Acoustic guitarists performing in larger venues use amplifiers to boost the volume of their instruments. Unlike electric guitar amps, acoustic amplifiers are usually designed primarily to project the tone rather than modify it. The settings that work most effectively will vary based on the acoustic amp, guitar, pickup design and room acoustics. There are some recommended settings that work fairly well regardless of these variables. The recommended settings are also a good starting point for trying to work out the best settings to use when amplifying an acoustic guitar.
The tone settings of an acoustic amplifier are usually designed into three frequency spectra: bass, mid and treble. Each control will reduce or boost the associated frequencies when adjusted. The recommended setting for the tone controls on an acoustic amp is the neutral setting. This is the setting where the tone control does not reduce or boost the guitar signal at all and is usually the “5” setting on most acoustic amps. This is also the best starting point for attempting to work out the optimum settings for your particular acoustic guitar.
Increasing the volume is the main purpose for amplifying an acoustic guitar. The recommended setting for turning on an acoustic guitar is “1,” the minimum setting. The acoustic amp will play little, if any, of the guitar signal through the speaker. The volume is then increased to the desired setting after it is turned on. The reason it is started so low is to avoid feedback. Feedback occurs when the sound produced by an amp is fed back into the amp through a microphone or pickup. This increases the power of the signal to the amp, which increases the amount of the signal going to the microphone or pickup. This process keeps looping until the signal to the amp is so large that it produces a loud, high-pitched squeal. If the amp is turned to a higher volume, any feedback could cause hearing damage or could damage the acoustic amp speaker. Dialling the volume up slowly after the amp is on will give you more control over the amp. Stop turning up the volume as soon as you hear feedback. Adjust the notch control on the acoustic amplifier before turning the volume to the desired level.
Notch Filter Setting
The notch filter setting on an acoustic amp is used to eliminate feedback. Unlike the other acoustic amp settings, there is no recommended setting for the notch filter. The frequency at which feedback is occurring will always vary based on a number of factors. You will need to readjust the notch filter any time one of these variables is changed, such as using a different guitar or moving the acoustic amp to a different room. The best setting for the notch filter will completely remove the feedback. This can only be found by trial and error. When the amp volume is just high enough to hear the feedback, turn the notch filter knob until the feedback disappears.