Audio T Verdict
The Fyne Audio S-Trax offers a fascinating and surprisingly effective way to enhance an established loudspeaker system without replacing its main speakers.
Its compact omnidirectional design extends high-frequency performance to 50kHz while spreading energy throughout the room rather than projecting it forwards in a narrow beam. The perceived result can be greater openness, clearer spatial information and a more natural sense of air around voices and instruments.
The adjustable output control makes it easier to match the S-Trax to different loudspeaker sensitivities and room acoustics, while its passive design requires no separate mains supply or additional amplifier channel.
It works particularly well with Fyne Audio IsoFlare loudspeakers, where published positioning measurements make accurate time alignment straightforward, but it can also be used with suitable speakers from other manufacturers.
Fyne Audio S-Trax Omnidirectional Super Tweeters
The Fyne Audio S-Trax is a compact passive super tweeter designed to extend a loudspeaker system’s high-frequency response and improve the perception of space, air and harmonic detail.
It distils technology developed for Fyne Audio’s larger SuperTrax into a smaller and more accessible design.
Its principal features include:
- Patented omnidirectional dispersion
- Time-aligned super-tweeter operation
- 25mm magnesium-dome diaphragm
- Neodymium magnet system
- Frequency response from 16kHz to 50kHz
- Third-order high-pass crossover at 16kHz
- CryoLite-treated crossover components
- Adjustable output over a plus or minus 4.5dB range
- Compatibility with loudspeakers up to approximately 98dB sensitivity
- Eight-ohm nominal impedance
- Passive operation without a separate power supply
- Compact black cabinet
- Supplied as a stereo pair
What Is a Super Tweeter?
A super tweeter supplements the existing high-frequency driver within a loudspeaker rather than replacing it.
The S-Trax begins operating at approximately 16kHz and extends the system’s response to 50kHz.
Although much of this range sits beyond conventional conscious hearing, its purpose is to preserve and reproduce high-frequency harmonic and phase information associated with musical instruments, recordings and wide-bandwidth source equipment.
When correctly integrated, the perceived changes may include:
- A greater sense of air around voices and instruments
- Improved perception of recorded space
- Clearer soundstage depth
- More natural decay from cymbals and percussion
- Greater separation between musical elements
- A more open and less enclosed presentation
- Improved perception of timing and harmonic structure
The result should feel integrated with the main speakers rather than sounding like a separate source of treble.
Omnidirectional 360-Degree Dispersion
Conventional forward-facing tweeters become increasingly directional as frequency rises.
At ultrasonic frequencies, this can produce a narrow beam of energy directed towards a relatively small listening area.
The S-Trax uses a patented dispersion system to radiate its output in every direction around the cabinet.
This 360-degree radiation pattern is designed to:
- Distribute high-frequency energy more evenly throughout the room
- Reduce narrow high-frequency beaming
- Improve reflected energy within the listening space
- Maintain a more consistent presentation across several seats
- Blend direct and room-reflected sound more naturally
- Enhance the perception of openness and spatial scale
Time-Aligned Performance
Correct positioning allows the S-Trax output to arrive in time with the acoustic output from the main loudspeaker.
With a Fyne Audio IsoFlare speaker, the S-Trax is placed at a specified distance from the front edge of the cabinet so that it aligns with the acoustic centre of the point-source driver.
Accurate time alignment helps:
- Preserve the harmonic structure of the original signal
- Reduce high-frequency phase error
- Blend the S-Trax with the main tweeter
- Avoid the impression of an added or detached high-frequency source
- Maintain stable stereo imaging
Positioning is therefore an important part of S-Trax setup rather than a purely visual consideration.
25mm Magnesium-Dome Driver
The S-Trax uses a 25mm magnesium-dome diaphragm driven by a neodymium magnet system.
Magnesium combines low moving mass with useful rigidity, allowing the diaphragm to respond quickly and extend well beyond the normal operating range of a conventional loudspeaker tweeter.
The driver is designed to provide:
- Extended response to 50kHz
- Fast transient behaviour
- Low moving mass
- Controlled high-frequency break-up
- Smooth integration with the main loudspeaker
- Consistent output through the S-Trax dispersion system
Neodymium Magnet System
A neodymium magnet provides a strong magnetic field from a compact motor assembly.
This allows the S-Trax cabinet to remain small while maintaining the control and sensitivity required for effective high-frequency reproduction.
