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A Guide to Re-Amping Guitars with Plugins

Oct 04, 2017

Is your recorded guitar or bass tone not making the cut? Re-Amping may be the perfect solution to shape your tone after-the-fact in ways that EQ can't. See our top tips for how to re-amp during the mix.

A Guide to Re-Amping Guitars with Plugins

Re-amping is the process of sending a previously recorded guitar or bass signal into an amplifier and accompanying loudspeaker to be enhanced, re-recorded and blended back into a mix.

To accomplish this using analog signals, impedance and gain considerations are of the utmost importance. As professional analog audio is balanced and low-impedance, and instrument signals are generally unbalanced and high-impedance, the audio signal needs to be converted for compatibility; this is the exact function of a DI, or direct injection box, but rather than converting an instrument signal for use in a recording console, re-amping converts audio in the opposite direction.

Luckily, undergoing the same process within your DAW is much easier and free of gain staging, cabling, grounding issues, unwanted hums and buzzes and can produce the same, if not more desirable results. With digital emulators, you also have a huge collection of amps, cabinets and mic configurations at your fingertips that you may never find together in one studio.

Re-amping to shape tone in ways EQ cannot

The sonic differences between a guitar recorded directly into a recording preamp with no additional processing, and one recorded through a guitar amp with speaker cabinet, lies in the complex frequency response and harmonic characteristics inherent to the multiple stages of amplification circuitry in an amplifier, along with a loudspeaker moving air from within a speaker cabinet. This shapes the tone and adds anywhere from subtle, pleasant harmonic distortion to the heavy, fuzzy distortion that we know and love as being characteristic to electric guitars and basses.

When a recorded guitar needs more grit or gain, more warmth or more twang, re-amping is often the best course of action. It can be a track-saving tool to add tone and character where the original recording may have been lacking.

If you are not a guitar player, or are not particularly familiar with amps, pedals and microphones, the idea of digging into a vast collection of emulations like GTR3‘s amp collection can seem daunting. The combinations of amps, cabinets and microphones alone makes for countless options and the potential for near-endless searching. But fret not, there are simple guidelines you can use to quickly get on the right track and minimize aimless wandering.

Know your amp: Pick your poison

Aside from the guitar itself, amplifiers provide the greatest ability to change the tonal character and personality of a guitar sound.

It’s important to differentiate between the “tonal character” of an amp and the amp’s frequency response. While almost all guitar amps are built with equalization circuits affecting frequency response, the tone of an amp is shaped by everything from the high-impedance input connection all the way through every electronic circuit in the amplifier, including tubes and transformers.

The reason why you would select a Vox AC30, for example, over a Fender Bassman amp is based on the tone you’re trying to achieve. Each amp has a distinct total character. When matched with a speaker cabinet and mic, the tonal variation potential grows exponentially. For this reason, re-amping, in many ways, is a much more powerful tool than EQ for shaping guitar sounds.

The type of amp you select determines the general tonal character you will get. The EQ circuits built into the amp will adjust the sound relative to this tone. Although the GTR Amp plugin has 37 types, each representing different amp emulations, they are organized into tonal categories so you can chase the sound you want, rather than the specific amp. This allows you to quickly set a sound, ranging from clean to completely overdriven, without having to rummage much through amp model names. If you click on the “?” icon in the top right of the Waves Toolbar, you can look up the specific model for reference, or to make note of a great sound you just created.

A Guide to Re-Amping Guitars with Plugins

A Guide to Re-Amping Guitars with Plugins

Signal flow: Treble vs. presence

Most settings on an amp are fairly straightforward, but there are a few notable points worth remembering: Bass, Mid and Treble EQ controls are typically part of the pre-amplification section, not the power amp.

On the GTR Amp plugin, the Drive control determines the amount of equalized signal feeding the preamp, which sets the amount of harmonic distortion and allows you to shape the tone of the distortion. The Presence control, however, is part of the main amplifier section, which applies EQ after the distortion created by the preamp. This allows you to add high-frequency ‘sparkle’ to a warm distortion without adding harshness, if that is the desired tone.

Understanding how cabinets shape sound

The second most powerful way to change the tonal character of a guitar is by speaker cabinet selection. Most amps are matched with speaker cabinets that are either separate from the amp itself, or combined into one unit called a “combo” amp. Matching speakers and cabinets to amps allows a manufacturer to specifically tailor the tonal character of the overall sound. When you use speaker cabinets that were not part of the original manufacturer’s design, many interesting tonal combinations can be created.

So, it’s time to get started re-amping:

1. Use presets: Aim for what’s missing in your current tone

Seldom is the preset more useful in the mixing process than while re-amping guitars. Even seasoned, professional engineers will toggle through presets rather than building a setup from scratch. In spite of the “fishing expedition” this approach may suggest, there are some guidelines that can help you quickly find what you are looking for:

When searching for a re-amp tone, consider what is missing from the original sound before opening presets. Understanding this, the GTR Amp plugin offers this end-approach method with presets like Clean, Warm, Punchy, Edgy, Sweet, and so on. If the guitars you have lack warmth, start with Warm presets. If they sound very flat, try the Punchy or Edgy presets. If the original sound is too distorted, start with Clean presets to add more definition.

