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choke tolerance

 
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iso
Senior Contributor 200+


Joined: 29 Aug 2011
Posts: 215
Location: Finland

PostPosted: Fri May 18, 2012 10:46 am    Post subject: choke tolerance Reply with quote

I have plans to build JBL L36 with Troels Gravensen L26 3-way crossover.

Falcon has offered 2% and 5% tolerance as extra cost option on caps and inductors. When buying capacitors this has been most helpful.

When I have measured air cored chokes from Intertechnick, they have measured within 1% from target values. So it seems that it is not worth to pay for tighter tolerance on air cored chokes.

I have not too much experience on cored inductors. Are magnetic properties of cores so predictable, that cored inductors can be wound to same precision as air cored chokes seems to be.

So... does it make sense to pay premium for tighter spec cored inductors. I suppose they are first over wound, then measured and exes inductance is wound off.

Best Regards,

Kimmo
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speakerguru
VIP Contributor 750+


Joined: 18 Nov 2005
Posts: 954
Location: Green Hut, Tovil

PostPosted: Fri Nov 30, 2012 9:24 am    Post subject: Reply with quote

Apologies, I don't often look in this part of the forum. There is no one answer to your question. In general air cored inductors have one less variable (the core) and so will have less variation for a particular wind. However, the design itself plays a major role.

If the inductor is a high value with a high resistance it will have lots of turns of wire. In this case +/- a half turn or so of wire would not affect the total inductance or resistance much. If the inductor is a low value with less than 100 turns of wire then, because the inductance is approx. proportional to the square of the turns, a fraction of a turn or even how you position the leadout wires may cause a significant change in inductance.

Hope this helps and is not too late.
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