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Author Topic: Phono hum  (Read 3724 times)

Offline non-prophet

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Phono hum
« on: December 04, 2011, 04:57:13 PM »
Ok, this might be a simple problem but I have never run across it.  I hooked up my turntable, finally, and it has a hum regardless of it being used, turntable off and phono on in the preamp.  I touch the tonearm and the hum gets amplified.  I checked the pre with another table and no problems.  I would guess this is a grounding problem, I checked the connections and did not see any problems.  Any help will be appreciated.  Here is the set up:

Melos GK-1 tube pre, tube phono
Fairchild 412 turntable
Melos CDP CD player
Melos CDT Tube buffer
Acurus A-200 amp
Adcom ACE-515 Power conditioner
Apogee Centaur Minor, hybrid ribbon speakers
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Duntech PCL-400 (Black Knight), KEF 105/3, Snell Type b
Aloia PST 11.1, Terra Song ss-1, Luxman c-1000, Melos MA333
Llano Phoenix CA-300, White Audio Labs A100, (2) Luxman M4000
McIntosh MA230

SunnyDaze

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Re: Phono hum
« Reply #1 on: December 04, 2011, 07:18:15 PM »
What is it setting on?

The only time I've ever had this issue, I had the TT sitting on an 18" x 18" concrete slab. It turns out, the center wasn't yet totally dry. It was somehow inducing a field that was significant enough to cause the 60hz "hum".

Weird, huh?

PS - Nick, call me. I need to send you cash.
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Offline Slim-Shaddy

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Re: Phono hum
« Reply #2 on: December 04, 2011, 09:21:24 PM »
Recheck the wires to your cart. Then try a different cart. neither work? Go to the arm wires
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I am confident that an SL-1200 is capable of outperforming turntables of much higher expense with minor modification.

Anders

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Re: Phono hum
« Reply #3 on: December 04, 2011, 10:35:49 PM »
If hum gets louder when you touch the arm then the arm isn't grounded.
Somewhere the separate ground wire is broken.

Anders
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OldiesButGoodies

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Re: Phono hum
« Reply #4 on: December 05, 2011, 07:20:12 PM »
Per Anders,  can you check continuity between the ground wire and the chassis,  arm assembly, etc to see if you find a break?
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