Speaker cabinet impedance concern.

thintheherd · 20th September 2009, 05:21 AM

I recently loaded a 4x12 cabinet with 16 ohm each speakers. My goal was to get the cabinet to 4 ohms, so I wired two of the 12's in parallel and the other two in parallel and then the met the two pairs at the input jack of the cabinet. So two positive ( one from each set) meet at the tip terminal of the jack and the two negative (one from each set) meet at the sleeve of the jack. Should be 4 ohms right? they are all in parallel at this point. Well, I measured the resistance with a multimeter to get an impedance close to 4 ohms but it is reading 1.8?

I realize that multimeters measure dc resistance but doesnt this seem too low? I am running a vintage 4 ohm tube amp through this cabinet and I dont want to put any strain on the output transformer. Any help or insight?

Thanks, TTH.

edjosh23 · 20th September 2009, 02:00 PM

Measure the DC resistance of the drivers individually. As you know the RE of a driver is quite a bit lower than the impedance. According to your 1.8Ohm measurement a single woofer should be ~7.2Ohhms, which is much more like the RE of an 8Ohm driver. You did connect everything properly if I understand everything properly.

Good luck,

Josh

woody · 20th September 2009, 02:38 PM

It is not always the case that the re is close to the stated impedience. I have a pair
jbl 2123j drivers this is a 16 ohm driver the re is 8.7ohms the same driver in the 8 ohm
version jbl2123h has a re of 4.2 ohms I took these figures directly from the JBL professional web page.

20th September 2009, 05:21 AM	#1
thintheherd diyAudio Member Join Date: Sep 2009	Speaker cabinet impedance concern. I recently loaded a 4x12 cabinet with 16 ohm each speakers. My goal was to get the cabinet to 4 ohms, so I wired two of the 12's in parallel and the other two in parallel and then the met the two pairs at the input jack of the cabinet. So two positive ( one from each set) meet at the tip terminal of the jack and the two negative (one from each set) meet at the sleeve of the jack. Should be 4 ohms right? they are all in parallel at this point. Well, I measured the resistance with a multimeter to get an impedance close to 4 ohms but it is reading 1.8? I realize that multimeters measure dc resistance but doesnt this seem too low? I am running a vintage 4 ohm tube amp through this cabinet and I dont want to put any strain on the output transformer. Any help or insight? Thanks, TTH.

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20th September 2009, 02:00 PM	#2
edjosh23 diyAudio Member Join Date: Oct 2004 Location: Raleigh/Atlanta	Measure the DC resistance of the drivers individually. As you know the RE of a driver is quite a bit lower than the impedance. According to your 1.8Ohm measurement a single woofer should be ~7.2Ohhms, which is much more like the RE of an 8Ohm driver. You did connect everything properly if I understand everything properly. Good luck, Josh

20th September 2009, 02:38 PM	#3
woody diyAudio Member Join Date: Jan 2002 Location: Tyrone Ga. U.S.A.	It is not always the case that the re is close to the stated impedience. I have a pair jbl 2123j drivers this is a 16 ohm driver the re is 8.7ohms the same driver in the 8 ohm version jbl2123h has a re of 4.2 ohms I took these figures directly from the JBL professional web page.

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