The compact motor also supports the S-Trax’s discreet appearance when positioned on top of a loudspeaker.
16kHz to 50kHz Frequency Response
Fyne Audio specifies a typical in-room frequency response from 16kHz to 50kHz within its published -6dB limits.
The S-Trax is therefore designed to overlap with the upper response of the main loudspeaker before extending substantially beyond it.
This gradual overlap helps the additional high-frequency energy blend with the existing tweeter rather than beginning at an abrupt point above the speaker’s natural range.
Third-Order High-Pass Crossover
A passive third-order high-pass crossover limits the frequencies sent to the S-Trax driver.
The crossover begins operating at 16kHz and prevents lower-frequency energy from reaching the magnesium diaphragm.
This protects the driver and allows it to concentrate on the high-frequency range for which it was designed.
CryoLite-Treated Crossover Components
The S-Trax crossover uses Fyne Audio’s CryoLite treatment.
The process is intended to reduce unwanted electrical resistance within selected crossover and connection components.
This supports:
- Low signal loss
- Consistent crossover behaviour
- Clean high-frequency transfer
- Preservation of low-level detail
- Stable integration with the main loudspeaker
Adjustable High-Frequency Output
An output control is positioned on top of each S-Trax cabinet.
The adjustment range extends approximately 4.5dB above and below the nominal setting.
This allows the S-Trax to be matched to:
- Different loudspeaker sensitivities
- Bright or heavily damped rooms
- Different listening distances
- The output character of the main tweeter
- Personal preference
- Different source and amplifier combinations
Starting with the Output Adjustment
Begin with both S-Trax controls set to the nominal or central position.
Use familiar recordings and make small, equal adjustments to both channels. The best setting should add openness and space without making cymbals, vocals or string harmonics sound detached or exaggerated.
Suitable for Speakers up to Approximately 98dB Sensitivity
Fyne Audio specifies the S-Trax for use with loudspeakers offering sensitivities up to approximately 98dB.
The adjustable output control helps match it to speakers across a broad range of sensitivities below that point.
Speaker sensitivity is only one part of successful integration. Positioning, crossover behaviour, existing tweeter output and room acoustics also influence the final result.
Compatible with Amplifiers up to 400W
Fyne Audio’s current S-Trax product specification lists a maximum recommended amplifier power of 400W RMS.
This does not mean that a high-powered amplifier is required. The S-Trax receives the same signal as the main loudspeaker and its internal high-pass crossover limits the frequencies reaching the driver.
The amplifier must still be suitable for the main loudspeakers and used within safe operating limits.
Passive Operation
The S-Trax is a passive accessory and does not contain its own power amplifier.
It therefore requires:
- No separate mains connection
- No additional power amplifier channel
- No wireless network
- No control application
- No digital signal processor
Each S-Trax is connected in parallel with its corresponding main loudspeaker using a suitable cable.
Switch the Amplifier Off Before Connecting
Switch off the amplifier and disconnect it from mains power before adding, removing or adjusting any loudspeaker connection.
Check positive and negative polarity carefully and ensure that no exposed conductor can touch another terminal.
Parallel Connection to the Main Speakers
The left S-Trax connects to the left loudspeaker channel and the right S-Trax connects to the right channel.
Depending on the main speaker and amplifier, the connection may be made through:
- The main loudspeaker terminals
- A compatible second set of terminals
- The existing speaker-cable connection point
- A purpose-designed Fyne Audio connection cable
The S-Trax must remain connected with the same polarity as the main loudspeaker.
Audio T can confirm the most suitable connection method for the amplifier, speaker terminals and existing cable arrangement.
Nominal Eight-Ohm Impedance
The S-Trax has a nominal impedance of eight ohms.
Because its crossover restricts operation to the highest frequencies, it does not behave like a second full-range eight-ohm loudspeaker connected across the amplifier.
The electrical suitability of the complete arrangement should still be confirmed where:
- The amplifier has unusual output requirements
- Valve amplification is being used
- The main loudspeaker presents a difficult load
- More than one speaker accessory is already connected
- The amplifier manufacturer restricts parallel speaker connections
Grounding Terminal
The S-Trax includes a grounding terminal connected to its driver chassis.
A suitable grounding connection can help reduce the influence of radio-frequency interference that may otherwise mask very fine detail.
