shielding driver magnets

[smitty69]

I am building this two-way design based off the Audio Physik Tempo 2. Based on the internal cross-bracing, I had to mount the cross-over pretty much directly behind the driver units. The driver units are not shielded (SEAS 27TFFC tweeter and Vifa PL18wo09-08 midwoofer). I purchased some magnet-shield to shield the inductors from the driver magnets. My question is this. Would it be better to mount the shielding material between the driver and the crossover, or should I mount it directly around the driver magnets? I know that the latter would be better based on the actual properties of EMR, however I am concerned that the extra weight of the shielding material might affect the performance of the driver. The material is fairly light, so maybe I am overly concerned about this. Also, I am wondering what the best way to mount it to the driver would be?
I am using magnetic shielding foil, 0.010" thickness (rather thick actually, it will be challenging to bend into formation around the driver magnet).

[twest820]

Can you share the measurements that show the performance differences between having the crossover in its desired position and, say, a couple feet away from the drivers? It'd be helpful to understand what problem the shielding needs to solve.

[smitty69]

Well, I don't actually know that the performance will differ. I just want to make sure that it doesn't. I have no measurement equipment to make this determination. But when I posted pictures of the speakers on a woodworking forum to get some advise on another issue, a speaker builder there told me that the driver magnets could interfere with the inductors unless they were shielded drivers (which they are not), and that I should mount the crossover in the bottom of the cabinet to avoid this. Unfortunately, the cabinets have been sealed and that solution is no longer possible. So, my solution was to use magnet shield to either shield the driver magnets or the inductors.

[twest820]

Sounds like a reasonable time to invest in measurement equipment. Magnetic shielding's tricky and my hunch is you'd get better field rejection by shielding the inductors than the magnets. However that'll change the field distrbution and shift the inductance and, without measurement gear, you'll have a tough time adjusting the winding back to the desired value. Same likely goes for any significant amount of magnet shielding and, possibly, the magnets themselves---from the pics it's hard to see how much front to back depth there is. In lieu of measurements I guess you can try blind A/B testing with different shield configurations and see if any of them offer statistically significant improvement.

Some measurements I have done are here. Don't work with passive crossovers much so, sorry, no inductors involved.

[smitty69]

Thanks for the input. Seems like A/B comparisons will have to work for the time being. The depth of the cabinets is 9 inches outside, so 7 inches internal depth, fyi.