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The stock wall-wart power supply with my new Roku 4 is causing a hum in my system. Can anyone suggest a proper linear power supply for it? Thanks.
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Image: ZEROZONE 30VA Linear Power Supply
A regulated linear power supply upgrade would at least provide substantially higher performance if you find the hum to be somehow unrelated to the stock switch mode PSU. You might consider this relatively inexpensive PSU found on eBay. It features a nice R-core transformer similar to what TeraDak implements for their PSUs. You will notice there are six versions to choose from (in your case, the 12V 2.08A option) to request from an eBay seller of your choice:
1: DC5V (5A)
2: DC9V (2.77A)
3: DC12V (2.08A)
4: DC15V (1.66A)
5: DC18V (1.38A)
6: DC24V (1.05A)
See link:
How do you know it's the Roku power supply that is causing hum? A linear power supply may not be the answer if the hum is being caused by a ground loop elsewhere in your system.
Sounds like you have already determined your power supply issues. Have you tried switching or adding ground points to see if that helps. Get a wire with an alligator clip on each end to experiment with alternate chassis ground points. Bringing lead acid batteries into the house is overkill and potentially problematic.
Process of elimination. I'm using a PS Audio P500 Power Plant, and when I plug in the Roku, I get a hum in the system. Unplug it, hum goes away. There's no third prong on the Roku plug or I'd twist it off, and no grounding stub on the Roku. Switching power supplies are noisy, so I though a cheap linear one would be something to try. I've had this trouble in my system with the Squeezebox stock power supplies, which I replaced with CIAudio linear upgrades to good effect. These were very nice sounding additions by the way.
Switching power supplies are noisy, so I thought a cheap linear one would be something to try.But a properly functioning switching power supply will not hum, and hum was the challenge you originally posted about. Yours might just be a cheaply made switching power adapter, or defective. Another switching power adapter may also solve the problem..... unless it's a ground loop.
If you want to try a linear supply that will work too, but if it's a ground loop there's no guarantee that it will solve that problem. The downside is that linear power supplies are relatively bulky, heavy, more costly, and not always a practical match for small consumer electronics.
The one I linked to in a previous post is just your everyday average DC linear power supply and it's pretty big.
Just to rule out your present switching power adapter, you could try another similar one that you might have around the house. You need one rated to supply 12VDC & 2-Amps (or more current). They're pretty common, cheap, and small.
Edits: 12/10/15
Someone who builds Isolation/Regeneration Power stuff and who must remain nameless, advised me to isolate all of the wall-wart switching supply devices to a different outlet, preferably with a separate "Isolation supply' etc. or a different outlet with differing phase, from all of the gear that has a transformer style PS.
Do you have a 12 V battery around the house from a lawn tractor, golf cart, even your car?
Hook the battery up to your Roku and try it. If the hum goes away, you can be more certain that it's your power supply, and not the Roku itself.
Good luck with it.
"You won't come back from Fletcher-Munson curve"-Jan and Dean
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