The grounding terminal is separate from the positive and negative audio connections and does not carry the normal music signal.
Use Only a Suitable Grounding Point
Connect the grounding terminal only to a grounding point supported by the partnering amplifier or system.
Do not connect it directly to a mains plug, mains-earth conductor or improvised chassis point without specific technical advice.
Designed for Fyne Audio IsoFlare Speakers
The S-Trax works particularly effectively with Fyne Audio loudspeakers using the company’s IsoFlare point-source driver.
Published positioning measurements allow the S-Trax to be aligned with the acoustic centre of each compatible IsoFlare design.
Current Audio T models designed to accept the S-Trax include:
F5S Positioning
Fyne Audio recommends positioning the S-Trax approximately 32mm from the front edge of the F5S cabinet.
Measure from the front edge of the main speaker to the corresponding reference point on the S-Trax and ensure both channels are positioned equally.
F500S, F500SP, F501E and F501S Positioning
For the F500S, F500SP, F501E and F501S, Fyne Audio recommends positioning the S-Trax approximately 44mm from the front edge of the cabinet.
The left and right units should be placed at matching distances to preserve consistent time alignment and stereo imaging.
Using the S-Trax with Other Fyne Audio Speakers
Fyne Audio publishes individual positioning measurements for a wide range of IsoFlare loudspeakers.
The correct measurement varies according to the size and acoustic centre of the main driver.
Confirm the appropriate position for the exact speaker model rather than assuming that one measurement applies across the entire range.
Using the S-Trax with Other Point-Source Speakers
The S-Trax may also be used with point-source or concentric loudspeakers from other manufacturers.
Fyne Audio recommends beginning with a position that approximates the acoustic centre of the main driver.
Some experimentation may be required because:
- The acoustic centre may not be externally marked
- Driver depth varies between designs
- The existing crossover frequency will differ
- Cabinet depth and top-panel shape vary
- The main tweeter may have different phase behaviour
Using the S-Trax with Conventional Multi-Driver Speakers
The S-Trax can also be used with conventional loudspeakers in which the tweeter and bass or midrange drivers are mounted separately.
Fyne Audio recommends beginning with the S-Trax positioned towards the front of the cabinet.
From there, small movements backwards can be compared while listening for:
- Soundstage focus
- Treble integration
- Image depth
- Vocal stability
- The natural decay of cymbals and strings
Both channels should always be moved by the same amount.
Placement on the Main Loudspeaker
The S-Trax is designed to sit on top of the main loudspeaker cabinet.
Before installation, confirm that:
- The speaker top is large enough to support the S-Trax safely
- The surface is stable and approximately level
- The cabinet finish will not be marked
- The S-Trax cannot slide during normal use
- The cable can reach without pulling on the terminals
- The omnidirectional opening remains unobstructed
Do not position ornaments, cloths or other objects immediately around the S-Trax dispersion area.
Speaker Cabinets with Sloping Tops
A sharply sloping, curved or unusually narrow speaker top may require additional support or an alternative installation method.
The S-Trax should remain stable and correctly aligned rather than resting at an unsafe angle.
Contact Audio T before installation where the main speaker does not provide a flat and secure supporting surface.
Fine-Tuning the Position
The published Fyne Audio measurement provides the correct starting point for compatible speakers.
After setting that position:
- Check that both S-Trax units are placed identically.
- Set both output controls to the same nominal position.
- Play a familiar recording with clear vocals and natural acoustic space.
- Compare the system with the S-Trax connected and disconnected at a safe volume.
- Make small, equal output adjustments if required.
- Only experiment with position after confirming the standard setup.
A correct adjustment should improve openness and integration without drawing attention to the S-Trax itself.
What Should You Listen For?
The S-Trax is not intended simply to make the system sound brighter.
Useful listening cues include:
- Greater space around a central vocal
- More natural reverberation
- Improved separation within layered recordings
- Clearer cymbal and percussion decay
- A wider or deeper soundstage
- More stable image placement
- A more convincing sense of the recording venue
- Improved clarity without added hardness
If the presentation becomes obviously brighter or detached, reduce the output adjustment or check the position.
Why Can High Frequencies Affect the Perception of Bass?
Musical notes contain a fundamental frequency and a series of harmonics extending above it.
By preserving more of that harmonic structure, a super tweeter can change the perceived definition, timing and texture of instruments across the musical range.
