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Subwoofer dual wired hum question

Hello

I have an interesting dilemma. I have a Yaqin tube amp and it doesn't have subwoofer output, so I 'biwire' one et of speaker terminals on the Yaqin and just run speaker wire into the Sub. All good there. 

I only use the Yaqin for music. Everything else goes through a Vizio soundbar that has a RCA style sub out. When I run a single, shielded RCA cable from that to Sub, I get a hum.

Yaqin, Vizio, Cable box etc plugged into one output. Sub plugged into different outlet across the room. Cable box has a coaxial isolation transformer. 

I did some research - sounds like a common ground loop issue solvable with an isolation transformer. No problem. 

But before I order a blue jean iso transformer, I thought I'd check: is the fact that I am running speaker wire from one source and an RCA from another potentially causing the hum?

any help or thoughts appreciated. 
stevecuss
millercarbon's avatar
millercarbon
12,531 posts
 
Perfect if your goal is to find yourself right back where you started only with less money and more gear you don't need. That is his specialty.

A transformer won't do anything unless everything is plugged into it. Ground loop hum is caused by differential ground which is caused by plugging into different outlets. You don't need an isolation transformer, and it won't help anyway. You just need to connect everything to the same outlet so it all has the same ground potential. 


hilde45's avatar
hilde45
4,974 posts
 
Who is the "his" in "his specialty"? I missed something.
stevecuss OP
38 posts
 
Yeah, I don't have a practical or elegant way to plug the sub into the same outlet as the other AV gear, so I'm hoping for other options. 
millercarbon's avatar
millercarbon
12,531 posts
 
Well the most practical and elegant solution is to eliminate the AV gear. Whatever made you think you need that stuff in the first place? Believe me, you don't. https://systems.audiogon.com/systems/8367 You will have better sound for movies and music without it. And a better looking room too.
stevecuss OP
38 posts
 
???

I don't want to use tube amp hours on TV, the soundbar is more than adequate for what we need for tv/movies. We're not home theater folks. 

My primary audio concern is good music, which I'm getting from tube amp and nice DIY monitors and the sub. 
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