Equipment: 2 Xcon 12's (dual 1's) on a Incriminator Audio 40.1 at 1 ohm (3600 watts rms at 12v on stable electrical), pioneer 5900ib

First off, I came home today and I decided to do a little testing on the Xcon's where I could actually see them. I noticed that the subwoofer farther away from the port has much more excursion (xmax) than the one close to the port. I feel like this might have something to do with a ported box where the port is on one side, but I'm not entirely sure. I also noticed that the one with more excursion is getting hot, (one close to the port is warm but not hot).

This concerns me, I feel like it points to one being at a different resistance than the other. That doesn't make much sense though, because I checked it with a multimeter before I hooked up the amp and it reads one ohm at the box.

Each sub's coils are wired in series (2 ohms) and then in parallel (2/2=1 ohm).

The only other thing that comes to mind is signal level clipping. I have no bass boost set or anything, but I have everything set for volume 55 on the hu (out of 62). As far as I know pioneers don't put out a clipped signal even at max, and this is how I have always had it set without a problem (doesn't sound like it's clipping either). Gain was set with a multimeter, then adjusted by ear.

The source of my problems seem to be stemming from this woofer that is getting too much excursion, any suggestions?

Does it point towards this design of ported box, cooked coils, or clipping?

Unfortunately the multimeter at my house is messed up so I'll have to measure the total ohm load again when I get back to school.

Thanks for any advice and feel free to ask if I forgot to mention something.

Edited September 11, 201015 yr by ulrisa

could be an un-loading issue with the box. Hard to tell from this end. Post up a video of your problem.

Triple check the wiring.

All my pioneer's along with my friend's and other friend's i have here on SSA the HU starts to send a clipping signal at 49+ everyone i know that use's a pioneer is volume 48 and lower. not sure if that fix's your prob or not just giving you my .02 on the HU

Good luck!

Is you subsonic set on your amp? Are you playing below tuning? Your subs are out of phase, and that is a common issue when you have multiple subs that are different distances from the port. Also if you can get the gains on your amp set with an o-scope.

All my pioneer's along with my friend's and other friend's i have here on SSA the HU starts to send a clipping signal at 49+ everyone i know that use's a pioneer is volume 48 and lower. not sure if that fix's your prob or not just giving you my .02 on the HU

Good luck!

Hmmm. I will try that. Never had such a high power set up before so I might not have noticed it. I will triple check my wiring and I'm not sure if I can do the video because my camera isn't high enough frame rate to capture it anyway FTL. Subsonic appears to be set correctly on the amp, I haven't noticed any severe unloading. I'll see if I can borrow an o scope from my school, that would be pretty handy. I'll try resetting my gains with a lower hu volume.

Sounds like a loading issue.

From what I can gather, a loading board behind the sub farthest from the port will help. Start with a board half the width of the cone and experiment with different widths and distances from the sub.

The funky loading could also cause different impedance functions on each of the subs. Lower impedance = more current, so the extra heat could be an effect of the loading.

Finally getting back to everyone on this, I'm actually pretty embarrassed of what it was. Apparently when you have a powerful amplifier even the littlest clipping can be quite destructive. I didn't get an o-scope yet, but I'm going to do that in a couple days. Using a multimeter, I determined the wattage from the ac voltage. It was supposed to be 59.17 volts for 3500 watts. It was playing at 80 volts on the loud songs! That's 6400 watts at 1 ohm! (I used both a song, and a -6db test tone to check this) Of course that assumes that clipping didn't change the resistance in the coils which would make the numbers higher of course (so probably wasn't really that much). Even still, I am amazed that the Xcon's survived the torture I gave them, and still didn't sound distorted (to the ear) even with clipping and overpowering.

Needless to say, I'm pretty sure that was why one had greater excursion than the other (possibly resistance change, heat dissipation etc). If only I had my multimeter with me that day. I have the gain set correctly now, and they sound pretty much just as loud and and with even better SQ. Coils still read at 1.2 ohms, so I'd say they are fine.

Mark and Aaron, this is one hell of a woofer. Hard to believe they took that much power for quite a long time and still work just fine. At least I have an even finer appreciation for the Xcon's as an outcome of this scare/embarrassment.

Moral of the story is TRIPLE check the gain if you don't have an o-scope. All it took was like a micrometer change on the potentiometer for the gain, to go from 59 v, to anything varying from 67-80v.

Thanks for the tips everyone, I will keep them in mind for future issues. I'll do some further testing, but I am pretty sure everything is all set now.

Wow, glad you got it figured out and happy to hear they held the abuse.