rnm4, It is a grounding issue. You have to play around with it. Disconnect turntable ground see if it gets worse. The turntable is probably separately grounded. Try grounding that along with the tonearm to the preamp ground. Some moving Iron cartridges like Grados can be very sensitive to nearby electromagnetic fields. Does the hum get worse as you move the cartridge towards the motor. Paradoxically high output cartridges can be worse with humming than low output ones as they are more sensitive. They produce a much higher output with the same input. What else is near the turntable producing stray fields. It takes patience. Good luck.
Oh great a new hum
Hi all,
Maybe you can suggests a diagnosis/solution/strategy:
I just swapped out an Ortofon low output MC-10 Supreme with a new Nagaoka MP-110 for a change of pace on my rebuilt Lenco with a Rega RB-303 tonearm, and, voila! - hum. The TT feeds my Rogue RP-1 preamp, which then feeds a Schiit Vidar amp powering KEF LS50s. I of course had to open up the RP-1 and switch the loading and gain. That process seemed to go without mishap I had no hum or buzz with the Ortofon even though I had to turn the volume level to over 40 out of 60 to get satisfying SPL out of the low output cartridge and low sensitivity KEFs. Having to turn up the gain that high is part of why I decided to make the switch. But I now get significant hum/buzz from the 5mv output Nagaoka, easily audible even by my 61 year old ears at volume level 15, irritating and increasingly so at 25 and above. It's not the cartridge, I think, since I attached the tonearm wire clips to another MM I had lying around with similar output, and the hum was there too. It appears not to be the phono section of the pre either, since I hooked the same cart and arm up to a Schiit Mani phono pre and a line input on the preamp, and got the same hum. And I do not think I tweaked the tonearm wiring in the course of changing the cartridges. I think the hum/buzz is higher pitched than a 60 cycle hum. The preamp is dead silent on all other inputs and remains unchanged when I unplug all other sources. And the hum remains on the headphone section of the pre even with the power amp turned off, so it doesn't seem to be coming from the power amp. I will say the cartridge tags fit a bit loosely on the Nagaoka, but I have tried with some success to tighten them. (I hate fiddling with cartridges, and the fixed head shell on the Rega arm makes it all the worse).
Any ideas what's going on and how to fix it??
Maybe you can suggests a diagnosis/solution/strategy:
I just swapped out an Ortofon low output MC-10 Supreme with a new Nagaoka MP-110 for a change of pace on my rebuilt Lenco with a Rega RB-303 tonearm, and, voila! - hum. The TT feeds my Rogue RP-1 preamp, which then feeds a Schiit Vidar amp powering KEF LS50s. I of course had to open up the RP-1 and switch the loading and gain. That process seemed to go without mishap I had no hum or buzz with the Ortofon even though I had to turn the volume level to over 40 out of 60 to get satisfying SPL out of the low output cartridge and low sensitivity KEFs. Having to turn up the gain that high is part of why I decided to make the switch. But I now get significant hum/buzz from the 5mv output Nagaoka, easily audible even by my 61 year old ears at volume level 15, irritating and increasingly so at 25 and above. It's not the cartridge, I think, since I attached the tonearm wire clips to another MM I had lying around with similar output, and the hum was there too. It appears not to be the phono section of the pre either, since I hooked the same cart and arm up to a Schiit Mani phono pre and a line input on the preamp, and got the same hum. And I do not think I tweaked the tonearm wiring in the course of changing the cartridges. I think the hum/buzz is higher pitched than a 60 cycle hum. The preamp is dead silent on all other inputs and remains unchanged when I unplug all other sources. And the hum remains on the headphone section of the pre even with the power amp turned off, so it doesn't seem to be coming from the power amp. I will say the cartridge tags fit a bit loosely on the Nagaoka, but I have tried with some success to tighten them. (I hate fiddling with cartridges, and the fixed head shell on the Rega arm makes it all the worse).
Any ideas what's going on and how to fix it??
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- 9 posts total
- 9 posts total