Peterma, you don't say what your problem building them is. Is it finding parts, reading the schematic, soldering?
Some assume expensive. The coils beside the drivers are high resistance. This can mean cheap, even a spool of cheap thin hookup wire might do the job . The caps don't have to be polys, electrolytics can sound very good. The L-pads can be replaced with resistors.
What parts d you have lying around that might be useful.
Peter, where in Sydney are you?
I have some L pads you can have, but as Allen says, it's better to replace them with fixed resistors.
there's a couple of hundred dollars worth of parts in that crossover, even using cheap ones for the high resistance inductors. Good parts can be sourced from Speakerbug
I live at Ropes Crossing near St Marys, I would love to try and get them as close to the original as much as I can, but maybe the cost would be too high.
its the L-pads and inductors that start to add up.
Adjustable L-pads might be worth making, tone adjust most likely will be needed to get best sound. Or then prepare for lots of extra diy with acoustic measurements and listening tests - and collapse of museum/resale value.
Perhaps we can assist in doing your own coils. I am positive that with help of a coil calculator, we can predict diameter and inductance within a couple of percent from the original value. If there were any issues finding right magnet wire for the higher dcr inductors, adding a resistor in series would solve it.
How much does awg 18 and awg 27 magnet wire cost in Australia?
There is also the option of purchasing ready made cheap Chinese crossovers employing iron core inductors. Modifying these to meet the original marantz values would not be hard, some caps might fit also. The excess wire from one could be used to increase the inductance of another.
it could work assuming the necessary changes to the inductance/capacitance values were done. Before that, you need to get a hold of an LCR meter, either a dedicated one or a sound card based one. You could even rewire the board to suit the original schematic.