Hi folks ! For the first time in the 13 years I have been playing the electric bass, I have blown a speaker in one of my 2 cabs. I use a 550w Hartke HA5500 head thru a Hartke 1x10 & 1x15 (non-aluminum). Both cabs are rated at 8 ohms, and my head has 2, independent, 8 ohm outs. I received a call from the repair shop today that my 1x15, which had stopped producing any sound about a week ago, had a blown speaker. Now, this will be fixed/replaced, as this cab is still under warranty, and I must admit that in the 12 years I have been using Hartke amps/cabs, this is a first. My question, tho, is how did I blow the 1x15, and not my 4x10 (which is perfectly fine)? Now, right off the bat, I gig heavily with this gear, and has proven it's road-worthiness to me countless times. I NEVER turn my volume past 3 (out of 10), as the headroom I get is just perfect for not only stage volume, but also for projecting to the crowd (which I might add, is just icing on the cake, because my head runs direct out of the PA as well). However, I DO use effects, such as a bass wah, envelope filter, fuzz, and harmonizer. Could the use of these effects cause a blown 1x15, or is there more that I am not aware of? Since this is again a first for me, any advise will be helpful, and I am willing to entertain additional questions if need be. Thanks again guys/gals!