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Crossover inductors near magnet assemblies

 
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iso
Senior Contributor 200+


Joined: 29 Aug 2011
Posts: 215
Location: Finland

PostPosted: Sun Aug 03, 2014 6:18 pm    Post subject: Crossover inductors near magnet assemblies Reply with quote

How close to the speaker magnet it is safe to locate crossover inductor? In LS3/5A design crossover PCB is only few cm behind T27 magnet.

In my Cantata rebuild, I noticed that crossover bolted to aluminium face plate caused some interaction between coils. It seems resonable to expect that magnet assemblies do have similar effect. Do tweeter, woofer, alnico and ceramic magnets have similar effect to nearby coils? Are air- and ferrite-cored inductors similar in this respect? How far from magnets you should place the coils, if good performance is needed?

Best Regards

Kimmo
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audiolabtower
VIP Contributor 500+


Joined: 06 Jan 2009
Posts: 544

PostPosted: Sun Aug 03, 2014 8:38 pm    Post subject: Reply with quote

The BBC designs, including the LS3/5a used radio metal core transformer inductors. These had much better overload characteristics than normal inductors and less leakage due to the closed core keeping the magnetic field within the inductor. This is why the 3/5a gets away with mounting the pcb where they do. Conventional ferrite or much better (used in the Reference series) iron dust inductors need to be mounted a right angles on the pcb because of leakage and need to be more carefully sited compared to very strong magnets.
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