Simply the Best
We make some very good tube preamps, and we are confident that you enjoy using them. But the ADL 600 is at another level. Rumor has it that some people are willing to sell their left eyeball to get one. And while we don’t accept eyeballs as payment, we do agree that the ADL 600 is the finest tube preamp money can buy. Not the finest for the price. The finest—period.
Designed with famed tube-circuit designer Anthony DeMaria, the ADL 600 employs a distinctive Class A, discrete design with three top-grade vacuum tubes per channel, operating with ±300V power rails for maximum headroom and superb tone. The dual-transformer design also ensures low-noise operation, with maximum common-mode rejection.
We use only the finest components, including switched attenuators, analog VU and LED meters, and custom-designed, proprietary transformers. There are no op-amps or ICs in the signal path. We went high-end all the way, right down to the last polypropylene film capacitor.
The result is an ultra-low-noise tube preamp with a big, warm, smooth, clear, distinctive sound. It produces big, smooth, and articulate vocals; deep and tight bass guitars; and rich, full mixes. It makes virtually anything you run through it sound better.
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.
Most mic preamps have a fixed microphone-input impedance of between 1 and 2 kΩ. The ADL 600 provides variable microphone-input impedance, which can be set at 150, 300, 900, or 1500Ω.
As the impedance on the ADL 600 is lowered, a resistive load is put on the microphone. This will not damage the microphone but lowering or raising the impedance can create subtle coloring and filtering effects, enabling you to get a wider variety of sounds.
In general, a lower input impedance can add color to the mic to produce effects that simulate a “darker,” or more “closed-in” tone, or that change the mic’s apparent sensitivity. This effect is easier to notice on passive microphones (ribbon or moving coil) than on active microphones (condensers or active ribbons/dynamics).
In addition, some microphones are finicky about impedance; with variable impedance, you can make virtually any mic deliver its best performance.
The ADL 600’s high-pass filter employs a rotary switch with three filter settings (40 Hz, 80 Hz, and 120 Hz at 6 dB/octave) for controlling room rumble and low-frequency noise.
The input-gain attenuator is a military-grade rotary switch that provides eight 5 dB stepped increments and a total preamplifier gain of over 73 dB. The output stage is controlled by a fully variable attenuator that delivers ±10 dB of fine-tune trim adjustment, enabling you to dial in the perfect gain structure for any application. And of course, you get +48V phantom power, polarity inversion, and a 20 dB pad, controlled by big, sturdy, military-grade switches.
We didn’t skimp on metering either. Fast-acting, eight-segment LED meters accurately detect fast transients and peaks. Large, backlit analog VU meters display output levels, and a -6 dB switch lets you meter particularly hot signals.
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.