This does not mean that the S-Trax produces low bass. Instead, the additional high-frequency and phase information can affect how the listener perceives the complete note and its relationship with the room.
Suitable Music Sources
The S-Trax can be used with analogue and digital music sources.
Potential source components include:
- Turntables
- CD and SACD players
- High-resolution music streamers
- Network music servers
- Digital-to-analogue converters
- Reel-to-reel tape machines
- Quality radio and broadcast sources
The improvement is not limited to recordings containing measurable ultrasonic information. The S-Trax is also intended to preserve phase and harmonic relationships within the conventional audio band.
S-Trax or SuperTrax?
Choose the S-Trax When
- A compact and discreet design is preferred
- A black finish suits the main speakers
- Strong performance and value are priorities
- A magnesium-dome super tweeter is suitable
- Extension to 50kHz meets the system requirements
- F500E, F500S or F500SP speakers are being used
Consider SuperTrax When
- The flagship Fyne Audio design is preferred
- A Thin Ply Carbon Diaphragm is required
- Extension to 60kHz is wanted
- A larger cabinet can be accommodated
- Walnut or Piano Gloss Black suits the speakers
- The partnering system justifies the additional investment
The S-Trax distils the principal omnidirectional and time-alignment concepts of the larger SuperTrax into a smaller and more affordable design.
Compact Black Cabinet
The S-Trax is available in black and is designed to sit discreetly on a wide range of modern loudspeaker cabinets.
Its narrow 82mm width means it can be accommodated on speakers that may not have enough top-panel space for the larger SuperTrax.
The compact cabinet measures approximately:
- 79mm high
- 82mm wide
- 149mm deep
One Kilogram per Unit
Each S-Trax weighs approximately 1kg.
The main loudspeaker cabinet must provide a stable surface capable of supporting the unit securely without rocking or sliding.
Take particular care with narrow standmount speakers, polished finishes and cabinets with sloping upper panels.
Care and Cleaning
Switch off the amplifier before cleaning or moving the S-Trax.
Use a clean, soft and dry or very slightly damp cloth on the cabinet.
Do not use:
- Abrasive cleaning products
- Furniture polish
- Solvents
- Aerosol sprays
- Excessive water
Do not press, touch or attempt to clean the magnesium diaphragm or internal dispersion surfaces.
Key Features
- Compact passive super tweeters
- Supplied as a stereo pair
- Patented omnidirectional design
- 360-degree high-frequency dispersion
- Time-aligned operation
- Designed for placement on top of the main speakers
- 25mm magnesium-dome diaphragm
- Neodymium magnet system
- 16kHz to 50kHz frequency response
- Third-order high-pass crossover
- 16kHz crossover point
- CryoLite-treated crossover components
- Plus or minus 4.5dB output adjustment
- Top-mounted adjustment control
- Compatible with speakers up to approximately 98dB sensitivity
- Eight-ohm nominal impedance
- Maximum recommended amplifier power of 400W RMS
- Passive parallel connection
- No separate mains power required
- No additional amplifier channel required
- Driver-chassis grounding terminal
- Optimised for Fyne Audio IsoFlare speakers
- Compatible with suitable point-source speakers
- Compatible with suitable conventional loudspeakers
- 32mm published position for F5S
- 44mm published position for F500S
- 44mm published position for F500SP
- 44mm published position for F501E
- 44mm published position for F501S
- Compact black finish
- 79mm height
- 82mm width
- 149mm depth
- 1kg weight per unit
- Two-year accessory warranty subject to Fyne Audio’s terms
Frequently Asked Questions
Are the Fyne Audio S-Trax super tweeters sold as a pair?
Yes. The product contains one S-Trax for the left speaker and one for the right.
What does a super tweeter do?
It supplements the main loudspeaker’s tweeter by extending high-frequency response and reproducing additional harmonic and phase information.
What is the S-Trax frequency response?
Fyne Audio specifies a typical in-room response from 16kHz to 50kHz within its published -6dB limits.
What material is the diaphragm?
The S-Trax uses a 25mm magnesium dome.
Does it use a neodymium magnet?
Yes. A compact neodymium magnet system drives the magnesium diaphragm.
What does omnidirectional mean?
The S-Trax disperses high-frequency energy around the cabinet through 360 degrees rather than projecting it forwards in a narrow beam.
