Model Behavior for Guitars
The Harmony Central Buyer's Guide To Digital Modeling Amps (Part Two)
by Emile Menasché
September 6, 2000
'If the amp is doing its job, the difference will not be simply in the basic
shape of the tone, but in the very character of the sound.'
How to Evaluate a Modeling Amp
When we took a look at Amp modeling back in June, we focused on the basic overview of digital modeling and how that technology relates to other forms of guitar processing. In our concluding installment, we'll examine some of the questions you'll need to answer before deciding which (if any) modeling system is right for you.
The Roland VGA-7 mates the modeling features found in their VG-88 to a fully operational amplifier |
When choosing a modeling amp, you must keep two rules in mind at all times.
Rule # 1: A modeling amp is nothing like a conventional amp.
Rule # 2: A modeling amp is exactly like a conventional amp.
That paradox is apparent when you run down the typical modeling amp's feature set.
Model List
Here's the biggest difference between modeling and conventional amps. Rather than give you clean and overdriven channels as building blocks for sound, you get a roster of digitally replicated amps to work with. The choices vary, but count on finding at least one model based on each of the following types of amp: Fender tweed and blackface-type combos, a '60s Marshall head or combo, '70s and '80s Marshall high-gain heads, a "Modern" high-gain amp with a scooped midrange (usually based on a Mesa Dual or Triple Rectifier), and a Vox AC30. From there, some units fill in the list by getting more specific within a given area (offering several blackface examples, for instance), or by being esoteric (Crate offers models of its own Blue Voodoo series), or by offering non-literal settings, such as the Blues sound on the Johnson J-Station and the POD Clean sound on the Line 6 POD.
Gain and Tone Controls
The basic control layout of a typical modeling amp resembles that of a conventional amp. You get gain, three-band EQ (Low, Mid, and Hi tone controls), a master volume knob, and some kind of reverb/effects control. In many ways, the controls even operate like your old amp's knobs (see User Interface). On most tube amps, the tone controls have an impact on the gain structure, and this is often the case with modeling amps as well. Some amps also provide a virtual bright switch, presence control (when appropriate to the digital model selected), and post-gain EQ that shapes the tone without altering the basic gain structure.
A couple of things to note: Since output distortion is considered such an important component of a tube amp's sound, many modeling amps offer two post-gain controls. A Master volume control can be used to simulate the drive characteristics of a tube amp's output stage, while the Level control alters the output of the amp without coloring the sound.
Unlike a conventional amp, where the tone controls adjust specific frequencies, a modeling amp's controls depend on the active digital model, each of which is designed with its own gain structure and inherent tonal curve.
In English, that means that if you set the gain and all three tone controls to 12 o'clock, you should get very different tone and distortion from a Fender tweed-based model than from one based on a Marshall or Vox. If the amp is doing its job, the difference will not be simply in the degree of distortion or the basic shape of the tone, but in the very character of the sound.
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Modern Class A MP3 (33.5 KB) |
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Brit Class A MP3 (33 KB) |
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Tweed Blues MP3 (149 KB) |
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12 0'clock highs and lows: With the Line 6 POD Pro set to manual mode, we flipped through a number of amp models. The EQ remained at 12 O'clock all around. Listen to how the results differed from amp to amp. |
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Brit Class A (Edited) MP3 (40.6 KB) |
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Tweed Blues (Edited)MP3 (31.9 KB) |
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British Class A and Tweed Blues models sounded better when we tweaked the controls to take advantage of their individual tonal character.
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Next Page: Effects, Speaker Emulation, Presets, Other Features....
Emile Menasché is the Senior Editor, Guitar/Bass at Harmony Central. He previously served as Editor-In-Chief for Guitar Shop magazine.
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