2. Audition presets in context of the mix

Auditioning re-amped guitar sounds is almost always better done in the context of the whole of the mix rather than in solo. The reason for this is simple: in solo, there are near-infinite possibilities for different sounds that could work. In the context of a mix, many frequency areas may already be filled by keyboards, bass, vocals and other instruments. When you audition in the mix, the possible range of tones that will certainly work is more limited and you will more quickly be able to find the preset that fits.

3. Shape tone with preamp drive and EQ

After you find an amp or preset sound that is close to what you want, the next best place to continue is in the EQ, Drive and Presence controls. Sometimes, small adjustments will give you that little bit extra that you need. Remember that the presence control is often the better way to get a guitar sound to cut through a mix, rather than the treble control. Consider backing off the treble and adding presence instead. This technique is especially powerful with heavily distorted sounds.

Notice how the treble boost increases distortion in the high frequencies in the first 4 bars, as opposed to the presence boost in the second set of 4 bars, which adds high frequencies without the added distortion:

GTR-Treble GTR-Presence

4. Select a desired microphone type and position

If a preset gets you very close but isn’t quite perfect yet, the microphone selection allows you to further shape the tonal character in unique ways. Generally, there are three basic mic types, each with distinct sounds: Dynamic, Condenser and Ribbon.

  • Dynamic mics have a tighter, more focused sound and are great for rhythmic guitar sounds.
  • Condenser mics have a more natural, full-frequency response and are great for adding clarity and detail.
  • Ribbon mics have a warmer, fuller sound and will cut back on harshness by warming the upper mid and high frequencies.
With each type, the mic position in relation to the loudspeaker is adjustable:

  • The Off-Axis position will create a sharper, more focused sound that generally cuts lower frequencies.
  • The On-Axis position will sound fuller and more natural, generally with plenty of low-end.
If an Off-Axis Dynamic mic is close to the sound you want, try the other Off-Axis Dynamic mic options before moving onto other mic types. Likewise, in the case that the preferred option is an On-Axis position.

In the following 12-bar example, each set of 4 bars is represented by one of three basic mic types: Dynamic, Condenser and Ribbon. Notice the focus of the Dynamic mic, the openness of the Condenser mic and the warmth of the Ribbon mic:

5. Tune your cabinet to your desired sound

The cabinet is often the best place to go if everything else is close, but not quite perfect. Remember, closed cabinets will often give you a dense sound and open cabinets will give you, you guessed it: a more open sound. Closed cabinets are better for warming up sounds and having them image well. Open cabinets will bring air around a sound that is too dense or dry.

Also, consider the size of the speaker and the number of speakers in the cabinet. Larger speakers will warm up the sound and smaller speakers with be brighter with less low end. The number of speakers is less important than the fact that the cabinet size is necessarily bigger or smaller. The cabinet size affects how ‘natural’ the sound is. Bigger cabinets are more balanced tonally; choosing an open or closed back can help to further shape the solidity or openness of the sound.

As with mics, try staying within the same speaker size or cabinet types if you are close to getting what you want. If you are not happy, go to a different setting to see if it gets you closer, then quickly narrow your focus from there. It is often a good idea to circle back to the mic selection to further shape the sound after a new cabinet selection. Certain cabinet types are automatically paired with the mics that were most commonly used in professional recording sessions.

Notice how the closed cabinet’s sound is tighter and focused in the first 4 bars, and the open cabinet is more open and dynamic in the second set of 4 bars:

6. Use additional processing if necessary

Don’t be afraid to use a bit of processing after the re-amping, just as you might for an originally recorded guitar. Specially-designed all-in-one plugins, built with seasoned, Grammy® award-winning mix engineers Chris Lord-Alge, Eddie Kramer, and Jack Joseph Puig, are specially tuned for use with guitars. From the range of the EQ bands to the compression settings and more, these tools are designed to quickly find the sounds that suit guitars; determined with years of combined experience for getting guitars of any musical style to sit well in a mix.

The CLA Guitars plugin also includes a re-amp section, making it an even quicker solution for adding grit or reshaping the character of a guitar or bass tone. If preferred, or if using with another re-amping tool, simply bypass the re-amp section and use the tone, dynamics, reverb and other processing sections to shape your tone.

Hear CLA’s re-amp in action:

One final bit of advice…

It’s often best to work quickly at first to find a good starting place, which is best accomplished with the presets. Try to avoid blindly ‘fishing’ for sounds as the number of possibilities can quickly become overwhelming and you may lose your perspective on the rest of the mix.

If you get frustrated, work on something else in the mix for a while and circle back after you have cleared your head. Finally, use the A>B and B>A feature in the Waves System Toolbar to compare options. Quickly select the one you like better and copy it to the other setup before tweaking. As always, audition your settings in the context of the whole mix to see what suits it best. Re-amping is a powerful tool if used intelligently, so use it wisely!

A Little History…

Many of the early DI box designs were passive circuits using transformers and did not require a power source. As such, the circuit design worked equally well in reverse as it did in traditional use, thus allowing engineers to convert the recorded audio signal to proper impedance before being plugged into an amp for re-amping. Usually, the low-impedance balanced signal would also have to be lowered by about 20 dB before being fed “backwards” into the passive DI box so as not to distort and overload the guitar or bass amp. The converted high-impedance signal could then be easily connected into the amp using a short 1/4-inch cable.

The rest of the process was in the amp settings, mic placement and tradition recording techniques.

For getting your guitars to sit well in a mix, see our reverb mixing tips and if a heavy sound is your cup of tea, see our tips on mixing metal with producer/mixer Andy Sneap.