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Lab Sub Impedance curve

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Brian Oppegaard:
Could someone please point me to or send me the impedance curve of the lab sub?

Thanks

Art Welter:
Brian Oppegaard wrote on Mon, 14 February 2011 14:50
Could someone please point me to or send me the impedance curve of the lab sub?

Thanks


I think Silas Pradetto posted an impedance curve not too long ago, check his posts.

To be safe, assume a 3 ohm load for a parallel wired LabSub, though most portions of the curve would be high enough to consider it a nominal 4 ohm load.

Silas Pradetto:
Art Welter wrote on Mon, 14 February 2011 17:21
Brian Oppegaard wrote on Mon, 14 February 2011 14:50
Could someone please point me to or send me the impedance curve of the lab sub?

Thanks


I think Silas Pradetto posted an impedance curve not too long ago, check his posts.

To be safe, assume a 3 ohm load for a parallel wired LabSub, though most portions of the curve would be high enough to consider it a nominal 4 ohm load.


And, at the same time, there are dips at certain frequencies that are at about 2 ohms.

The curve was in a For Sale post, so it won't be around forever.

Quote:

Here's the impedance of the two I just shipped today. Green and purple are the individuals, blue is both in parallel.

Brian Oppegaard:
Thanks for the replies. The voice coil resistance of Gen II woofer 4.29 ohms is low compared to the nominal 8 ohm impedance of the driver. And I see now that the actual cabinet impedance dips to almost that resistance. I am trying to determine which version of my subwoofer amplifier to recommend for this speaker. Normally I would say the 2400W/4 ohm capable model, but with this low impedance perhaps the 4000W/2 ohm model could be justified.

Silas Pradetto:
Brian Oppegaard wrote on Wed, 16 February 2011 13:42
Thanks for the replies. The voice coil resistance of Gen II woofer 4.29 ohms is low compared to the nominal 8 ohm impedance of the driver. And I see now that the actual cabinet impedance dips to almost that resistance. I am trying to determine which version of my subwoofer amplifier to recommend for this speaker. Normally I would say the 2400W/4 ohm capable model, but with this low impedance perhaps the 4000W/2 ohm model could be justified.


Brian, let me clarify. First, the woofer nominal impedance has nothing to do with anything once it's in a horn.

The LAB12 woofer is actually nominally a 6-ohm driver, but a LAB sub has two drivers in parallel. This would make for a theoretical 3-ohm nominal impedance, but the horn adds to the impedance.

You will want an amplifier that is very good at driving reactive loads, as many amps can't handle the impedance varying so much.

It would be better to get a 2-ohm amp for a pair of LABs and a 4-ohm amp for a single LAB.

Also, there is no gen I woofer, it was the prototype and was never for sale.

Also again, DC resistance is useful for little more than confirming that the VC isn't open.

And another also, the impedance plot I posted is for TWO LAB12 woofers in the LAB sub box. Note that even thought hey have similar names, they are different things.

If you were to use the LAB12 woofers in any other box (sealed, ported, different horn, etc) then the impedance plot won't be even close to the same.

What are you actually doing, and why do you need this plot?

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