Fyne Audio F704SP

The Fyne Audio F704SP is the flagship of the SP Series floorstanders — and the most direct expression of what Fyne Audio's Special Production engineering philosophy achieves when applied without reservation to the F704's twin 300mm driver architecture. It is a 2.5-way floorstanding loudspeaker that takes the F704's IsoFlare driver and bass driver configuration and refines every element of the signal path beyond it: F1 Series crossover components, cryogenically treated throughout, in an aluminium sandwich plinth derived from the F1-12S flagship. At £19,999 per pair, it is one of the most capable floorstanders we stock, and the clearest statement of how far the SP Series engineering approach can take a driver architecture before the step into the F1 Series becomes the only remaining direction.

The distinction between the F704 and the F704SP is not one of driver size or cabinet format. Both use twin 300mm drivers. Both use the BassTrax Tractrix downfiring port system. The distinction is in the crossover and the plinth — and those two differences, taken together, constitute a transformation of what the F704's drivers are capable of delivering.

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 cone, so both drivers radiate sound from precisely the same point in space. This point-source geometry produces consistent time alignment and isotropic dispersion across the full listening area: the frequency response heard from the side of the room is the same as the response heard from the sweet spot, and the imaging stability that results is a direct consequence of this geometry rather than a consequence of careful listening position management.

In the F704SP, the IsoFlare driver is a 300mm multi-fibre cone unit 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 delivers greater dynamic headroom in the upper frequency range and a lower crossover point from the compression tweeter into the main cone, which contributes directly to the F704SP's coherence across the critical midrange-to-treble transition. A second 300mm multi-fibre bass driver crosses in at 250Hz, handling the lowest frequencies and freeing the IsoFlare unit to operate from 250Hz upward. Frequency response extends from 22Hz to 26kHz. Sensitivity is 96dB — high enough to perform well with valve amplifiers of modest output power, and equally rewarding of 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 maintains accurate phase behaviour 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 would introduce errors into the filter characteristic — errors that are audible as a subtle hardness or discontinuity at the crossover frequencies under complex musical material at higher levels.

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 the removal of a subtle hardness that becomes apparent on complex musical passages at higher listening levels: not a dramatic transformation, but a consistent and cumulative improvement that defines the character of the SP Series crossover engineering.

BassTrax and Twin Cavity Loading

The F704SP uses a downfiring port with a BassTrax Tractrix diffuser integrated into the aluminium sandwich plinth. The Tractrix profile maintains a consistent expansion angle as bass energy exits the port, reducing reflections and smoothing the bass-to-room transition — the controlled, defined bass character that the BassTrax geometry produces is meaningfully different from the looser, port-noise-prone output of a conventional reflex design under high excursion.

The twin cavity loading system — 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 from a speaker of this cabinet volume — an unusually deep figure — with the definition and control that the BassTrax port geometry and twin cavity tuning produce together.

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, reducing energy storage in the base structure and improving the definition of bass frequencies that couple through the plinth to the floor. It incorporates the BassTrax port exit, the twin cavity loading volume, and 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 twin 300mm driver architecture — 22Hz bass, 96dB sensitivity, a 75mm titanium dome compression tweeter — in the most refined crossover and mechanical implementation Fyne Audio can deliver outside the F1 Series. It suits medium to large rooms where its 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, though it equally rewards a high-current solid-state amplifier with the authority to control a speaker of this scale.

Those considering the F704SP should hear it alongside the Fyne Audio F1-10s and the Fyne Audio F1-8s — the F1 Series represents the next level of the same engineering philosophy, and the comparison is instructive at this price point. The Fyne Audio SuperTrax super tweeter is a natural complement for F704SP owners who want to extend the system's high-frequency performance further. The Fyne Audio Vintage Five is the place to start for those whose interest in the Fyne Audio range begins with the Vintage Series aesthetic.

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.

When you get in touch, you'll be speaking with Dave, Chris and Tim — experienced specialists who 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.