AmadeusMozart
R.I.P.
I am leaning towards the Monacor SPH-145HQ / DT-19SU combination. Apart from anything else there is a crossover design avaviable. But it's this I really need some help with - some elements of it I understand and others I don't. I should say at this point I was, many years ago, an electronics engineer dealing with sophisticated control systems. The crossover looks like this.
Monacor_SPH-145HQ_Crossover by Robin Martin, on Flickr
For the Bas/midrange SPG-145 circuit
L2 and C2 form a 2nd order filter. But what is R2 for?
And C1, L1 and R1 I don't understand at all.
C1, L1 and R1 are for baffle step adjustment: basically at the low frequencies the sound "wraps" around the box. At a certain level the speakers start to beam and only radiate forwards. The result is loss of bass/ lower end of the spectrum and where the roll off starts depends on the width of the baffle. How much loss there is depends on how far out from the wall they are, if not implemented the speakers will sound like not having enough bass.
R2 is to tailor the phase of the driver at crossover frequency - if the two drivers are out of phase then strange things start to happen, "lobing" or even cancellation. Lobing means stronger in certain direction, you want the main lobe to be straight forward, not pointing at the floor or to the sky.
PS Kudos on the job with the car. I once started on something similar but health intervened and I had to give up.
PS2 I would give serious thought towards phoning Wilmslow Audio and see if they'll sell you the Dolce without cabinet but with crossover. It would surprise me if they said no.