The ADL 600 from PreSonus is a two-channel, high voltage tube microphone preamplifier designed by Anthony DeMaria. The unit is a Class A discrete design with three military-grade vacuum tubes per channel, operating at voltages of +/-300V power rails for maximum tube tonality and headroom. The unit was designed for the ultimate in sonic performance, ease of use and input flexibility.
The input selector allows for selection between Hi-Z instrument input, line input and four different microphone impedances. A high pass filter is a rotary switch with three filter settings for passively controlling room rumble and low frequency noise. The input gain attenuator is a military-grade rotary switch delivering 5dB step increments and a total preamplifier gain of over 72dB, sufficient for even the most demanding microphone application.
The output stage is controlled by a fully variable conductive plastic attenuator delivering +/-10dB of fine tune trim adjustment. The ADL 600 includes 48V phantom power and a -20dB pad per channel. Also included are fast-acting eight-segment LED meters for the accurate detection of fast transients and peaks, as well as large high quality analog VU meters for metering output level. There are no op-amps or integrated circuits (IC's) in the signal path to ensure the purest sound possible. The dual transformer design also ensures ultra low noise operation with maximum common mode rejection.