F-01

The Esoteric F-01 is a fully balanced dual mono preamplifier with the scale and architecture of a separate preamp. It includes 3 ES-Link Analogue inputs for Esoteric’s proprietary current-based signal connection from K Series and N Series digital source players. The F Series also introduces the Ultra Fidelity Attenuator System and an upgraded preamplifier power supply section. Other features include a fully balanced headphone amplifier, a dual mono MM/MC phonostage preamp and a balanced 3-band tone control.

Its ES-Link Analogue pre-outs allow an Esoteric S-05 power amplifier to be connected for a multi-amplifier system. The preamplifier can also be upgraded with the optional PS-01F external power supply, which is to be announced. An option board slot accepts the OP-DAC1 DAC board and OP-ESLA1 ES-Link Analogue input board from the previous-generation F Series models.

Ultra Fidelity Attenuator System

The amplitude of an audio signal in an active attenuator is proportional to its supply voltage. A low supply voltage limits signal amplitude, reducing dynamic range and worsening the signal-to-noise ratio. The F-01 uses Esoteric’s Ultra Fidelity Attenuator System, also used in the Grandioso C1X, with a high-voltage supply designed to maximise dynamics and improve the signal-to-noise ratio.

The stepped attenuator provides 1,120 volume steps of 0.1dB, giving more than 10 times the number of steps found in a typical preamplifier. Its UFA-1792 module is an Esoteric design manufactured using advanced process technology. The resistors required for the 0.1dB steps are produced under stringent quality control, while the materials, circuit patterns and layout have been examined for the module. Each circuit block has independent power and ground signal paths.

Balanced Dual Mono Headphone Amplifier

The headphone amplifier follows the fully balanced dual mono architecture of the linestage preamp. It provides a balanced 4-pin XLR output and an unbalanced 6.3mm output, with 600mW of fully balanced power into a 32Ω load. Gain is adjustable from 0dB to +18dB in 3dB increments to suit the connected headphones.

Dual Mono Phonostage Preamp

For analogue playback, the Esoteric F-01 includes a dual mono MM/MC phonostage preamp with independent left and right circuits. The left and right power supplies are also independent to maintain channel separation.

3-Band Balanced Tone Control (Treble / Middle / Bass)

The tone control uses a balanced dual mono circuit and can be preset separately for each input source. Treble and bass operate with variable bandwidths and centre frequencies of 14kHz and 63Hz, allowing adjustment towards higher or lower frequencies than usual for use with wide-range high-end speakers. Adjustment is available in 0.5dB steps over a maximum range of ±12dB. The 630Hz middle band can be used as a loudness preset by setting it to the minus side and combining it with tone bypass mode.

Flexible System Upgradability

The F-01 can form part of a separate-amplifier system by connecting an S-05 class A amplifier to its XLR or ES-Link Analogue pre-outs. The PS-01F external power supply can be added to the preamplifier, subject to its announcement. The option board slot is compatible with the OP-DAC1 DAC board and OP-ESLA1 ES-Link Analogue input board developed for the previous-generation F Series models.

Mechanical Construction

The F-01 chassis is designed to control vibrations that can affect sound quality, with its mechanical structure balancing rigidity and flexibility. Its total mass is 32kg. Aluminium blocks are used extensively in the enclosure to provide rigidity and reduce resonance, while the top panel uses a semi-floating structure. Esoteric’s patented isolation foot combines a spike and saucer in a structure designed to reduce mechanical stress. The amplifier block uses large heat sinks with a wave-shaped profile that disperses peak resonance from the fins.