mijostyn: I tried your wire from ground lug to arm trick. No change.
jwpstayman: thanks!
jwpstayman: thanks!
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??
9 responses Add your response
Soundsmith has a very thorough, step by step procedure to track down the source of hum in a phono system. Here is the link:https://www.sound-smith.com/hum-and-or-noise-problems |
This is unusual. The Rega arm does not have a separate ground wire? If not than it must be using signal ground. I seem to remember something about a three wire system in Rega arms. Do you have a volt/ohm meter? We can trace it out. Try this. Attach a wire to your phono stage ground lug. Touch the wire to your tone arm and see if the hum goes away. You can also touch the turntable chassis then both at the same time. |
Rnm4, I had a similar hum problem like you. I grounded everything possible from amp to phono pre, to turntable. The last thing I was ask to try was going from the cheaper switching wallwort power supply to a linear PS wallwort. Voila! No more hum. Not saying this will correct your problem, but maybe worth a try? The linear PS unit I bought was made by Triadmagnetics. $15 plus shipping. |
Thanks mijostyn. There's no separate ground for the TT. The Rega tonearm has no separate ground either. . Hum does not change as the arm moves. I've turned off all other sources and also the power amp, and that makes no difference, No other electronics nearby. Doesn't seem to matter if I move cabling, etc. Maybe I will switch the Nagaoka to another turntable to see if it hums there. |
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. |
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