While there’s nothing like the experience of playing guitar through a cranked-up amp, the modeled amp sims that are so widely available nowadays offer an excellent alternative, for those sessions or rooms that don’t allow for the real thing. But no matter how carefully the designers have done their job modeling the circuits and components that provide the sound and feel of real amps, getting the best out of these emulations is not necessarily a plug-and-play experience—there are a few settings that must be given appropriate attention for the most realistic modeling, and a few options that may offer a better results. Here are a some brief suggestions for working with amp sims.
When musicians sit down to cut a track with an amp sim that provides emulations of classic guitar amps, they usually expect the different amp models to be fairly faithful to the tone and overdrive characteristics of the originals. This includes the level and tone of the distortion they get when turning up the drive/gain knob on the virtual amp’s front panel—some amps provide a lot of distortion, even at lower settings, while others offer only a little overdrive/crunch at max.
But to ensure that virtual amp’s drive corresponds to the gain characteristic of the various originals, the incoming level of the DI’d guitar must fall within the range expected by the amp model’s designers; if it doesn’t, you might end up with a Fender Twin model that overdrives like a Dual-Rectifier, or a Marshall that can’t manage to generate more than a modest amount of grind, even with everything on ten—or eleven!
To ensure that the virtual amp sees more or less the same level that the real amps would—the input level it’s designed to work with for the most realistic response—the user may need to calibrate the level of the incoming DI guitar signal. There’s usually an Input Level control and Input Metering in the plug-in—separate from the initial gain/drive knob that’s part of the amp model—which lets the user set the incoming level before the audio hits the virtual amp—this is where you’d set the proper input level to feed the plug-in.
Many virtual amps will offer a recommendation in their docs for how to set this level, and if they do it should be followed as best as possible. If there’s no specific spec offered for input gain, I find that an input level that maxes out at around -6dBfs or so (for single-coils, maybe -3dBfs for humbuckers)—set while banging out some loud-as-possible open-E chords—usually manages to drive the virtual amp to levels of drive and distortion appropriate to each of the different amp models. This should help the various amp models achieve the best sound—and most importantly, the best dynamic response—they’re capable of.
Just as setting an appropriate input level for the virtual amp is important, so is setting the output level of the plug-in. Here, it’s important to distinguish between the two output controls usually available on an amp sim—the amp’s Master Volume knob, and the plug-in’s final Output Volume control.
Many older/smaller amps don’t have a Master Volume knob—in that case, no problem, there’ll certainly be an Output Level control somewhere to set the final output level of the plug-in. But many amps—especially high-gain amps—do have a Master Volume knob that was present on the original hardware as well. It’s important to remember that this control is part of the emulation, and just as with the real amp, the setting dialed up with this knob has a big effect on the amount and most importantly, the character of the distortion.
On amps—real and virtual—with an input Gain/Drive knob and a Master Volume knob, the Drive or Gain knob sets the level feeding the amp’s preamp tubes, and the Master Volume knob sets the level feeding the amp’s power tubes. These two provide different distortion qualities: overdriving the preamp tubes is more likely to produce buzzier or “fizzier” distortion, while driving the poweramp tubes usually offers more crunch and grind—often the latter is more responsible for the specific distortion character associated with that particular amp. Amp sims with a Master Volume knob should be expected to emulate this distinction, and if you use the Master Volume as a plug-in output control—tweaking it to set mix levels—you might not achieve the best distortion tone the amp sim is capable of.
The proper way to work with these virtual amps is to use the Master Volume knob—in conjunction with the preamp Drive/Gain knob—to set the distortion tone and overall character of the amp sim, and use only the separate Output Level control to actually set the final output level of the plug-in. The plug-in Output Level control follows all the amp front-panel knobs—including the Master Volume—and will let you set the final level feeding the mix without changing the tone or distortion of the amp sim unintentionally.
The strong midrange peak of a typical guitar amp speaker is what gives electric guitar its punch and tames the over-bright buzz of high distortion levels, and a guitar amp’s speaker is a big part of the specific amp’s tone. That said, out in the real world many guitarists like to expand their tonal palette by swapping out their amp’s included speaker(s) for a different-sounding external cabinet, or even doubling up on cabinets, for a richer tonal quality—the latter trick works especially well with ADT guitar parts panned to different sides of the mix.
Though swapping out cabinets in the real world requires a little attention to detail—keep an eye out for potential impedance issues—in the virtual world it’s a no-brainer. Every amp sim I’ve seen makes it a simple matter to un-couple the amp models from their matching cabinets and substitute any cabinet from any other model.
The fancier virtual amps often include the option for dual cabinets with a single amp model, with the ability to choose different cabinets (and virtual mics) for each. This can be a real eye-opener—saving a bunch of presets with different cabinets can be almost like adding extra amp models to the plug-in’s collection. It’s a great way to extend your tonal options, or help a guitar track sit better in a mix—especially a mix with multiple guitar parts.
Some virtual amps use modeling to simulate the sounds of the cabinet, while others use IRs—Impulse Responses—of different real cabinets. (Remember, impulse responses are recordings of the sound of real rooms—or in this case speakers—loaded into a convolution processor, providing the actual sound of the real room or speaker.) Many guitarists feel that cabinet IRs sound better than modeled cabs—that they capture the very subtle comb-filtering and ambience of the actual miked-up cabinets for a more natural/open three-dimensional quality.
In accordance with the popularity of cabinet IRs, there are many companies/websites offering IRs of guitar speaker cabinets, both paid and free. If your favorite amp sim uses modeled cabinets, and you feel it sounds good but is a little lacking in openness or depth, you might find you prefer a cabinet IR. There’s always a way to disable the built-in speaker emulation, and you can then instantiate a convolution plug-in right after the amp sim and try some cab IRs instead.
This last point is pretty obvious, but it’s still easy to overlook. While the raison d’être for virtual amps is use with DI’d electric guitars, they can add some welcome punch and grit to many different instruments and even vocals. The most obvious classic non-guitar application for a virtual amp is electric piano—run a clean Rhodes or Wurli—real or samples—through a modeled Fender Twin Reverb and you’ll immediately achieve that funky, midrangy EP sound you’ve heard on so many recordings (Fender used to voice real Rhodes though a Fender Twin).
An amp sim can add some edge to drums, and a nice grind to clean organs, strings, or synth pads, turning a run-of-the-mill patch into a much more aggressive part—sometimes running the amp’d track in parallel will achieve the best results. And a small virtual practice amp—like a Fender Champ—can be a great way to get an effect similar to the classic telephone voice, but with extra richness and bite. A little experimentation will likely reveal many other suitable applications, and it’s a good way to fatten up tracks than might otherwise be a little lacking in oomph.
Virtual guitar amps are here to stay, and when calibrated properly and used creatively, they can be a big part of the sound design for any track or mix. A little time spent getting familiar with the layout and operation of a particular amp sim will go a long way toward possibly making it a go-to plug-in in your creative toolbox.