Rega P10 - I have a hum

[MichaelHiFi]

A few months back I purchased an inexpensive preamp for which one has the ability to easily swap out not just input tubes but input caps, PS caps, rectifier tubes, even chokes although the choke perhaps not so easily. It sounded good after a day with stock components but after some tube rolling, and cap upgrades, it opened up our system like I've never heard a component do so. It was a Jupiter cap on the preamps power supply that really 'cleaned the window'. I digress.

When I plugged my phono stage interconnects into this preamp I got a pretty good hum going on with both my phono stages, an Allnic H5500 and a MoFi Master. And for weeks, I have not been able to solve that hum no matter how I placed grounds, cheater plugs, cable swaps, physically moving the vinyl gear, different outlets, and finally, completely unplugging my system and simply connecting my Allnic H5500 into my Allnic T2000 30th Anniversary integrated, and wouldn't you know it, it still didn't solve the hum! I was sure it was due to the newly acquired preamp but strangely to me anyway, the hum seems to come from the Rega.

I have not had any problems with the Rega prior to the new preamp as it replaced a Serbian JFET preamp, the Acoustic Invader. So I was sure it had something to do with the new preamp and or grounding problems. So how do I know it's the Rega? I plugged in my elderly (like me) Technics SL1800 into the Allnic and no hum, just music. Sure there's a bit of noise but it's not intrusive.

Thoughts?

 

[dan31]

Ground wire from phono pre to the Rega. Do your best to get bare ground wire to touch the arm base. I could slip it under a gap in the arm base for the P9.

 

[GroovySauce]

Similar to Dan. When I had a Rega table I attached a ground cable to the bottom of the bearing and that solved the hum problem. I used tape to snuggly hold it. Wasn’t pretty but worked.

 

[MichaelHiFi]

Thanks guys, I would have never thought to do that. So I did it.

Here's what I found:

Normal room noise = 32db
Room noise with Rega/Allnic 5500@0 volume = 48.3db
Room noise with furnace in next room running 2ft away from door = 48.2db
Ground wire connected to Rega bearing = 48.1db

Little to no change.

MichaelHiFi sitting on couch with NO music playing volume control at a reasonable listening level, I show 48.3db.
I can barely hear the hum however when our furnace is working. The Rega's hum doing battle with the furnace I'd say the furnace has a slight edge in loudness. With music playing I don't hear the hum but perhaps with more scrutiny such as soft female vocals, or a long silence, I may notice. I need to spend more time listening to see if it's really a problem. Also, when I know there's "hum" behind the music, my feeble brain might lock onto the hum then go into the endless problem solving loop inside my head instead of simply listening to the music playing. I'm a bit OCD I guess.

Maybe, due to my focus of digital for so many decades, that I don't have the experience in high end vinyl until I got the Rega P10 which is leagues better than my VPI, that I lag behind in knowledge and no doubt that's the case. The Rega, to my ears, sounds incredible, especially with the Aphelion 2 cart, besting my very stout digital rig in many ways. I know there's far better out there, of course, but I have been happy listening to vinyl. I simply hadn't noticed this problem since I changed preamps.

 

[DonH50]

Is it possible the hum has always been there but you didn't notice until adding the new preamp forced more focused listening?

Is the P10's power supply well away from the turntable and cartridge, including isolating the cable runs? Was anything moved when you added the new phono preamp, like TT wires (signal or power)?

It's also possible the TT's motor or power supply failed, just enough to hum and not completely die...

 

[MichaelHiFi]

My phonostage and TT has moved much closer to my rack in order to help find a solution for the hum affording me shorter interconnects. That didn't help really. I could move the PS further away however.

Its never been completely silent and perhaps is more noticeable with the new preamp.

The MoFi Master has 8db less noise than the Allnic, so its staying as my reference for now.

One day I dream of having the Allnic H7000V. For now I'll live with a bit of noise. It still sounds fantastic.

Thanks for your help!