Most Effective Tweaks?

 
dweller
1,243 posts
02-24-2016 9:48pm
geoff kait: Any idea where I can lay my mitts on some? thx

no, sorry, long gone.

mapman,
Thanks for the details!
This has been an ongoing issue for me for years. It’s managable but creeps into audibility at higher volumes. I’ve chased it with ICs, power cords, rack placement, "cheater plugs", medium output cartridges, etc. I think the hum is associated with the placement of my rack in the room (in front of an ornamental fireplace with the furnace/boiler directly below in the basement) and I have no options to move the entire rig. I have the system on a dedicated line also. So seeing your post, I was wondering if the mu metal might be wrapped around my already shielded ICs or some other placement around the rack, or even in the basement.....
Might be worth the experiment.
Thanks again!
Dave
PS: I know there are many Audiogon forums on RF.


Mu mu metal does not address RF issues. It’s a high permeability magnetic alloy used primarily to absorb the low frequency magnetic field produced by transformers, the toxic magnetic field that would otherwise degrade the audio signal anywhere in proximity to the xformer. In some cases audible hum is produced by the 60 Hz transformer but it can also be produced by other causes such as low level signal wires being too close to AC cords which is not an RF issue either.

Yep, as mentioned several times above, hum is most likely ground and/or EM related due to close proximity to transformers and the ilk.

RF is typically higher frequency noise, not unlike the noise other than hiss one might hear listening to FM stereo radio. Older digital gear, microwaves, light dimmers are just some of the more common culprits.

I realize this will probably come across as argumentative or beating a dead donkey, nevertheless what I’m actually referring to is not EM or RF. I’m referring to the induced Magnetic field from the transformer or in some cases from adjacent AC cords. That’s why wrapping mu metal around a transformer improves the sound, because the mu metal absorbs the magnetic field. Mu metal has nada to do with shielding RF or any such thing. It’s also why it’s a good idea to avoid parallel runs of any cables or cords. In some cases the 60 Hz hum is due to the physical mechanical vibration of the transformer.

Most Effective Tweaks?

Fuses are the most effective tweaks.....   price/gain ratio  is by far the best.