There are usual one or two volume controls on an amplifier. As of fall 2014, Fender amps equipped with a presence control include the ’59 Bassman LTD, ’57 Band-Master, Blues Deluxe Reissue, Hot Rod DeVille 212 III, 410 III and ML 212, Hot Rod Deluxe III, Blues Deluxe Reissue, and GB Hot Rod Deluxe.So this one is pretty obvious. Presence controls were found on several notable Fender “tweed” amps of the 1950s. The louder you play, the more it does and the more noticeable it becomes. It changes the “texture” of the distortion and adds complexity to the sound, making the amp feel a little “less predictable” for higher notes.Īs you can see then, the function of the presence control varies with volume. When pushing an amp into distortion, though, the presence control behaves differently. When playing an amp cleanly, increasing the presence control simply results in more upper midrange and treble. Also, it decreases the amp’s ability to precisely control the actual speaker cone at high frequencies-this is what makes the amp sound wilder and raspier in a way that the treble control knob isn’t capable of. Increasing the presence control decreases high-frequency-only feedback in the power amp, which makes the amp distort more easily for higher notes. Because of the nature of power amp design and function (specifically power amp feedback, the science of which fills volumes if not entire libraries) the presence control affects upper-mid and high frequencies in a completely different way that than the normal tone controls found in the preamp stage. Here’s where things get a little complicated, but hang in there with us. Turning it up actually does boost part of the frequency band. Technically, it’s a “high frequency shelving boost” control, which is much like the treble control on a traditional stereo. The presence control, on the other hand, resides in the power amp stage. These tone controls are generally “subtractive”-that is, they don’t boost anything they control the amount of frequency band removed from the signal. Your amp’s traditional tone controls-“bass,” “mid” and “treble”-reside in the preamp stage and thus accomplish their work before the signal reaches the power amp. The preamp stage comes first and is where most of the tone shaping happens the power amp stage comes second and provides the muscle that blasts your sound out into the world and makes the neighbors call the cops. Namely, that an amp consists of at least two “sections”-a preamp stage and a power amp stage. To explain what a presence control does in greater detail, let us note a fundamental basic of amplifier design.
Nor does the presence control affect the tone in the same manner as the amp’s “mid” and “treble” tone controls.
Saying that the upper-mid and treble frequencies become more present doesn’t exactly mean they become “louder” in the sense that an amp’s volume control affects all frequencies evenly. The quality of this livelier, wilder tone is typically described as being more “present,” thus the name. What does it do? Well, it controls “presence", which boosts upper-mid and treble frequencies in a specific manner that makes the tone sound notably livelier a little “wilder” than normal. One of the most confusing controls that has appeared on Fender amplifiers over the years is the "presence" control.
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