Review Velodyne MicroVee X:Design and Technology
The enclosure of the new MicroVee is the same as that of the MicroVee MKII, consequently the "X-cube" also has an edge length of 23 centimetres - that's hardly more than the width of a DIN A4 sheet of paper. In relation to the size of the drivers, the MicroVee X's enclosure therefore has little internal volume, and this circumstance demands special attention, even though the enclosure has no reflex tuning: Moving air cannot escape inside a closed construction anyway, but a small enclosure is more easily excited to vibrate. The driver placement and arrangement of the MicroVee X does its part to avoid compression effects and cabinet vibrations, but more on that in a moment. The be-all and end-all in the case of a closed subwoofer remains a stable cabinet, which is why the engineers continue to rely here on the extremely robust construction that has already proven itself in the predecessor.
It includes a circumferential aluminium profile and an aluminium baffle, with all parts having a high wall thickness. The rear connection terminal is also made of aluminium; here, too, the material thickness ensures particularly high torsional rigidity. Avoiding resonances, however, is only half the battle: The enclosure must be hermetically sealed so that defined pressure conditions prevail. To achieve this, the connector panel and the chassis are precisely fitted; then the joints are sealed on the inside. The characteristic wave pattern on the cabinet surfaces adds an attractive design accent, but also serves to additionally stiffen the cabinet.
Digital signal processing is handled by a DSP from Analog Devices; it realises all adjustable parameters and also offers protection against overdriving. The algorithm gently limits the level to avoid abrupt "holes". While the predecessor used a Class D module, the amplification stage of the MicroVee X is built discretely in Class A/B topology: Four 180-volt MOSFET power transistors provide a remarkable 34 amps of current and enable a sovereign output power of 300 watts - during impulse peaks, the power amplifier can release up to 800 watts of power. The power supply is generously dimensioned and is fed by a fast switching power supply with two 650 volt MOSFETs with a current delivery capacity of 17 amps.
An active 6.5" driver is responsible for power delivery; its drive system is equipped with a powerful double ferrite magnet. The second key feature of the current evolutionary stage is the diaphragm: instead of the aluminium diaphragm used up to now, the new chassis has a diaphragm made of carbon fibre mesh, which is particularly resistant to partial vibrations. The air moved by the active driver excites two laterally positioned 6.5" passive radiators, whose diaphragms are also made of carbon fibre mesh. First and foremost, they considerably increase the effective sound-radiating area, but in addition, they also relieve the cabinet through their movement.