The Vagabond Tremolo embellishes upon one of the most tried and true effects of all time. Tremolo with vintage personality fused with added depth, more speed and more control.
In the simplest terms tremolo modulates volume. This definition doesn’t exude the inflection of wah, the blunt weaponry of fuzz, or the obvious psychedelic ramifications of echo. In spite of the boring definition, tremolo is a defining sound of so many classic songs and artists. Like many other things in music the early classic designs were imperfect, and those imperfections made them what they were. It made them interesting.
Harmonic and Bias Tremolo
Bias Tremolos, like some Fender black face amps create subtle distortions and alter frequency response. Harmonic tremolos, like the older brown face amps weren’t really tremolo at all. They were cross fade effects between high and low-pass filters. Because of the phase shift in the filters, they often have subtle hints of phaser or vibrato.
Both of these tremolo styles use a large bias voltage added to your guitar signal to modulate the volume. (bias tremolos in the power amp and harmonic tremolos in the preamp) The only reason that you don’t hear this added signal is because the LFO is below frequencies our ears can hear. In fact, if you take the grill cloth off the amp you’ll see the speaker moving in rhythm with the effect.
This creates some limitations in these types of effects. If the LFO went any faster you’d hear low frequency hum. If you’ve used bias tremolo before you’ve surely noticed that some sound is always audible. The volume never completely turns to zero. If it went any deeper you’d hear a popping sound as tubes turn completely off.
Tube amp LFOs also had a limited range. Most tube amp LFOs use a phase shift oscillator employing a single triode. This setup doesn’t work over a large frequency range. It can be extended with triode stages and a multigang potentiometer, but this was a time when tubes were at a premium and everything was wired by hand. Most amp companies would opt for simple rather than anything seeming unnecessarily or complicated.