2. amps-preamps
  3. 973005224

Yet another Hum problem

Okay, here goes. I have a Monster 2000 power center. The ground indicator light shows that the outlet into which it is plugged is grounded. Other surge protectors also show the same thing. I have a Rega Planar 25 with a Rega cartridge, I have a Musical Surroundings Phononome phono preamp, a Krell KAV300i, CAL Audio CL 20, a crappy VCR and a crappy TV with cable. Everything is plugged into the Monster. When I turn the volume up I have a steady hum when the phono is chosen as the source. When the volume is set at the typical level at which I listen to records, without music playing, the hum is not audible, or just barely audible, even with listening very close to the speakers. The hum is steady and audible as I turn up the volume towards the midway point. There is no hum with any other source selected. I unplugged everything from the power center except the Krell and the phono preamp and the hum was still present. I tried cheater plugs, a different turntable, a Creek integrated that I have and the hum is still present. I tried plugging the amp and the phono preamp directly into the wall socket and the hum is there. I also tried different cables but the hum persists. Should I ignore it since it isn't audible when I listen to music? Is something wrong with the preamp (the dealer told he would swap it) or is there something wrong with the wiring in the wall? (I live in an apartment building) Thanks for your input.
smwdrbf8f

Showing 2 responses by vantageaudio

vantageaudio
182 posts
 
Have a read of the following webpage as this may help you. http://www.jensen-transformers.com/an/an004.pdf, regards, Richard.
vantageaudio
182 posts
 
Regarding your phono "hum" problem - try and isolate the source of the "hum". With volume turned down to minimum first try dis-connecting the interconnect from the turntable to the phono input. Then very carefully turn the volume up to see if the "hum" is still there. If the "hum" has gone then look to sorting the turntable side out (see below**). If it is still there then the problem could be from the position of the preamp, try turning this thru 90 deg to see if the "hum" reduces, also try moving it further away from other powered components. Also check all the cables - ensure they are "dressed" correctly, interconnects away from power cords and transformers, etc (if they have to cross power cords ensure this is at 90 degrees). If the "hum" is there still after moving your pre and/or cables, there could be a problem internally from the phono stage and the unit should be checked out. **If the "hum" is from the turntable side then try a ground wire from the turntable back to a preamp signal ground point and see if this reduces the "hum". Also try and "dress" the cables again as above, avoiding power cords and transformers, etc. You will just have to logically work you way thru until the "hum" disappears. Hope this helps? Richard.
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