Bottlehead Forum
Other Gear => Phono => Topic started by: rockpassion on January 12, 2015, 04:38:29 PM
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Hello all,
I built a Cinemag 3440a SUT years ago and think it is great. I used to use a Seduction Phone Preamp but have upgraded to the EROS. I had a hum with the Seduction but it was so low that it was not really to noticeable. I recently noticed with the EROS that the hum is much louder and noticeable. I believe I have figured out the SUT is causing the hum. The reason for this conclusion is as I move the SUT closer to the EROS the hum gets louder. I read over on Audio Asylum that getting shielded cables might take care of this problem.
Are the Bottlenect Interconnects shielded and would this help? Or, should I also shield the box the SUT is in. The box is plastic.
Thanks
Richard
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Are you able to rotate the individual SUT's and to rotate the entire assembly? Often such hum can be nulled by both distance and orientation. I am also guessing that you provided a ground connection for the shields of the SUT cans? (On a separate post, not the RCA jacks)
-PB
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Paul,
You are right the hum decreases as I rotate the SUT. Right now it is in a position that lessens the hum to its lowest level. The SUT is grounded to its own post which is grounded to the post on the EROS. I have played with this a couple of different ways and does not seem to have an affect on the hum.
If I was to add copper foil to the SUT box would that help shield the Transformers from the other transformers?
Richard
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Try this:
http://www.mcmaster.com/#mu-metal-foil/=vfxx8e (http://www.mcmaster.com/#mu-metal-foil/=vfxx8e)
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Distance and orientation are probably going to be the most effective things you can change to reduce hum pickup. I've got triple shielded transformers that I spent many hours on and there seems to be a limit to how effective you (or rather, I) can make a magnetic shield. I used molyperm tape, copper tape, a mumetal can and aluminum. Also tried a steel can over the whole thing, with no improvement. After trying many different configurations mine got only slightly more quiet than Altec 4722s. They all pick up a little hum.
The real pisser is that the active step up we built had even more noise.
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Thanks guys, I have some pretty long interconnects so I will move them away even further and continue the orientation to see how much hum can be decreased.
Richard