The drive units form the heart of any speaker system, and their quality is the key to its sonic capability. Castle drive units are developed to the highest standards, often featuring innovative technology normally found only in the most expensive designs.
Most of the bass units in our range feature cones made from woven carbon fibre, a light yet exceptionally stiff material with good internal damping, properties which led Castle to pioneer its use in bass mid drivers. Likewise, we use Kapton for our voice coil formers because of its exceptional power handling ability. Now, for the first time, we have introduced two new elements to our drive unit design - the use of T-shaped poles in the magnet assembly and copper coated aluminium voice coil wire. The former allows a far more linear motion to be maintained, improving accuracy and dynamics while reducing distortion. The latter results in a reduction of the moving mass of the driver, a vital parameter in producing speakers capable of maximising the impact of modern source components and programme material.
We have designed our tweeters to match the sonic performance of our bass units and so to enhance the musical accuracy of all Castle speakers. They offer extended and substantially flat response characteristics with very low distortion and are married with bass units through crossovers built with the highest quality components.
TPT (Twin-Pipe Technology) Loading Design
Castle’s unique Twin-Pipe Technology (TPT) transforms the performance of all floor-standing models with the use of the cabinet’s internal volume to extend bass response diminishing the need to use unruly reflex ports.
TPT is a new generation of transmission-line, vented through the speaker base, which prevents port output coupling with the room modes. A meld of quarter wave loading and reflex loading, achieving what is essentially a mass loaded quarter wave reflex pipe.
In most loudspeaker designs, room modes are easily excited by forward or rear-firing reflex ports, which can cause resonance and a resulting ‘boom’ at particular bass frequencies. While this can give the impression of an impressive bass response, this boom frequency masks all others making bass indistinct and slow.
The TPT system instead couples the bass response within the cabinet enclosure, using a twin-pipe quarter wave design to provide a smooth and even bass response which augments that from the main bass driver with clarity.