Height: 1020 mm
any major internal volume (2 litres or more) changes if adding extensive bracing.
of finished speaker should be around 24kg/53lb, however choice of lighter weight materials may not affect the sound.
Port is 140mm long by 75mm internal diameter and located about 350mm from top of
cabinet, and if desired with internal flanges placed at both port ends inside the cabinet to reduce air turbulence (use either 100 x 100mm square MDF which can also brace side walls or PVC pipe flange)
Tweeter positioned 50mm from top of cabinet and off set 35mm from side edge (Note: CAD drawing mistake should read 84mm from side of cabinet not 74mm), with 10mm gap between drivers. Woofer located 25mm from side edges or centred in middle of cabinet and 160mm from top. Both drivers are recessed into the cabinet.
Cabinet material and bracing: 25mm medium
density fibreboard (MDF) front and back, 18mm sides/top and bottom, single
150mm wide brace around the port or none at all.
It appears some
ProAc 2.5 models were braced while others are not and the choice is entirely yours to make. Reports from builders indicate both sound very good. CAD drawing brace shown is positioned under the port in the middle of the cabinet height.
Cabinet lining is 3-5mm bituminous felt damping or similar mass loaded
material, 30-50mm polyester (Dacron 200g/m2 density) stuffing/lining. Wall lining and damping is added to all internal walls, except the front wall. It is important not to over specify or use too much lining so the correct amount and density of lining is used in order to maintain the same voice balance of the speaker. This can have more effect on the sound than other over specified and expensive crossover parts (capacitors and inductors). Over stuffed cabinets will result in undesirable and constrained sounding speakers with less bass and midrange voicing. If you cannot find the correct density or thickness, simply peel away estimated amounts of lining.
Cabinet internal volume is 34 litres after wall damping is inserted. However, up to 38 litres volume have been reported to offer deeper bass extension. Changes to cabinet dimensions for this should be done by increasing the depth and keeping the front baffle dimension the same at 225mm.
Install 25mm thick plinth that overlaps by 20mm on all sides, on spikes which improves stability and bass response.