The Nautilus brings the dual-mono layout onto a single chassis. We start with our most versatile circuit, the Mogwai, and go about creating two separate amps that share a single chassis. 2 Power Transformers, Separate Power Supplies, Chokes, and input transformers. The amps are built with separate turret boards, with the one shared component being the input tube, volume control, and outputs. We were unconstrainted with parts selection and layout and chose the most robust power transformer and widest/least distortion output transformers we could find.
The Nautilus’ hand build nature and part selection necessitated a robust hand fabricated chassis. We partnered with our existing CNC metal fab house to build a 12 gauge steel chassis with bracing that could support the 40lbs of transformers without a hint of strain. In total, the Nautilus is 55lbs before packing. We additionally choose to cover all the transformers and business end of the amp with a gorgeous chrome cover.
The Nautilus is a classic and decidedly prosaic design, as it employs turrets and point-to-point wiring & there is no silicone, ICs, or regulators. We consider this a standard-bearer of purest audio with an American sensibility. The Nautilus is built in a way few modern amplifiers are. This is not due to intrinsic inferiority, but rather it is impossible to rush and is incredibly expensive to produce. Some of the most familiar tube amps ever produced utilize this method, including; McIntosh, HK, Leek, Quad, & Western Electric. These amplifiers demand to be played and built to last a lifetime.
The Nautilus does not use a voltage divider network but depends on transformers instead. We use multiple dedicated taps for headphones to offer a dedicated selection for the most comprehensive range of headphones.
The Nautilus has been described as a tube integrated amp for personal audio users. We mean by this, the Nautilus allows for five separate impedances to be selected for system matching and has a pair of 8ohm 5 way binding posts. The speaker vs. headphone output is selected with a small toggle switch on the back of the amp. This simple addition was not without compromise. You can choose between headphones or speakers without wiring changes to your system.
Transformers are one of the most special aspects of the amps. The Nautilus performance is made possible with custom wound ultra-high quality output transformers from Transcendar, which provide excellent frequency extension and a flat response.
Cinemag transformers are used as input transformers for XLR to RCA conversion.
The input of Nautilus unitizes input transformers for reduced noise floor, greater clarity, and sub-bass response.
For this reference amplifier, we paired the finest coupling caps, Jupiter copper foil in wax caps. The increases in micro-detail retrieval were remarkable.
Volume control is handled via a 24step stepped attenuator. This ensures precise channel matching.
The Nautilus allows for a wide range of tubes, including 6l6gc through KT90s. KT120s and KT150s are not compatible. The tube complement form factor is spec’d as a matched pair of 6L6GC STR or KT88, a single 12AX7, and two 5AR4 or 5U4 rectifiers.
The Nautilus utilizes a single-ended Class A operation with zero feedback to provide the essence of sound, strictly old-school SET sound.
Bench report with 5751 inputs with 5ARA4 recifiers and KT88's
Input sensitive: with 5751 input @ 1.72V P-P
Noise: @ 300ohm/HiZ 1.33mV RMS
Noise: @ 100ohm 1.1mV RMS
Noise: @ 32ohm 650mV RMS
Noise: @ 8ohm LoZ 430mV RMS
Max Power @ 8ohm @ 8watts RMS
Max Power @ 32ohm@ 5watts RMS
Max Power @ 100ohm @ 6watts RMS
Max Power @ 300ohm @ 6watts RMS
Ultra-wide bandwidth; 8hz to 26khz @ 1 watt
Compatible with nearly every headphone.
Power and Noise specs are dependent on tube selection.
Actual size is 17.5"wide, 14.5"deep, 7" tall
Amp weighs in at 68lbs/93lbs shipped in a large Pelican style case.