Leaderboard

Change would be bad, VERY bad. If it's a 4 ohm driver it should read around 3.xx ohms DC. No matter what it reads, it shouldn't change from moving the cone.

I would suggest manually moving the cone up and down a good bit with a DMM on the terminals to see if there is a significant change.

I really don't see why impedance rise would be a problem or causing the amplifier to cut out. The impedance of a driver could be 20-40ohm at resonance and amplifiers handle this with no problem. I would double check to make sure you don't have any shorts in the speaker wire or the terminals touching any metal. I'm wondering if maybe there isn't a physical problem with the drivers themselves, leads or VC shorting out or something along those lines.

I'm of the opinion that the amp has a problem. If it just went from playing for awhile to cutting out immediately when you turn it up there has to be a real problem. I'd start looking for a bad spot in the speaker wires just to make absolutely sure there's no short anywhere for starters. (I know you did a fantastic job running everything in this build, but it's still worth a look) Otherwise, yeah the load could be a problem at high power levels but it still seems to me that the amp should be fine on impedance rise. If the impedance was falling out real low then I could see that being a problem, but rising shouldn't cause the amp to freak out IMO. That's why I think the amp may have an internal problem. On the other hand, an impedance matching circuit (I believe it's also known as a Zobel network) would be ideal to flatten the impedance curve, however I'm pretty sure it would require a little retuning AND the worst problem is that in order to build an IMC or Zobel to handle that kind of power requires some very large (high power handling) coil's and resistor's to handle several hundred watts and that could be expensive to build or even very hard to find the parts to handle 300+ watts. I dunno for sure, that's just how I see it.

For a house? An enclosure? An amusement park? Download Google Sketchup 7 and you won't have to count on anyone else for providing help.

What do you mean by "not cutting the signal out"? Is it not affecting the voltage at all? To set the SSF to a specific frequency, turn the filter all the way down (10hz) and disconnect the sub. Turn the volume on the HU up to some arbitrary level (the volume level itself doesn't matter), and play the 33hz test tone (if that is what you are trying to set your SSF to). Measure the voltage output of the amplifier with a DMM. Then multiply this voltage by .707. So if you measure the voltage output and it's 2V, then you would multiply 2 * .707 = 1.414. With the test tone still playing and your HU at the same volume level, turn the SSF knob up until the voltage drops to your calculated voltage, in my example that would be 1.414V. This will set your SSF to 33hz. The SSF is not a brick wall. It will not eliminate the signal below 33hz. It simply attenuates those frequencies at a certain rate based on the slope of the SSF. A SSF is nothing more than a highpass filter.