EXTENDED OVERVIEW

It’s tough not to fall in love with the simple delay pedal. The very first effect I ever heard in a non-concert setting was a Boss DD-3, and I am now designing and building these devices 25 years later. Such is the power of the delay sound; life-changing to say the least.

Delay devices echo the output back into the signal path at a time and intensity defined by the player, and they are (usually) equipped with a mix control that functions exactly like the mix controls found on compressors and distortions alike. With these three simple controls, amazing walls of sound can be created and discharged at will. In short, even the simplest delay circuit is an amazing creative tool.

First rising to prominence in the ‘70s, coinciding with the advent of commercially available bucket-brigade chips, delay circuits have come from truly humble beginnings. When Japanese manufacturers figured out how to manufacture these chips for a fraction of the cost, delay pedals dotted the effects landscape forcefully and immediately. And as digital circuitry became cheaper than analog, so followed digital delays.

Established in 1986, Princeton Technology Corp unknowingly gave rise to the next generation of delay circuits. By manufacturing its now-infamous PT2399—an all-in-one digital IC designed for use in karaoke machines—it unwittingly developed the easiest way to DIY a delay circuit to date.

Delay circuits of any type are exceedingly difficult to design, mostly because the circuits are so huge and temperamental. Even the simplest analog design has an incredibly exhaustive component list. However, the PT2399 IC takes care of most of that in a concise package.

Our Knight School delay is a great sounding circuit that actually fits on a small PCB, and it’s surprisingly customizable if you’re into that kind of thing. You can easily dial in a lo-fi distorted sound if you so choose (past 400ms), as well as the cutoff frequency of the repeats. It’s a great starting point for one of the pedal world’s most complicated effects.

CONTROLS

TIME:  Selects the delay time, from 30ms to 400ms. If you have a higher-value pot installed here, you can get up to one second, at the expense of sound quality, hence “lo-fi”.

MIX: This controls the mixing of the dry and effected signals. When the knob is all the way down, you will hear no repeats, when the knob is maxed, you will hear only repeats, i.e. your fundamental note disappears.

REPEATS: This controls the amount of repeats the delay gives, from none at minimum to “many” at maximum. The architecture of the PT2399 chip makes it so this circuit is incapable of “self-oscillation” also known as “runaway feedback”, as some delay circuits have.