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Linn LP 12 hum not coming from Bryton phono stage.

I’m getting a pretty significant hum with my Linn Sondek LP12 turntable sitting on top of my equipment stand. My new Bryston MM phono stage does not hum at all when the turntable RCA interconnects are disconnected.

Yes, I have the grounding wire attached to the grounding lug on the phono preamp. I plan to move the TT to the original Sound Organization wall shelf to get it away from the adjacent electronics.

Will moving it to the wall shelf do anything to eliminate hum? What about transitioning to the better "Radikal" power supply and DC motor (the original has the Valhalla board I believe and the AC motor).

Thanks, for any suggestion you might have for things I can check.


edit: I must be tired, I noted that I mis-spelled Bryston as "Bryton". Titles cannot be edited, arghh!

masi61
masi61 OP
97 posts
 

@daveyf  - I'm glad to hear you say that the Bryston Phono stage is really good. I don't have much to compare it to other than the one in my old NAD pre-amp. The gain on my MM only stage is a bit lower apparently than is should be because on some records I have noticed a need to turn the volume control up quite a bit higher compared with my Sony XA-5400ES SACD player or my Wadia -171i iPod dock.

lewm
13,101 posts
 
Have you noticed whether the intensity of the hum changes as you listen to an LP, from outer grooves to innermost grooves?  If not, you might do that experiment and report back.  Absent a defect in your current power supply, I doubt that the PS itself is the problem.  Or to put it another way, don't spend the money on a new PS solely in order to cure this problem.
masi61 OP
97 posts
 

@lewm  - I have noticed that occasionally the hum increases after the turntable has been running for a bit. I mean when I first turn on the turntable the hum is barely audible. By the end of the first side of music, it starts to become intrusive.

I had already planned to update the power supply for the supposed improved sonics and the ability to play 45's.

lewm
13,101 posts
 
What I was getting at is whether the hum is due to a direct interaction between the cartridge and the TT motor.  One manifestation of that would be that the hum is loudest when the cartridge is nearest to the motor.
cd318
2,636 posts
 
I'd start by checking the headshell wires of the K9.

Sometimes they can get too close to other pins. If so you could try to move them with a small non-metal implement like a toothpick etc. Just to see what happens to the hum.

You could also check the mains cable by moving it to see if that has an effect. Loose connections are notorious for causing hum issues.

As for the Valhalla board, I would not recommend an examination. It carries lethal voltages and you would also risk disturbing the suspension. Without the correct suspension setup, the sound of an LP12 collapses pitifully.

It might well be possible that the thin earth lead which grounds the sub-chassis may have strayed a little and is now picking up something from one of the board's high voltage components.

In this case you will be better off getting it checked by someone who has the required setup jig. They'd be able to take a closer look and give it a service and oil change etc at the same time.

I'm also far from convinced that the Linn belongs on a wall shelf. It's suspension can cope remarkably well with vertical resonances sat on a table, but not so well on a shelf with resonances coming from a wall.

However this is what I found some 15 - 20 years ago. Linn may have changed the suspension components a few times since. You should definitely consider ringing a dealer or maybe ringing Linn themselves. Sending an email certainly won't hurt either.

Turntable hum is the nightmare of every vinyl enthusiast, so the best of luck in getting it fixed 
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