I am building outboard x-overs using the Northcreek inductors on the woofers and low mid, and Solen Heptalitz inductors on everything else (it is a 6-way design with 10 inductors, 9 capacitors, 5 resistors and three adjustment pots per speaker). Needless to say if I went Duelund for caps and inductors I'd be broke, so I'm using Mundorf Supreme caps and the above-mentioned inductors!! I might spring for some Duelund resistors, however.
I did the driver induction experiment just to see how close I could get to the inductors before I heard interference - it was very surprising how much of a magnetic field they set up. If you put those inductors inside a speaker enclosure you'd better make sure they are far from the drivers.
Also, inductors will interfere with each other (look up "inductor crosstalk"). The inductors need to be well separated in space if they are in the same plane (i.e. both lying flat), I found that the bigger inductors need ~8 inches between them in that sort of arrangement. If you place them with their axes at 90 degrees, you can get them closer - see the chart I linked below:
http://techtalk.parts-express.com/showthread.php?p=1500176
Iron has a much higher magnetic permeability than air, and that causes the magnetic field of iron-core inductors to be contained in a much smaller space, so they can be placed closer together than air cores without interfering. Iron cores, however suffer from hysteresis distortion and can saturate at high power levels.
I have not heard the Northcreeks in a finished speaker yet, only on the crossover prototype board with a driver wired into them - they sound good, but I won't know any more until I finish putting the speakers back together.
I did the driver induction experiment just to see how close I could get to the inductors before I heard interference - it was very surprising how much of a magnetic field they set up. If you put those inductors inside a speaker enclosure you'd better make sure they are far from the drivers.
Also, inductors will interfere with each other (look up "inductor crosstalk"). The inductors need to be well separated in space if they are in the same plane (i.e. both lying flat), I found that the bigger inductors need ~8 inches between them in that sort of arrangement. If you place them with their axes at 90 degrees, you can get them closer - see the chart I linked below:
http://techtalk.parts-express.com/showthread.php?p=1500176
Iron has a much higher magnetic permeability than air, and that causes the magnetic field of iron-core inductors to be contained in a much smaller space, so they can be placed closer together than air cores without interfering. Iron cores, however suffer from hysteresis distortion and can saturate at high power levels.
I have not heard the Northcreeks in a finished speaker yet, only on the crossover prototype board with a driver wired into them - they sound good, but I won't know any more until I finish putting the speakers back together.