On 14 Jun 2006 10:14:27 -0700, johnelstad wrote:


Well, I'm at my wit's end, but I'm hoping this will be obvious to
someone with more experience. Please help if you can.

I recently noticed a mild-moderate hum coming from my speakers that is
constant regardless of volume or input. Here are the results of my
attempts to isolate it.

Turn off and unplug pre-amp = hum (no change)
Disconnect pre-amp output cable = no hum
Replace cable connecting pre-amp to amp = hum

Not sure if this is helpful, but my pre-amp has a headphone amp that
produces no hum.

Equipment:
Sonic Frontiers Line 1 Tube Preamp w/ 5-year-old tubes
McCormack DNA-1 Solid State Amplifier
NHT 1.5 speakers.

Step 1: simplify!

Connect only your amp and speakers. If it hums, then the problem is your
amp. Then connect amp to preamp with no source devices. Still no hum? Then the
problem is with an input source; then connect the source devices one at a
time.