How different are the drivers (tweeter and woofer) between DIY available and commercial customised ProAcs?
The DIY speaker is the closest possible attempt at replicating the ProAc 2.5 given the lack of public access to the ProAc customised Scan Speak 18W/8535 woofer that is used. But with Jacq’s crossover modifications and your chosen better quality parts it is believed the difference can be compensated or exceeded. Reported and measured differences of the commercial ProAc 18W/8535 type woofer and those available from Scan Speak to the public appear to be minimal. Visually the customised woofer has about 20% less rough fibre lumps on the cone surface, and basic measurements show approximately 5 dB higher response in the 2500-3000hz region for the non-customised woofer.
