2. analog
  3. 1403362185

phono hum

I have a stock Thorens 146 with a Luxman SQ-30U integrated amp. The TT and amp are sitting at the same level in my cabinet separated by only a 3/4 inch wood partition. So they are only 2-3 inches apart. I have a hum in both speakers when the volume is turned up close to normal listening level (30%). Hum increases with volume. As the tonearm moves toward the spindle (further away from the amp) the hum decreases. Phono cart is Signet TK5E. If I mount a Shure M97x the hum is less. I do not recall the hum when I had a Denon DL-110. The Signet is the best sounding of the 3. It appears that there is interference from the amp. Is there a way to block this interference? More wood, metal, or just more distance between the 2? Or, do I need to stay with MC carts? Any recommendations for MC carts? Thanks Tim
waxer
terry9
2,209 posts
 
Magnetic fields decrease according to an inverse square law, that is, twice as far away means one quarter of the field strength. Try moving the amp 20 inches away - cheaper than new hardware.
montytx
138 posts
 
You've probably got a tube that has gone microphonic. Finding which one might be a bit of a pain. Most likely it's a signal level tube, but it's still possible that it's a power tube.
waxer OP
9 posts
 
OK. I turned the TT 90 degrees and the hum is mostly gone, except at high volume, well above listening level. At rest the cart is about 13 inches from side of amp. At end of play it is about 9-10 inches from amp. Until I find a better location for my equipment, I will have get used to using my TT from the side.Thanks for the help with this.

Tim
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