Hi everyone, first of all,please accept my apologies if this question has already been answered. Here's my problem:
I have a Pioneer VSX-D509S amp running 5 Wharfedale front,center and rear speakers. The problem is the sub,which is a powered unit,also wharfedale. It has a stereo input,yet the amp has a mono sub pre-out. I hooked it up with a mono cable into one of the channels,which produces a hum. The sub also has speaker level inputs, so I bridged out of one of the fronts into the sub. This cures the hum, but I would really like to use the amps dedicated sub output, but it produces the hum. Please help.
You said you "hooked it up with a mono cable into one of the channels". Does that mean you didn't try the other channel? Normally the right channel input on the sub is for a mono input. Check your owner's manual to see if your sub confers with this.
Otherwise, a humming sub usually means there is a ground loop somewhere in the system. If the receiver and sub are plugged into different AC outlets, this could cause the problem. Frequently a cable TV input will cause the subwoofer hum due to its being grounded at a different location that the main system. There is even the possiblity you used either a bad cable for the connection or the cable has its shield lifted at one end and reversing the direction of the cable could help.
In this case, trial and error of unplugging various components and making certain the cables you are using are good and installed correctly, is about the best course of action I can recommend. Start with unplugging the cable box if you use one and getting all components plugged into the same AC outlet, preferably through a good quality line conditioner/surge suppressor.
Thanks Jan, I'll give it a try. Yes, I did try the other channel as well,same problem. The sub and receiver are on different wall outlets thou,as the sub sits to the rear of the room becuase of a fireplace in the front. I dont have cable, but I do have satelite TV,as there is no cable in South Africa. Could the satelite decoder produce the same problem?
I'll give the power outlet scenario a trial,will take some time before I can post the results thou as I have to run the power to the back now when I have some time.
In your opinion,is it worth the trouble if it does work bridged out of the front speaker? Will the quality be better through the amp's dedicated sub output?
Thanks again for your help and have a great weekend.
Satellite system should not cause the problem as it is all grounded within your own house. Only if the satellite receiver would be plugged into a different AC outlet from the system could there possibly be grounding problems.
Which hook up you use is mostly a matter of choice. The line in provides a simple path with no more than two cables running to the sub (one will usually be sufficient) and will work well with the fixed output/crossover of a Home Theater system. Otherwise it is really a matter of what you prefer and what the system demands.
For source components that do not draw much current, the convenience outlets are OK. Additional power amplifiers, including the plate amps in subwoofers, should be plugged into a dedicated AC outlet.
Preferrably all components should be plugged into a high quality line conditioner/surge suppressor if your location is subject to lightning strikes. Some surge supressors can limit current delivery to an amplifier and you should have a product that doesn't affect the listening quality of the system or you've taken a step backwards.
The problem with cable TV installs, however, is that while the AC plug is connected to your AC line, the source component is feeding a cable input in which the signal ground is established quite some distance from your AC ground and in most cases has no relationship to your grounding point. A true earth ground will often solve the problem or lifting the ground at the offending ground loop.
Jan, you figgur 2 ground spikes, 6' deep, 12 feet apart bonded to a water main? I use that for industrial equipment, maybe that would help me here in the boonies...hmmm. How did I miss that?