Impedance changes on p audio 18" drivers

Re: Impedance changes on p audio 18" drivers

Ivan Beaver said:
Unless some turns are shorted-that would be very strange.
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There are (8) p audio sd-18's with remove able baskets, I unbolted the magnets and did a visual inspection of the coils and all looks fine, no scrapes no burns, they don't even smell funny. They are allegedly 8 ohm drivers and the dc resistance reads 4.8 +- an ohm :?~:-?~:???:
 
Re: Impedance changes on p audio 18" drivers

Chris Greco said:
There are (8) p audio sd-18's with remove able baskets, I unbolted the magnets and did a visual inspection of the coils and all looks fine, no scrapes no burns, they don't even smell funny. They are allegedly 8 ohm drivers and the dc resistance reads 4.8 +- an ohm :?~:-?~:???:
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That sounds about right. 8 ohm nominal speakers will have a dc resistance greater than 4 ohms but less than 8 ohms. Impedance measurement is based on an ac signal, not dc.
 
Re: Impedance changes on p audio 18" drivers

Also, impedance varies with frequency so it's only going to actually be 8 ohms at 2 or 3 frequencies depending on the band pass. Most of the time it's higher or lower.
 
Re: Impedance changes on p audio 18" drivers

Greg Cameron said:
That sounds about right. 8 ohm nominal speakers will have a dc resistance greater than 4 ohms but less than 8 ohms. Impedance measurement is based on an ac signal, not dc.
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And just to add. the DC resistance (opposition to direct current) and the AC IMPEDANCE (opposition to AC current) are different things.

Most 8 ohm speaker will read between 5-6 ohms on a DC voltmeter-but there are exceptions.

You should be able to look up the DC resistance in the Thielel/small parameters of the driver.
 
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