Chorus

This chorus effect is a staple of lush, atmospheric guitar tones, designed to simulate the sound of multiple instruments playing in unison. This circuit offers a clever, modern take on the effect by repurposing the PT2399 echo chip—typically used for delays—as a short-modulation engine. By pairing it with a 2N7000 MOSFET, the design achieves a rich, shimmering warble that rivals classic analog bucket-brigade (BBD) designs.

The Engineering Behind the Shimmer

The magic of this chorus lies in how it manipulates time. By keeping the delay time extremely short and constantly fluctuating, it creates the "pitch-shifting" illusion that defines the chorus sound.

1. The PT2399 as a Short-Delay Core

While the PT2399 is famous for echoes, this circuit forces it into its lowest possible delay range (sub-30ms). At these speeds, the human ear doesn't perceive a distinct "echo," but rather a thickening of the original note. The high-quality internal converters of the chip ensure the modulated signal remains crisp and vibrant.

2. The 2N7000 Modulation Engine

The 2N7000 MOSFET acts as the interface between the Low-Frequency Oscillator (LFO) and the PT2399.

• The "Wobble": The 2N7000 is used as a voltage-controlled resistor to "pull" the clock of the PT2399 back and forth.

• The Benefit: Using a MOSFET provides a smooth, musical transition in the pitch modulation, avoiding the "clicking" or harsh steps found in lesser modulation circuits.

Tonal Command: Rate & Depth

This pedal features a streamlined two-knob interface to dial in everything from subtle movement to rotary-speaker effects:

• Rate (Speed): This controls the frequency of the LFO. At low settings, it produces a slow, syrupy "wave" that adds dimension to clean chords. At high settings, it creates a fast, vibrato-like shimmer perfect for lead lines.

• Depth (Intensity): This determines how wide the pitch swing is. A low depth offers a subtle "thickening" of the tone, while a high depth provides a deep, dramatic detune that captures the classic "80s New Wave" aesthetic.

Why This Design?

By using the PT2399 and 2N7000, this circuit bypasses the need for rare, expensive, and noisy vintage BBD chips. The result is a quiet, reliable, and highly tweakable chorus that retains the warmth of analog gear while benefiting from the stability of modern silicon. It’s an elegant solution for players seeking a boutique modulation sound without the boutique price tag.

INQUIRY / PRE-ORDER : channel@medamps.com

FOLLOW US

© 2026 MED AMPLIFICATION, ALL RIGHTS RESERVED