch in spades. The GVT52-112 loves humbuckers, and at the same gain level, the punchy, fuzz-like tone I extracted from the Stratocaster was transformed into a killer raspy sizzle, roaring with girth.
The higher gain Channel 2 remained defined in grittier settings—even on the Les Paul’s neck pickup. Though the amp’s slight tendency toward the bright side is accentuated in this environment, it works great with humbuckers. Huge sustained chords in the vein of Thin Lizzy’s “The Boys Are Back in Town” ring out in full glory at lower gain levels, with great bloom and sustain. Turning up the gain to noon and switching to the bridge humbucker yielded a thick “Reelin’ in the Years” lead sound that became more focused and gritty when I emphasized the mids with the EQ. After nailing so many classic distortion flavors, I was impressed that the GVT52-112 had much more usable gain on tap—the upper reaches of the Gain knob put me well on the way to Mastodon territory. The footswitchable boost offered a usable bump in output, perfect for the quick switch from rhythm to lead.
The Verdict
From the spot-on vintage design to the
unique-but-familiar palate of clean and
overdriven tones, the GVT52-112 offers a
fresh alternative for those in search of classic
sounds and styling that also isn’t from the
usual suspects. And its ability to stand apart
from the crowd while fitting just about any
classic rock setting is its greatest accomplishment.
The switchable power, classic, userfriendly
control layout, ample gain range,
and added modern features lend real-world
versatility to this tastefully styled throwback
design. And at an accessible price, there’s little
reason not to give this combo an audition.
Buy if...
you’ve been looking for an affordable Fender/Marshall/Vox alternative to set you apart sonically and visually.Skip if...
you have little interest in deviating from proven tone templates.Rating...