[Mike P.]

Is your AA avalanche 15 the older model that was XBL?

 

[Mike P.]

The older versions with the XBL don't bottom out as hard due to the design. You don't mention a Hi-Pass filter in your setup. I'm assuming you don't have one. I'm thinking your sub is being over driven at the lower frequencies.

 

[Mike P.]

Since you're using a EP2500 you'll have to use an add on unit like the Reckhorn B2. But first things first, can you post the parameters for the sub so it can be modeled and we'll see where you're at with the low frequencies.

 

[Mike P.]

Is the EP2500 in bridged mode?

 

[Mike P.]

It's either the amp clipping or the sub being pushed to its mechanical limits. The original AA subs were XBL and by design they won't "hard bottom" like most subs.

 

[Mike P.]

Try unbridging the amp and using one channel to feed the sub. If the sound continues then you'll need a Hi-Pass filter at the lower frequencies.

 

[Mike P.]

In bridged mode you have probably been pushing the sub way beyond its limits. Here is the cone excursion of your sub modeled without (pink) and with a HPF at 14 hz (green). As you can see the HPF stops the sub from exceeding Xmax. Input power on both models is 750 watts.

 

[Mike P.]

To get the B1 to work you set the HPF frequency and turn boost up to the 12 o'clock position at 20 hz to achieve a second order HPF. The unit was tested and this is what was discovered.

 

[Mike P.]

The boost in this application is to get the B1 to perform the way it should. Read this:

http://www.hometheatershack.com/for...devices/21838-reckhorn-b1-b2-differences.html

 

[Mike P.]

Keep us updated on how it turns out.

 

[Mike P.]

Maybe I should have said under "normal" conditions.