Maxon AD-999 Pro Analog Delay

The AD999 Pro combines features from two of Maxon’s most popular delay pedals into a single, powerful package.
Based on Maxon’s popular AD999 circuit, the AD999 Pro offers the same 900 milliseconds of fat, warm analog delay tone thanks to 8 x custom-made Maxon MC4107D Bucket Brigade IC’s.
Like the AD-9 Pro, the delay repeats of the AD999 Pro are filtered using Maxon’s proprietary noise reduction circuitry which reduces the aliasing, clock noise and distortion common to analogs. The result is a rounder, smoother delay repeat that doesn’t overpower the original note.
With a Dynamic range that is 18 dB wider than most delays and a maximum input level of +12 dB, the AD999 Pro can accept any signal from any source. This improved full-range response offers a better balance between low and high frequency ranges, creating a delay tone that is clear and firm while still retaining that characteristic analog warmth. It also allows the AD999 Pro to be used in line level effects loops on amplifiers.
The AD999 Pro features three Multi-Head modes controlled via top-mounted mini switches. These switches activate delay feedback loops, creating polyrhythmic repeats such as triplets and sixteenth-notes against the main delay repeat. The Multi-Head mode can create a striking Tape Echo simulation, or it can be used to create ambient effects such as large room and concert hall reverberation at lower delay time settings.

Topping The AD999 Pro off are dual outputs that allow routing of the dry and delayed signals to two separate amps or mixer channels. Both outputs feature Mechanical True Bypass via a 4PDT switch.

Tech Talk
A high impedance input buffer passes signal to a Compander stage that acts as a compressor/expander, bringing the input signal up to an ideal level and keeping it there as it decays. This is good for signal-to- noise ratio and also gives the delay chips a clean, strong signal to work with.
The eight x BBD delay IC’s are controlled by 2 of the 3 clock drivers in the pedal. The clock drivers are running the BBDs at a very low clock rate to achieve maximum delay time. This rolls off a fair amount of highs, giving the AD999 Pro a big, warm delay sound.
The delay circuit has individually switchable taps at the 3rd, 4th, and 5th BBD chips that add delayed signals from those points back in with the original delay signal. This setup is very reminiscent of the multi-head feature of old tape echoes (Roland Space Echo, etc.).
One unique thing about this setup is that you can have any or all of the taps running simultaneously, providing a big, near-oscillating wash of sound that’s very random yet organic enough to still be pleasing to the ear.
The delay and tap signals are then combined in a mixing circuit and sent through another the Compander to level everything out. Signal then goes to a mixer/amplifier that blends the clean and delay and provides a low impedance output.
The AD999 Pro features Maxon’s custom DC to DC voltage converter/regulator circuit to insure consistent performance of the effect regardless of AC power fluctuations.
The AD999 Pro features Mechanical True Bypass switching on both outputs via a Fujisoku 4PDT switch.
NOTE ON POWERING THE AD999 Pro – this pedal’s voltage regulator IC requires a high inrush current of approximately 2000 mA upon startup. When using with a Power Brick such as the Voodoo Labs Pedal Power 2+, this pedal should be connected to a high current power jack when possible.
If it is not possible to connect to a high current jack, you can power the AD999 Pro by leaving a battery in the pedal. Upon initial start-up, unplug the external DC power input cable, engage the pedal, and then plug the DC power input cable back in – the pedal will now power up normally off the external power supply until you power down your pedalboard.