Fyne Audio F704SP

The F704SP is Fyne Audio's Special Production interpretation of the F704 — a 2.5-way floorstanding loudspeaker that takes the F704's driver architecture and upgrades it with F1 Series crossover technology, cryogenically treated components, and an aluminium sandwich plinth derived from the flagship F1-12S. The result is a speaker that uses the F704's 300mm IsoFlare driver and 300mm bass driver in a substantially more refined signal path, with measurable improvements to crossover phase accuracy and component quality throughout. At £19,999 per pair, it is the most ambitious floorstander in the SP range and one of the most capable speakers we stock.

The distinction between the F704 and the F704SP is not primarily one of driver size or cabinet format — both use twin 300mm drivers and the same BassTrax Tractrix port system. The distinction is in the crossover: premium ClarityCap capacitors, Vishay resistors, and cryogenic treatment throughout the crossover assembly. These are not cosmetic differences. Cryogenic treatment reduces grain in metallic conductor materials, which affects signal transmission in the crossover at a level that is audible in direct comparison. The aluminium sandwich plinth adds mechanical stability and bass dispersion beyond what the standard F704 plinth provides.

IsoFlare Driver Technology

The IsoFlare driver combines the bass/midrange cone and the high-frequency compression tweeter on a shared axis — the tweeter fires from the centre of the bass/midrange cone — so both drivers radiate sound from the same point in space. In the F704SP, the IsoFlare driver is a 300mm multi-fibre cone with a 75mm titanium dome compression tweeter — a substantially larger compression driver than the 25mm units used in the F500 and F700 Series below it. The larger compression driver gives greater dynamic headroom in the upper frequency range and a lower compression tweeter crossover point, which contributes to the F704SP's coherence across the critical midrange-to-treble transition.

Below the IsoFlare unit, a second 300mm multi-fibre bass driver crosses in at 250Hz, handling the lowest frequencies and freeing the IsoFlare driver to operate from 250Hz upwards. Frequency response extends from 22Hz to 26kHz. Sensitivity is 96dB — high enough that the F704SP will perform well with valve amplifiers of modest output power, though it equally rewards a high-quality solid-state amplifier with the drive current to control a 71.5kg speaker cleanly.

F1 Series Crossover Technology

The crossover in the F704SP is a bi-wired passive design using ClarityCap capacitors and Vishay resistors throughout — the same component specification as the F1 Series. ClarityCap capacitors are selected for low dielectric absorption and high self-resonance frequency, which keeps the crossover's phase behaviour accurate at the crossover frequencies of 250Hz and 850Hz. Vishay resistors offer very low inductance compared to wirewound alternatives, which matters in crossover applications where frequency-dependent impedance variation in the resistor itself would introduce errors into the filter characteristic.

All crossover components undergo cryogenic treatment — cooling to cryogenic temperatures and returning to ambient at a controlled rate — which relieves internal stress in the metallic conductor materials and reduces grain boundaries. The audible result, in direct comparison with an untreated crossover using the same components, is a reduction in a subtle hardness that becomes apparent on complex musical passages at higher listening levels.

BassTrax and Twin Cavity Loading

The F704SP uses a downfiring port with a BassTrax Tractrix diffuser integrated into the aluminium sandwich plinth. The twin cavity loading system — a feature derived from the F1 Series — combines the main cabinet volume with a second cavity in the plinth, tuned to extend bass loading and improve the transition between the main cabinet and the BassTrax port output. The practical result is 22Hz bass extension — an unusually deep figure for a speaker of this cabinet volume — with the controlled, defined character that the BassTrax port geometry produces rather than the looser, port-noise-prone bass of a conventional reflex design under high excursion.

Aluminium Sandwich Plinth

The plinth is a sandwich construction using aluminium skins over a high-density core — derived directly from the F1-12S flagship. The aluminium sandwich provides significantly greater rigidity than a conventional MDF plinth, which reduces energy storage in the base structure and improves the definition of bass frequencies that couple through the plinth to the floor. It also incorporates the BassTrax port exit and provides the mounting points for the adjustable floor spikes.

Technical Specifications

Who Is It For?

The F704SP is for the listener who wants the F704's driver architecture — twin 300mm drivers, 22Hz bass, 96dB sensitivity — in the most refined crossover and mechanical implementation Fyne Audio can deliver outside the F1 Series. It suits medium to large rooms where the speaker's dynamics and deep bass extension can develop fully. The 96dB sensitivity makes it compatible with a wide range of amplifiers, including quality valve designs at relatively modest power outputs.

Those considering the F704SP should compare it directly with the Fyne Audio F1-10s and the Fyne Audio F1-12s — the F1 Series represents the next level of the same engineering philosophy. The SuperTrax super tweeter is a natural complement for F704SP owners who want to extend the system's high-frequency performance further. The F701SP is the SP Series standmount for those who want the same engineering approach in a smaller form.

Buying from Martins Hi-Fi

Martins Hi-Fi has been in Norwich since 1968. Elizabeth Gould runs the business today, and we stock only brands we have heard properly and stand behind. The F704SP is available to hear in our Norwich showroom — a speaker of this scale and price deserves a proper audition, and we will arrange a demonstration on a relevant system. Dave and Chris can advise on amplifier matching, room suitability, and how the F704SP compares with the F1 Series above it.

Contact us at info@martinshifi.co.uk, call 01603 627010, or WhatsApp on 07554 687137. You can read more about how we work on our Why Martins Hi-Fi page. We are at 85–91 Ber Street, Norwich, NR1 3EY.