Hello all,
here is my DCX464 crossover layout - it contains 4 coils. The bottom part is low pass for the mid part (LCL) and the upper part has a highpass (LC) on the left and a notch filter inductor on the right. The board is now 240 x 240 mm. The C-C distance of the inductors as shown is 170 mm along the edges. The squares are other components and terminals. Can I get the board smaller by rotating the inductors better? I could follow the orientation rules for two or three, but what would be the preference when having 4 with these functions? I think I can leave the boards this large, maybe shift the smaller inductors further away a bit closer to the edges if there is nothing much to be gained from different orientation of the inductors. Any opinion is welcome.
here is my DCX464 crossover layout - it contains 4 coils. The bottom part is low pass for the mid part (LCL) and the upper part has a highpass (LC) on the left and a notch filter inductor on the right. The board is now 240 x 240 mm. The C-C distance of the inductors as shown is 170 mm along the edges. The squares are other components and terminals. Can I get the board smaller by rotating the inductors better? I could follow the orientation rules for two or three, but what would be the preference when having 4 with these functions? I think I can leave the boards this large, maybe shift the smaller inductors further away a bit closer to the edges if there is nothing much to be gained from different orientation of the inductors. Any opinion is welcome.
Try to rotate axis of one inductor orthogonal to the other so that they don’t cross couple. Distance helps but it is surprising how audible the cross coupling can be when axis are parallel. You have all 4 parallel here.
Here is a video I made of air core inductor cross talk. One XO board transmitting sound to another XO board that is not connected to an amp.
Here is a video I made of air core inductor cross talk. One XO board transmitting sound to another XO board that is not connected to an amp.
Yes, but how to arrange 4 of them? I can make 3 orthogonal. An angle should help as well, if I am correct? So three orthogonal and one turned 45 degrees away from the closest pair?
Makes sense, from what I remember about induced voltage in a coil is that it is proportional to the magnetic field intensity and cosine of the normal of the coil and tangent of the field line or something like that.
That’s what I would do too. Also, a tweeter coil may be less susceptible to crosstalk from low frequencies of a woofer since so far apart.
I came across this solution to the problem recently:
There was a suggestion to also raise up the horizontal ones so they sit more or less opposite the mid points of the opposing inductors, something like so:
I didn't measure the inductor values once I installed them but the FR measurements I took showed no variation in response from when I had the xo (and inductors) spread out on the floor during the testing/fine tuning sessions. And my distance between inductors was closer to about 70mm than 170 (that's the 2 xo's side by each in the pic below btw):
There was a suggestion to also raise up the horizontal ones so they sit more or less opposite the mid points of the opposing inductors, something like so:
I didn't measure the inductor values once I installed them but the FR measurements I took showed no variation in response from when I had the xo (and inductors) spread out on the floor during the testing/fine tuning sessions. And my distance between inductors was closer to about 70mm than 170 (that's the 2 xo's side by each in the pic below btw):
Yes, the top right one 90 deg around X axis should improve it a little bit more. I will not raise the horizintally oriented coils, but sink the others.
Is the choice of inductors already fixed? If not, then there are a few toroidal inductors that are good enough for crossover use which could be substituted for the largest one. These are both less susceptible to external fields and produce less, so their positioning is less critical. The remaining three can then all be orthogonal.
In my case, I already have them. The largest two are identical value. I cannot share the values since it is a licensed design I bought.
I don’t think you need to elevate or sink the parts to keep things on the same plane. That’s a minor “sin(theta)” effect - negligible for small angles.