Source Audio One Series True Spring Reverb with Tap Tempo Switch New | On Order

The True Spring Reverb also allows you to combine any of its iconic spring reverbs with any of the pedal’s three tremolo effects. The True Spring’s tremolos are the same organic effects that originally appeared in our Vertigo Tremolo – the winner ofGuitar Player’s“Hall of Fame 2015” andPremier Guitar’s“Premier Gear Award.”

• Opto Tremolo:Optical tremolo (a.k.a. “Photocell Tremolo”) is the effect found in many combo amps of the 1960s. This version of tremolo relies upon a neon light bulb and a light dependent resistor called an “optocoupler.” The non-symmetrical aspects of the light and the optocoupler give the tremolo a distinct choppy character. 
• Harmonic Tremolo:This unique effect first appeared in Fender™  “brownface” amps made between 1959 and 1963, which alternately modulated the levels of bass and treble frequencies in the audio signal. The result is a very pleasing and complex tremolo that has characteristics reminiscent of a phaser.
• Bias Tremolo:This approach to tremolo involves using an LFO to modulate the bias voltage of the tubes in an amplifier. This essentially pushes the tubes in and out of saturation. The result is a smooth amplitude modulation with a mild overdrive created by the tube saturation.

But it gets even better! You also receive a Tap Tempo Switch!