ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
About 2 years ago, I took over a project with several B&O systems, 1 of which consists of the following:
System3
BeoMaster5
BeoSound9000
Lab5 (pair for fronts)
Lab3 (2 pair for rear)
There is also a BeoLink Wireless 1 in the mix.
I am having an issue with a ground hum. It was very loud and seemed to only be coming from 1 or 2 of the Lab3s. When disconnecting the Lab3s from the System3, the hum got louder. I turned off the power for the Lab3s and noticed there was a slight hum in the Lab5s as well. After some troubleshooting, I found that one of the analog audio cables connected to the System3 was causing the hum in the Lab5s, I reconnected the Lab3s.
The Lab3s are connected via thin PowerLink cable that is spliced into some gray multi-conductor shielded cable as the speakers are located on the back wall of the room up high. There are a total of 5 splice points (one of which is buried in the wall somewhere). I have re-terminated the other 4 connections to ensure proper connection, but I still have a slight ground hum. I should also note that 3 of the connections are located outside under an eave as the speakers are located on an exterior wall. I have weatherproofed the connections as best I could. The PL cable and mains are in separate piping outside, but all connections are in the same box and pulled through the concrete block wall using the same passthrough. Could the concrete have eaten through the cable causing this problem?
Any help is greatly appreciated.
Regards,
Ben
3s are very sensitive to hum - you need to use the correct cables or they do hum. The correct ones are either the thick fully shielded ones or the thin ones with the small triangle mark on the plugs. Splicing the wires will likely be the problem. Doubt the concrete will have eaten into the cable but the in wall connection could be an issue. ? consider wireless connection.
Peter
Thanks Peter. The cables used are the thin PL and I'm fairly certain they have the small triangle you mentioned. I was most certain the connections were the problem, which is why I re-terminated all of them. The connection that is in the wall may very well be an issue, however, that is the last speaker in the line and not one of the speakers causing the issue. What would be needed for a wireless connection to these speakers?
If you already have the Wireless transmitter, maybe just a receiver. Obviously there is power already. Have to confess to not being a wireless fan but rewiring what you have sounds a real job! Before doing that, I would get a long unbroken Powerlink wire and check that the hum goes first! Just to test!