Think an old Fender Blackface amp with a tremolo circuit like a Twin or Super Reverb. Now imagine that warm, pulsating effect of the sine-wave oscillator working its magic as perfected by Leo Fender. Pretty awesome, right? Reality check: your amp doesn’t have a classic Leo tremolo circuit, or it just doesn’t work well anymore. Fact is, a lot of those old tremolo circuits get pretty dodgy over time, often ending up delivering a jarring on/off square-wave effect or a weird popcorn-popping sound.