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References
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AHarbeth Monitor 30.3 XD2BCastle Windsor Duke
Harbeth Monitor 30.3 XD2vsCastle Windsor Duke
The Castle Windsor Duke stands 47.0 cm tall — about 1.0 cm more than the Harbeth Monitor 30.3 XD2 at 46.0 cm. At 90 dB against 85 dB, the Castle Windsor Duke is the easier load to drive and plays louder from the same amplifier. The Harbeth Monitor 30.3 XD2 reaches deeper in the bass, down to 50 Hz versus 52 Hz. The Harbeth Monitor 30.3 XD2 is a sealed cabinet and the Castle Windsor Duke is rear-ported. Both land in a similar price bracket, around $6,025 a pair.
| A | B | |
|---|---|---|
| Manufacturer | Harbeth | Castle |
| Model | Harbeth Monitor 30.3 XD2 | Castle Windsor Duke |
| Height | 460 mm | 470 mm |
| Width | 277 mm | 280 mm |
| Depth | 275 mm | 346 mm |
| Weight | 11.6 kg | 13.5 kg |
| Enclosure | sealed | bass-reflex-rear |
| Drivers | 1× 25 mm tweeter (ferrofluid-cooled dome), 1× 200 mm mid-bass (RADIAL polymer cone) | 1× 200 mm mid-bass (woven polypropylene), 1× 28 mm tweeter (micro-fibre dome) |
| Frequency — low | 50 Hz | 52 Hz |
| Frequency — high | 20000 Hz | 22000 Hz |
| Sensitivity | 85 dB | 90 dB |
| Impedance | 6 Ω | 8 Ω |
| Recommended amp | — | 30–150 W |
| MAP (USD) | $6,290 / pair | $5,760 / pair |
| Where to buy | Check availability ↗ | Check availability ↗ |
| Brand website | harbeth.co.uk ↗ | castle.uk.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.

