I listen from the other room sometimes which means I need to use a bit of power from the sand amp in my main rig. I did this one day a couple months ago and a disc or two into the music I'm smelling something. What is that, that doesn't smell like things in the house are right. I get up to investigate and I haven't started cooking yet so no burning going on in the kitchen. Sniffing around I get to the sound room and as I approach the right speaker I see some wisps of smoke. Well, wonder what part of the crossover I am cooking? It is coming from the two 4Ω-15W resistors that are cooking off some of the remaining wax on them. These boards are wax coated and when I rebuilt the crossovers I removed most of the wax. Anyway...
More investigation got the IR thermometer and I get a reading of oh 370°F or so on the right channel and something a step or two lower on the left channel. These are cement block resistors so other than hot are they ok. I look up the specs for similar resistors and they can be used at operating temps over 500°F so I'm not in the least worried. Chalk it up to running some watts through the speakers.
Plans are to make accommodations for high temps and lift them off the board or JBWeld a chunk of heat sink to them to allow them to operate a bit cooler but not worried at this time. It was mentioned that maybe my DC offset was high. Don't think so, amp sounds great but I'll check. Did that today, speaker wires at the speakers, easy access point. 0.3mV left, 0.9mV right. First time I have checked that amp. A 1991 or so build, rocking along just fine after all these years.
So it is all good and I know if I really try I can get my speakers to smoke. It was pretty loud that day, louder for longer that usual. I guess I'd smoke to after all that.
More investigation got the IR thermometer and I get a reading of oh 370°F or so on the right channel and something a step or two lower on the left channel. These are cement block resistors so other than hot are they ok. I look up the specs for similar resistors and they can be used at operating temps over 500°F so I'm not in the least worried. Chalk it up to running some watts through the speakers.
Plans are to make accommodations for high temps and lift them off the board or JBWeld a chunk of heat sink to them to allow them to operate a bit cooler but not worried at this time. It was mentioned that maybe my DC offset was high. Don't think so, amp sounds great but I'll check. Did that today, speaker wires at the speakers, easy access point. 0.3mV left, 0.9mV right. First time I have checked that amp. A 1991 or so build, rocking along just fine after all these years.
So it is all good and I know if I really try I can get my speakers to smoke. It was pretty loud that day, louder for longer that usual. I guess I'd smoke to after all that.
