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Compare speakers at true scale
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References
Front view — side by side at true scale
ACastle Knight 4BFyne Audio F55E
Castle Knight 4vsFyne Audio F55E
The Fyne Audio F55E stands 92.5 cm tall — about 2.5 cm more than the Castle Knight 4 at 90.0 cm. On footprint the Fyne Audio F55E is the wider cabinet (21.0 cm versus 16.5 cm). At 90 dB against 88 dB, the Castle Knight 4 is the easier load to drive and plays louder from the same amplifier. The Castle Knight 4 reaches deeper in the bass, down to 36 Hz versus 42 Hz. The Castle Knight 4 is a transmission line and the Fyne Audio F55E is down-firing ported. Both land in a similar price bracket, around $1,082 a pair.
| A | B | |
|---|---|---|
| Manufacturer | Castle | Fyne Audio |
| Model | Castle Knight 4 | Fyne Audio F55E |
| Height | 900 mm | 925 mm |
| Width | 165 mm | 210 mm |
| Depth | 270 mm | 236 mm |
| Weight | 12.5 kg | 11.9 kg |
| Enclosure | transmission-line | bass-reflex-down |
| Drivers | 2× 130 mm mid-bass, 1× 25 mm tweeter (soft dome) | 1× 19 mm tweeter (titanium dome), 1× 125 mm mid-bass (multi-fibre cone), 1× 125 mm woofer (multi-fibre cone) |
| Frequency — low | 36 Hz | 42 Hz |
| Frequency — high | 24000 Hz | 38000 Hz |
| Sensitivity | 90 dB | 88 dB |
| Impedance | 8 Ω | 8 Ω |
| Recommended amp | 25–150 W | 30–120 W |
| MAP (USD) | $1,020 / pair | $1,143 / pair |
| Where to buy | Check availability ↗ | Check availability ↗ |
| Brand website | castle.uk.com ↗ | fyneaudio.com ↗ |
| Product page | Open product page ↗ | Open product page ↗ |
Larger value highlighted in green. For low-frequency extension, lower Hz = greater bass reach, so the deeper side is highlighted.

