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are some phono stages more resistant to hum?

After a tonearm upgrade, which mostly involved "improved" shielded cable, it now hums with tube phono stage (upgraded AR PH3-SE)but no hum with backup ss device (DB Systems). It appears the hum originates with the new wiring, but why would one phono stage be impervious to the hum? Do phono stages have different grounding schemes, making them more compatible with certain tt/tonearm/wiring combos in unpredicable ways? Are ss phono pres less susceptible to hum? Have you ever changed phono pre to cure a hum incompatibility? I see from forums that tt hum problems are common and sometimes difficult to solve. Shouldn't a shielded cable be more immune to hum, not less?
128x128lloydc

Showing 2 responses by rtilden

rtilden
156 posts
 
Thanks, Lewm. I will check out that possibility in my next step.
rtilden
156 posts
 
Lloydc:
I am wrestling with a similar condition after replacing my ss pre with a tube unit. Are you sure that your problem is a 'hum' and not a 'buzz'? Mine is definitely a buzz (heard only in the tweeter), and my current thinking is that it relates to external circuit noise which is induced into the system and picked up by the tubes and sent through the rest of the system. I must admit that I am early in my process of diagnosis, but nearby lighting dimmers cause similar a similar buzz when activated. Anybody else have comments on that line of thinking?
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