Thank you, Al, we will try it this evening.
Deb
Deb
Protection circuitry on mufi kw500--help?
Soren and Al, Thank you for the input. When we unhooked the sub and the interconnects, she did her full startup routine, then after 15 seconds went to purple feet. After speaking to the mufi repair center, he got permission to open it and take a peek. Looks like we blew a teeeeeny capacitor on a board in the left bank. So we are packing up for a repair. We think that we pushed theREL sub too hard, and the extra wattage reflected back into our amp. Grrrrrrr. Anyways...no audiophile amp for a few weeks, but we didn't kill our kw500. Only made her limp a little. Looks like we will use line-level interconnects with the sub from now on. Oh well...learning curve! Deb |
Thanks for letting us know, Deb. I just found a couple of threads, including this one and another one at a different forum, indicating that the outputs of the KW500 are bridged. Which means that its negative output terminals, as well as its positive output terminals, provide signals to the speakers (as opposed to the more usual situation where the negative output terminal is grounded). In general it is not good practice to connect a powered sub to the speaker outputs of a bridged amp, because depending on how the grounds are handled in the specific designs the sub might introduce a path between the negative output terminal and ground, resulting in that output being either loaded excessively or directly shorted to ground. If that were occurring, though, I would have expected it to have resulted in hum or other audible consequences all along, which leaves me a bit puzzled. What I would fault in this situation is the manual, which makes no mention of the outputs being bridged, and does not provide the cautions that are usually stated in such cases about not connecting the negative output terminals to anything that could ground them. In any event, I'm glad the problem wasn't anything more serious. Regards, -- Al |