Artemus_5, I haven’t read the rest of this thread, but re your last post Dave could very well be right. The input impedance of the high-level inputs of REL subs is very high, 100K in the case of many models. An unconnected high impedance input is inherently susceptible to hum pickup, that might even be coupled into the input from the sub’s own amplifier.
The input impedance of the line-level inputs of most REL subs is much lower, 10K in the case of many models, which reduces that susceptibility somewhat, but may not eliminate it.
What you can do for test purposes is any one of the following:
1) Connect shorting plugs to the sub’s RCA inputs, if you have them.
2) Alternatively, connect the sub’s high-level cable to the sub, and connect its yellow, red, and black wires together, to each other. That will result in a near zero impedance at the sub’s high-level input, which is not much different than the impedance a power amplifier would present to it.
3) Alternatively, connect the sub’s line-level inputs to the line-level outputs of a preamp or source component, with that component being powered up but not processing a signal. And with its volume control, if it has one, set to minimum. That will result in the sub’s line-level inputs being forced to a relatively low impedance.
Obviously, have the sub turned off while you are implementing these connections.
Regards,
-- Al
The input impedance of the line-level inputs of most REL subs is much lower, 10K in the case of many models, which reduces that susceptibility somewhat, but may not eliminate it.
What you can do for test purposes is any one of the following:
1) Connect shorting plugs to the sub’s RCA inputs, if you have them.
2) Alternatively, connect the sub’s high-level cable to the sub, and connect its yellow, red, and black wires together, to each other. That will result in a near zero impedance at the sub’s high-level input, which is not much different than the impedance a power amplifier would present to it.
3) Alternatively, connect the sub’s line-level inputs to the line-level outputs of a preamp or source component, with that component being powered up but not processing a signal. And with its volume control, if it has one, set to minimum. That will result in the sub’s line-level inputs being forced to a relatively low impedance.
Obviously, have the sub turned off while you are implementing these connections.
Regards,
-- Al