Hello diyAudio experts,
I'm experiencing a buzz/humming issue with a used Crown XLS 802 amp that I purchased($200) and a pair of Dayton Audio 12" subwoofers (RSS315HO-4). I'm using them in my home theater by connecting through the AVR's preamp outputs.
I've isolated the speaker-humming to either the (Crown amp/subs/rca's) because I disconnected any other components that might be causing the buzz. With Power ON and the 2 subs connected to the speaker outputs, as soon as I connect the RCA cables to my XLR>RCA adapter I begin to hear the buzzing. I've tried different RCA cables and even new ones but the buzzing remains and gets louder as I increase the gain. I expect this has something to do with a ground loop so I'm using an adapter plug on the end of the amp's power cable to eliminate the ground prong. The XLR>RCA adapter is the solder type, so I soldered XLR PIN 2 --> RCA's tip and PIN 1 --> RCA ground. XLR PIN 3 is not connected to anything. I also measured the DC Offset on both speaker output terminals and with nothing connected I'm getting readings in the 65 - 70 millivolt range. Not sure how much of a difference this makes but I hope that 65-70 mV is semi-acceptable and that I didn't purchase a lemon.
I welcome any suggestion to help eliminate this problem, I just want to be done with it....
I'm experiencing a buzz/humming issue with a used Crown XLS 802 amp that I purchased($200) and a pair of Dayton Audio 12" subwoofers (RSS315HO-4). I'm using them in my home theater by connecting through the AVR's preamp outputs.
I've isolated the speaker-humming to either the (Crown amp/subs/rca's) because I disconnected any other components that might be causing the buzz. With Power ON and the 2 subs connected to the speaker outputs, as soon as I connect the RCA cables to my XLR>RCA adapter I begin to hear the buzzing. I've tried different RCA cables and even new ones but the buzzing remains and gets louder as I increase the gain. I expect this has something to do with a ground loop so I'm using an adapter plug on the end of the amp's power cable to eliminate the ground prong. The XLR>RCA adapter is the solder type, so I soldered XLR PIN 2 --> RCA's tip and PIN 1 --> RCA ground. XLR PIN 3 is not connected to anything. I also measured the DC Offset on both speaker output terminals and with nothing connected I'm getting readings in the 65 - 70 millivolt range. Not sure how much of a difference this makes but I hope that 65-70 mV is semi-acceptable and that I didn't purchase a lemon.
I welcome any suggestion to help eliminate this problem, I just want to be done with it....
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Get a proper powered unbalanced (RCA) to balanced line (e.g. TRS or XLR) converter and do not use the thing you have, which is just connecting some wires around and is subject to EMI pickup. They are not expensive. For example Samson S-convert, ART CleanBoxPro, or Henry Matchbox HD. Use a short RCA between your source equipment and the converter and than as long a balanced run as you like from there to the amp.
So I shorted pin 1 and 3 and the signal now coming though the subwoofer is inaudible, which is strange. I even checked continuity for each pin and everything seems to check out. The reason I did not short these pins to begin with is because of recommendations from this video -
Thanks for the suggestion, had I known XLR>RCA conversion could be at the root of my issue I probably would not have purchased the amp. If all else fails I'll try to score a used one on eBay, new ones would be more expensive than the amp itself!!
Are there any other tips or tricks? Before I spend another chunk of money I want to exhaust all other avenues.
All solutions welcome 👍
All solutions welcome 👍
I wonder if there might be excessive power transformer leakage to the chassis. A test experiment: short the free end of a RCA cable (i.e. signal to shield) and confirm low hum; then touch shield of cable to source signal ground. If there's still hum, I think there may be a leakage issue. I confess no familiarity with XLR connection.