Advice on eBay Amp Modules and PSU's please.

[Qwin]

Ah, I'm with you, I'm not familiar with miniDSP so you had lost me at "coefficients calculator".

Rod Elliot does PCB's to make a real world Linkwitz Transform circuit that can be wired in front or behind of an analogue active filter and this is what grabbed my attention.

The SB Acoustics driver I was looking at plots out at F3 approx 42.5Hz, Qtc 0.707 in a 33L sealed box. It has a gentle roll off so 10Hz down (32.5Hz) it is almost exactly at -6db. All the advice for using the transform seems to suggest not being too ambitious by setting your target frequency too low. Aiming at 32.5Hz for my F3 point would only require a 3dB lift at that frequency, which would double the power requirement in theory. This should be within the drivers capability, so it is an itch I may have to scratch at some point.

You would be surprised what the BK XLS200 can produce, they only quote a -6db figure which is 17Hz, this is only achievable with the crossover control at its lowest setting of 40Hz. Using a pair of them, with a bit of room reinforcement, I think an F3 of 25Hz would not be far from the mark.

To be honest, my thoughts are moving away from subs. The idea of a wide range 5" driver mated with the woofer above for reasonably low bass, maybe adding the Transform circuit at a later date, is more appealing.