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Detecting “Dirty” Power

I bought a used BHK 250 still under warranty. It is plugged into a Denali S power conditioner.  I heard a hum coming from the area around the tubes.  I cannot hear it from my sitting position and it doesn’t effect SQ, but I want it gone.  

I sent it to PS Audio; they tell me there is no hum and sent it back. They implied I mostly likely have a power problem and recommended some troubleshooting steps.  I unplugged everything from the 250 and plugged it straight into the PS Audio receptacle.  The hum is still there, but it is not as pronounced.  A P15 power regenerator might fix the problem, but I want to know if I have a power problem before I do anything.

How can I determine the quality of the power coming into my house and out of the receptacle? FYI, the Denali is plugged into a PS Audio receptacle/dedicated 20 amp line.  I have a whole house generator w/ transfer switch and whole house surge protector. 
128x128oldschool1948

Showing 1 response by oldhvymec

oldhvymec
5,101 posts
 
Do you have a DMM Digital Multi Meter? Most valve amps like a certain voltage. Normally if it's LOW the transformer can be noisy. What will fix a low voltage issue is a Variac. I keep one here just for troubleshooting things like this. I also use it to bring up the old valve gear. 

It will supply 0 - 140 vac. 

See what the wall current is and swap to the other rail and see if that helps too. BUT I got a feeling you have low voltage and a BAD location for echoing the noise right into YOUR ears.. LOL

I use Triplites 2400s. BUT heck they have a transformer buzz. It maintains 120VAC on the button. I fixed 95% of THAT noise with silicone and dampening on the top and bottom of the conditioner along with about 15 lbs on top of the unit..

Regards..
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