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Hum is usually caused by a grounding or cable issue. Only the power amp should be grounded. I still like things plugged directly into the wall. No power conditioners in my house. I still contend that for power amps especially their added resistance is not favorable.
My amplifiers have serious filtration and RF protection and very few problems with ground loops.
Try the Van Alstine Humdinger, sounds like you got DC going into your stuff... Not necessarily a power conditioner thing, but I can tell you there's probably a lot of noise on your lines given where you live. A lot could be as little as 4%. That's how little one reviewer of an Audience Adept unit had, but won't listen without a conditioner now (6moons article).
I actually got one of those last year. Had no effect on my tube amp but did help my sub amp.
They are only for blocking DC, which causes a loud hum in transformers when it's bad. Now if DC isn't your problem, look back to what Roger said, you probably got grounding issues. It's not easy to address, I know...
What about lightning strikes, brown outs, etc?Do you have any recommendations for the DIY amp builder for filtration and RF protection?What about "dirty" AC? I seem to have a problem with the AC in my apartment in that it can cause power transformers to hum/resonate. It happens randomly with some of my amps/ receivers and I've even noticed my variac do it. The ceiling fans in the apartment hum too. (100 year old building with regular 3-phase wiring according to my landlord) What's weird is that I have a couple of amps that don't seem affected by it and are always quiet.
With inputs shorted it's virtually dead quiet from the speakers. But the power transformer hums roughly 5db measured 1" from the transformer.
Actually North American residential power is single phase with a center tap for Neutral. It's also known as split phase 120/240.But corndog may live in a large building, serviced by 3 phase power.
To measure the DC on the line you have to remove the AC with a filter that you can make. Take a film cap around 0.47 uF or larger and put that in parallel with the input of the Digital meter. Put a 100 K resistor in series with the hot lead. Connect the hot and negative across the line, preferably the negative to the neutral and the 100 K to the hot. The neutral is the wide slot. Set the meter to DC volts. Note what the DC is for various noises from your transformers and fans. The noise they make should be louder when there is more DC. Let us know what happens.
Before I do anything I would just like to confirm that I understood what you wrote. Does this look correct?
Your drawing is correct. I don't think 10 Uf is necessary. I go find mine or go build one right now and let you know. I am curious about my home too.
Ok, I measured 6.5VAC and -0.010 to -0.018VDC. By the way, I picked up a used Hitachi Oscilloscope. Still figuring out how to use it.
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