Blas
New member
The Grotto subwoofer in my home theater is about 8 years old. This past December, I started to hear a soft buzz/hum. The amp would buzz even with the subwoofer input cable unplugged (but A/C plugged in). I took it to a repair shop recommended by a local Martin Logan dealer, and at first they could not hear the buzz and told me I probably had ground loop and to try a cheater plug (converts a 3 prong plug to 2). Before I picked it up, they called me back and said they were able to eliminate the buzz by tying the servo wires up and away from the transformer at the bottom of the amp.
After getting the subwoofer home, I plugged it into directly into a wall outlet instead of the Monster power strip where it and all my other home theater components had been plugged in. After 3 weeks, the buzz came back. I tried a cheater plug and the buzz went away. But after a couple of months, the buzz was back. Unplugging the subwoofer for a day seemed to eliminate the buzz for a week or two but it continued to come back. I also tried using an EBtech HumX Voltage Hum Filter instead of the cheater plug but this did not have much of an effect on eliminating the buzz.
A week ago, I took the Grotto back to the repair shop. After they had it for a week, they returned it to me because they never heard the buzz while it was in the shop. (To their credit, they did not charge me for the second visit.)
Has anyone else experience anything similar with a Martin Logan sub? It takes at least a week for the buzz to show up and once it does, it only goes away when the sub has been unplugged for at least a day. Could a ground loop cause an intermittent problem like this? Could something in the Grotto amp be over heated and unplugging it cools it off? Could it be caused by a bad capacitor that takes a day to discharge? The tech at the repair shop suggested that I buy a heavier duty A/C power cable. (They used their own power cable when they tried to repair it.) Could that help? Any suggestions would be appreciated.
After getting the subwoofer home, I plugged it into directly into a wall outlet instead of the Monster power strip where it and all my other home theater components had been plugged in. After 3 weeks, the buzz came back. I tried a cheater plug and the buzz went away. But after a couple of months, the buzz was back. Unplugging the subwoofer for a day seemed to eliminate the buzz for a week or two but it continued to come back. I also tried using an EBtech HumX Voltage Hum Filter instead of the cheater plug but this did not have much of an effect on eliminating the buzz.
A week ago, I took the Grotto back to the repair shop. After they had it for a week, they returned it to me because they never heard the buzz while it was in the shop. (To their credit, they did not charge me for the second visit.)
Has anyone else experience anything similar with a Martin Logan sub? It takes at least a week for the buzz to show up and once it does, it only goes away when the sub has been unplugged for at least a day. Could a ground loop cause an intermittent problem like this? Could something in the Grotto amp be over heated and unplugging it cools it off? Could it be caused by a bad capacitor that takes a day to discharge? The tech at the repair shop suggested that I buy a heavier duty A/C power cable. (They used their own power cable when they tried to repair it.) Could that help? Any suggestions would be appreciated.
