The AD-999’s cast aluminum casing is rugged yet lightweight, though somewhat large for a three-knob pedal. [Maxon says this is so the components can be positioned to avoid crosstalk and other noise problems.] The pedal features true-bypass switching, and is powered via a supplied 9-volt AC adapter.
Operating the AD-999 is entirely straightforward. The Delay Time knob ranges from ultra-tight delays that sound almost like a spring-reverb—which is unusual—to nearly a second, and the Repeat knob only begins self-oscillating at its maximum position, and never really gets out of control. The pedal is atypically quiet for an analog delay, though there is some hiss and clock noise when you max out the delay time. Also, the delays exhibit very little high-frequency response.
The AD-999 does only one thing, but it does it exceptionally well. The delays are super fat and harmonically rich, making it very musical and inspiring to use. And it also takes the cake for smooth spaceship effects. This pedal isn’t cheap by any stretch of the imagination, but when it comes to superior analog delay with no-frills, it’s truly in a class by itself.