Gain on the Amplifier

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How does adjusting the gain control affect the sound? What exactly is the difference between adjusting gain and volume? We explain the technical aspects of gain and how its settings impact the sound.

What Exactly Does Gain Mean on an Amplifier?

To approach the optimal settings, we first need to understand the function of the gain control on the amp. Let’s start by looking at how tube amplifiers or tubes work: The signal from the input source is processed in the preamp, passed to the power amp, and then boosted to a level that can be converted into acoustic vibrations by connected speakers or cabinets.

While the power amp level only affects the amp’s volume, the gain control does much more: It influences the input signal level in the preamp before it reaches the different amplifier components. This affects the amplifier’s level, i.e., volume, but this is more of a side effect.

How Does the Gain Control Affect the Sound?

Turning the gain control influences the volume, but its main function is different: By increasing the input level in the preamp, the guitar’s sound is fundamentally changed and reproduced differently as the signal is further amplified. The increased input load puts more strain on the preamp and its tubes, causing them to overdrive and distort the signal. The English term “distortion” aptly describes what happens to the signal:

The electron tubes work near their load limits, adding linear harmonics to the signal, resulting in typical tube distortion. However, the signal in the preamp is not yet fully processed and is further boosted by the power amp. The result: an aggressive, penetrating, and very harsh distortion sound. With moderate gain settings, a softer, less aggressive sound can be achieved. Lightly driven preamp tubes produce cleaner, less gritty distortion with a softer tone.

Distinguishing Gain and Volume Controls

When the gain on the amplifier is adjusted at lower levels, a significant increase in volume can be observed. However, these functions serve different purposes. While the gain control drives the preamp, the volume control increases the overall loudness of the system, primarily affecting the power amp working later in the amp’s internal sequence.

The classic power amp tubes are responsible for boosting the signal to a level that stimulates the speakers to produce sound – converting electrical signals into mechanical movement. A cranked volume pot can also produce considerable distortion – in the context of tube amplifiers, power amp distortion or saturation is referred to as overdrive. The sound of a driven power amp is softer and more natural than distortion. Overdrive has a woody tone, reminiscent of the well-utilized EL34 tubes in Jimi Hendrix’s power amps during his legendary Woodstock performance or Malcolm and Angus Young’s work with AC/DC.

Setting the Amplifier Gain – Examples

Tube amplifiers are among the most powerful and versatile amps available to guitarists. In addition to effects like reverb, the type of distortion used is crucial. Here are three basic settings every guitarist should try.

Clean Sound with Character

A crystal-clear clean sound can be captivating, but a well-balanced amp’s characteristic, rough voicing is especially atmospheric. Achieving this sound requires care and finesse. Both the preamp and power amp are equally driven, giving the sound a distinctive quality. A great example of combining minimal preamp and power amp saturation is the song “Windowpane” by the Swedish band Opeth. Band mastermind and guitarist Mikael Akerfeldt skillfully keeps the sound just below perceptible distortion without losing the structure of the gain on the amplifier.

British Rock-Sound

Fans of AC/DC, The Who, and similar bands take note: Not all British-sounding bands are from the UK, but their equipment heavily influenced their sounds. The widely used amps from Marshall, Orange, and Vox often feature the popular EL34 tube in the power amp. This tube provides structured, assertive power amp distortion. However, achieving genuine, full-sounding power amp distortion requires very high volumes!

Modern Distortion Sound

What would heavy metal be without a well-overdriven preamp sound? Bands like Metallica, Rammstein, and Trivium owe their sound to well-used gain controls – regardless of the ear-splitting volumes! This is characterized by a mid-heavy, cutting, and penetrating tone that retains structure and the often-cited “tightness” effect even at high tempos.

Setting the Gain on the Amplifier – Conclusion

Gain and volume controls are sometimes used almost synonymously by some musicians. However, their technical characteristics are fundamentally different. Gain on the amplifier primarily affects the preamp, sending a “hot” signal to the power amp. Achieving the desired sound requires balancing gain and volume settings – experimentation is key to the search for the perfect sound!
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Image sources:
Title image: © si evans – stock.adobe.com
Electric Guitar Amp: © CaptureMedia – stock.adobe.com
E-guitar player adjusts amplifier: © LIGHTFIELD STUDIOS – stock.adobe.com