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HELP Sudden Phonomena II Groundloop Hum

Hi. I have a Musical Surroundings Phonomena II Phono amp and a nuded Denon DL-103R which sounds great. I was planning to send the Denon to Soundsmith for a retip. In the meantime I purchased a Nagaoka MP-200 MM cartridge to hold me off until the retip was completed. It arrived today and when I reset the input load switches to 50K and gain 40db to match the Nagaoka I suddenly heard feedback hum (the buzzing noise a PA system makes). It gets louder as the volume goes up. I played with the connections on the cartridge and nothing changed. Then I adjusted the load switches and that affected the hum but it also affected the sound quality, dramatically. I then put everything back to the Denon mode and the noise disappeared. What really kills me is that even with the noise I heard a better sounding Nagaoka than the Denon.
I have never had feedback noise buzz in the past. This is new and began today as soon as I adjusted the dip switches on the back of the Phonomena II. Any suggestions on removing the noise is highly appreciated.
Cheers.
cinellipro

Showing 1 response by cinellipro

cinellipro OP
26 posts
 
Thanks for your advice. I contacted Michael Yee the designer of the Phonomena and explained what was happening with the sound. He believes the problem could be located in the 50k output resistors. He asked if he should send me a pair to install or if I should send in the unit. That is customer service.
I'll report back on the results.
Cheers!
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