Sub impedance

[J2phat4u 9]

I was wondering if the SP4 dual 2 ohm sub is actually 2 ohm or less than 2 ohm impedance? I see the RE on the subwoofer is 1.27. Just curious for wiring options.

[Impious 1,476]

Realistically with an Re that low it's probably closer to a 1.5ohm nominal than a 2ohm. For example the JL 13W7 with dual "1.5ohm" coils has an Re of 2.4ohm (coils in series). According to IEC standards the impedance shouldn't drop below 80% of the nominal impedance over the intended bandwidth. So for a 2ohm nominal driver to be correctly classified as "2ohm" the impedance shouldn't drop below 1.6ohm.

Simple answer is to plug the driver into WinISD and look at the impedance curve, and then realize that the Re and hence impedance will increase some once real power is applied to the driver due to heat. You would be fine to consider it a 2ohm coil for wiring options, whether or not it fits with the technical definition.

[95Honda 486]

Yes^^

 

And remember, Re is just the DC resistance of the wire the coil is made of.  It has little to do with what load the amplifier sees.  In reality, an amplifier will never under any circumstances even see a load as low as Re due to losses in the interconnect cabling...  It may be close, but it will always see just above Re and higher...

 

The only way to see the actual load (excluding interconnect cabling) is to model the driver in your enclosure, as the enclosure is the #1 contributor to a majority of the load your amplifier sees...

[jonbearsmt 919]

see dog thats why my subs are louder.. minz has 4 ohms and yourz only haz 1

[J2phat4u 9]

The reason I was wondering is because I have 3 subs and will run them on one big amp. The way it seems I will sit at 1.33 ohms with the dual 2 ohm SP4's.

[jonbearsmt 919]

get dual 1s you will be at .67

[J2phat4u 9]

Too late had already ordered the dual 2ohm versions. If I wire all in parallel they will sit at .33 ohms but with rise the amp should play higher than that.