The ADL 600 preamplifier runs on power rails of ±300V. Most off-the-shelf, op-amp-based designs run on power rails of 10V to 18V. Higher-voltage power rails deliver more headroom, deeper lows, smoother highs, and a richer overall sound.
We only use genuine transistors, resistors, and capacitors in the ADL 600 because this provides ultra-low noise and transparency. Op-amps add noise, coloration, and harshness to a signal. You won’t find them in the ADL 600.
Power amplifiers are classified primarily by the design of the output stage and are designated Class A, B, AB, D, G, or H. In a Class A preamp, the output circuits are always on for the entire cycle of signal swing or the bias current flows at all times. As a result, Class A preamps have the most linear design, with no crossover distortion, and they deliver purer, clearer, and more musical results than the Class AB designs that are found in many preamps.
The ADL600 employs large, high quality, custom-wound, shielded input and output transformers. Among other things, these securely decouple the preamp from the outside world (the mic and the A/D or following devices), which is very important in a high-voltage tube design such as this one.
The ADL 600’s Cinemag input transformer sets the stage for the preamp’s nearly ruler-flat/linear and detailed sound; the rest of the preamp amplifies what the Cinemag delivers. No other input transformer sounds like the Cinemag does—and we tried others.
The nickel/iron-core, large-scale output transformer delivers high headroom. It will begin to saturate in a pleasing (some would say “creamy”) manner at very high levels. This adds the bit of finish to the sound.
Beyond superb sound quality, the ADL 600 is special because of its ease of use and flexibility. Each of the two input channels has separate mic, line, and instrument inputs, and you can select among four mic-input impedances, so the preamp works great with any type of microphone.
Hearing is Believing
Technical explanations are well and nice but hearing is believing. Try the ADL 600 yourself and experience the thrill of using the world’s finest tube preamp.
Features And Specs
2 input channels, each with:
adl o/s/l 1000 Mic, line, and instrument inputs
adl o/s/l 1000 High-voltage, Class A, dual-transformer, vacuum-tube preamp