Copper coil inductor vs. round core inductor

[tomchaoda]

If cost is not an issue, what's the pro and con of using copper coil inductor in the L part of a pi-filter, when compare to a regular round core inductor?

Thanks,

Thomas

[Nelson Pass]

Do you mean air core vs something with a core?

[tomchaoda]

Originally posted by Nelson Pass
Do you mean air core vs something with a core?

Yes, the air core (round core wire) vs. the copper foil (flat foil type). What's the pro and con of both?

http://www.partsexpress.com/aircoreinductorpage.html
vs.
http://www.partsexpress.com/copperfoil.html

Thanks,

Thomas

[Nelson Pass]

Obviously the ones with cores have lower resistance. An
inductor on the order of 2 mH witha big iron core is good to
5 or 6 amps DC in my experience before it starts saturating and
losing inductance. The air cores don't saturate, but they can
get pretty hot unless the wire is really thick, like 12 Gauge.

I'm not really certain about the advantage that foil is supposed
to give, particularly if they're just being used as power supply
filter chokes. They look good, though.

[Pjotr]

Hi,

The flat foil coils have simply lower losses. They have lower DC resistance and due the relative thin conductor the skin-effect is lower. They have advantages for a mid-high x-over but if they really make your speakers sound better …

[tomchaoda]

Nelson and Pjotr:

Great info. THanks!

Thomas

[promitheus]

The copper foil ones have less losses and very thick cross section. They cost though a lot more.

[thoriated]

The copper foil inductors are pretty much solid masses of material - far less prone to magnetostriction than round wire inductors. You don't want magnetostriction in your magnetic components if high SQ is the objective. Magnetostriction introduces additional frequency dependent losses on top of those due to skin effects as well as mechanical resonances into the inductors's sonic signature.