For its new ADL 600, PreSonus has teamed up with world-renowned tube circuit designer Anthony DeMaria to deliver what is becoming one of the most in-demand preamps on the market. During the design phase, about 20 classic circuit designs for preamps from studios like Abbey Road were studied. How could they improve on the best analog circuits? How could they get more performance, more versatility? By over building the power supply, using three tubes per channel powered at 300 V,and using low-wound transformers with lots of iron to start with, not to mention all of the magic in between. I mean Anthony is the guy who reverseengineered the legendary Fairchild 670 compressor, so I felt pretty fortunate to have the ADL 600 on my desk, even for a little while. As I mentioned, the tube plates are powered with 300 V to offer a huge amount of headroom. Also, the ADL 600 has a frequency response of 10 Hz to 45 kHz - quite the achievement for a tube pre with this high of a plate voltage. Also worth noting is its transformer in and out design and its three tubes per channel - one 12AT7A and two 6922s.
Mullen, Joe (2014) PreSonus ADL 600 Tube Mic Preamp. In: Professional Sound, Vol. 25, No. 6, pp. 27. Available at https://openmusiclibrary.org/article/847572/.