What does time aligned mean?
It means the S-Trax is positioned so that its output reaches the listener in the correct timing relationship with the main loudspeaker.
Does it only work with Fyne Audio speakers?
No. It is optimised for Fyne Audio IsoFlare speakers but can also be used with suitable point-source and conventional loudspeakers from other manufacturers.
Does it work with the Fyne Audio F5S?
Yes. Fyne Audio recommends positioning it approximately 32mm from the front edge of the F5S cabinet.
Does it work with the F500S?
Yes. The recommended position is approximately 44mm from the front edge of the cabinet.
Does it work with the F500SP?
Yes. The recommended position is approximately 44mm from the front edge of the cabinet.
Does it work with the F501E?
Yes. The recommended position is approximately 44mm from the front edge of the cabinet.
Does it work with the F501S?
Yes. The recommended position is approximately 44mm from the front edge of the cabinet.
Where should it be positioned on another point-source speaker?
Begin by aligning it with the approximate acoustic centre of the main point-source driver, then make small and equal adjustments to both channels.
Where should it be positioned on a conventional speaker?
Fyne Audio recommends beginning near the front of the cabinet and experimenting carefully from that position.
Does the S-Trax require mains power?
No. It is a completely passive design.
Does it require another amplifier?
No. It connects in parallel with the main loudspeaker channel.
How is it connected?
Each S-Trax connects to the same amplifier channel as its corresponding main speaker, with positive and negative polarity observed carefully.
Does it change the loudspeaker impedance?
The S-Trax has a nominal impedance of eight ohms, but its high-pass crossover limits its operation to the highest frequencies. Compatibility should still be checked with unusual amplifiers or speaker loads.
Can it be used with a valve amplifier?
Potentially, but the connection and impedance arrangement should be confirmed for the particular valve amplifier and output transformer.
What is the maximum amplifier power?
Fyne Audio’s current product specification lists a maximum recommended amplifier power of 400W RMS.
Which speaker sensitivities are suitable?
Fyne Audio specifies compatibility with loudspeakers offering sensitivities up to approximately 98dB.
Can the output be adjusted?
Yes. Each S-Trax provides approximately plus or minus 4.5dB of output adjustment around the nominal setting.
Where should I start with the adjustment?
Begin with both controls set equally at the nominal or central position.
Will it simply make the system brighter?
That is not the intention. Correctly adjusted S-Trax units should improve openness, spatial information and harmonic detail without producing an obviously separate or exaggerated treble source.
Why use a super tweeter when human hearing is usually limited to around 20kHz?
The S-Trax is designed to reproduce harmonic and phase information extending beyond conventional conscious hearing, which can influence the perception of space, timing and musical realism.
Can it improve CD playback?
It may still affect the perceived phase and harmonic presentation even when the source itself does not contain substantial ultrasonic information.
Can it be used with vinyl?
Yes. It can be used with analogue or digital source systems.
What is the grounding terminal for?
It provides a connection to the driver chassis that may help reduce the influence of radio-frequency interference within a suitably configured system.
Should the grounding terminal be connected directly to mains earth?
No. Use only a suitable system grounding point approved for the partnering equipment.
Which finish is available?
The S-Trax is currently available in black.
What are the dimensions?
Approximately 79 x 82 x 149mm (H x W x D).
How much does each S-Trax weigh?
Approximately 1kg.
What is the warranty?
Fyne Audio accessories carry a two-year manufacturer warranty from the date of purchase through an authorised dealer, subject to registration, proof of purchase and the full warranty terms.
Related Fyne Audio Products and Audio T Guides
Why Buy From Audio T?
- Fyne Audio S-Trax demonstrations
- Before-and-after comparisons with your main speakers
- Compatibility checks for Fyne Audio and other loudspeakers
- Accurate time-alignment and positioning guidance
- Published Fyne Audio positioning measurements
- High-frequency output adjustment
- Amplifier and impedance compatibility checks
- Parallel speaker-cable connection advice
- Grounding-terminal guidance
- Speaker-cable and connector selection
- Comparisons with the flagship Fyne Audio SuperTrax
- System and room-matching advice
- Fyne Audio warranty-registration guidance
- Ongoing system and after-sales support
Contact your local Audio T store to arrange a demonstration or discuss loudspeaker compatibility, positioning, connection and output adjustment for the Fyne Audio S-Trax.