Sooo...got a bit of a rude awakening today. Found out my e12a is actually presenting close to a 10 ohm load to the PG Tantrum 1200.1 in box - impedance rise is killing me. The sub is a 2 ohm DVC currently wired in series, and it's close to 2.5 times what I was thinking the impedance was.

Pardon the extreme n00bish question, but is such a drastic rise common? It just feels a little strange running my sub at a lower impedance than my amp is rated for (if I drop it to 1 ohm), but if it models out well, hey...that's what I'll do.

Jim---for you van and the air space you have to pressurize---you did VERY well today.

PS----for your size van vs my car----you are louder than me!

......?

Jim, at what volume are You testing the impedance? You are using voltage & amperage, right?

Jim, at what volume are You testing the impedance? You are using voltage & amperage, right?

<{POST_SNAPBACK}>

Yeah...at about volume 28 out of 35...although as Jmac posted, my 7894 has the same problems with low preout voltage as his 7893 does.

okay, skipping over the signal path for the moment, impedance drops with higher voltages. @ 2 ohm You're tantrum is rated for 1200, yes? reset the gain of the (HU @ vol 28) amp using the clamp & dmm method until You see the rated 1.2kw. Obviously, You'll need to watch for clipping. I advise an Oscope when setting gain up this way. IMO this is the "compeition method" of gain setting - You basically want to get just a tad bit of clipping.

As You crank the input current, the impedance should drop further. But be careful, I dunno if You woofer's thermal rating is REALISTIC. If it's a 3" >4 layer coil, it should be fine with 1.2k actual.

I dunno the specs on Your woofer, so I cannot guesstimate to other reasons.

Hope it helps.

Or a simpler method would be to wire parallel and try to measure the rise. Be cautious of course, but if the rise is similar, the amplfier should be able to handle it IF it can get over the initial 1 ohm reading at rest, which should be instantly risen given the introduction of voltage at turn-on.